Association of Body Mass Index with Depression, Anxiety and Suicide-An Instrumental Variable Analysis of the HUNT Study.

PubMed

Bjørngaard, Johan Håkon; Carslake, David; Lund Nilsen, Tom Ivar; Linthorst, Astrid C E; Davey Smith, George; Gunnell, David; Romundstad, Pål Richard

2015-01-01

While high body mass index is associated with an increased risk of depression and anxiety, cumulative evidence indicates that it is a protective factor for suicide. The associations from conventional observational studies of body mass index with mental health outcomes are likely to be influenced by reverse causality or confounding by ill-health. In the present study, we investigated the associations between offspring body mass index and parental anxiety, depression and suicide in order to avoid problems with reverse causality and confounding by ill-health. We used data from 32,457 mother-offspring and 27,753 father-offspring pairs from the Norwegian HUNT-study. Anxiety and depression were assessed using the Hospital Anxiety and Depression Scale and suicide death from national registers. Associations between offspring and own body mass index and symptoms of anxiety and depression and suicide mortality were estimated using logistic and Cox regression. Causal effect estimates were estimated with a two sample instrument variable approach using offspring body mass index as an instrument for parental body mass index. Both own and offspring body mass index were positively associated with depression, while the results did not indicate any substantial association between body mass index and anxiety. Although precision was low, suicide mortality was inversely associated with own body mass index and the results from the analysis using offspring body mass index supported these results. Adjusted odds ratios per standard deviation body mass index from the instrumental variable analysis were 1.22 (95% CI: 1.05, 1.43) for depression, 1.10 (95% CI: 0.95, 1.27) for anxiety, and the instrumental variable estimated hazard ratios for suicide was 0.69 (95% CI: 0.30, 1.63). The present study's results indicate that suicide mortality is inversely associated with body mass index. We also found support for a positive association between body mass index and depression, but not for anxiety.

Investigation of the refractive index repeatability for tantalum pentoxide coatings, prepared by physical vapor film deposition techniques.

PubMed

Stenzel, O; Wilbrandt, S; Wolf, J; Schürmann, M; Kaiser, N; Ristau, D; Ehlers, H; Carstens, F; Schippel, S; Mechold, L; Rauhut, R; Kennedy, M; Bischoff, M; Nowitzki, T; Zöller, A; Hagedorn, H; Reus, H; Hegemann, T; Starke, K; Harhausen, J; Foest, R; Schumacher, J

2017-02-01

Random effects in the repeatability of refractive index and absorption edge position of tantalum pentoxide layers prepared by plasma-ion-assisted electron-beam evaporation, ion beam sputtering, and magnetron sputtering are investigated and quantified. Standard deviations in refractive index between 4*10^-4 and 4*10^-3 have been obtained. Here, lowest standard deviations in refractive index close to our detection threshold could be achieved by both ion beam sputtering and plasma-ion-assisted deposition. In relation to the corresponding mean values, the standard deviations in band-edge position and refractive index are of similar order.

Enhancing active and passive remote sensing in the ocean using broadband acoustic transmissions and coherent hydrophone arrays

NASA Astrophysics Data System (ADS)

Tran, Duong Duy

The statistics of broadband acoustic signal transmissions in a random continental shelf waveguide are characterized for the fully saturated regime. The probability distribution of broadband signal energies after saturated multi-path propagation is derived using coherence theory. The frequency components obtained from Fourier decomposition of a broadband signal are each assumed to be fully saturated, where the energy spectral density obeys the exponential distribution with 5.6 dB standard deviation and unity scintillation index. When the signal bandwidth and measurement time are respectively larger than the correlation bandwidth and correlation time of its energy spectral density components, the broadband signal energy obtained by integrating the energy spectral density across the signal bandwidth then follows the Gamma distribution with standard deviation smaller than 5.6 dB and scintillation index less than unity. The theory is verified with broadband transmissions in the Gulf of Maine shallow water waveguide in the 300-1200 Hz frequency range. The standard deviations of received broadband signal energies range from 2.7 to 4.6 dB for effective bandwidths up to 42 Hz, while the standard deviations of individual energy spectral density components are roughly 5.6 dB. The energy spectral density correlation bandwidths of the received broadband signals are found to be larger for signals with higher center frequency. Sperm whales in the New England continental shelf and slope were passively localized, in both range and bearing using a single low-frequency (< 2500 Hz), densely sampled, towed horizontal coherent hydrophone array system. Whale bearings were estimated using time-domain beamforming that provided high coherent array gain in sperm whale click signal-to-noise ratio. Whale ranges from the receiver array center were estimated using the moving array triangulation technique from a sequence of whale bearing measurements. The dive profile was estimated for a sperm whale in the shallow waters of the Gulf of Maine with 160 m water-column depth, located close to the array's near-field where depth estimation was feasible by employing time difference of arrival of the direct and multiply reflected click signals received on the array. The dependence of broadband energy on bandwidth and measurement time was verified employing recorded sperm whale clicks in the Gulf of Maine.

The MSFC Solar Activity Future Estimation (MSAFE) Model

NASA Technical Reports Server (NTRS)

Suggs, Ronnie J.

2017-01-01

The MSAFE model provides forecasts for the solar indices SSN, F10.7, and Ap. These solar indices are used as inputs to many space environment models used in orbital spacecraft operations and space mission analysis. Forecasts from the MSAFE model are provided on the MSFC Natural Environments Branch's solar webpage and are updated as new monthly observations come available. The MSAFE prediction routine employs a statistical technique that calculates deviations of past solar cycles from the mean cycle and performs a regression analysis to predict the deviation from the mean cycle of the solar index at the next future time interval. The prediction algorithm is applied recursively to produce monthly smoothed solar index values for the remaining of the cycle. The forecasts are initiated for a given cycle after about 8 to 12 months of observations are collected. A forecast made at the beginning of cycle 24 using the MSAFE program captured the cycle fairly well with some difficulty in discerning the double peak that occurred at solar cycle maximum.

Middle school transition and body weight outcomes: Evidence from Arkansas Public Schoolchildren.

PubMed

Zeng, Di; Thomsen, Michael R; Nayga, Rodolfo M; Rouse, Heather L

2016-05-01

There is evidence that middle school transition adversely affects educational and psychological outcomes of pre-teen children, but little is known about the impacts of middle school transition on other aspects of health. In this article, we estimate the impact of middle school transition on the body mass index (BMI) of public schoolchildren in Arkansas, United States. Using an instrumental variable approach, we find that middle school transition in grade 6 led to a moderate decrease of 0.04 standard deviations in BMI z-scores for all students. Analysis by subsample indicated that this result was driven by boys (0.06-0.07 standard deviations) and especially by non-minority boys (0.09 standard deviations). We speculate that the changing levels of physical activities associated with middle school transition provide the most reasonable explanation for this result. Copyright © 2015 Elsevier B.V. All rights reserved.

A proposed selection index for feedlot profitability based on estimated breeding values.

PubMed

van der Westhuizen, R R; van der Westhuizen, J

2009-04-22

It is generally accepted that feed intake and growth (gain) are the most important economic components when calculating profitability in a growth test or feedlot. We developed a single post-weaning growth (feedlot) index based on the economic values of different components. Variance components, heritabilities and genetic correlations for and between initial weight (IW), final weight (FW), feed intake (FI), and shoulder height (SHD) were estimated by multitrait restricted maximum likelihood procedures. The estimated breeding values (EBVs) and the economic values for IW, FW and FI were used in a selection index to estimate a post-weaning or feedlot profitability value. Heritabilities for IW, FW, FI, and SHD were 0.41, 0.40, 0.33, and 0.51, respectively. The highest genetic correlations were 0.78 (between IW and FW) and 0.70 (between FI and FW). EBVs were used in a selection index to calculate a single economical value for each animal. This economic value is an indication of the gross profitability value or the gross test value (GTV) of the animal in a post-weaning growth test. GTVs varied between -R192.17 and R231.38 with an average of R9.31 and a standard deviation of R39.96. The Pearson correlations between EBVs (for production and efficiency traits) and GTV ranged from -0.51 to 0.68. The lowest correlation (closest to zero) was 0.26 between the Kleiber ratio and GTV. Correlations of 0.68 and -0.51 were estimated between average daily gain and GTV and feed conversion ratio and GTV, respectively. These results showed that it is possible to select for GTV. The selection index can benefit feedlotting in selecting offspring of bulls with high GTVs to maximize profitability.

Frequency comb calibrated frequency-sweeping interferometry for absolute group refractive index measurement of air.

PubMed

Yang, Lijun; Wu, Xuejian; Wei, Haoyun; Li, Yan

2017-04-10

The absolute group refractive index of air at 194061.02 GHz is measured in real time using frequency-sweeping interferometry calibrated by an optical frequency comb. The group refractive index of air is calculated from the calibration peaks of the laser frequency variation and the interference signal of the two beams passing through the inner and outer regions of a vacuum cell when the frequency of a tunable external cavity diode laser is scanned. We continuously measure the refractive index of air for 2 h, which shows that the difference between measured results and Ciddor's equation is less than 9.6×10^-8, and the standard deviation of that difference is 5.9×10^-8. The relative uncertainty of the measured refractive index of air is estimated to be 8.6×10^-8. The data update rate is 0.2 Hz, making it applicable under conditions in which air refractive index fluctuates fast.

The Gait Deviation Index Is Associated with Hip Muscle Strength and Patient-Reported Outcome in Patients with Severe Hip Osteoarthritis-A Cross-Sectional Study.

PubMed

Rosenlund, Signe; Holsgaard-Larsen, Anders; Overgaard, Søren; Jensen, Carsten

2016-01-01

The Gait Deviation Index summarizes overall gait 'quality', based on kinematic data from a 3-dimensional gait analysis. However, it is unknown which clinical outcomes may affect the Gait Deviation Index in patients with primary hip osteoarthritis. The aim of this study was to investigate associations between Gait Deviation Index as a measure of gait 'quality' and hip muscle strength and between Gait Deviation Index and patient-reported outcomes in patients with primary hip osteoarthritis. Forty-seven patients (34 males), aged 61.1 ± 6.7 years, with BMI 27.3 ± 3.4 (kg/m2) and with severe primary hip osteoarthritis underwent 3-dimensional gait analysis. Mean Gait Deviation Index, pain after walking and maximal isometric hip muscle strength (flexor, extensor, and abductor) were recorded. All patients completed the 'Physical Function Short-form of the Hip disability and Osteoarthritis Outcome Score (HOOS-Physical Function) and the Hip disability and Osteoarthritis Outcome Score subscales for pain (HOOS-Pain) and quality-of-life (HOOS-QOL). Mean Gait Deviation Index was positively associated with hip abduction strength (p<0.01, r = 0.40), hip flexion strength (p = 0.01, r = 0.37), HOOS-Physical Function (p<0.01, r = 0.41) HOOS-QOL (p<0.01, r = 0.41), and negatively associated with HOOS-Pain after walking (p<0.01, r = -0.45). Adjusting the analysis for walking speed did not affect the association. Patients with the strongest hip abductor and hip flexor muscles had the best gait 'quality'. Furthermore, patients with higher physical function, quality of life scores and lower pain levels demonstrated better gait 'quality'. These findings indicate that interventions aimed at improving hip muscle strength and pain management may to a moderate degree improve the overall gait 'quality' in patients with primary hip OA.

The Gait Deviation Index Is Associated with Hip Muscle Strength and Patient-Reported Outcome in Patients with Severe Hip Osteoarthritis—A Cross-Sectional Study

PubMed Central

Rosenlund, Signe; Holsgaard-Larsen, Anders; Overgaard, Søren; Jensen, Carsten

2016-01-01

Background The Gait Deviation Index summarizes overall gait ‘quality’, based on kinematic data from a 3-dimensional gait analysis. However, it is unknown which clinical outcomes may affect the Gait Deviation Index in patients with primary hip osteoarthritis. The aim of this study was to investigate associations between Gait Deviation Index as a measure of gait ‘quality’ and hip muscle strength and between Gait Deviation Index and patient-reported outcomes in patients with primary hip osteoarthritis. Method Forty-seven patients (34 males), aged 61.1 ± 6.7 years, with BMI 27.3 ± 3.4 (kg/m2) and with severe primary hip osteoarthritis underwent 3-dimensional gait analysis. Mean Gait Deviation Index, pain after walking and maximal isometric hip muscle strength (flexor, extensor, and abductor) were recorded. All patients completed the ‘Physical Function Short-form of the Hip disability and Osteoarthritis Outcome Score (HOOS-Physical Function) and the Hip disability and Osteoarthritis Outcome Score subscales for pain (HOOS-Pain) and quality-of-life (HOOS-QOL). Results Mean Gait Deviation Index was positively associated with hip abduction strength (p<0.01, r = 0.40), hip flexion strength (p = 0.01, r = 0.37), HOOS-Physical Function (p<0.01, r = 0.41) HOOS-QOL (p<0.01, r = 0.41), and negatively associated with HOOS-Pain after walking (p<0.01, r = -0.45). Adjusting the analysis for walking speed did not affect the association. Conclusion Patients with the strongest hip abductor and hip flexor muscles had the best gait ‘quality’. Furthermore, patients with higher physical function, quality of life scores and lower pain levels demonstrated better gait ‘quality’. These findings indicate that interventions aimed at improving hip muscle strength and pain management may to a moderate degree improve the overall gait ‘quality’ in patients with primary hip OA. PMID:27065007

Variability of pesticide detections and concentrations in field replicate water samples collected for the National Water-Quality Assessment Program, 1992-97

USGS Publications Warehouse

Martin, Jeffrey D.

2002-01-01

Correlation analysis indicates that for most pesticides and concentrations, pooled estimates of relative standard deviation rather than pooled estimates of standard deviation should be used to estimate variability because pooled estimates of relative standard deviation are less affected by heteroscedasticity. The 2 Variability of Pesticide Detections and Concentrations in Field Replicate Water Samples, 1992–97 median pooled relative standard deviation was calculated for all pesticides to summarize the typical variability for pesticide data collected for the NAWQA Program. The median pooled relative standard deviation was 15 percent at concentrations less than 0.01 micrograms per liter (µg/L), 13 percent at concentrations near 0.01 µg/L, 12 percent at concentrations near 0.1 µg/L, 7.9 percent at concentrations near 1 µg/L, and 2.7 percent at concentrations greater than 5 µg/L. Pooled estimates of standard deviation or relative standard deviation presented in this report are larger than estimates based on averages, medians, smooths, or regression of the individual measurements of standard deviation or relative standard deviation from field replicates. Pooled estimates, however, are the preferred method for characterizing variability because they provide unbiased estimates of the variability of the population. Assessments of variability based on standard deviation (rather than variance) underestimate the true variability of the population. Because pooled estimates of variability are larger than estimates based on other approaches, users of estimates of variability must be cognizant of the approach used to obtain the estimate and must use caution in the comparison of estimates based on different approaches.

Estimate of standard deviation for a log-transformed variable using arithmetic means and standard deviations.

PubMed

Quan, Hui; Zhang, Ji

2003-09-15

Analyses of study variables are frequently based on log transformations. To calculate the power for detecting the between-treatment difference in the log scale, we need an estimate of the standard deviation of the log-transformed variable. However, in many situations a literature search only provides the arithmetic means and the corresponding standard deviations. Without individual log-transformed data to directly calculate the sample standard deviation, we need alternative methods to estimate it. This paper presents methods for estimating and constructing confidence intervals for the standard deviation of a log-transformed variable given the mean and standard deviation of the untransformed variable. It also presents methods for estimating the standard deviation of change from baseline in the log scale given the means and standard deviations of the untransformed baseline value, on-treatment value and change from baseline. Simulations and examples are provided to assess the performance of these estimates. Copyright 2003 John Wiley & Sons, Ltd.

Hydrophobicity diversity in globular and nonglobular proteins measured with the Gini index.

PubMed

Carugo, Oliviero

2017-12-01

Amino acids and their properties are variably distributed in proteins and different compositions determine all protein features, ranging from solubility to stability and functionality. Gini index, a tool to estimate distribution uniformity, is widely used in macroeconomics and has numerous statistical applications. Here, Gini index is used to analyze the distribution of hydrophobicity in proteins and to compare hydrophobicity distribution in globular and intrinsically disordered proteins. Based on the analysis of carefully selected high-quality data sets of proteins extracted from the Protein Data Bank (http://www.rcsb.org) and from the DisProt database (http://www.disprot.org/), it is observed that hydrophobicity is distributed in a more diverse way in intrinsically disordered proteins than in folded and soluble globular proteins. This correlates with the observation that the amino acid composition deviates from the uniformity (estimate with the Shannon and the Gini-Simpson indices) more in intrinsically disordered proteins than in globular and soluble proteins. Although statistical tools tike the Gini index have received little attention in molecular biology, these results show that they allow one to estimate sequence diversity and that they are useful to delineate trends that can hardly be described, otherwise, in simple and concise ways. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

A Simple Accurate Alternative to the Minimum-Deviation Method for the Determination of the Refractive Index of a Prism.

ERIC Educational Resources Information Center

Waldenstrom, S.; Naqvi, K. Razi

1978-01-01

Proposes an alternative to the classical minimum-deviation method for determining the refractive index of a prism. This new "fixed angle of incidence method" may find applications in research. (Author/GA)

Evaluation of breathing patterns for respiratory-gated radiation therapy using the respiration regularity index

NASA Astrophysics Data System (ADS)

Cheong, Kwang-Ho; Lee, MeYeon; Kang, Sei-Kwon; Yoon, Jai-Woong; Park, SoAh; Hwang, Taejin; Kim, Haeyoung; Kim, KyoungJu; Han, Tae Jin; Bae, Hoonsik

2015-01-01

Despite the considerable importance of accurately estimating the respiration regularity of a patient in motion compensation treatment, not to mention the necessity of maintaining that regularity through the following sessions, an effective and simply applicable method by which those goals can be accomplished has rarely been reported. The authors herein propose a simple respiration regularity index based on parameters derived from a correspondingly simplified respiration model. In order to simplify a patient's breathing pattern while preserving the data's intrinsic properties, we defined a respiration model as a cos4( ω( t) · t) wave form with a baseline drift. According to this respiration formula, breathing-pattern fluctuation could be explained using four factors: the sample standard deviation of respiration period ( s f ), the sample standard deviation of amplitude ( s a ) and the results of a simple regression of the baseline drift (slope as β, and standard deviation of residuals as σ r ) of a respiration signal. The overall irregularity ( δ) was defined as , where is a variable newly-derived by using principal component analysis (PCA) for the four fluctuation parameters and has two principal components ( ω 1, ω 2). The proposed respiration regularity index was defined as ρ = ln(1 + (1/ δ))/2, a higher ρ indicating a more regular breathing pattern. We investigated its clinical relevance by comparing it with other known parameters. Subsequently, we applied it to 110 respiration signals acquired from five liver and five lung cancer patients by using real-time position management (RPM; Varian Medical Systems, Palo Alto, CA). Correlations between the regularity of the first session and the remaining fractions were investigated using Pearson's correlation coefficient. Additionally, the respiration regularity was compared between the liver and lung cancer patient groups. The respiration regularity was determined based on ρ; patients with ρ < 0.3 showed worse regularity than the others whereas ρ > 0.7 was suitable for respiratory-gated radiation therapy (RGRT). Fluctuations in the breathing cycle and the amplitude were especially determinative of ρ. If the respiration regularity of a patient's first session was known, it could be estimated through subsequent sessions. Notably, the breathing patterns of the lung cancer patients were more irregular than those of the liver cancer patients. Respiration regularity could be objectively determined by using a composite index, ρ. Such a single-index testing of respiration regularity can facilitate determination of RGRT availability in clinical settings, especially for free-breathing cases.

Refractive index, molar refraction and comparative refractive index study of propylene carbonate binary liquid mixtures.

PubMed

Wankhede, Dnyaneshwar Shamrao

2012-06-01

Refractive indices (n) have been experimentally determined for the binary liquid-liquid mixtures of Propylene carbonate (PC) (1) with benzene, ethylbenzene, o-xylene and p-xylene (2) at 298.15, 303.15 and 308.15 K over the entire mole fraction range. The experimental values of n are utilised to calculate deviation in refractive index (Δn), molar refraction (R) and deviation in molar refraction (ΔR). A comparative study of Arago-Biot (A-B), Newton (NW), Eyring and John (E-J) equations for determining refractive index of a liquid has been carried out to test their validity for all the binary mixtures over the entire composition range at 298.15 K. Comparison of various mixing relations is represented in terms of average deviation (AVD). The Δn and ΔR values have been fitted to Redlich-Kister equation at 298.15 K and standard deviations have been calculated. The results are discussed in terms of intermolecular interactions present amongst the components.

On the Distribution of Protein Refractive Index Increments

PubMed Central

Zhao, Huaying; Brown, Patrick H.; Schuck, Peter

2011-01-01

The protein refractive index increment, dn/dc, is an important parameter underlying the concentration determination and the biophysical characterization of proteins and protein complexes in many techniques. In this study, we examine the widely used assumption that most proteins have dn/dc values in a very narrow range, and reappraise the prediction of dn/dc of unmodified proteins based on their amino acid composition. Applying this approach in large scale to the entire set of known and predicted human proteins, we obtain, for the first time, to our knowledge, an estimate of the full distribution of protein dn/dc values. The distribution is close to Gaussian with a mean of 0.190 ml/g (for unmodified proteins at 589 nm) and a standard deviation of 0.003 ml/g. However, small proteins <10 kDa exhibit a larger spread, and almost 3000 proteins have values deviating by more than two standard deviations from the mean. Due to the widespread availability of protein sequences and the potential for outliers, the compositional prediction should be convenient and provide greater accuracy than an average consensus value for all proteins. We discuss how this approach should be particularly valuable for certain protein classes where a high dn/dc is coincidental to structural features, or may be functionally relevant such as in proteins of the eye. PMID:21539801

On the distribution of protein refractive index increments.

PubMed

Zhao, Huaying; Brown, Patrick H; Schuck, Peter

2011-05-04

The protein refractive index increment, dn/dc, is an important parameter underlying the concentration determination and the biophysical characterization of proteins and protein complexes in many techniques. In this study, we examine the widely used assumption that most proteins have dn/dc values in a very narrow range, and reappraise the prediction of dn/dc of unmodified proteins based on their amino acid composition. Applying this approach in large scale to the entire set of known and predicted human proteins, we obtain, for the first time, to our knowledge, an estimate of the full distribution of protein dn/dc values. The distribution is close to Gaussian with a mean of 0.190 ml/g (for unmodified proteins at 589 nm) and a standard deviation of 0.003 ml/g. However, small proteins <10 kDa exhibit a larger spread, and almost 3000 proteins have values deviating by more than two standard deviations from the mean. Due to the widespread availability of protein sequences and the potential for outliers, the compositional prediction should be convenient and provide greater accuracy than an average consensus value for all proteins. We discuss how this approach should be particularly valuable for certain protein classes where a high dn/dc is coincidental to structural features, or may be functionally relevant such as in proteins of the eye. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Analysis of geomagnetic hourly ranges

NASA Astrophysics Data System (ADS)

Danskin, D. W.; Lotz, S. I.

2015-08-01

In an attempt to develop better forecasts of geomagnetic activity, hourly ranges of geomagnetic data are analyzed with a focus on how the data are distributed. A lognormal distribution is found to be able to characterize the magnetic data for all observatories up to moderate disturbances with each distribution controlled by the mean of the logarithm of the hourly range. In the subauroral zone, the distribution deviates from the lognormal, which is interpreted as motion of the auroral electrojet toward the equator. For most observatories, a substantial deviation from the lognormal distribution was noted at the higher values and is best modeled with a power law extrapolation, which gives estimates of the extreme values that may occur at observatories which contribute to the disturbance storm time (Dst) index and in Canada.

Acoustic characteristics of voice after severe traumatic brain injury.

PubMed

McHenry, M

2000-07-01

To describe the acoustic characteristics of voice in individuals with motor speech disorders after traumatic brain injury (TBI). Prospective study of 100 individuals with TBI based on consecutive referrals for motor speech evaluations. Subjects were audio tape-recorded while producing sustained vowels and single word and sentence intelligibility tests. Laryngeal airway resistance was estimated, and voice quality was rated perceptually. None of the subjects evidenced vocal parameters within normal limits. The most frequently occurring abnormal parameter across subjects was amplitude perturbation, followed by voice turbulence index. Twenty-three percent of subjects evidenced deviation in all five parameters measured. The perceptual ratings of breathiness were significantly correlated with both the amplitude perturbation quotient and the noise-to-harmonics ratio. Vocal quality deviation is common in motor speech disorders after TBI and may impact intelligibility.

Correlation Between Ki-67 Index, World Health Organization Grade and Patient Survival in Glial Tumors With Astrocytic Differentiation

PubMed Central

Dzhenkov, Deyan L; Kitanova, Martina; Donev, Ivan S; Ghenev, Peter

2017-01-01

Background Glioblastoma multiforme (GBM) is a class IV astrocytic tumor, the most malignant of the four groups of World Health Organization (WHO) tumors with astrocytic differentiation. Aim The aim of this study was to estab­lish whether a correlation exists between the Ki-67 index of tumors with astrocytic differentiation, WHO grade, and patient survival. Materials and methods A retrospective non-clinical approach to patient selection was chosen for the aim of the study. A total of 47 patients diagnosed and treated for CNS tumors with astrocytic differentiation in the St. Marina University Hospital, Varna, Bulgaria, from September 2012 to July 2016 were retrospectively included into the study cohort. The cases were tested for their immunohistochemistry (IHC) reaction with Ki-67 after their original Hematoxylin and Eosin and IHC slides were reviewed by a single author and blind coded. The Ki-67 positivity index of the nuclei was estimated after digitalization of the slides and calculated by the ImmunoRatio automated count­ing tool. The individual Ki-67 index and patient survival of each case were statistically compared. Results The histopathological groups, after the blind Ki-67 index automated calculation was carried out, revealed no WHO grade I, two WHO grade II samples, four WHO grade III samples and 41 WHO grade IV cases, and these were included in the analysis. The two samples of WHO grade II astrocytic tumors had a mean Ki-67 index of 25%; however, they comprised tumors with an individual index of 43% and 7%, both individual values with a highly unlikely index for this group. The four samples of WHO grade III had a mean Ki-67 index of 4%, standard deviation ±2.16 (p>0.05), with the lowest index being 1% and the highest one being 6%. Both WHO grade II and III did not include enough samples to allow for a proper statistical analysis of patient survival. The 41 GBM cases had a mean Ki-67 index of 17.34%, standard deviation ±10.79 (p>0.05). Statistical analysis of the Ki-67 index divid­ed dichotomously into two groups and patient survival revealed that cases with a high Ki-67 index had no significant difference in survival when compared to those with low expression. Conclusions Based on the reported results, the mean Ki-67 percentage of positive nuclei in GBM tumor sam­ples cannot be used to estimate the survival of patients. However, Ki-67 remains a valuable IHC pathological tool. PMID:28845375

Influence of the apex angle of a hollow prism made from an ordinary commercial glass plate as a simple refractometer to the accuracy of the refractive index measurement of the edible oil

NASA Astrophysics Data System (ADS)

Idris, N.; Maswati; Yusibani, E.

2018-05-01

The influence of the apex angle of a hollow prism used as a simple refractometer to the accuracy of a refractive index measurement of the edible oil samples was studied. The hollow prism was made from an ordinary commercial glass plate with a thickness of 2 mm. The apex angle of the constructed hollow prism was varied. The edible oil sample used in this study was palm oil, namely the packaged, branded oil sample and the bulk oil sample. For measuring the refractive index, the oil sample was filled in the constructed hollow prism, and then a helium-neon laser beam was passed through the oil sample at a certain angle of incidence. The angle of minimum deviation of the transmitted laser He-Ne beam was measured and then was used for calculating the refractive index of the oil sample. The refractive index measurement was made using the hollow prism with different apex angles, ranging from 300 to 600. The measurement accuracy was estimated by comparing the refractive index measured using the hollow prisms to that of obtained using a standard Abbe refractometer. It was found that the refractive index of the edible oil can be measured accurately by using the hollow prism. It was also found that the accuracy of the refractive index measurement significantly changes with the apex angle of the hollow prism. The refractive index values measured using this simple refractometer deviate up to 3,49% from the refractive index value measured using the standard Abbe refractometer, especially when the apex angle of the prism is 30°. The measurement results with high accuracies obtained when using the hollow prisms with apex angles of 450 and 600. The optimum apex angle for the present constructed hollow prism is 450. The refractive index obtained using the hollow prism with the apex angle of 450 is 1,4623 and 1,4438 for the bulk oil and the packed, branded oil samples, respectively. This result suggests that the apex angle of the prism used affects largely the accuracy of the refractive index measurement.

Influence of local inhomogeneities induced in corneal ablation on the evolution of contrast sensitivity

NASA Astrophysics Data System (ADS)

Ortiz, Dolores; Saiz, Jose M.; González, Francisco

2004-04-01

The presence of local inhomogeneities in corneal tissue after refractive surgery has an influence on visual performance. Here we focus on the corneal ablation associated with Lasik surgery and its effect on the modulation transfer function (MTF) that we obtained by modifying a personalized Kooijman model. Inhomogeneities induced by the ablation occur in the form of Gaussian-distributed refractive-index variations of a given correlation length. We show how variation of refractive-index deviation and correlation length (size) of the inhomogeneities allows us to obtain pairs of values that are able to achieve a MTF evolution similar to that observed for contrast sensitivity in the same patients. An estimate of the characteristics of the local effects is obtained.

Mapping the Paediatric Quality of Life Inventory (PedsQL™) Generic Core Scales onto the Child Health Utility Index-9 Dimension (CHU-9D) Score for Economic Evaluation in Children.

PubMed

Lambe, Tosin; Frew, Emma; Ives, Natalie J; Woolley, Rebecca L; Cummins, Carole; Brettell, Elizabeth A; Barsoum, Emma N; Webb, Nicholas J A

2018-04-01

The Paediatric Quality of Life Inventory (PedsQL™) questionnaire is a widely used, generic instrument designed for measuring health-related quality of life (HRQoL); however, it is not preference-based and therefore not suitable for cost-utility analysis. The Child Health Utility Index-9 Dimension (CHU-9D), however, is a preference-based instrument that has been primarily developed to support cost-utility analysis. This paper presents a method for estimating CHU-9D index scores from responses to the PedsQL™ using data from a randomised controlled trial of prednisolone therapy for treatment of childhood corticosteroid-sensitive nephrotic syndrome. HRQoL data were collected from children at randomisation, week 16, and months 12, 18, 24, 36 and 48. Observations on children aged 5 years and older were pooled across all data collection timepoints and were then randomised into an estimation (n = 279) and validation (n = 284) sample. A number of models were developed using the estimation data before internal validation. The best model was chosen using multi-stage selection criteria. Most of the models developed accurately predicted the CHU-9D mean index score. The best performing model was a generalised linear model (mean absolute error = 0.0408; mean square error = 0.0035). The proportion of index scores deviating from the observed scores by <  0.03 was 53%. The mapping algorithm provides an empirical tool for estimating CHU-9D index scores and for conducting cost-utility analyses within clinical studies that have only collected PedsQL™ data. It is valid for children aged 5 years or older. Caution should be exercised when using this with children younger than 5 years, older adolescents (>  13 years) or patient groups with particularly poor quality of life. 16645249.

Third molar development by measurements of open apices in an Italian sample of living subjects.

PubMed

De Luca, Stefano; Pacifici, Andrea; Pacifici, Luciano; Polimeni, Antonella; Fischetto, Sara Giulia; Velandia Palacio, Luz Andrea; Vanin, Stefano; Cameriere, Roberto

2016-02-01

The aim of this study is to analyse the age-predicting performance of third molar index (I3M) in dental age estimation. A multiple regression analysis was developed with chronological age as the independent variable. In order to investigate the relationship between the I3M and chronological age, the standard deviation and relative error were examined. Digitalized orthopantomographs (OPTs) of 975 Italian healthy subjects (531 female and 444 male), aged between 9 and 22 years, were studied. Third molar development was determined according to Cameriere et al. (2008). Analysis of covariance (ANCOVA) was applied to study the interaction between I3M and the gender. The difference between age and third molar index (I3M) was tested with Pearson's correlation coefficient. The I3M, the age and the gender of the subjects were used as predictive variable for age estimation. The small F-value for the gender (F = 0.042, p = 0.837) reveals that this factor does not affect the growth of the third molar. Adjusted R(2) (AdjR(2)) was used as parameter to define the best fitting function. All the regression models (linear, exponential, and polynomial) showed a similar AdjR(2). The polynomial (2nd order) fitting explains about the 78% of the total variance and do not add any relevant clinical information to the age estimation process from the third molar. The standard deviation and relative error increase with the age. The I3M has its minimum in the younger group of studied individuals and its maximum in the oldest ones, indicating that its precision and reliability decrease with the age. Copyright © 2015 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.

An Optical Flow-Based Full Reference Video Quality Assessment Algorithm.

PubMed

K, Manasa; Channappayya, Sumohana S

2016-06-01

We present a simple yet effective optical flow-based full-reference video quality assessment (FR-VQA) algorithm for assessing the perceptual quality of natural videos. Our algorithm is based on the premise that local optical flow statistics are affected by distortions and the deviation from pristine flow statistics is proportional to the amount of distortion. We characterize the local flow statistics using the mean, the standard deviation, the coefficient of variation (CV), and the minimum eigenvalue ( λ min ) of the local flow patches. Temporal distortion is estimated as the change in the CV of the distorted flow with respect to the reference flow, and the correlation between λ min of the reference and of the distorted patches. We rely on the robust multi-scale structural similarity index for spatial quality estimation. The computed temporal and spatial distortions, thus, are then pooled using a perceptually motivated heuristic to generate a spatio-temporal quality score. The proposed method is shown to be competitive with the state-of-the-art when evaluated on the LIVE SD database, the EPFL Polimi SD database, and the LIVE Mobile HD database. The distortions considered in these databases include those due to compression, packet-loss, wireless channel errors, and rate-adaptation. Our algorithm is flexible enough to allow for any robust FR spatial distortion metric for spatial distortion estimation. In addition, the proposed method is not only parameter-free but also independent of the choice of the optical flow algorithm. Finally, we show that the replacement of the optical flow vectors in our proposed method with the much coarser block motion vectors also results in an acceptable FR-VQA algorithm. Our algorithm is called the flow similarity index.

Kinetic Features Observed in the Solar Wind Electron Distributions

NASA Astrophysics Data System (ADS)

Pierrard, V.; Lazar, M.; Poedts, S.

2016-12-01

More than 120 000 of velocity distributions measured by Helios, Cluster and Ulysses in the ecliptic have been analyzed within an extended range of heliocentric distances from 0.3 to over 4 AU. The velocity distribution of electrons reveal a dual structure with a thermal (Maxwellian) core and a suprathermal (Kappa) halo. A detailed observational analysis of these two components provides estimations of their temperatures and temperature anisotropies, and we decode any potential interdependence that their properties may indicate. The core temperature is found to decrease with the radial distance, while the halo temperature slightly increases, clarifying an apparent contradiction in previous observational analysis and providing valuable clues about the temperature of the Kappa-distributed populations. For low values of the power-index kappa, these two components manifest a clear tendency to deviate from isotropy in the same direction, that seems to confirm the existence of mechanisms with similar effects on both components, e.g., the solar wind expansion, or the particle heating by the fluctuations. However, the existence of plasma states with anti-correlated anisotropies of the core and halo populations and the increase of their number for high values of the power-index kappa suggest a dynamic interplay of these components, mediated most probably by the anisotropy-driven instabilities. Estimating the temperature of the solar wind particles and their anisotropies is particularly important for understanding the origin of these deviations from thermal equilibrium as well as their effects.

Degrees of Freedom for Allan Deviation Estimates of Multiple Clocks

DTIC Science & Technology

2016-04-01

Allan deviation . Allan deviation will be represented by σ and standard deviation will be represented by δ. In practice, when the Allan deviation of a...the Allan deviation of standard noise types. Once the number of degrees of freedom is known, an approximate confidence interval can be assigned by...measurement errors from paired difference data. We extend this approach by using the Allan deviation to estimate the error in a frequency standard

MO-F-CAMPUS-T-03: Data Driven Approaches for Determination of Treatment Table Tolerance Values for Record and Verification Systems

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

Gupta, N; DiCostanzo, D; Fullenkamp, M

2015-06-15

Purpose: To determine appropriate couch tolerance values for modern radiotherapy linac R&V systems with indexed patient setup. Methods: Treatment table tolerance values have been the most difficult to lower, due to many factors including variations in patient positioning and differences in table tops between machines. We recently installed nine linacs with similar tables and started indexing every patient in our clinic. In this study we queried our R&V database and analyzed the deviation of couch position values from the acquired values at verification simulation for all patients treated with indexed positioning. Mean and standard deviations of daily setup deviations weremore » computed in the longitudinal, lateral and vertical direction for 343 patient plans. The mean, median and standard error of the standard deviations across the whole patient population and for some disease sites were computed to determine tolerance values. Results: The plot of our couch deviation values showed a gaussian distribution, with some small deviations, corresponding to setup uncertainties on non-imaging days, and SRS/SRT/SBRT patients, as well as some large deviations which were spot checked and found to be corresponding to indexing errors that were overriden. Setting our tolerance values based on the median + 1 standard error resulted in tolerance values of 1cm lateral and longitudinal, and 0.5 cm vertical for all non- SRS/SRT/SBRT cases. Re-analizing the data, we found that about 92% of the treated fractions would be within these tolerance values (ignoring the mis-indexed patients). We also analyzed data for disease site based subpopulations and found no difference in the tolerance values that needed to be used. Conclusion: With the use of automation, auto-setup and other workflow efficiency tools being introduced into radiotherapy workflow, it is very essential to set table tolerances that allow safe treatments, but flag setup errors that need to be reassessed before treatments.« less

Scanner K-line photometry of Orion stars

NASA Technical Reports Server (NTRS)

Hesser, J. E.; Mcclintock, W.; Henry, R. C.

1977-01-01

Results are presented for two-channel scanner measurements of calcium K-line strengths in 39 Orion sword and belt stars. Values of the calcium k index and its associated standard error are given for each observed star, and the K-line strengths are compared with those of K-line standard stars and Hyades stars. Plots of k index against reddening-corrected color and of k-index deviation against metal-strength index deviation are provided which show that the Orion sword and belt stars do not differ significantly in their calcium and metal abundances from general field stars.

Subjective Estimation of Task Time and Task Difficulty of Simple Movement Tasks.

PubMed

Chan, Alan H S; Hoffmann, Errol R

2017-01-01

It has been demonstrated in previous work that the same neural structures are used for both imagined and real movements. To provide a strong test of the similarity of imagined and actual movement times, 4 simple movement tasks were used to determine the relationship between estimated task time and actual movement time. The tasks were single-component visually controlled movements, 2-component visually controlled, low index of difficulty (ID) moves and pin-to-hole transfer movements. For each task there was good correspondence between the mean estimated times and actual movement times. In all cases, the same factors determined the actual and estimated movement times: the amplitudes of movement and the IDs of the component movements, however the contribution of each of these variables differed for the imagined and real tasks. Generally, the standard deviations of the estimated times were linearly related to the estimated time values. Overall, the data provide strong evidence for the same neural structures being used for both imagined and actual movements.

Estimating fractional vegetation cover and the vegetation index of bare soil and highly dense vegetation with a physically based method

NASA Astrophysics Data System (ADS)

Song, Wanjuan; Mu, Xihan; Ruan, Gaiyan; Gao, Zhan; Li, Linyuan; Yan, Guangjian

2017-06-01

Normalized difference vegetation index (NDVI) of highly dense vegetation (NDVIv) and bare soil (NDVIs), identified as the key parameters for Fractional Vegetation Cover (FVC) estimation, are usually obtained with empirical statistical methods However, it is often difficult to obtain reasonable values of NDVIv and NDVIs at a coarse resolution (e.g., 1 km), or in arid, semiarid, and evergreen areas. The uncertainty of estimated NDVIs and NDVIv can cause substantial errors in FVC estimations when a simple linear mixture model is used. To address this problem, this paper proposes a physically based method. The leaf area index (LAI) and directional NDVI are introduced in a gap fraction model and a linear mixture model for FVC estimation to calculate NDVIv and NDVIs. The model incorporates the Moderate Resolution Imaging Spectroradiometer (MODIS) Bidirectional Reflectance Distribution Function (BRDF) model parameters product (MCD43B1) and LAI product, which are convenient to acquire. Two types of evaluation experiments are designed 1) with data simulated by a canopy radiative transfer model and 2) with satellite observations. The root-mean-square deviation (RMSD) for simulated data is less than 0.117, depending on the type of noise added on the data. In the real data experiment, the RMSD for cropland is 0.127, for grassland is 0.075, and for forest is 0.107. The experimental areas respectively lack fully vegetated and non-vegetated pixels at 1 km resolution. Consequently, a relatively large uncertainty is found while using the statistical methods and the RMSD ranges from 0.110 to 0.363 based on the real data. The proposed method is convenient to produce NDVIv and NDVIs maps for FVC estimation on regional and global scales.

Daily values flow comparison and estimates using program HYCOMP, version 1.0

USGS Publications Warehouse

Sanders, Curtis L.

2002-01-01

A method used by the U.S. Geological Survey for quality control in computing daily value flow records is to compare hydrographs of computed flows at a station under review to hydrographs of computed flows at a selected index station. The hydrographs are placed on top of each other (as hydrograph overlays) on a light table, compared, and missing daily flow data estimated. This method, however, is subjective and can produce inconsistent results, because hydrographers can differ when calculating acceptable limits of deviation between observed and estimated flows. Selection of appropriate index stations also is judgemental, giving no consideration to the mathematical correlation between the review station and the index station(s). To address the limitation of the hydrograph overlay method, a set of software programs, written in the SAS macrolanguage, was developed and designated Program HYDCOMP. The program automatically selects statistically comparable index stations by correlation and regression, and performs hydrographic comparisons and estimates of missing data by regressing daily mean flows at the review station against -8 to +8 lagged flows at one or two index stations and day-of-week. Another advantage that HYDCOMP has over the graphical method is that estimated flows, the criteria for determining the quality of the data, and the selection of index stations are determined statistically, and are reproducible from one user to another. HYDCOMP will load the most-correlated index stations into another file containing the ?best index stations,? but will not overwrite stations already in the file. A knowledgeable user should delete unsuitable index stations from this file based on standard error of estimate, hydrologic similarity of candidate index stations to the review station, and knowledge of the individual station characteristics. Also, the user can add index stations not selected by HYDCOMP, if desired. Once the file of best-index stations is created, a user may do hydrographic comparison and data estimates by entering the number of the review station, selecting an index station, and specifying the periods to be used for regression and plotting. For example, the user can restrict the regression to ice-free periods of the year to exclude flows estimated during iced conditions. However, the regression could still be used to estimate flow during iced conditions. HYDCOMP produces the standard error of estimate as a measure of the central scatter of the regression and R-square (coefficient of determination) for evaluating the accuracy of the regression. Output from HYDCOMP includes plots of percent residuals against (1) time within the regression and plot periods, (2) month and day of the year for evaluating seasonal bias in the regression, and (3) the magnitude of flow. For hydrographic comparisons, it plots 2-month segments of hydrographs over the selected plot period showing the observed flows, the regressed flows, the 95 percent confidence limit flows, flow measurements, and regression limits. If the observed flows at the review station remain outside the 95 percent confidence limits for a prolonged period, there may be some error in the flows at the review station or at the index station(s). In addition, daily minimum and maximum temperatures and daily rainfall are shown on the hydrographs, if available, to help indicate whether an apparent change in flow may result from rainfall or from changes in backwater from melting ice or freezing water. HYDCOMP statistically smooths estimated flows from non-missing flows at the edges of the gaps in data into regressed flows at the center of the gaps using the Kalman smoothing algorithm. Missing flows are automatically estimated by HYDCOMP, but the user also can specify that periods of erroneous, but nonmissing flows, be estimated by the program.

Estimating the brain pathological age of Alzheimer’s disease patients from MR image data based on the separability distance criterion

NASA Astrophysics Data System (ADS)

Li, Yongming; Li, Fan; Wang, Pin; Zhu, Xueru; Liu, Shujun; Qiu, Mingguo; Zhang, Jingna; Zeng, Xiaoping

2016-10-01

Traditional age estimation methods are based on the same idea that uses the real age as the training label. However, these methods ignore that there is a deviation between the real age and the brain age due to accelerated brain aging. This paper considers this deviation and searches for it by maximizing the separability distance value rather than by minimizing the difference between the estimated brain age and the real age. Firstly, set the search range of the deviation as the deviation candidates according to prior knowledge. Secondly, use the support vector regression (SVR) as the age estimation model to minimize the difference between the estimated age and the real age plus deviation rather than the real age itself. Thirdly, design the fitness function based on the separability distance criterion. Fourthly, conduct age estimation on the validation dataset using the trained age estimation model, put the estimated age into the fitness function, and obtain the fitness value of the deviation candidate. Fifthly, repeat the iteration until all the deviation candidates are involved and get the optimal deviation with maximum fitness values. The real age plus the optimal deviation is taken as the brain pathological age. The experimental results showed that the separability was apparently improved. For normal control-Alzheimer’s disease (NC-AD), normal control-mild cognition impairment (NC-MCI), and MCI-AD, the average improvements were 0.178 (35.11%), 0.033 (14.47%), and 0.017 (39.53%), respectively. For NC-MCI-AD, the average improvement was 0.2287 (64.22%). The estimated brain pathological age could be not only more helpful to the classification of AD but also more precisely reflect accelerated brain aging. In conclusion, this paper offers a new method for brain age estimation that can distinguish different states of AD and can better reflect the extent of accelerated aging.

Association between different measurements of blood pressure variability by ABP monitoring and ankle-brachial index.

PubMed

Wittke, Estefânia; Fuchs, Sandra C; Fuchs, Flávio D; Moreira, Leila B; Ferlin, Elton; Cichelero, Fábio T; Moreira, Carolina M; Neyeloff, Jeruza; Moreira, Marina B; Gus, Miguel

2010-11-05

Blood pressure (BP) variability has been associated with cardiovascular outcomes, but there is no consensus about the more effective method to measure it by ambulatory blood pressure monitoring (ABPM). We evaluated the association between three different methods to estimate BP variability by ABPM and the ankle brachial index (ABI). In a cross-sectional study of patients with hypertension, BP variability was estimated by the time rate index (the first derivative of SBP over time), standard deviation (SD) of 24-hour SBP; and coefficient of variability of 24-hour SBP. ABI was measured with a doppler probe. The sample included 425 patients with a mean age of 57 ± 12 years, being 69.2% women, 26.1% current smokers and 22.1% diabetics. Abnormal ABI (≤ 0.90 or ≥ 1.40) was present in 58 patients. The time rate index was 0.516 ± 0.146 mmHg/min in patients with abnormal ABI versus 0.476 ± 0.124 mmHg/min in patients with normal ABI (P = 0.007). In a logistic regression model the time rate index was associated with ABI, regardless of age (OR = 6.9, 95% CI = 1.1- 42.1; P = 0.04). In a multiple linear regression model, adjusting for age, SBP and diabetes, the time rate index was strongly associated with ABI (P < 0.01). None of the other indexes of BP variability were associated with ABI in univariate and multivariate analyses. Time rate index is a sensible method to measure BP variability by ABPM. Its performance for risk stratification of patients with hypertension should be explored in longitudinal studies.

Inverse correlation between the standard deviation of R-R intervals in supine position and the simplified menopausal index in women with climacteric symptoms.

PubMed

Yanagihara, Nobuyuki; Seki, Meikan; Nakano, Masahiro; Hachisuga, Toru; Goto, Yukio

2014-06-01

Disturbance of autonomic nervous activity has been thought to play a role in the climacteric symptoms of postmenopausal women. This study was therefore designed to investigate the relationship between autonomic nervous activity and climacteric symptoms in postmenopausal Japanese women. The autonomic nervous activity of 40 Japanese women with climacteric symptoms and 40 Japanese women without climacteric symptoms was measured by power spectral analysis of heart rate variability using a standard hexagonal radar chart. The scores for climacteric symptoms were determined using the simplified menopausal index. Sympathetic excitability and irritability, as well as the standard deviation of mean R-R intervals in supine position, were significantly (P < 0.01, 0.05, and 0.001, respectively) decreased in women with climacteric symptoms. There was a negative correlation between the standard deviation of mean R-R intervals in supine position and the simplified menopausal index score. The lack of control for potential confounding variables was a limitation of this study. In climacteric women, the standard deviation of mean R-R intervals in supine position is negatively correlated with the simplified menopausal index score.

Frontal-temporal synchronization of EEG signals quantified by order patterns cross recurrence analysis during propofol anesthesia.

PubMed

Shalbaf, Reza; Behnam, Hamid; Sleigh, Jamie W; Steyn-Ross, D Alistair; Steyn-Ross, Moira L

2015-05-01

Characterizing brain dynamics during anesthesia is a main current challenge in anesthesia study. Several single channel electroencephalogram (EEG)-based commercial monitors like the Bispectral index (BIS) have suggested to examine EEG signal. But, the BIS index has obtained numerous critiques. In this study, we evaluate the concentration-dependent effect of the propofol on long-range frontal-temporal synchronization of EEG signals collected from eight subjects during a controlled induction and recovery design. We used order patterns cross recurrence plot and provide an index named order pattern laminarity (OPL) to assess changes in neuronal synchronization as the mechanism forming the foundation of conscious perception. The prediction probability of 0.9 and 0.84 for OPL and BIS specified that the OPL index correlated more strongly with effect-site propofol concentration. Also, our new index makes faster reaction to transients in EEG recordings based on pharmacokinetic and pharmacodynamic model parameters and demonstrates less variability at the point of loss of consciousness (standard deviation of 0.04 for OPL compared with 0.09 for BIS index). The result show that the OPL index can estimate anesthetic state of patient more efficiently than the BIS index in lightly sedated state with more tolerant of artifacts.

The MSFC Solar Activity Future Estimation (MSAFE) Model

NASA Technical Reports Server (NTRS)

Suggs, Ron

2017-01-01

The MSAFE model provides forecasts for the solar indices SSN, F10.7, and Ap. These solar indices are used as inputs to space environment models used in orbital spacecraft operations and space mission analysis. Forecasts from the MSAFE model are provided on the MSFC Natural Environments Branch's solar web page and are updated as new monthly observations become available. The MSAFE prediction routine employs a statistical technique that calculates deviations of past solar cycles from the mean cycle and performs a regression analysis to calculate the deviation from the mean cycle of the solar index at the next future time interval. The forecasts are initiated for a given cycle after about 8 to 9 monthly observations from the start of the cycle are collected. A forecast made at the beginning of cycle 24 using the MSAFE program captured the cycle fairly well with some difficulty in discerning the double peak that occurred at solar cycle maximum.

IR GRIN optics: design and fabrication

NASA Astrophysics Data System (ADS)

Gibson, Daniel; Bayya, Shyam; Nguyen, Vinh; Sanghera, Jas; Kotov, Mikhail; McClain, Collin; Deegan, John; Lindberg, George; Unger, Blair; Vizgaitis, Jay

2017-06-01

Infrared (IR) transmitting gradient index (GRIN) materials have been developed for broad-band IR imaging. This material is derived from the diffusion of homogeneous chalcogenide glasses has good transmission for all IR wavebands. The optical properties of the IR-GRIN materials are presented and the fabrication and design methodologies are discussed. Modeling and optimization of the diffusion process is exploited to minimize the deviation of the index profile from the design profile. Fully diffused IR-GRIN blanks with Δn of 0.2 are demonstrated with deviation errors of +/-0.01 refractive index units.

Robust Alternatives to the Standard Deviation in Processing of Physics Experimental Data

NASA Astrophysics Data System (ADS)

Shulenin, V. P.

2016-10-01

Properties of robust estimations of the scale parameter are studied. It is noted that the median of absolute deviations and the modified estimation of the average Gini differences have asymptotically normal distributions and bounded influence functions, are B-robust estimations, and hence, unlike the estimation of the standard deviation, are protected from the presence of outliers in the sample. Results of comparison of estimations of the scale parameter are given for a Gaussian model with contamination. An adaptive variant of the modified estimation of the average Gini differences is considered.

The Electron Temperature and Anisotropy in the Solar Wind. Comparison of the Core and Halo Populations

NASA Astrophysics Data System (ADS)

Pierrard, V.; Lazar, M.; Poedts, S.; Štverák, Š.; Maksimovic, M.; Trávníček, P. M.

2016-08-01

Estimating the temperature of solar wind particles and their anisotropies is particularly important for understanding the origin of their deviations from thermal equilibrium and the effects this has. In the absence of energetic events, the velocity distribution of electrons reveals a dual structure with a thermal (Maxwellian) core and a suprathermal (kappa) halo. This article presents a detailed observational analysis of these two components, providing estimations of their temperatures and temperature anisotropies, and decoding any potential interdependence that their properties may indicate. The dataset used in this study includes more than 120 000 of the distributions measured by three missions in the ecliptic within an extended range of heliocentric distances from 0.3 to over 4 AU. The core temperature is found to decrease with the radial distance, while the halo temperature slightly increases, clarifying an apparent contradiction in previous observational analyses and providing valuable clues about the temperature of the kappa-distributed populations. For low values of the power-index kappa, these two components manifest a clear tendency to deviate from isotropy in the same direction, which seems to confirm the existence of mechanisms with similar effects on both components, e.g., the solar wind expansion, or the particle heating by the fluctuations. However, the existence of plasma states with anticorrelated anisotropies of the core and halo populations and the increase in their number for high values of the power-index kappa suggest a dynamic interplay of these components, mediated, most probably, by the anisotropy-driven instabilities.

Improving Spleen Volume Estimation via Computer Assisted Segmentation on Clinically Acquired CT Scans

PubMed Central

Xu, Zhoubing; Gertz, Adam L.; Burke, Ryan P.; Bansal, Neil; Kang, Hakmook; Landman, Bennett A.; Abramson, Richard G.

2016-01-01

OBJECTIVES Multi-atlas fusion is a promising approach for computer-assisted segmentation of anatomical structures. The purpose of this study was to evaluate the accuracy and time efficiency of multi-atlas segmentation for estimating spleen volumes on clinically-acquired CT scans. MATERIALS AND METHODS Under IRB approval, we obtained 294 deidentified (HIPAA-compliant) abdominal CT scans on 78 subjects from a recent clinical trial. We compared five pipelines for obtaining splenic volumes: Pipeline 1–manual segmentation of all scans, Pipeline 2–automated segmentation of all scans, Pipeline 3–automated segmentation of all scans with manual segmentation for outliers on a rudimentary visual quality check, Pipelines 4 and 5–volumes derived from a unidimensional measurement of craniocaudal spleen length and three-dimensional splenic index measurements, respectively. Using Pipeline 1 results as ground truth, the accuracy of Pipelines 2–5 (Dice similarity coefficient [DSC], Pearson correlation, R-squared, and percent and absolute deviation of volume from ground truth) were compared for point estimates of splenic volume and for change in splenic volume over time. Time cost was also compared for Pipelines 1–5. RESULTS Pipeline 3 was dominant in terms of both accuracy and time cost. With a Pearson correlation coefficient of 0.99, average absolute volume deviation 23.7 cm3, and 1 minute per scan, Pipeline 3 yielded the best results. The second-best approach was Pipeline 5, with a Pearson correlation coefficient 0.98, absolute deviation 46.92 cm3, and 1 minute 30 seconds per scan. Manual segmentation (Pipeline 1) required 11 minutes per scan. CONCLUSION A computer-automated segmentation approach with manual correction of outliers generated accurate splenic volumes with reasonable time efficiency. PMID:27519156

Individual differences in the shape of the nasal visual field.

PubMed

Swanson, William H; Dul, Mitchell W; Horner, Douglas G; Malinovsky, Victor E

2017-12-01

Between-subject differences in the shape of the nasal visual field were assessed for 103 volunteers 21-85years of age and free of visual disorder. Perimetry was conducted with a stimulus for which contrast sensitivity is minimally affected by peripheral defocus and decreased retinal illumination. One eye each was tested for 103 volunteers free of eye disease in a multi-center prospective longitudinal study. A peripheral deviation index was computed as the difference in log contrast sensitivity at outer (25-29° nasal) and inner (8° from fixation) locations. Values for this index ranged from 0.01 (outer sensitivity slightly greater than inner sensitivity) to -0.7 log unit (outer sensitivity much lower than inner sensitivity). Mean sensitivity for the inner locations was independent of the deviation index (R 2 <1%), while mean sensitivity for the outer locations was not (R 2 =38%, p<0.0005). Age was only modestly related to the index, with a decline by 0.017 log unit per decade (R 2 =10%). Test-retest data for 21 volunteers who completed 7-10 visits yielded standard deviations for the index from 0.04 to 0.17 log unit, with a mean of 0.09 log unit. Between-subject differences in peripheral deviation persisted over two years of longitudinal testing. Peripheral deviation indices were correlated with indices for three other perimetric stimuli used in a subset of 24 volunteers (R 2 from 20% to 49%). Between-subject variability in shape of the visual field raises concerns about current clinical visual field indices, and further studies are needed to develop improved indices. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Estimating the sample mean and standard deviation from the sample size, median, range and/or interquartile range.

PubMed

Wan, Xiang; Wang, Wenqian; Liu, Jiming; Tong, Tiejun

2014-12-19

In systematic reviews and meta-analysis, researchers often pool the results of the sample mean and standard deviation from a set of similar clinical trials. A number of the trials, however, reported the study using the median, the minimum and maximum values, and/or the first and third quartiles. Hence, in order to combine results, one may have to estimate the sample mean and standard deviation for such trials. In this paper, we propose to improve the existing literature in several directions. First, we show that the sample standard deviation estimation in Hozo et al.'s method (BMC Med Res Methodol 5:13, 2005) has some serious limitations and is always less satisfactory in practice. Inspired by this, we propose a new estimation method by incorporating the sample size. Second, we systematically study the sample mean and standard deviation estimation problem under several other interesting settings where the interquartile range is also available for the trials. We demonstrate the performance of the proposed methods through simulation studies for the three frequently encountered scenarios, respectively. For the first two scenarios, our method greatly improves existing methods and provides a nearly unbiased estimate of the true sample standard deviation for normal data and a slightly biased estimate for skewed data. For the third scenario, our method still performs very well for both normal data and skewed data. Furthermore, we compare the estimators of the sample mean and standard deviation under all three scenarios and present some suggestions on which scenario is preferred in real-world applications. In this paper, we discuss different approximation methods in the estimation of the sample mean and standard deviation and propose some new estimation methods to improve the existing literature. We conclude our work with a summary table (an Excel spread sheet including all formulas) that serves as a comprehensive guidance for performing meta-analysis in different situations.

Cross correlation and time-lag between cosmic ray intensity and solar activity during solar cycles 21, 22 and 23

NASA Astrophysics Data System (ADS)

Sierra-Porta, D.

2018-07-01

In the present paper a systematic study is carried out to validate the similarity or co-variability between daily terrestrial cosmic-ray intensity and three parameters of the solar corona evolution, i.e., the number of sunspots and flare index observed in the solar corona and the Ap index for regular magnetic field variations caused by regular solar radiation changes. The study is made for a period including three solar cycles starting with cycle 21 (year 1976) and ending on cycle 23 (year 2008). A cross-correlation analysis was used to establish patterns and dependence of the variables. This study focused on the time lag calculation for these variables and found a maximum of negative correlation over CC1≈ 0.85, CC2≈ 0.75 and CC3≈ 0.63 with an estimation of 181, 156 and 2 days of deviation between maximum/minimum of peaks for the intensity of cosmic rays related with sunspot number, flare index and Ap index regression, respectively.

Behavior of visual field index in advanced glaucoma.

PubMed

Rao, Harsha L; Senthil, Sirisha; Choudhari, Nikhil S; Mandal, Anil K; Garudadri, Chandra S

2013-01-14

To evaluate the magnitude of Visual Field Index (VFI) change attributable to change in the estimation algorithm from the pattern deviation probability plot (PDPP) to the total deviation probability plot (TDPP) when the mean deviation (MD) crosses -20 decibels (dB). In a retrospective study, 37 stable glaucoma eyes in which MD of the VFs crossed -20 dB were identified. For each eye, a pair of VFs was selected so that one VF of the pair had a MD better than but close to -20 dB and the other had a MD worse than but again close to -20 dB. The change in VFI in the VF pairs and its associations with the number of points in probability plots with normal threshold sensitivities were evaluated. Similar pairs of VFs from 28 stable glaucoma eyes where the MD crossed -10 dB were chosen as controls. The change in VFI in VF pairs when the MD crossed 20 dB ranged from 3% to 33% (median: 15%), while the change when MD crossed -10 dB ranged from 1% to 8% (median: 4%). Difference in the number of points with normal threshold sensitivities in PDPP when MD was better than -20 dB compared to those in TDPP when MD crossed -20 dB significantly influenced the VFI change (R(2) = 0.65). Considering the eccentricity of these points further explained the VFI change (R(2) = 0.81). The decrease in VFI when MD crosses -20 dB can be highly variable. This has to be considered with the use of VFI in clinical and research settings.

Wildfire Risk Mapping over the State of Mississippi: Land Surface Modeling Approach

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

Cooke, William H.; Mostovoy, Georgy; Anantharaj, Valentine G

2012-01-01

Three fire risk indexes based on soil moisture estimates were applied to simulate wildfire probability over the southern part of Mississippi using the logistic regression approach. The fire indexes were retrieved from: (1) accumulated difference between daily precipitation and potential evapotranspiration (P-E); (2) top 10 cm soil moisture content simulated by the Mosaic land surface model; and (3) the Keetch-Byram drought index (KBDI). The P-E, KBDI, and soil moisture based indexes were estimated from gridded atmospheric and Mosaic-simulated soil moisture data available from the North American Land Data Assimilation System (NLDAS-2). Normalized deviations of these indexes from the 31-year meanmore » (1980-2010) were fitted into the logistic regression model describing probability of wildfires occurrence as a function of the fire index. It was assumed that such normalization provides more robust and adequate description of temporal dynamics of soil moisture anomalies than the original (not normalized) set of indexes. The logistic model parameters were evaluated for 0.25 x0.25 latitude/longitude cells and for probability representing at least one fire event occurred during 5 consecutive days. A 23-year (1986-2008) forest fires record was used. Two periods were selected and examined (January mid June and mid September December). The application of the logistic model provides an overall good agreement between empirical/observed and model-fitted fire probabilities over the study area during both seasons. The fire risk indexes based on the top 10 cm soil moisture and KBDI have the largest impact on the wildfire odds (increasing it by almost 2 times in response to each unit change of the corresponding fire risk index during January mid June period and by nearly 1.5 times during mid September-December) observed over 0.25 x0.25 cells located along the state of Mississippi Coast line. This result suggests a rather strong control of fire risk indexes on fire occurrence probability over this region.« less

Effect of increased exercise in school children on physical fitness and endothelial progenitor cells: a prospective randomized trial.

PubMed

Walther, Claudia; Gaede, Luise; Adams, Volker; Gelbrich, Götz; Leichtle, Alexander; Erbs, Sandra; Sonnabend, Melanie; Fikenzer, Kati; Körner, Antje; Kiess, Wieland; Bruegel, Mathias; Thiery, Joachim; Schuler, Gerhard

2009-12-01

The aim of this prospective, randomized study was to examine whether additional school exercise lessons would result in improved peak oxygen uptake (primary end point) and body mass index-standard deviation score, motor and coordinative abilities, circulating progenitor cells, and high-density lipoprotein cholesterol (major secondary end points). Seven sixth-grade classes (182 children, aged 11.1+/-0.7 years) were randomized to an intervention group (4 classes with 109 students) with daily school exercise lessons for 1 year and a control group (3 classes with 73 students) with regular school sports twice weekly. The significant effects of intervention estimated from ANCOVA adjusted for intraclass correlation were the following: increase of peak o(2) (3.7 mL/kg per minute; 95% confidence interval, 0.3 to 7.2) and increase of circulating progenitor cells evaluated by flow cytometry (97 cells per 1 x 10(6) leukocytes; 95% confidence interval, 13 to 181). No significant difference was seen for body mass index-standard deviation score (-0.08; 95% confidence interval, -0.28 to 0.13); however, there was a trend to reduction of the prevalence of overweight and obese children in the intervention group (from 12.8% to 7.3%). No treatment effect was seen for motor and coordinative abilities (4; 95% confidence interval, -1 to 8) and high-density lipoprotein cholesterol (0.03 mmol/L; 95% confidence interval, -0.08 to 0.14). Regular physical activity by means of daily school exercise lessons has a significant positive effect on physical fitness (o(2)max). Furthermore, the number of circulating progenitor cells can be increased, and there is a positive trend in body mass index-standard deviation score reduction and motor ability improvement. Therefore, we conclude that primary prevention by means of increasing physical activity should start in childhood. URL: http://www.clinicaltrials.gov. Identifier: NCT00176371.

Outcome at 3 years of age in a population-based cohort of extremely preterm infants.

PubMed

De Groote, Isabel; Vanhaesebrouck, Piet; Bruneel, Els; Dom, Lina; Durein, Isabelle; Hasaerts, Danielle; Laroche, Sabine; Oostra, Ann; Ortibus, Els; Roeyers, Herbert; van Mol, Christine

2007-10-01

To assess health and neurodevelopmental outcome at 3 years of age in neonatal intensive care unit (NICU)-surviving children who were born at 26 or fewer weeks of gestation in a geographically defined region of Belgium from 1999 through 2000. The study included a clinical examination and a standardized neurologic and developmental assessment. Disabilities were defined by international criteria. In 97% (92 of 95) of the children, accurate information on the presence of overall disability could be collected. Thirty-six percent (95% confidence interval [CI] 25-47%) of the formally assessed children (28 of 77) had deficient neuromotor development, with 5% of them showing severe sensory-communicative impairment. Mean (+/-standard deviation) scores on the Mental Developmental Index and Psychomotor Developmental Index were 81.2 (18.8) and 73.2 (17.8), respectively. Seventy percent (95% CI 60-80%) had a mental (Mental Developmental Index) or psychomotor (Psychomotor Developmental Index) impairment or both, assessed to be more than 1 standard deviation below the population mean. Mental and psychomotor outcome did not differ significantly when compared according to either gestational age, gender, or multiple birth (all P>.05). When either minor central dysfunction or cerebral palsy was not taken into account, normal mental development was recorded in 62% of the subjects. The cumulative of poor outcome (ie, disability- or prematurity-related death) among the 95 infants discharged alive was estimated to be 58% (95% CI 48-68%), representing 25 (26%) mildly-to-moderately disabled and 28 (29%) severely disabled toddlers, including two infants whose postdischarge deaths were directly related to prematurity. The average developmental outcome is poor in children born as extremely preterm infants. Finding early predictors of adverse outcome is a major challenge.

Education and health knowledge: evidence from UK compulsory schooling reform.

PubMed

Johnston, David W; Lordan, Grace; Shields, Michael A; Suziedelyte, Agne

2015-02-01

We investigate if there is a causal link between education and health knowledge using data from the 1984/85 and 1991/92 waves of the UK Health and Lifestyle Survey (HALS). Uniquely, the survey asks respondents what they think are the main causes of ten common health conditions, and we compare these answers to those given by medical professionals to form an index of health knowledge. For causal identification we use increases in the UK minimum school leaving age in 1947 (from 14 to 15) and 1972 (from 15 to 16) to provide exogenous variation in education. These reforms predominantly induced adolescents who would have left school to stay for one additionally mandated year. OLS estimates suggest that education significantly increases health knowledge, with a one-year increase in schooling increasing the health knowledge index by 15% of a standard deviation. In contrast, estimates from instrumental-variable models show that increased schooling due to the education reforms did not significantly affect health knowledge. This main result is robust to numerous specification tests and alternative formulations of the health knowledge index. Further research is required to determine whether there is also no causal link between higher levels of education - such as post-school qualifications - and health knowledge. Copyright © 2014 Elsevier Ltd. All rights reserved.

Estimating structural attributes of Douglas-fir/western hemlock forest stands from Landsat and SPOT imagery

NASA Technical Reports Server (NTRS)

Cohen, Warren B.; Spies, Thomas A.

1992-01-01

Relationships between spectral and texture variables derived from SPOT HRV 10 m panchromatic and Landsat TM 30 m multispectral data and 16 forest stand structural attributes is evaluated to determine the utility of satellite data for analysis of hemlock forests west of the Cascade Mountains crest in Oregon and Washington, USA. Texture of the HRV data was found to be strongly related to many of the stand attributes evaluated, whereas TM texture was weakly related to all attributes. Data analysis based on regression models indicates that both TM and HRV imagery should yield equally accurate estimates of forest age class and stand structure. It is concluded that the satellite data are a valuable source for estimation of the standard deviation of tree sizes, mean size and density of trees in the upper canopy layers, a structural complexity index, and stand age.

Measurement of the refractive index by using a rectangular cell with a fs-laser engraved diffraction grating inner wall.

PubMed

Durán-Ramírez, Víctor M; Martínez-Ríos, Alejandro; Guerrero-Viramontes, J Ascención; Muñoz-Maciel, Jesús; Peña-Lecona, Francisco G; Selvas-Aguilar, Romeo; Anzueto-Sánchez, Gilberto

2014-12-01

A very simple method to obtain the refractive index of liquids by using a rectangular glass cell and a diffraction grating engraved by fs laser ablation on the inner face of one of the walls of the cell is presented. When a laser beam impinges normally on the diffraction grating, the diffraction orders are deviated when they pass through the cell filled with the liquid to be measured. By measuring the deviation of the diffraction orders, we can determine the refractive index of the liquid.

Determining the bias and variance of a deterministic finger-tracking algorithm.

PubMed

Morash, Valerie S; van der Velden, Bas H M

2016-06-01

Finger tracking has the potential to expand haptic research and applications, as eye tracking has done in vision research. In research applications, it is desirable to know the bias and variance associated with a finger-tracking method. However, assessing the bias and variance of a deterministic method is not straightforward. Multiple measurements of the same finger position data will not produce different results, implying zero variance. Here, we present a method of assessing deterministic finger-tracking variance and bias through comparison to a non-deterministic measure. A proof-of-concept is presented using a video-based finger-tracking algorithm developed for the specific purpose of tracking participant fingers during a psychological research study. The algorithm uses ridge detection on videos of the participant's hand, and estimates the location of the right index fingertip. The algorithm was evaluated using data from four participants, who explored tactile maps using only their right index finger and all right-hand fingers. The algorithm identified the index fingertip in 99.78 % of one-finger video frames and 97.55 % of five-finger video frames. Although the algorithm produced slightly biased and more dispersed estimates relative to a human coder, these differences (x=0.08 cm, y=0.04 cm) and standard deviations (σ x =0.16 cm, σ y =0.21 cm) were small compared to the size of a fingertip (1.5-2.0 cm). Some example finger-tracking results are provided where corrections are made using the bias and variance estimates.

Determination of the combustion behavior for pure components and mixtures using a 20-liter sphere

NASA Astrophysics Data System (ADS)

Mashuga, Chad Victor

1999-11-01

The safest method to prevent fires and explosions of flammable vapors is to prevent the existence of flammable mixtures in the first place. This methodology requires detailed knowledge of the flammability region as a function of the fuel, oxygen, and nitrogen concentrations. A triangular flammability diagram is the most useful tool to display the flammability region, and to determine if a flammable mixture is present during plant operations. An automated apparatus for assessing the flammability region and for determining the potential effect of confined fuel-air explosions is described. Data derived from the apparatus included the limits of combustion, maximum combustion pressure, and the deflagration index, or KG. Accurate measurement of these parameters can be influenced by numerous experimental conditions, including igniter energy, humidity and gas composition. Gas humidity had a substantial effect on the deflagration index, but had little effect on the maximum combustion pressure. Small changes in gas compositions had a greater effect on the deflagration index than the maximum combustion pressure. Both the deflagration indices and the maximum combustion pressure proved insensitive to the range of igniter energies examined. Estimation of flammability limits using a calculated adiabatic flame temperature (CAFT) method is demonstrated. The CAFT model is compared with the extensive experimental data from this work for methane, ethylene and a 50/50 mixture of methane and ethylene. The CAFT model compares well to methane and ethylene throughout the flammability zone when using a 1200K threshold temperature. Deviations between the method and the experimental data occurs in the fuel rich region. For the 50/50 fuel mixture the CAFT deviates only in the fuel rich region---the inclusion of carbonaceous soot as one of the equilibrium products improved the fit. Determination of burning velocities from a spherical flame model utilizing the extensive pressure---time data was also completed. The burning velocities determined compare well to other investigators using this method. The data collected for the methane/ethylene mixture was used to evaluate mixing rules for the flammability limits, maximum combustion pressure, deflagration index, and burning velocity. These rules attempt to predict the behavior of fuel mixtures from pure component data. Le Chatelier's law and averaging both work well for predicting the flammability boundary in the fuel lean region and for mixtures of inerted fuel and air. Both methods underestimate the flammability boundary in the fuel rich region. For a mixture of methane and ethylene, we were unable to identify mixing rules for estimating the maximum combustion pressure and the burning velocity from pure component data. Averaging the deflagration indices for fuel air mixtures did provide a adequate estimation of the mixture behavior. Le Chatelier's method overestimated the maximum deflagration index in air but provided a satisfactory estimation in the extreme fuel lean and rich regions.

Simulation-based estimation of mean and standard deviation for meta-analysis via Approximate Bayesian Computation (ABC).

PubMed

Kwon, Deukwoo; Reis, Isildinha M

2015-08-12

When conducting a meta-analysis of a continuous outcome, estimated means and standard deviations from the selected studies are required in order to obtain an overall estimate of the mean effect and its confidence interval. If these quantities are not directly reported in the publications, they must be estimated from other reported summary statistics, such as the median, the minimum, the maximum, and quartiles. We propose a simulation-based estimation approach using the Approximate Bayesian Computation (ABC) technique for estimating mean and standard deviation based on various sets of summary statistics found in published studies. We conduct a simulation study to compare the proposed ABC method with the existing methods of Hozo et al. (2005), Bland (2015), and Wan et al. (2014). In the estimation of the standard deviation, our ABC method performs better than the other methods when data are generated from skewed or heavy-tailed distributions. The corresponding average relative error (ARE) approaches zero as sample size increases. In data generated from the normal distribution, our ABC performs well. However, the Wan et al. method is best for estimating standard deviation under normal distribution. In the estimation of the mean, our ABC method is best regardless of assumed distribution. ABC is a flexible method for estimating the study-specific mean and standard deviation for meta-analysis, especially with underlying skewed or heavy-tailed distributions. The ABC method can be applied using other reported summary statistics such as the posterior mean and 95 % credible interval when Bayesian analysis has been employed.

Band head spin assignment of superdeformed bands in 133Pr using two-parameter formulae

NASA Astrophysics Data System (ADS)

Sharma, Honey; Mittal, H. M.

2018-03-01

The two-parameter formulae viz. the power index formula, the nuclear softness formula and the VMI model are adopted to accredit the band head spin (I0) of four superdeformed rotational bands in 133Pr. The technique of least square fitting is used to accredit the band head spin for four superdeformed rotational bands in 133Pr. The root mean deviation among the computed transition energies and well-known experimental transition energies are attained by extracting the model parameters from the two-parameter formulae. The determined transition energies are in excellent agreement with the experimental transition energies, whenever exact spins are accredited. The power index formula coincides well with the experimental data and provides minimum root mean deviation. So, the power index formula is more efficient tool than the nuclear softness formula and the VMI model. The deviation of dynamic moment of inertia J(2) against the rotational frequency is also examined.

Statistical models for estimating daily streamflow in Michigan

USGS Publications Warehouse

Holtschlag, D.J.; Salehi, Habib

1992-01-01

Statistical models for estimating daily streamflow were analyzed for 25 pairs of streamflow-gaging stations in Michigan. Stations were paired by randomly choosing a station operated in 1989 at which 10 or more years of continuous flow data had been collected and at which flow is virtually unregulated; a nearby station was chosen where flow characteristics are similar. Streamflow data from the 25 randomly selected stations were used as the response variables; streamflow data at the nearby stations were used to generate a set of explanatory variables. Ordinary-least squares regression (OLSR) equations, autoregressive integrated moving-average (ARIMA) equations, and transfer function-noise (TFN) equations were developed to estimate the log transform of flow for the 25 randomly selected stations. The precision of each type of equation was evaluated on the basis of the standard deviation of the estimation errors. OLSR equations produce one set of estimation errors; ARIMA and TFN models each produce l sets of estimation errors corresponding to the forecast lead. The lead-l forecast is the estimate of flow l days ahead of the most recent streamflow used as a response variable in the estimation. In this analysis, the standard deviation of lead l ARIMA and TFN forecast errors were generally lower than the standard deviation of OLSR errors for l < 2 days and l < 9 days, respectively. Composite estimates were computed as a weighted average of forecasts based on TFN equations and backcasts (forecasts of the reverse-ordered series) based on ARIMA equations. The standard deviation of composite errors varied throughout the length of the estimation interval and generally was at maximum near the center of the interval. For comparison with OLSR errors, the mean standard deviation of composite errors were computed for intervals of length 1 to 40 days. The mean standard deviation of length-l composite errors were generally less than the standard deviation of the OLSR errors for l < 32 days. In addition, the composite estimates ensure a gradual transition between periods of estimated and measured flows. Model performance among stations of differing model error magnitudes were compared by computing ratios of the mean standard deviation of the length l composite errors to the standard deviation of OLSR errors. The mean error ratio for the set of 25 selected stations was less than 1 for intervals l < 32 days. Considering the frequency characteristics of the length of intervals of estimated record in Michigan, the effective mean error ratio for intervals < 30 days was 0.52. Thus, for intervals of estimation of 1 month or less, the error of the composite estimate is substantially lower than error of the OLSR estimate.

Foot-to-foot bioelectrical impedance analysis: a valuable tool for the measurement of body composition in children.

PubMed

Tyrrell, V J; Richards, G; Hofman, P; Gillies, G F; Robinson, E; Cutfield, W S

2001-02-01

To determine the accuracy of foot-to-foot bioelectrical impedance analysis (BIA) and anthropometric indices as measures of body composition in children. Comparison of foot-to-foot BIA and anthropometry to dual-energy X-ray absorptiometry (DEXA)-derived body composition in a multi-ethnic group of children. : Eighty-two European, NZ Maori and Pacific Island children aged 4.9-10.9 y. DEXA body composition, foot-to-foot bioelectrical impedance, height, weight, hip and waist measurements. Using a BIA prediction equation derived from our study population we found a high correlation between DEXA and BIA in the estimation of fat-free mass (FFM), fat mass (FM) and percentage body fat (PBF) (r=0.98, 0.98 and 0.94, respectively). BIA-FFM underestimated DEXA-FFM by a mean of 0.75 kg, BIA-FM overestimated DEXA-FM by a mean of 1.02 kg and BIA-PBF overestimated DEXA-PBF by a mean of 2.53%. The correlation between six anthropometric indices (body mass index (BMI), ponderal index, Chinn's weight-for-height index, BMI standard deviation score, weight-for-length index and Cole's weight-for-height index) and DEXA were also examined. The correlation of these indices with PBF was remarkably similar (r=0.85-0.87), more variable with FM (r=0.77-0.94) and poor with FFM (r=0.41-0.75). BIA correlated better than anthropometric indices in the estimation of FFM, FM and PBF. Foot-to-foot BIA is an accurate technique in the measurement of body composition.

Statistics as Unbiased Estimators: Exploring the Teaching of Standard Deviation

ERIC Educational Resources Information Center

Wasserman, Nicholas H.; Casey, Stephanie; Champion, Joe; Huey, Maryann

2017-01-01

This manuscript presents findings from a study about the knowledge for and planned teaching of standard deviation. We investigate how understanding variance as an unbiased (inferential) estimator--not just a descriptive statistic for the variation (spread) in data--is related to teachers' instruction regarding standard deviation, particularly…

Comprehensive Assessment of Coronary Artery Disease by Using First-Pass Analysis Dynamic CT Perfusion: Validation in a Swine Model.

PubMed

Hubbard, Logan; Lipinski, Jerry; Ziemer, Benjamin; Malkasian, Shant; Sadeghi, Bahman; Javan, Hanna; Groves, Elliott M; Dertli, Brian; Molloi, Sabee

2018-01-01

Purpose To retrospectively validate a first-pass analysis (FPA) technique that combines computed tomographic (CT) angiography and dynamic CT perfusion measurement into one low-dose examination. Materials and Methods The study was approved by the animal care committee. The FPA technique was retrospectively validated in six swine (mean weight, 37.3 kg ± 7.5 [standard deviation]) between April 2015 and October 2016. Four to five intermediate-severity stenoses were generated in the left anterior descending artery (LAD), and 20 contrast material-enhanced volume scans were acquired per stenosis. All volume scans were used for maximum slope model (MSM) perfusion measurement, but only two volume scans were used for FPA perfusion measurement. Perfusion measurements in the LAD, left circumflex artery (LCx), right coronary artery, and all three coronary arteries combined were compared with microsphere perfusion measurements by using regression, root-mean-square error, root-mean-square deviation, Lin concordance correlation, and diagnostic outcomes analysis. The CT dose index and size-specific dose estimate per two-volume FPA perfusion measurement were also determined. Results FPA and MSM perfusion measurements (P FPA and P MSM ) in all three coronary arteries combined were related to reference standard microsphere perfusion measurements (P MICRO ), as follows: P FPA_COMBINED = 1.02 P MICRO_COMBINED + 0.11 (r = 0.96) and P MSM_COMBINED = 0.28 P MICRO_COMBINED + 0.23 (r = 0.89). The CT dose index and size-specific dose estimate per two-volume FPA perfusion measurement were 10.8 and 17.8 mGy, respectively. Conclusion The FPA technique was retrospectively validated in a swine model and has the potential to be used for accurate, low-dose vessel-specific morphologic and physiologic assessment of coronary artery disease. © RSNA, 2017.

Development of a transformation model to derive general population-based utility: Mapping the pruritus-visual analog scale (VAS) to the EQ-5D utility.

PubMed

Park, Sun-Young; Park, Eun-Ja; Suh, Hae Sun; Ha, Dongmun; Lee, Eui-Kyung

2017-08-01

Although nonpreference-based disease-specific measures are widely used in clinical studies, they cannot generate utilities for economic evaluation. A solution to this problem is to estimate utilities from disease-specific instruments using the mapping function. This study aimed to develop a transformation model for mapping the pruritus-visual analog scale (VAS) to the EuroQol 5-Dimension 3-Level (EQ-5D-3L) utility index in pruritus. A cross-sectional survey was conducted with a sample (n = 268) drawn from the general population of South Korea. Data were randomly divided into 2 groups, one for estimating and the other for validating mapping models. To select the best model, we developed and compared 3 separate models using demographic information and the pruritus-VAS as independent variables. The predictive performance was assessed using the mean absolute deviation and root mean square error in a separate dataset. Among the 3 models, model 2 using age, age squared, sex, and the pruritus-VAS as independent variables had the best performance based on the goodness of fit and model simplicity, with a log likelihood of 187.13. The 3 models had similar precision errors based on mean absolute deviation and root mean square error in the validation dataset. No statistically significant difference was observed between the mean observed and predicted values in all models. In conclusion, model 2 was chosen as the preferred mapping model. Outcomes measured as the pruritus-VAS can be transformed into the EQ-5D-3L utility index using this mapping model, which makes an economic evaluation possible when only pruritus-VAS data are available. © 2017 John Wiley & Sons, Ltd.

Effect of Temperature on the Physico-Chemical Properties of a Room Temperature Ionic Liquid (1-Methyl-3-pentylimidazolium Hexafluorophosphate) with Polyethylene Glycol Oligomer

PubMed Central

Wu, Tzi-Yi; Chen, Bor-Kuan; Hao, Lin; Peng, Yu-Chun; Sun, I-Wen

2011-01-01

A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol) (PEG) [Mw = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ρ, refractive index, n, viscosity, η, and surface tension, γ, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values. PMID:21731460

Ionospheric reflection of the magnetic activity described by the index η

NASA Astrophysics Data System (ADS)

Dziak-Jankowska, Beata; Stanisławska, Iwona; Ernst, Tomasz; Tomasik, Łukasz

2011-09-01

Differences in the external part of the vertical geomagnetic component point to the existence of local inhomogeneities in the magnetosphere or the ionosphere. Usually used magnetic indices are not sufficient to express the state of ionosphere, the common used global Kp index derived in the three-hour interval does not indicate much more rapidly changes appearing in ionosphere. Magnetic index η reflects ionospheric disturbances when other indices show very quiet conditions. Data of ionospheric characteristics (foE, foEs, h'E, h'F2) during 28-day long quiet day conditions (Kp = 0-2) in 2004 were analyzed. The correlations between strong local disturbances in ionosphere during very quiet days and high values of magnetic index η were found. The most sensitive to magnetic influence - ionospheric E layer data (foE characteristic) - reaches median deviations up to (+0.8 MHz and -0.8 MHz) during very low magnetic activity (Kp = 0-1). The high peaks (2-2.7) of the magnetic index η correlate in time with large local median deviations of foE. Such local deviations can suggest local inhomogeneities (vertical drifts) in the ionosphere. The correlation in space is not trivial. The strong peak of η is situated between the positive and negative deviations of foE. Additional observation is connected with correlation in time of the high η value with the negative median deviations of h'F2 (in some cases up to -90 km). The analysis was based on one-minute data recorded at each of 20 European Magnetic Observatories working in the INTERMAGNET network and from 19 ionosondes for 2004. Ionospheric data are sparse in time and in space in opposite to the magnetic data. The map of the magnetic indices can suggest the behavior of ionospheric characteristics in the areas where we have no data.

Isometric Arm Strength and Subjective Rating of Upper Limb Fatigue in Two-Handed Carrying Tasks

PubMed Central

Li, Kai Way; Chiu, Wen-Sheng

2015-01-01

Sustained carrying could result in muscular fatigue of the upper limb. Ten male and ten female subjects were recruited for measurements of isometric arm strength before and during carrying a load for a period of 4 minutes. Two levels of load of carrying were tested for each of the male and female subjects. Exponential function based predictive equations for the isometric arm strength were established. The mean absolute deviations of these models in predicting the isometric arm strength were in the range of 3.24 to 17.34 N. Regression analyses between the subjective ratings of upper limb fatigue and force change index (FCI) for the carrying were also performed. The results indicated that the subjective rating of muscular fatigue may be estimated by multiplying the FCI with a constant. The FCI may, therefore, be adopted as an index to assess muscular fatigue for two-handed carrying tasks. PMID:25794159

Isometric arm strength and subjective rating of upper limb fatigue in two-handed carrying tasks.

PubMed

Li, Kai Way; Chiu, Wen-Sheng

2015-01-01

Sustained carrying could result in muscular fatigue of the upper limb. Ten male and ten female subjects were recruited for measurements of isometric arm strength before and during carrying a load for a period of 4 minutes. Two levels of load of carrying were tested for each of the male and female subjects. Exponential function based predictive equations for the isometric arm strength were established. The mean absolute deviations of these models in predicting the isometric arm strength were in the range of 3.24 to 17.34 N. Regression analyses between the subjective ratings of upper limb fatigue and force change index (FCI) for the carrying were also performed. The results indicated that the subjective rating of muscular fatigue may be estimated by multiplying the FCI with a constant. The FCI may, therefore, be adopted as an index to assess muscular fatigue for two-handed carrying tasks.

Spatial generalised linear mixed models based on distances.

PubMed

Melo, Oscar O; Mateu, Jorge; Melo, Carlos E

2016-10-01

Risk models derived from environmental data have been widely shown to be effective in delineating geographical areas of risk because they are intuitively easy to understand. We present a new method based on distances, which allows the modelling of continuous and non-continuous random variables through distance-based spatial generalised linear mixed models. The parameters are estimated using Markov chain Monte Carlo maximum likelihood, which is a feasible and a useful technique. The proposed method depends on a detrending step built from continuous or categorical explanatory variables, or a mixture among them, by using an appropriate Euclidean distance. The method is illustrated through the analysis of the variation in the prevalence of Loa loa among a sample of village residents in Cameroon, where the explanatory variables included elevation, together with maximum normalised-difference vegetation index and the standard deviation of normalised-difference vegetation index calculated from repeated satellite scans over time. © The Author(s) 2013.

Analysis of PVA/AA based photopolymers at the zero spatial frequency limit using interferometric methods.

PubMed

Gallego, Sergi; Márquez, Andrés; Méndez, David; Ortuño, Manuel; Neipp, Cristian; Fernández, Elena; Pascual, Inmaculada; Beléndez, Augusto

2008-05-10

One of the problems associated with photopolymers as optical recording media is the thickness variation during the recording process. Different values of shrinkages or swelling are reported in the literature for photopolymers. Furthermore, these variations depend on the spatial frequencies of the gratings stored in the materials. Thickness variations can be measured using different methods: studying the deviation from the Bragg's angle for nonslanted gratings, using MicroXAM S/N 8038 interferometer, or by the thermomechanical analysis experiments. In a previous paper, we began the characterization of the properties of a polyvinyl alcohol/acrylamide based photopolymer at the lowest end of recorded spatial frequencies. In this work, we continue analyzing the thickness variations of these materials using a reflection interferometer. With this technique we are able to obtain the variations of the layers refractive index and, therefore, a direct estimation of the polymer refractive index.

Body Composition Predicts Growth in Infants and Toddlers With Chronic Liver Disease.

PubMed

Hurtado-López, Erika F; Vásquez-Garibay, Edgar M; Trujillo, Xóchitl; Larrosa-Haro, Alfredo

2017-12-01

This cross-sectional study was conducted on 15 infants and toddlers with chronic liver disease to validate arm anthropometry as an accurate measure of body composition (BC) compared to dual-energy x-ray absorptiometry and to predict growth from BC. The z score means of the anthropometric indicators were <-2 standard deviation, except for body fat index and subscapular skinfold, which were between -2 and +2 standard deviation. Fat mass was predicted by arm adiposity indicators and fat-free mass by arm muscle area. Bone mineral content explained 87% of variation in length. Two multiple regression models predicted length: 1 with fat mass plus fat-free mass; and the second with fat mass and bone mineral content. These observations suggest that arm anthropometry is a useful tool to estimate BC and the nutritional status in infants and toddlers with chronic liver disease. Length and head circumference can be predicted by fat mass, fat-free mass, and bone mineral content.

On the estimation algorithm used in adaptive performance optimization of turbofan engines

NASA Technical Reports Server (NTRS)

Espana, Martin D.; Gilyard, Glenn B.

1993-01-01

The performance seeking control algorithm is designed to continuously optimize the performance of propulsion systems. The performance seeking control algorithm uses a nominal model of the propulsion system and estimates, in flight, the engine deviation parameters characterizing the engine deviations with respect to nominal conditions. In practice, because of measurement biases and/or model uncertainties, the estimated engine deviation parameters may not reflect the engine's actual off-nominal condition. This factor has a necessary impact on the overall performance seeking control scheme exacerbated by the open-loop character of the algorithm. The effects produced by unknown measurement biases over the estimation algorithm are evaluated. This evaluation allows for identification of the most critical measurements for application of the performance seeking control algorithm to an F100 engine. An equivalence relation between the biases and engine deviation parameters stems from an observability study; therefore, it is undecided whether the estimated engine deviation parameters represent the actual engine deviation or whether they simply reflect the measurement biases. A new algorithm, based on the engine's (steady-state) optimization model, is proposed and tested with flight data. When compared with previous Kalman filter schemes, based on local engine dynamic models, the new algorithm is easier to design and tune and it reduces the computational burden of the onboard computer.

Band head spin assignment of superdeformed bands in Hg isotopes through power index formula

NASA Astrophysics Data System (ADS)

Sharma, Honey; Mittal, H. M.

2018-05-01

The power index formula has been used to obtain the band head spin (I 0) of all the superdeformed (SD) bands in Hg isotopes. A least squares fitting approach is used. The root mean square deviations between the determined and the observed transition energies are calculated by extracting the model parameters using the power index formula. Whenever definite spins are available, the determined and the observed transition energies are in accordance with each other. The computed values of dynamic moment of inertia J (2) obtained by using the power index formula and its deviation with the rotational frequency is also studied. Excellent agreement is shown between the calculated and the experimental results for J (2) versus the rotational frequency. Hence, the power index formula works very well for all the SD bands in Hg isotopes expect for 195Hg(2, 3, 4).

Repeatable source, site, and path effects on the standard deviation for empirical ground-motion prediction models

USGS Publications Warehouse

Lin, P.-S.; Chiou, B.; Abrahamson, N.; Walling, M.; Lee, C.-T.; Cheng, C.-T.

2011-01-01

In this study, we quantify the reduction in the standard deviation for empirical ground-motion prediction models by removing ergodic assumption.We partition the modeling error (residual) into five components, three of which represent the repeatable source-location-specific, site-specific, and path-specific deviations from the population mean. A variance estimation procedure of these error components is developed for use with a set of recordings from earthquakes not heavily clustered in space.With most source locations and propagation paths sampled only once, we opt to exploit the spatial correlation of residuals to estimate the variances associated with the path-specific and the source-location-specific deviations. The estimation procedure is applied to ground-motion amplitudes from 64 shallow earthquakes in Taiwan recorded at 285 sites with at least 10 recordings per site. The estimated variance components are used to quantify the reduction in aleatory variability that can be used in hazard analysis for a single site and for a single path. For peak ground acceleration and spectral accelerations at periods of 0.1, 0.3, 0.5, 1.0, and 3.0 s, we find that the singlesite standard deviations are 9%-14% smaller than the total standard deviation, whereas the single-path standard deviations are 39%-47% smaller.

Nighttime oxygen desaturation and symptoms of sleep-disordered breathing in long-stay nursing home residents.

PubMed

Martin, Jennifer L; Mory, Aaron K; Alessi, Cathy A

2005-01-01

Sleep-disordered breathing (SDB) is common in older adults and has been implicated as a cause of decreased quality of life and even death. Sparse data exist on SDB in the nursing home setting. The authors evaluated SDB (using attended nocturnal pulse oximetry) in nursing home residents with daytime sleepiness and nighttime sleep disturbance. Pulse oximetry was used to estimate the prevalence of nighttime oxygen desaturation in 109 long-stay nursing home residents (mean [standard deviation] age = 86.2 [9.2] years; 74% women). Pulse oximetry findings were compared to a structured observational measurement of symptoms of SDB, the Observational Sleep Assessment Instrument. Seventy-one participants had concurrent wrist actigraphy to estimate total sleep time during oximetry recording. Using the oxygen desaturation index (ODI; average number of oxygen desaturations 4% or more below the baseline level per hour), the authors found that 40% of the residents had abnormal ODI (ODI more than 5, which is suggestive of SDB). Of all observational variables assessed, only loud breathing during sleep was significantly correlated with ODI (r =.284; p =.003). When ODI was adjusted for estimated total sleep time, higher adjusted ODI was associated with higher body mass index (kg/m(2)). Abnormal ODI is common in nursing home residents. Observed loud breathing at night and high body mass index may suggest that further assessment of SDB is indicated. Future research should determine the importance of SDB and abnormal nocturnal oxygen desaturation on functioning and quality of life in nursing home residents.

Clouds and troughs of total electron content detected with the ionospheric weather index

NASA Astrophysics Data System (ADS)

Gulyaeva, Tamara

2016-07-01

The ionospheric weather W index has been developed with the different thresholds of change in the F2 layer peak electron density NmF2 (proportional to foF2 critical frequency) or total electron content TEC relative their quiet reference for quantifying the ionosphere variability. The thresholds of DTEC=log(TEC/TECq) are selected for the positive and negative logarithm of TEC ratio to the quiet reference median, TECq, at any given location on the Earth. The global W-index maps are produced from Global Ionospheric Maps of Total Electron Content, GIM-TEC, and provided online at http://www.izmiran.ru/services/iweather/ and http://www.iololab.org/. Based on W-index maps, Catalogues of the ionospheric storms and sub-storms are produced available for the users. The second generation of the ionospheric weather indices, designated V index, is recently introduced and applied for the retrospective study of GIM-TEC variability during 1999-2015. Using sliding-window statistical analysis, moving daily-hourly TEC median TECq for 15 preceding days with estimated variance bounds are obtained at cells of GIM-TEC. The ionosphere variability index, V, is expressed in terms of ΔTEC deviation from the median normalized by the standard deviation STD. V index segmentation is introduced from Vn=-4 in step of 1 to Vp=4 specifying TEC storm if an instant TEC is outside of TECq+-1STD. The global maps of V index allow distinguish the clouds of enhanced TEC (positive storm signatures) and troughs of TEC depletion (negative storm signatures) as compared to the background quiet reference TECq map. It is found that the large-scale TEC clouds and troughs are observed in space all over the world constituting up to 20-50 percent of cells of GIM-TEC. The time variation of these plasma patches is partly following to geomagnetic SSC storm onset. As concerns the interplanetary and the solar wind, SW, sources of the ionospheric storms the TEC storms are observed both with IMF and SW precursors and without the IMF and SW storm signatures. Results of the ionospheric storm studies with the ionospheric weather indices are discussed in the paper. This study is supported by TUBITAK EEEAG 115E915.

The recursive combination filter approach of pre-processing for the estimation of standard deviation of RR series.

PubMed

Mishra, Alok; Swati, D

2015-09-01

Variation in the interval between the R-R peaks of the electrocardiogram represents the modulation of the cardiac oscillations by the autonomic nervous system. This variation is contaminated by anomalous signals called ectopic beats, artefacts or noise which mask the true behaviour of heart rate variability. In this paper, we have proposed a combination filter of recursive impulse rejection filter and recursive 20% filter, with recursive application and preference of replacement over removal of abnormal beats to improve the pre-processing of the inter-beat intervals. We have tested this novel recursive combinational method with median method replacement to estimate the standard deviation of normal to normal (SDNN) beat intervals of congestive heart failure (CHF) and normal sinus rhythm subjects. This work discusses the improvement in pre-processing over single use of impulse rejection filter and removal of abnormal beats for heart rate variability for the estimation of SDNN and Poncaré plot descriptors (SD1, SD2, and SD1/SD2) in detail. We have found the 22 ms value of SDNN and 36 ms value of SD2 descriptor of Poincaré plot as clinical indicators in discriminating the normal cases from CHF cases. The pre-processing is also useful in calculation of Lyapunov exponent which is a nonlinear index as Lyapunov exponents calculated after proposed pre-processing modified in a way that it start following the notion of less complex behaviour of diseased states.

Estimation of the neural drive to the muscle from surface electromyograms

NASA Astrophysics Data System (ADS)

Hofmann, David

Muscle force is highly correlated with the standard deviation of the surface electromyogram (sEMG) produced by the active muscle. Correctly estimating this quantity of non-stationary sEMG and understanding its relation to neural drive and muscle force is of paramount importance. The single constituents of the sEMG are called motor unit action potentials whose biphasic amplitude can interfere (named amplitude cancellation), potentially affecting the standard deviation (Keenan etal. 2005). However, when certain conditions are met the Campbell-Hardy theorem suggests that amplitude cancellation does not affect the standard deviation. By simulation of the sEMG, we verify the applicability of this theorem to myoelectric signals and investigate deviations from its conditions to obtain a more realistic setting. We find no difference in estimated standard deviation with and without interference, standing in stark contrast to previous results (Keenan etal. 2008, Farina etal. 2010). Furthermore, since the theorem provides us with the functional relationship between standard deviation and neural drive we conclude that complex methods based on high density electrode arrays and blind source separation might not bear substantial advantages for neural drive estimation (Farina and Holobar 2016). Funded by NIH Grant Number 1 R01 EB022872 and NSF Grant Number 1208126.

Intelligent trend analysis for a solar thermal energy collector field

NASA Astrophysics Data System (ADS)

Juuso, E. K.

2018-03-01

Solar thermal power plants collect available solar energy in a usable form at a temperature range which is adapted to the irradiation levels and seasonal variations. Solar energy can be collected only when the irradiation is high enough to produce the required temperatures. During the operation, a trade-off of the temperature and the flow is needed to achieve a good level for the collected power. The scaling approach brings temporal analysis to all measurements and features: trend indices are calculated by comparing the averages in the long and short time windows, a weighted sum of the trend index and its derivative detects the trend episodes and severity of the trend is estimated by including also the variable level in the sum. The trend index, trend episodes and especially, the deviation index reveal early evolving changes in the operating conditions, including cloudiness and load disturbances. The solution is highly compact: all variables, features and indices are transformed to the range [-2, 2] and represented in natural language which is important in integrating data-driven solutions with domain expertise. The special situations detected during the test campaigns are explained well.

Toddle temporal-spatial deviation index: Assessment of pediatric gait.

PubMed

Cahill-Rowley, Katelyn; Rose, Jessica

2016-09-01

This research aims to develop a gait index for use in the pediatric clinic as well as research, that quantifies gait deviation in 18-22 month-old children: the Toddle Temporal-spatial Deviation Index (Toddle TDI). 81 preterm children (≤32 weeks) with very-low-birth-weights (≤1500g) and 42 full-term TD children aged 18-22 months, adjusted for prematurity, walked on a pressure-sensitive mat. Preterm children were administered the Bayley Scales of Infant Development-3rd Edition (BSID-III). Principle component analysis of TD children's temporal-spatial gait parameters quantified raw gait deviation from typical, normalized to an average(standard deviation) Toddle TDI score of 100(10), and calculated for all participants. The Toddle TDI was significantly lower for preterm versus TD children (86 vs. 100, p=0.003), and lower in preterm children with <85 vs. ≥85 BSID-III motor composite scores (66 vs. 89, p=0.004). The Toddle TDI, which by design plateaus at typical average (BSID-III gross motor 8-12), correlated with BSID-III gross motor (r=0.60, p<0.001) and not fine motor (r=0.08, p=0.65) in preterm children with gross motor scores ≤8, suggesting sensitivity to gross motor development. The Toddle TDI demonstrated sensitivity and specificity to gross motor function in very-low-birth-weight preterm children aged 18-22 months, and has been potential as an easily-administered, revealing clinical gait metric. Copyright © 2016 Elsevier B.V. All rights reserved.

Visual field changes after cataract extraction: the AGIS experience.

PubMed

Koucheki, Behrooz; Nouri-Mahdavi, Kouros; Patel, Gitane; Gaasterland, Douglas; Caprioli, Joseph

2004-12-01

To test the hypothesis that cataract extraction in glaucomatous eyes improves overall sensitivity of visual function without affecting the size or depth of glaucomatous scotomas. Experimental study with no control group. One hundred fifty-eight eyes (of 140 patients) from the Advanced Glaucoma Intervention Study with at least two reliable visual fields within a year both before and after cataract surgery were included. Average mean deviation (MD), pattern standard deviation (PSD), and corrected pattern standard deviation (CPSD) were compared before and after cataract extraction. To evaluate changes in scotoma size, the number of abnormal points (P < .05) on the pattern deviation plot was compared before and after surgery. We described an index ("scotoma depth index") to investigate changes of scotoma depth after surgery. Mean values for MD, PSD, and CPSD were -13.2, 6.4, and 5.9 dB before and -11.9, 6.8, and 6.2 dB after cataract surgery (P < or = .001 for all comparisons). Mean (+/- SD) number of abnormal points on pattern deviation plot was 26.7 +/- 9.4 and 27.5 +/- 9.0 before and after cataract surgery, respectively (P = .02). Scotoma depth index did not change after cataract extraction (-19.3 vs -19.2 dB, P = .90). Cataract extraction caused generalized improvement of the visual field, which was most marked in eyes with less advanced glaucomatous damage. Although the enlargement of scotomas was statistically significant, it was not clinically meaningful. No improvement of sensitivity was observed in the deepest part of the scotomas.

The association of very-low-density lipoprotein with ankle-brachial index in peritoneal dialysis patients with controlled serum low-density lipoprotein cholesterol level

PubMed Central

2013-01-01

Background Peripheral artery disease (PAD) represents atherosclerotic disease and is a risk factor for death in peritoneal dialysis (PD) patients, who tend to show an atherogenic lipid profile. In this study, we investigated the relationship between lipid profile and ankle-brachial index (ABI) as an index of atherosclerosis in PD patients with controlled serum low-density lipoprotein (LDL) cholesterol level. Methods Thirty-five PD patients, whose serum LDL cholesterol level was controlled at less than 120mg/dl, were enrolled in this cross-sectional study in Japan. The proportions of cholesterol level to total cholesterol level (cholesterol proportion) in 20 lipoprotein fractions and the mean size of lipoprotein particles were measured using an improved method, namely, high-performance gel permeation chromatography. Multivariate linear regression analysis was adjusted for diabetes mellitus and cardiovascular and/or cerebrovascular diseases. Results The mean (standard deviation) age was 61.6 (10.5) years; PD vintage, 38.5 (28.1) months; ABI, 1.07 (0.22). A low ABI (0.9 or lower) was observed in 7 patients (low-ABI group). The low-ABI group showed significantly higher cholesterol proportions in the chylomicron fraction and large very-low-density lipoproteins (VLDLs) (Fractions 3–5) than the high-ABI group (ABI>0.9). Adjusted multivariate linear regression analysis showed that ABI was negatively associated with serum VLDL cholesterol level (parameter estimate=-0.00566, p=0.0074); the cholesterol proportions in large VLDLs (Fraction 4, parameter estimate=-3.82, p=0.038; Fraction 5, parameter estimate=-3.62, p=0.0039) and medium VLDL (Fraction 6, parameter estimate=-3.25, p=0.014); and the size of VLDL particles (parameter estimate=-0.0352, p=0.032). Conclusions This study showed that the characteristics of VLDL particles were associated with ABI among PD patients. Lowering serum VLDL level may be an effective therapy against atherosclerosis in PD patients after the control of serum LDL cholesterol level. PMID:24093487

Weibull Modulus Estimated by the Non-linear Least Squares Method: A Solution to Deviation Occurring in Traditional Weibull Estimation

NASA Astrophysics Data System (ADS)

Li, T.; Griffiths, W. D.; Chen, J.

2017-11-01

The Maximum Likelihood method and the Linear Least Squares (LLS) method have been widely used to estimate Weibull parameters for reliability of brittle and metal materials. In the last 30 years, many researchers focused on the bias of Weibull modulus estimation, and some improvements have been achieved, especially in the case of the LLS method. However, there is a shortcoming in these methods for a specific type of data, where the lower tail deviates dramatically from the well-known linear fit in a classic LLS Weibull analysis. This deviation can be commonly found from the measured properties of materials, and previous applications of the LLS method on this kind of dataset present an unreliable linear regression. This deviation was previously thought to be due to physical flaws ( i.e., defects) contained in materials. However, this paper demonstrates that this deviation can also be caused by the linear transformation of the Weibull function, occurring in the traditional LLS method. Accordingly, it may not be appropriate to carry out a Weibull analysis according to the linearized Weibull function, and the Non-linear Least Squares method (Non-LS) is instead recommended for the Weibull modulus estimation of casting properties.

Sample sizes needed for specified margins of relative error in the estimates of the repeatability and reproducibility standard deviations.

PubMed

McClure, Foster D; Lee, Jung K

2005-01-01

Sample size formulas are developed to estimate the repeatability and reproducibility standard deviations (Sr and S(R)) such that the actual error in (Sr and S(R)) relative to their respective true values, sigmar and sigmaR, are at predefined levels. The statistical consequences associated with AOAC INTERNATIONAL required sample size to validate an analytical method are discussed. In addition, formulas to estimate the uncertainties of (Sr and S(R)) were derived and are provided as supporting documentation. Formula for the Number of Replicates Required for a Specified Margin of Relative Error in the Estimate of the Repeatability Standard Deviation.

The braking index of a radio-quiet gamma-ray pulsar

DOE PAGES

Clark, C. J.; Pletsch, H. J.; Wu, J.; ...

2016-11-16

Here, we report the discovery and timing measurements of PSR J1208-6238, a young and highly magnetized gamma-ray pulsar, with a spin period of 440 ms. The pulsar was discovered in gamma-ray photon data from the Fermi Large Area Telescope (LAT) during a blind-search survey of unidentified LAT sources, running on the distributed volunteer computing system Einstein@Home. No radio pulsations were detected in dedicated follow-up searches with the Parkes radio telescope, with a flux density upper limit at 1369 MHz of 30 μJy. Furthermore, by timing this pulsar's gamma-ray pulsations, we measure its braking index over five years of LAT observationsmore » to be n = 2.598 ± 0.001 ± 0.1, where the first uncertainty is statistical and the second estimates the bias due to timing noise. Assuming its braking index has been similar since birth, the pulsar has an estimated age of around 2700 years, making it the youngest pulsar to be found in a blind search of gamma-ray data and the youngest known radio-quiet gamma-ray pulsar. Despite its young age, the pulsar is not associated with any known supernova remnant or pulsar wind nebula. The pulsar's inferred dipolar surface magnetic field strength is 3.8 × 10 13 G, almost 90% of the quantum-critical level. Finally, we investigate some potential physical causes of the braking index deviating from the simple dipole model but find that LAT data covering a longer time interval will be necessary to distinguish between these.« less

Experiments with central-limit properties of spatial samples from locally covariant random fields

USGS Publications Warehouse

Barringer, T.H.; Smith, T.E.

1992-01-01

When spatial samples are statistically dependent, the classical estimator of sample-mean standard deviation is well known to be inconsistent. For locally dependent samples, however, consistent estimators of sample-mean standard deviation can be constructed. The present paper investigates the sampling properties of one such estimator, designated as the tau estimator of sample-mean standard deviation. In particular, the asymptotic normality properties of standardized sample means based on tau estimators are studied in terms of computer experiments with simulated sample-mean distributions. The effects of both sample size and dependency levels among samples are examined for various value of tau (denoting the size of the spatial kernel for the estimator). The results suggest that even for small degrees of spatial dependency, the tau estimator exhibits significantly stronger normality properties than does the classical estimator of standardized sample means. ?? 1992.

Variation in the standard deviation of the lure rating distribution: Implications for estimates of recollection probability.

PubMed

Dopkins, Stephen; Varner, Kaitlin; Hoyer, Darin

2017-10-01

In word recognition semantic priming of test words increased the false-alarm rate and the mean of confidence ratings to lures. Such priming also increased the standard deviation of confidence ratings to lures and the slope of the z-ROC function, suggesting that the priming increased the standard deviation of the lure evidence distribution. The Unequal Variance Signal Detection (UVSD) model interpreted the priming as increasing the standard deviation of the lure evidence distribution. Without additional parameters the Dual Process Signal Detection (DPSD) model could only accommodate the results by fitting the data for related and unrelated primes separately, interpreting the priming, implausibly, as decreasing the probability of target recollection (DPSD). With an additional parameter, for the probability of false (lure) recollection the model could fit the data for related and unrelated primes together, interpreting the priming as increasing the probability of false recollection. These results suggest that DPSD estimates of target recollection probability will decrease with increases in the lure confidence/evidence standard deviation unless a parameter is included for false recollection. Unfortunately the size of a given lure confidence/evidence standard deviation relative to other possible lure confidence/evidence standard deviations is often unspecified by context. Hence the model often has no way of estimating false recollection probability and thereby correcting its estimates of target recollection probability.

Evaluating Silent Reading Performance with an Eye Tracking System in Patients with Glaucoma

PubMed Central

Murata, Noriaki; Fukuchi, Takeo

2017-01-01

Objective To investigate the relationship between silent reading performance and visual field defects in patients with glaucoma using an eye tracking system. Methods Fifty glaucoma patients (Group G; mean age, 52.2 years, standard deviation: 11.4 years) and 20 normal controls (Group N; mean age, 46.9 years; standard deviation: 17.2 years) were included in the study. All participants in Group G had early to advanced glaucomatous visual field defects but better than 20/20 visual acuity in both eyes. Participants silently read Japanese articles written horizontally while the eye tracking system monitored and calculated reading duration per 100 characters, number of fixations per 100 characters, and mean fixation duration, which were compared with mean deviation and visual field index values from Humphrey visual field testing (24–2 and 10–2 Swedish interactive threshold algorithm standard) of the right versus left eye and the better versus worse eye. Results There was a statistically significant difference between Groups G and N in mean fixation duration (G, 233.4 msec; N, 215.7 msec; P = 0.010). Within Group G, significant correlations were observed between reading duration and 24–2 right mean deviation (rs = -0.280, P = 0.049), 24–2 right visual field index (rs = -0.306, P = 0.030), 24–2 worse visual field index (rs = -0.304, P = 0.032), and 10–2 worse mean deviation (rs = -0.326, P = 0.025). Significant correlations were observed between mean fixation duration and 10–2 left mean deviation (rs = -0.294, P = 0.045) and 10–2 worse mean deviation (rs = -0.306, P = 0.037), respectively. Conclusions The severity of visual field defects may influence some aspects of reading performance. At least concerning silent reading, the visual field of the worse eye is an essential element of smoothness of reading. PMID:28095478

Quantitative metrics for evaluating parallel acquisition techniques in diffusion tensor imaging at 3 Tesla.

PubMed

Ardekani, Siamak; Selva, Luis; Sayre, James; Sinha, Usha

2006-11-01

Single-shot echo-planar based diffusion tensor imaging is prone to geometric and intensity distortions. Parallel imaging is a means of reducing these distortions while preserving spatial resolution. A quantitative comparison at 3 T of parallel imaging for diffusion tensor images (DTI) using k-space (generalized auto-calibrating partially parallel acquisitions; GRAPPA) and image domain (sensitivity encoding; SENSE) reconstructions at different acceleration factors, R, is reported here. Images were evaluated using 8 human subjects with repeated scans for 2 subjects to estimate reproducibility. Mutual information (MI) was used to assess the global changes in geometric distortions. The effects of parallel imaging techniques on random noise and reconstruction artifacts were evaluated by placing 26 regions of interest and computing the standard deviation of apparent diffusion coefficient and fractional anisotropy along with the error of fitting the data to the diffusion model (residual error). The larger positive values in mutual information index with increasing R values confirmed the anticipated decrease in distortions. Further, the MI index of GRAPPA sequences for a given R factor was larger than the corresponding mSENSE images. The residual error was lowest in the images acquired without parallel imaging and among the parallel reconstruction methods, the R = 2 acquisitions had the least error. The standard deviation, accuracy, and reproducibility of the apparent diffusion coefficient and fractional anisotropy in homogenous tissue regions showed that GRAPPA acquired with R = 2 had the least amount of systematic and random noise and of these, significant differences with mSENSE, R = 2 were found only for the fractional anisotropy index. Evaluation of the current implementation of parallel reconstruction algorithms identified GRAPPA acquired with R = 2 as optimal for diffusion tensor imaging.

A study comparison of two system model performance in estimated lifted index over Indonesia.

NASA Astrophysics Data System (ADS)

lestari, Juliana tri; Wandala, Agie

2018-05-01

Lifted index (LI) is one of atmospheric stability indices that used for thunderstorm forecasting. Numerical weather Prediction Models are essential for accurate weather forecast these day. This study has completed the attempt to compare the two NWP models these are Weather Research Forecasting (WRF) model and Global Forecasting System (GFS) model in estimates LI at 20 locations over Indonesia and verified the result with observation. Taylor diagram was used to comparing the models skill with shown the value of standard deviation, coefficient correlation and Root mean square error (RMSE). This study using the dataset on 00.00 UTC and 12.00 UTC during mid-March to Mid-April 2017. From the sample of LI distributions, both models have a tendency to overestimated LI value in almost all region in Indonesia while the WRF models has the better ability to catch the LI pattern distribution with observation than GFS model has. The verification result shows how both WRF and GFS model have such a weak relationship with observation except Eltari meteorologi station that its coefficient correlation reach almost 0.6 with the low RMSE value. Mean while WRF model have a better performance than GFS model. This study suggest that estimated LI of WRF model can provide the good performance for Thunderstorm forecasting over Indonesia in the future. However unsufficient relation between output models and observation in the certain location need a further investigation.

A head motion estimation algorithm for motion artifact correction in dental CT imaging

NASA Astrophysics Data System (ADS)

Hernandez, Daniel; Elsayed Eldib, Mohamed; Hegazy, Mohamed A. A.; Hye Cho, Myung; Cho, Min Hyoung; Lee, Soo Yeol

2018-03-01

A small head motion of the patient can compromise the image quality in a dental CT, in which a slow cone-beam scan is adopted. We introduce a retrospective head motion estimation method by which we can estimate the motion waveform from the projection images without employing any external motion monitoring devices. We compute the cross-correlation between every two successive projection images, which results in a sinusoid-like displacement curve over the projection view when there is no patient motion. However, the displacement curve deviates from the sinusoid-like form when patient motion occurs. We develop a method to estimate the motion waveform with a single parameter derived from the displacement curve with aid of image entropy minimization. To verify the motion estimation method, we use a lab-built micro-CT that can emulate major head motions during dental CT scans, such as tilting and nodding, in a controlled way. We find that the estimated motion waveform conforms well to the actual motion waveform. To further verify the motion estimation method, we correct the motion artifacts with the estimated motion waveform. After motion artifact correction, the corrected images look almost identical to the reference images, with structural similarity index values greater than 0.81 in the phantom and rat imaging studies.

Modeling returns volatility: Realized GARCH incorporating realized risk measure

NASA Astrophysics Data System (ADS)

Jiang, Wei; Ruan, Qingsong; Li, Jianfeng; Li, Ye

2018-06-01

This study applies realized GARCH models by introducing several risk measures of intraday returns into the measurement equation, to model the daily volatility of E-mini S&P 500 index futures returns. Besides using the conventional realized measures, realized volatility and realized kernel as our benchmarks, we also use generalized realized risk measures, realized absolute deviation, and two realized tail risk measures, realized value-at-risk and realized expected shortfall. The empirical results show that realized GARCH models using the generalized realized risk measures provide better volatility estimation for the in-sample and substantial improvement in volatility forecasting for the out-of-sample. In particular, the realized expected shortfall performs best for all of the alternative realized measures. Our empirical results reveal that future volatility may be more attributable to present losses (risk measures). The results are robust to different sample estimation windows.

More reliable inference for the dissimilarity index of segregation

PubMed Central

Allen, Rebecca; Burgess, Simon; Davidson, Russell; Windmeijer, Frank

2015-01-01

Summary The most widely used measure of segregation is the so‐called dissimilarity index. It is now well understood that this measure also reflects randomness in the allocation of individuals to units (i.e. it measures deviations from evenness, not deviations from randomness). This leads to potentially large values of the segregation index when unit sizes and/or minority proportions are small, even if there is no underlying systematic segregation. Our response to this is to produce adjustments to the index, based on an underlying statistical model. We specify the assignment problem in a very general way, with differences in conditional assignment probabilities underlying the resulting segregation. From this, we derive a likelihood ratio test for the presence of any systematic segregation, and bias adjustments to the dissimilarity index. We further develop the asymptotic distribution theory for testing hypotheses concerning the magnitude of the segregation index and show that the use of bootstrap methods can improve the size and power properties of test procedures considerably. We illustrate these methods by comparing dissimilarity indices across school districts in England to measure social segregation. PMID:27774035

Random errors in interferometry with the least-squares method

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

Wang Qi

2011-01-20

This investigation analyzes random errors in interferometric surface profilers using the least-squares method when random noises are present. Two types of random noise are considered here: intensity noise and position noise. Two formulas have been derived for estimating the standard deviations of the surface height measurements: one is for estimating the standard deviation when only intensity noise is present, and the other is for estimating the standard deviation when only position noise is present. Measurements on simulated noisy interferometric data have been performed, and standard deviations of the simulated measurements have been compared with those theoretically derived. The relationships havemore » also been discussed between random error and the wavelength of the light source and between random error and the amplitude of the interference fringe.« less

Estimation of inflation parameters for Perturbed Power Law model using recent CMB measurements

NASA Astrophysics Data System (ADS)

Mukherjee, Suvodip; Das, Santanu; Joy, Minu; Souradeep, Tarun

2015-01-01

Cosmic Microwave Background (CMB) is an important probe for understanding the inflationary era of the Universe. We consider the Perturbed Power Law (PPL) model of inflation which is a soft deviation from Power Law (PL) inflationary model. This model captures the effect of higher order derivative of Hubble parameter during inflation, which in turn leads to a non-zero effective mass meff for the inflaton field. The higher order derivatives of Hubble parameter at leading order sources constant difference in the spectral index for scalar and tensor perturbation going beyond PL model of inflation. PPL model have two observable independent parameters, namely spectral index for tensor perturbation νt and change in spectral index for scalar perturbation νst to explain the observed features in the scalar and tensor power spectrum of perturbation. From the recent measurements of CMB power spectra by WMAP, Planck and BICEP-2 for temperature and polarization, we estimate the feasibility of PPL model with standard ΛCDM model. Although BICEP-2 claimed a detection of r=0.2, estimates of dust contamination provided by Planck have left open the possibility that only upper bound on r will be expected in a joint analysis. As a result we consider different upper bounds on the value of r and show that PPL model can explain a lower value of tensor to scalar ratio (r<0.1 or r<0.01) for a scalar spectral index of ns=0.96 by having a non-zero value of effective mass of the inflaton field m2eff/H2. The analysis with WP + Planck likelihood shows a non-zero detection of m2eff/H2 with 5.7 σ and 8.1 σ respectively for r<0.1 and r<0.01. Whereas, with BICEP-2 likelihood m2eff/H2 = -0.0237 ± 0.0135 which is consistent with zero.

Reliability Analysis and Reliability-Based Design Optimization of Circular Composite Cylinders Under Axial Compression

NASA Technical Reports Server (NTRS)

Rais-Rohani, Masoud

2001-01-01

This report describes the preliminary results of an investigation on component reliability analysis and reliability-based design optimization of thin-walled circular composite cylinders with average diameter and average length of 15 inches. Structural reliability is based on axial buckling strength of the cylinder. Both Monte Carlo simulation and First Order Reliability Method are considered for reliability analysis with the latter incorporated into the reliability-based structural optimization problem. To improve the efficiency of reliability sensitivity analysis and design optimization solution, the buckling strength of the cylinder is estimated using a second-order response surface model. The sensitivity of the reliability index with respect to the mean and standard deviation of each random variable is calculated and compared. The reliability index is found to be extremely sensitive to the applied load and elastic modulus of the material in the fiber direction. The cylinder diameter was found to have the third highest impact on the reliability index. Also the uncertainty in the applied load, captured by examining different values for its coefficient of variation, is found to have a large influence on cylinder reliability. The optimization problem for minimum weight is solved subject to a design constraint on element reliability index. The methodology, solution procedure and optimization results are included in this report.

The influence of temperature to a refractive index sensor based on a macro-bending tapered plastic optical fiber

NASA Astrophysics Data System (ADS)

Teng, Chuan-xin; Yu, Fang-da; Jing, Ning; Zheng, Jie

2016-09-01

The temperature influence to a refractive index (RI) sensor based on a macro-bending tapered plastic optical fiber (POF) was investigated experimentally. The total temperature dependence loss (TDLtotal) and total temperature dependence RI deviation (TDRtotal) were measured at different temperature (10-60 °C) over an RI range of 1.33-1.41. The temperature dependence RI deviation of the sensor itself was obtained by subtracting the temperature dependence RI of measured liquid from TDRtotal. Therefore, the influence of temperature variation to the sensor was characterized and corrected.

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

Clark, C. J.; Pletsch, H. J.; Wu, J.

Here, we report the discovery and timing measurements of PSR J1208-6238, a young and highly magnetized gamma-ray pulsar, with a spin period of 440 ms. The pulsar was discovered in gamma-ray photon data from the Fermi Large Area Telescope (LAT) during a blind-search survey of unidentified LAT sources, running on the distributed volunteer computing system Einstein@Home. No radio pulsations were detected in dedicated follow-up searches with the Parkes radio telescope, with a flux density upper limit at 1369 MHz of 30 μJy. Furthermore, by timing this pulsar's gamma-ray pulsations, we measure its braking index over five years of LAT observationsmore » to be n = 2.598 ± 0.001 ± 0.1, where the first uncertainty is statistical and the second estimates the bias due to timing noise. Assuming its braking index has been similar since birth, the pulsar has an estimated age of around 2700 years, making it the youngest pulsar to be found in a blind search of gamma-ray data and the youngest known radio-quiet gamma-ray pulsar. Despite its young age, the pulsar is not associated with any known supernova remnant or pulsar wind nebula. The pulsar's inferred dipolar surface magnetic field strength is 3.8 × 10 13 G, almost 90% of the quantum-critical level. Finally, we investigate some potential physical causes of the braking index deviating from the simple dipole model but find that LAT data covering a longer time interval will be necessary to distinguish between these.« less

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

Clark, C. J.; Pletsch, H. J.; Allen, B.

We report the discovery and timing measurements of PSR J1208−6238, a young and highly magnetized gamma-ray pulsar, with a spin period of 440 ms. The pulsar was discovered in gamma-ray photon data from the Fermi Large Area Telescope (LAT) during a blind-search survey of unidentified LAT sources, running on the distributed volunteer computing system Einstein@Home . No radio pulsations were detected in dedicated follow-up searches with the Parkes radio telescope, with a flux density upper limit at 1369 MHz of 30 μ Jy. By timing this pulsar’s gamma-ray pulsations, we measure its braking index over five years of LAT observationsmore » to be n = 2.598 ± 0.001 ± 0.1, where the first uncertainty is statistical and the second estimates the bias due to timing noise. Assuming its braking index has been similar since birth, the pulsar has an estimated age of around 2700 years, making it the youngest pulsar to be found in a blind search of gamma-ray data and the youngest known radio-quiet gamma-ray pulsar. Despite its young age, the pulsar is not associated with any known supernova remnant or pulsar wind nebula. The pulsar’s inferred dipolar surface magnetic field strength is 3.8 × 10{sup 13} G, almost 90% of the quantum-critical level. We investigate some potential physical causes of the braking index deviating from the simple dipole model but find that LAT data covering a longer time interval will be necessary to distinguish between these.« less

Two-Component Structure of the Radio Source 0014+813 from VLBI Observations within the CONT14 Program

NASA Astrophysics Data System (ADS)

Titov, O. A.; Lopez, Yu. R.

2018-03-01

We consider a method of reconstructing the structure delay of extended radio sources without constructing their radio images. The residuals derived after the adjustment of geodetic VLBI observations are used for this purpose. We show that the simplest model of a radio source consisting of two point components can be represented by four parameters (the angular separation of the components, the mutual orientation relative to the poleward direction, the flux-density ratio, and the spectral index difference) that are determined for each baseline of a multi-baseline VLBI network. The efficiency of this approach is demonstrated by estimating the coordinates of the radio source 0014+813 observed during the two-week CONT14 program organized by the International VLBI Service (IVS) in May 2014. Large systematic deviations have been detected in the residuals of the observations for the radio source 0014+813. The averaged characteristics of the radio structure of 0014+813 at a frequency of 8.4 GHz can be calculated from these deviations. Our modeling using four parameters has confirmed that the source consists of two components at an angular separation of 0.5 mas in the north-south direction. Using the structure delay when adjusting the CONT14 observations leads to a correction of the average declination estimate for the radio source 0014+813 by 0.070 mas.

New concept for a toxicity assay based on multiple indexes from the wave shape of damped metabolic oscillation induced in living yeast cells (part I): characterization of the phenomenon.

PubMed

Nakamura, H; Suzuki, M

2007-10-01

The damped glycolytic oscillation phenomenon occurring in starved cells of the yeast Saccharomyces cerevisiae (NBRC 0565) was characterization for application to a toxicity bioassay. S. cerevisiae was grown under semi-anaerobic conditions. The transient oscillations were observed photometrically as the time course of the fluorescent intensity of reduced pyridine nucleotide resulting from instantaneous addition of glucose to a cell suspension. In this study, simple and reproducible conditions inducing damped oscillations were obtained by modifying a literature method. For estimation of the wave shapes of the damped oscillations we used six indexes. To investigate the total reproducibility as the averaged relative standard deviation (RSD(av)) for the six indexes obtained from the wave shapes, the damped oscillations were induced under the optimum conditions and the RSD(av) values were calculated as 14% in a buffer cell suspension (n = 62) and 22% in a water cell suspension (n = 78). Finally, the effects of glucose concentration on the six indexes were examined, and all the indexes changed when the glucose concentration was changed. Excellent correlations were obtained between the index of oscillation-state time and the concentration of glucose in a buffer cell suspension (r = 0.9985, 0.5-250 mmol L(-1), 10 points) and in a water cell suspension (r = 0.9989, 2.5 micromol L(-1)-250 mmol L(-1), 12 points), respectively.

Static Scene Statistical Non-Uniformity Correction

DTIC Science & Technology

2015-03-01

Error NUC Non-Uniformity Correction RMSE Root Mean Squared Error RSD Relative Standard Deviation S3NUC Static Scene Statistical Non-Uniformity...Deviation ( RSD ) which normalizes the standard deviation, σ, to the mean estimated value, µ using the equation RS D = σ µ × 100. The RSD plot of the gain...estimates is shown in Figure 4.1(b). The RSD plot shows that after a sample size of approximately 10, the different photocount values and the inclusion

Eigenvalue density of cross-correlations in Sri Lankan financial market

NASA Astrophysics Data System (ADS)

Nilantha, K. G. D. R.; Ranasinghe; Malmini, P. K. C.

2007-05-01

We apply the universal properties with Gaussian orthogonal ensemble (GOE) of random matrices namely spectral properties, distribution of eigenvalues, eigenvalue spacing predicted by random matrix theory (RMT) to compare cross-correlation matrix estimators from emerging market data. The daily stock prices of the Sri Lankan All share price index and Milanka price index from August 2004 to March 2005 were analyzed. Most eigenvalues in the spectrum of the cross-correlation matrix of stock price changes agree with the universal predictions of RMT. We find that the cross-correlation matrix satisfies the universal properties of the GOE of real symmetric random matrices. The eigen distribution follows the RMT predictions in the bulk but there are some deviations at the large eigenvalues. The nearest-neighbor spacing and the next nearest-neighbor spacing of the eigenvalues were examined and found that they follow the universality of GOE. RMT with deterministic correlations found that each eigenvalue from deterministic correlations is observed at values, which are repelled from the bulk distribution.

Estimation of optical properties of aerosols and bidirectional reflectance from PARASOL/POLDER data over land

NASA Astrophysics Data System (ADS)

Kusaka, Takashi; Miyazaki, Go

2014-10-01

When monitoring target areas covered with vegetation from a satellite, it is very useful to estimate the vegetation index using the surface anisotropic reflectance, which is dependent on both solar and viewing geometries, from satellite data. In this study, the algorithm for estimating optical properties of atmospheric aerosols such as the optical thickness (τ), the refractive index (Nr), the mixing ratio of small particles in the bimodal log-normal distribution function (C) and the bidirectional reflectance (R) from only the radiance and polarization at the 865nm channel received by the PARASOL/POLDER is described. Parameters of the bimodal log-normal distribution function: mean radius, r1, standard deviation, σ1, of fine aerosols, and r2, σ2 of coarse aerosols were fixed, and these values were estimated from monthly averaged size distribution at AERONET sites managed by NASA near the target area. Moreover, it is assumed that the contribution of the surface reflectance with directional anisotropy to the polarized radiance received by the satellite is small because it is shown from our ground-based polarization measurements of light ray reflected by the grassland that degrees of polarization of the reflected light by the grassland are very low values at the 865nm channel. First aerosol properties were estimated from only the polarized radiance and then the bidirectional reflectance given by the Ross-Li BRDF model was estimated from only the total radiance at target areas in PARASOL/POLDER data over the Japanese islands taken on April 28, 2012 and April 25, 2010. The estimated optical thickness of aerosols was checked with those given in AERONET sites and the estimated parameters of BRDF were compared with those of vegetation measured from the radio-controlled helicopter. Consequently, it is shown that the algorithm described in the present study provides reasonable values for aerosol properties and surface bidirectional reflectance.

How random is a random vector?

NASA Astrophysics Data System (ADS)

Eliazar, Iddo

2015-12-01

Over 80 years ago Samuel Wilks proposed that the "generalized variance" of a random vector is the determinant of its covariance matrix. To date, the notion and use of the generalized variance is confined only to very specific niches in statistics. In this paper we establish that the "Wilks standard deviation" -the square root of the generalized variance-is indeed the standard deviation of a random vector. We further establish that the "uncorrelation index" -a derivative of the Wilks standard deviation-is a measure of the overall correlation between the components of a random vector. Both the Wilks standard deviation and the uncorrelation index are, respectively, special cases of two general notions that we introduce: "randomness measures" and "independence indices" of random vectors. In turn, these general notions give rise to "randomness diagrams"-tangible planar visualizations that answer the question: How random is a random vector? The notion of "independence indices" yields a novel measure of correlation for Lévy laws. In general, the concepts and results presented in this paper are applicable to any field of science and engineering with random-vectors empirical data.

Influence of electrocautery-induced electromagnetic interference on quantitative electroencephalographic monitoring of hypnosis during general anesthesia: comparison between the ADMS® and the BIS VISTATM.

PubMed

Kim, Dae-Hee; Yoo, Ji-Young; Kim, Jong-Yeop; Ahn, Soo-Hwan; Kim, Seongsu; Min, Sang-Kee

2018-04-24

Hypnosis monitors analyze small-amplitude electrical signals transmitted from the brain that could be exposed to the electromagnetic field that occurs around the body during electrocautery (ECT). We investigated the influence of ECT on hypnosis monitoring during anesthesia. We simultaneously monitored BIS and uCON during 50 gynecologic oncology surgeries. During the episodes of ECT, we compared the absolute difference (a-Diff) between the baseline index and the most deviated index after ECT over either 30-60 s (ECT30-60) or more than 60 s (ECT > 60) between the monitors. We also investigated the bias and the limits of agreement between the monitors. Between the two monitors, the a-Diff of ECT30-60 was 1.4 ± 1.1 for the BIS, which was significantly greater than 0.6 ± 0.9 for the uCON (P = 0.003), and the a-Diff of ECT > 60 was 16.5 ± 8.2 for the BIS, which was also significantly greater than 1.4 ± 1.3 for uCON (P < 0.001). The intra-monitor index differences showed that the BIS during ECT > 60 was significantly greater than that during ECT30-60 (P < 0.001), but the uCON showed no significant difference between ECT30-60 and ECT > 60 (P = 0.056). The estimated bias between the monitors was 6.3 ± 9.8 and 95% limits agreement was -12.3 to 25.0. Prolonged ECT intervention might lead to spurious estimations of quantitative EEG indexes. Therefore, hypnosis should be clinically assessed in combination with scrutinized judgment of relevant clinical symptoms and signs for hypnosis.

Sleep stage classification by body movement index and respiratory interval indices using multiple radar sensors.

PubMed

Kagawa, Masayuki; Sasaki, Noriyuki; Suzumura, Kazuki; Matsui, Takemi

2015-01-01

Disturbed sleep has become more common in recent years. To increase the quality of sleep, undergoing sleep observation has gained interest as an attempt to resolve possible problems. In this paper, we evaluate a non-restrictive and non-contact method for classifying real-time sleep stages and report on its potential applications. The proposed system measures body movements and respiratory signals of a sleeping person using a multiple 24-GHz microwave radar placed beneath the mattress. We determined a body-movement index to identify wake and sleep periods, and fluctuation indices of respiratory intervals to identify sleep stages. For identifying wake and sleep periods, the rate agreement between the body-movement index and the reference result using the R&K method was 83.5 ± 6.3%. One-minute standard deviations, one of the fluctuation indices of respiratory intervals, had a high degree of contribution and showed a significant difference across the three sleep stages (REM, LIGHT, and DEEP; p <; 0.001). Although the degree that the 5-min fractal dimension contributed-another fluctuation index-was not as high as expected, its difference between REM and DEEP sleep was significant (p <; 0.05). We applied a linear discriminant function to classify wake or sleep periods and to estimate the three sleep stages. The accuracy was 79.3% for classification and 71.9% for estimation. This is a novel system for measuring body movements and body-surface movements that are induced by respiration and for measuring high sensitivity pulse waves using multiple radar signals. This method simplifies measurement of sleep stages and may be employed at nursing care facilities or by the general public to increase sleep quality.

A Squeezed Artificial Neural Network for the Symbolic Network Reliability Functions of Binary-State Networks.

PubMed

Yeh, Wei-Chang

Network reliability is an important index to the provision of useful information for decision support in the modern world. There is always a need to calculate symbolic network reliability functions (SNRFs) due to dynamic and rapid changes in network parameters. In this brief, the proposed squeezed artificial neural network (SqANN) approach uses the Monte Carlo simulation to estimate the corresponding reliability of a given designed matrix from the Box-Behnken design, and then the Taguchi method is implemented to find the appropriate number of neurons and activation functions of the hidden layer and the output layer in ANN to evaluate SNRFs. According to the experimental results of the benchmark networks, the comparison appears to support the superiority of the proposed SqANN method over the traditional ANN-based approach with at least 16.6% improvement in the median absolute deviation in the cost of extra 2 s on average for all experiments.Network reliability is an important index to the provision of useful information for decision support in the modern world. There is always a need to calculate symbolic network reliability functions (SNRFs) due to dynamic and rapid changes in network parameters. In this brief, the proposed squeezed artificial neural network (SqANN) approach uses the Monte Carlo simulation to estimate the corresponding reliability of a given designed matrix from the Box-Behnken design, and then the Taguchi method is implemented to find the appropriate number of neurons and activation functions of the hidden layer and the output layer in ANN to evaluate SNRFs. According to the experimental results of the benchmark networks, the comparison appears to support the superiority of the proposed SqANN method over the traditional ANN-based approach with at least 16.6% improvement in the median absolute deviation in the cost of extra 2 s on average for all experiments.

Multi- and monofractal indices of short-term heart rate variability.

PubMed

Fischer, R; Akay, M; Castiglioni, P; Di Rienzo, M

2003-09-01

Indices of heart rate variability (HRV) based on fractal signal models have recently been shown to possess value as predictors of mortality in specific patient populations. To develop more powerful clinical indices of HRV based on a fractal signal model, the study investigated two HRV indices based on a monofractal signal model called fractional Brownian motion and an index based on a multifractal signal model called multifractional Brownian motion. The performance of the indices was compared with an HRV index in common clinical use. To compare the indices, 18 normal subjects were subjected to postural changes, and the indices were compared on their ability to respond to the resulting autonomic events in HRV recordings. The magnitude of the response to postural change (normalised by the measurement variability) was assessed by analysis of variance and multiple comparison testing. Four HRV indices were investigated for this study: the standard deviation of all normal R-R intervals; an HRV index commonly used in the clinic; detrended fluctuation analysis, an HRV index found to be the most powerful predictor of mortality in a study of patients with depressed left ventricular function; an HRV index developed using the maximum likelihood estimation (MLE) technique for a monofractal signal model; and an HRV index developed for the analysis of multifractional Brownian motion signals. The HRV index based on the MLE technique was found to respond most strongly to the induced postural changes (95% CI). The magnitude of its response (normalised by the measurement variability) was at least 25% greater than any of the other indices tested.

Investigation of the broadband ELF turbulence by observations of the FAST satellite

NASA Astrophysics Data System (ADS)

Golovchanskaya, I. V.; Kozelov, B. V.; Despirak, I. V.

2012-07-01

Scaling properties of variable electric fields in the topside ionosphere have been investigated on scales s from ˜30 m to 2 km by FAST electric field observations with sample rate of 512 s-1, in sixteen events of the broadband ELF turbulence. It is shown that down to scales of a few hundred meters, the power of turbulent electric fluctuations is a power law, ˜ s α. Scaling index α derived from the slope of logarithmic diagrams (LD) constructed by the discrete wavelet transform of data can be estimated as α = 2.2 ± 0.3, which is close to α estimate earlier reported for scales 1-30 km by electric field observations of the Dynamics Explorer 2 satellite. The behavior of α index is analyzed near the scale of the order of electron inertial length λe = c/ω0 (ω0 being the electron plasma frequency). At altitudes considered (700-2500 km), λe makes 100-900 m. We demonstrate that at scales ≤λe, a decrease of LD slope and deviation from the power law are typically observed. As pointed out in the discussion, this feature cannot be identified as a transition to the diffusion range, where dissipation of the turbulence occurs.

Chlorpyrifos Exposure and Urban Residential Environment Characteristics as Determinants of Early Childhood Neurodevelopment

PubMed Central

Quinn, James W.; Rauh, Virginia A.; Perera, Frederica P.; Andrews, Howard F.; Garfinkel, Robin; Hoepner, Lori; Whyatt, Robin; Rundle, Andrew

2011-01-01

Objectives. We evaluated whether neighborhood characteristics correlated with early neurodevelopment and whether these characteristics confounded the previously reported association between exposure to chlorpyrifos (an organophosphate insecticide) and neurodevelopment. Methods. We obtained prenatal addresses, chlorpyrifos exposure data, and 36-month Psychomotor Development Index (PDI) and Mental Development Index (MDI) scores for a birth cohort in New York City (born 1998–2002). We used data from the 2000 US Census to estimate measures of physical infrastructure, socioeconomic status, crowding, demographic composition, and linguistic isolation for 1-kilometer network areas around each child's prenatal address. Generalized estimating equations were adjusted for demographics, maternal education and IQ, prenatal exposure to tobacco smoke, caretaking environment quality, and building dilapidation. Results. Of 266 children included as participants, 47% were male, 59% were Dominican, and 41% were African American. For each standard deviation higher in neighborhood percent poverty, the PDI score was 2.6 points lower (95% confidence interval [CI] = −3.7, −1.5), and the MDI score was 1.7 points lower (95% CI = −2.6, −0.8). Neighborhood-level confounding of the chlorpyrifos-neurodevelopment association was not apparent. Conclusions. Neighborhood context and chlorpyrifos exposure were independently associated with neurodevelopment, thus providing distinct opportunities for health promotion. PMID:20299657

Attenuation Coefficient Estimation of the Healthy Human Thyroid In Vivo

NASA Astrophysics Data System (ADS)

Rouyer, J.; Cueva, T.; Portal, A.; Yamamoto, T.; Lavarello, R.

Previous studies have demonstrated that attenuation coefficients can be useful towards characterizing thyroid tissues. In this work, ultrasonic attenuation coefficients were estimated from healthy human thyroids in vivo using a clinical scanner. The selected subjects were five young, healthy volunteers (age: 26 ± 6 years old, gender: three females, two males) with no reported history of thyroid diseases, no palpable thyroid nodules, no smoking habits, and body mass index less than 30 kg/m2. Echographic examinations were conducted by a trained sonographer using a SonixTouch system (Ultrasonix Medical Corporation, Richmond, BC) equipped with an L14-5 linear transducer array (nominal center frequency of 10 MHz, transducer footprint of 3.8 cm). Radiofrequency data corresponding to the collected echographic images in both transverse and longitudinal views were digitized at a sampling rate of 40 MHz and processed with Matlab codes (MathWorks, Natick, MA) to estimate attenuation coefficients using the spectral log difference method. The estimation was performed using an analysis bandwidth spanning from 4.0 to 9.0 MHz. The average value of the estimated ultrasonic attenuation coefficients was equal to 1.34 ± 0.15 dB/(cm.MHz). The standard deviation of the estimated average attenuation coefficient across different volunteers suggests a non-negligible inter-subject variability in the ultrasonic attenuation coefficient of the human thyroid.

Estimating Accuracy of Land-Cover Composition From Two-Stage Clustering Sampling

EPA Science Inventory

Land-cover maps are often used to compute land-cover composition (i.e., the proportion or percent of area covered by each class), for each unit in a spatial partition of the region mapped. We derive design-based estimators of mean deviation (MD), mean absolute deviation (MAD), ...

A proof for Rhiel's range estimator of the coefficient of variation for skewed distributions.

PubMed

Rhiel, G Steven

2007-02-01

In this research study is proof that the coefficient of variation (CV(high-low)) calculated from the highest and lowest values in a set of data is applicable to specific skewed distributions with varying means and standard deviations. Earlier Rhiel provided values for d(n), the standardized mean range, and a(n), an adjustment for bias in the range estimator of micro. These values are used in estimating the coefficient of variation from the range for skewed distributions. The d(n) and an values were specified for specific skewed distributions with a fixed mean and standard deviation. In this proof it is shown that the d(n) and an values are applicable for the specific skewed distributions when the mean and standard deviation can take on differing values. This will give the researcher confidence in using this statistic for skewed distributions regardless of the mean and standard deviation.

Estimating active layer thickness and volumetric water content from ground penetrating radar measurements in Barrow, Alaska

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

Jafarov, E. E.; Parsekian, A. D.; Schaefer, K.

Ground penetrating radar (GPR) has emerged as an effective tool for estimating active layer thickness (ALT) and volumetric water content (VWC) within the active layer. In August 2013, we conducted a series of GPR and probing surveys using a 500 MHz antenna and metallic probe around Barrow, Alaska. Here, we collected about 15 km of GPR data and 1.5 km of probing data. We describe the GPR data processing workflow from raw GPR data to the estimated ALT and VWC. We then include the corresponding uncertainties for each measured and estimated parameter. The estimated average GPR-derived ALT was 41 cm,more » with a standard deviation of 9 cm. The average probed ALT was 40 cm, with a standard deviation of 12 cm. The average GPR-derived VWC was 0.65, with a standard deviation of 0.14.« less

Estimating active layer thickness and volumetric water content from ground penetrating radar measurements in Barrow, Alaska

DOE PAGES

Jafarov, E. E.; Parsekian, A. D.; Schaefer, K.; ...

2018-01-09

Ground penetrating radar (GPR) has emerged as an effective tool for estimating active layer thickness (ALT) and volumetric water content (VWC) within the active layer. In August 2013, we conducted a series of GPR and probing surveys using a 500 MHz antenna and metallic probe around Barrow, Alaska. Here, we collected about 15 km of GPR data and 1.5 km of probing data. We describe the GPR data processing workflow from raw GPR data to the estimated ALT and VWC. We then include the corresponding uncertainties for each measured and estimated parameter. The estimated average GPR-derived ALT was 41 cm,more » with a standard deviation of 9 cm. The average probed ALT was 40 cm, with a standard deviation of 12 cm. The average GPR-derived VWC was 0.65, with a standard deviation of 0.14.« less

Determination of the optimal level for combining area and yield estimates

NASA Technical Reports Server (NTRS)

Bauer, M. E. (Principal Investigator); Hixson, M. M.; Jobusch, C. D.

1981-01-01

Several levels of obtaining both area and yield estimates of corn and soybeans in Iowa were considered: county, refined strata, refined/split strata, crop reporting district, and state. Using the CCEA model form and smoothed weather data, regression coefficients at each level were derived to compute yield and its variance. Variances were also computed with stratum level. The variance of the yield estimates was largest at the state and smallest at the county level for both crops. The refined strata had somewhat larger variances than those associated with the refined/split strata and CRD. For production estimates, the difference in standard deviations among levels was not large for corn, but for soybeans the standard deviation at the state level was more than 50% greater than for the other levels. The refined strata had the smallest standard deviations. The county level was not considered in evaluation of production estimates due to lack of county area variances.

The two errors of using the within-subject standard deviation (WSD) as the standard error of a reliable change index.

PubMed

Maassen, Gerard H

2010-08-01

In this Journal, Lewis and colleagues introduced a new Reliable Change Index (RCI(WSD)), which incorporated the within-subject standard deviation (WSD) of a repeated measurement design as the standard error. In this note, two opposite errors in using WSD this way are demonstrated. First, being the standard error of measurement of only a single assessment makes WSD too small when practice effects are absent. Then, too many individuals will be designated reliably changed. Second, WSD can grow unlimitedly to the extent that differential practice effects occur. This can even make RCI(WSD) unable to detect any reliable change.

Use of Standard Deviations as Predictors in Models Using Large-Scale International Data Sets

ERIC Educational Resources Information Center

Austin, Bruce; French, Brian; Adesope, Olusola; Gotch, Chad

2017-01-01

Measures of variability are successfully used in predictive modeling in research areas outside of education. This study examined how standard deviations can be used to address research questions not easily addressed using traditional measures such as group means based on index variables. Student survey data were obtained from the Organisation for…

Satellite-derived land covers for runoff estimation using SCS-CN method in Chen-You-Lan Watershed, Taiwan

NASA Astrophysics Data System (ADS)

Zhang, Wen-Yan; Lin, Chao-Yuan

2017-04-01

The Soil Conservation Service Curve Number (SCS-CN) method, which was originally developed by the USDA Natural Resources Conservation Service, is widely used to estimate direct runoff volume from rainfall. The runoff Curve Number (CN) parameter is based on the hydrologic soil group and land use factors. In Taiwan, the national land use maps were interpreted from aerial photos in 1995 and 2008. Rapid updating of post-disaster land use map is limited due to the high cost of production, so the classification of satellite images is the alternative method to obtain the land use map. In this study, Normalized Difference Vegetation Index (NDVI) in Chen-You-Lan Watershed was derived from dry and wet season of Landsat imageries during 2003 - 2008. Land covers were interpreted from mean value and standard deviation of NDVI and were categorized into 4 groups i.e. forest, grassland, agriculture and bare land. Then, the runoff volume of typhoon events during 2005 - 2009 were estimated using SCS-CN method and verified with the measured runoff data. The result showed that the model efficiency coefficient is 90.77%. Therefore, estimating runoff by using the land cover map classified from satellite images is practicable.

Regional variation in the refractive-index of the bovine and human cornea.

PubMed

Vasudevan, Balamurali; Simpson, Trefford L; Sivak, Jacob G

2008-10-01

Given the refractive importance of the human cornea, surprisingly little attention has been directed to the study of local variation in corneal refractive-index. This in vitro and in vivo study measures the refractive-index of different portions of the bovine and human cornea. Fifty fresh bovine corneas (obtained from an abattoir) and 10 human subjects were used for the study. The refractive-index of the central, nasal, and temporal corneal epithelium was measured with a bench-top Abbe refractometer in the case of bovine corneas and with a hand-held refractometer with humans. The mean (+/-standard deviation) refractive-indices of the central, nasal, and temporal bovine corneal epithelium were 1.3760 (+/-0.003), 1.3757 (+/-0.002), and 1.3746 (+/-0.002), respectively. Refractive-indices of the anterior and posterior bovine corneal stroma were 1.3731 (+/-0.002) and 1.3708 (+/-0.004), respectively. The mean (+/-standard deviation) refractive-index in the central, nasal, and temporal periphery of the human cornea epithelium were 1.3970 (+/-0.001), 1.3946 (+/-0.001), and 1.3940 (+/-0.001), respectively. There are small local differences in the refractive-index of the bovine and human corneal epithelium and the refractive-index of the epithelium is higher than that of the anterior and posterior stroma of the bovine cornea.

The effects of auditory stimulation with music on heart rate variability in healthy women.

PubMed

Roque, Adriano L; Valenti, Vitor E; Guida, Heraldo L; Campos, Mônica F; Knap, André; Vanderlei, Luiz Carlos M; Ferreira, Lucas L; Ferreira, Celso; Abreu, Luiz Carlos de

2013-07-01

There are no data in the literature with regard to the acute effects of different styles of music on the geometric indices of heart rate variability. In this study, we evaluated the acute effects of relaxant baroque and excitatory heavy metal music on the geometric indices of heart rate variability in women. We conducted this study in 21 healthy women ranging in age from 18 to 35 years. We excluded persons with previous experience with musical instruments and persons who had an affinity for the song styles. We evaluated two groups: Group 1 (n = 21), who were exposed to relaxant classical baroque musical and excitatory heavy metal auditory stimulation; and Group 2 (n = 19), who were exposed to both styles of music and white noise auditory stimulation. Using earphones, the volunteers were exposed to baroque or heavy metal music for five minutes. After the first music exposure to baroque or heavy metal music, they remained at rest for five minutes; subsequently, they were re-exposed to the opposite music (70-80 dB). A different group of women were exposed to the same music styles plus white noise auditory stimulation (90 dB). The sequence of the songs was randomized for each individual. We analyzed the following indices: triangular index, triangular interpolation of RR intervals and Poincaré plot (standard deviation of instantaneous beat-by-beat variability, standard deviation of the long-term RR interval, standard deviation of instantaneous beat-by-beat variability and standard deviation of the long-term RR interval ratio), low frequency, high frequency, low frequency/high frequency ratio, standard deviation of all the normal RR intervals, root-mean square of differences between the adjacent normal RR intervals and the percentage of adjacent RR intervals with a difference of duration greater than 50 ms. Heart rate variability was recorded at rest for 10 minutes. The triangular index and the standard deviation of the long-term RR interval indices were reduced during exposure to both music styles in the first group and tended to decrease in the second group whereas the white noise exposure decreased the high frequency index. We observed no changes regarding the triangular interpolation of RR intervals, standard deviation of instantaneous beat-by-beat variability and standard deviation of instantaneous beat-by-beat variability/standard deviation in the long-term RR interval ratio. We suggest that relaxant baroque and excitatory heavy metal music slightly decrease global heart rate variability because of the equivalent sound level.

The effects of auditory stimulation with music on heart rate variability in healthy women

PubMed Central

Roque, Adriano L.; Valenti, Vitor E.; Guida, Heraldo L.; Campos, Mônica F.; Knap, André; Vanderlei, Luiz Carlos M.; Ferreira, Lucas L.; Ferreira, Celso; de Abreu, Luiz Carlos

2013-01-01

OBJECTIVES: There are no data in the literature with regard to the acute effects of different styles of music on the geometric indices of heart rate variability. In this study, we evaluated the acute effects of relaxant baroque and excitatory heavy metal music on the geometric indices of heart rate variability in women. METHODS: We conducted this study in 21 healthy women ranging in age from 18 to 35 years. We excluded persons with previous experience with musical instruments and persons who had an affinity for the song styles. We evaluated two groups: Group 1 (n = 21), who were exposed to relaxant classical baroque musical and excitatory heavy metal auditory stimulation; and Group 2 (n = 19), who were exposed to both styles of music and white noise auditory stimulation. Using earphones, the volunteers were exposed to baroque or heavy metal music for five minutes. After the first music exposure to baroque or heavy metal music, they remained at rest for five minutes; subsequently, they were re-exposed to the opposite music (70-80 dB). A different group of women were exposed to the same music styles plus white noise auditory stimulation (90 dB). The sequence of the songs was randomized for each individual. We analyzed the following indices: triangular index, triangular interpolation of RR intervals and Poincaré plot (standard deviation of instantaneous beat-by-beat variability, standard deviation of the long-term RR interval, standard deviation of instantaneous beat-by-beat variability and standard deviation of the long-term RR interval ratio), low frequency, high frequency, low frequency/high frequency ratio, standard deviation of all the normal RR intervals, root-mean square of differences between the adjacent normal RR intervals and the percentage of adjacent RR intervals with a difference of duration greater than 50 ms. Heart rate variability was recorded at rest for 10 minutes. RESULTS: The triangular index and the standard deviation of the long-term RR interval indices were reduced during exposure to both music styles in the first group and tended to decrease in the second group whereas the white noise exposure decreased the high frequency index. We observed no changes regarding the triangular interpolation of RR intervals, standard deviation of instantaneous beat-by-beat variability and standard deviation of instantaneous beat-by-beat variability/standard deviation in the long-term RR interval ratio. CONCLUSION: We suggest that relaxant baroque and excitatory heavy metal music slightly decrease global heart rate variability because of the equivalent sound level. PMID:23917660

Comparison of therapy augmentation and deviation rates from the recommended once-daily dosing regimen between LDX and commonly prescribed long-acting stimulants for the treatment of ADHD in youth and adults.

PubMed

Setyawan, Juliana; Hodgkins, Paul; Guérin, Annie; Gauthier, Geneviève; Cloutier, Martin; Wu, Eric; Erder, M Haim

2013-10-01

To compare therapy augmentation and deviation rates from the recommended once-daily dosing regimen in Attention Deficit Hyperactivity Disorder (ADHD) patients initiated on lisdexamfetamine (LDX) vs other once-daily Food and Drug Administration (FDA) approved stimulants. ADHD patients initiated on a long-acting ADHD stimulant medication (index medication) in/after 2007 were selected from a large U.S. administrative claims database. Patients were required to be persistent for ≥90 days and continuously enrolled in their healthcare plan for ≥12 months following treatment initiation date. Based on age and previous treatment status, patients were classified into treatment-naïve children and adolescents (6-17 years old), previously treated children and adolescents, treatment-naïve adults (≥18 years old), and previously treated adults. Furthermore, patients were classified into four mutually exclusive treatment groups, based on index medication: lisdexamfetamine (LDX), osmotic release methylphenidate hydrochloride long-acting (OROS MPH), other methylphenidate/dexmethylphenidate long-acting (MPH LA), and amphetamine/dextroamphetamine long-acting (AMPH LA). The average daily consumption was measured as the quantity of index medication supplied in the 12-month study period divided by the total number of days of supply. Therapy augmentation was defined as the use of another ADHD medication concomitantly with the index medication for ≥28 consecutive days. Therapy augmentation and deviation rates from the recommended once-daily dosing regimen were compared between treatment groups using multivariate logistic regression models. Compared to the other treatment groups, LDX patients were less likely to augment with another ADHD medication (range odds ratios [OR]; 1.28-3.30) and to deviate from the recommended once-daily dosing regimen (range OR; 1.73-4.55), except for previously treated adult patients, where therapy augmentation differences were not statistically significant when compared to OROS MPH and MPH LA patients. This study did not control for ADHD severity. Overall, compared to LDX-treated patients, patients initiated on other ADHD medications were equally or more likely to have a therapy augmentation and more likely to deviate from the recommended once-daily dosing regimen.

Overcoming the limitations of the Harmonic Ratio for the reliable assessment of gait symmetry.

PubMed

Pasciuto, Ilaria; Bergamini, Elena; Iosa, Marco; Vannozzi, Giuseppe; Cappozzo, Aurelio

2017-02-28

The Harmonic Ratio (HR) is an index based on the spectral analysis of lower trunk accelerations that is commonly used to assess the quality of gait. However, it presents several issues concerning reliability and interpretability. As a consequence, the literature provides very different values albeit corresponding to the same populations. In the present work, an improved harmonic ratio (iHR) was defined, relating the power of the intrinsic harmonics (i.e. associated with the symmetric component of gait) to the total power of the signal for each stride, leading to a normalised index ranging from 0 to 100%. The effect of the considered number of harmonics and strides on the estimate of both HR and iHR was assessed. The gait of three groups of volunteers was investigated: young healthy adults, elderly women and male trans-femoral amputees. Both HR and iHR were able to discriminate gait deviations from the gait of young healthy adults. Moreover, iHR proved to be more robust with respect to the number of considered harmonics and strides, and to exhibit a lower inter-stride variability. Additionally, using a normalised index as iHR led to a more straightforward interpretation and improved comparability. The importance of standardised conditions for the index evaluation was unveiled, and, in order to enhance the future comparability of the index, the following guidelines were presented: considering at least 20 harmonics and 20 strides; expressing the acceleration components in a repeatable, anatomical, local system of reference; and evaluating the iHR index, rather than the traditional HR. Copyright © 2017 Elsevier Ltd. All rights reserved.

Internal Variations in Empirical Oxygen Abundances for Giant H II Regions in the Galaxy NGC 2403

NASA Astrophysics Data System (ADS)

Mao, Ye-Wei; Lin, Lin; Kong, Xu

2018-02-01

This paper presents a spectroscopic investigation of 11 {{H}} {{II}} regions in the nearby galaxy NGC 2403. The {{H}} {{II}} regions are observed with a long-slit spectrograph mounted on the 2.16 m telescope at XingLong station of National Astronomical Observatories of China. For each of the {{H}} {{II}} regions, spectra are extracted at different nebular radii along the slit-coverage. Oxygen abundances are empirically estimated from the strong-line indices R23, N2O2, O3N2, and N2 for each spectrophotometric unit, with both observation- and model-based calibrations adopted into the derivation. Radial profiles of these diversely estimated abundances are drawn for each nebula. In the results, the oxygen abundances separately estimated with the prescriptions on the basis of observations and models, albeit from the same spectral index, systematically deviate from each other; at the same time, the spectral indices R23 and N2O2 are distributed with flat profiles, whereas N2 and O3N2 exhibit apparent gradients with the nebular radius. Because our study naturally samples various ionization levels, which inherently decline at larger radii within individual {{H}} {{II}} regions, the radial distributions indicate not only the robustness of R23 and N2O2 against ionization variations but also the sensitivity of N2 and O3N2 to the ionization parameter. The results in this paper provide observational corroboration of the theoretical prediction about the deviation in the empirical abundance diagnostics. Our future work is planned to investigate metal-poor {{H}} {{II}} regions with measurable T e, in an attempt to recalibrate the strong-line indices and consequently disclose the cause of the discrepancies between the empirical oxygen abundances.

Breast Cancer Incidence and Predictors of Surgical Outcome: a Nationwide Longitudinal Study in Taiwan.

PubMed

Chang, Hong-Tai; Shi, Hon-Yi; Wang, Being-Whey; Yeh, Shu-Chuan Jennifer

2017-06-01

Despite the huge and growing global burden of patients who require breast cancer surgery, high-quality population-based studies of breast cancer trends and outcomes are scarce. The purpose of this study was to explore the incidence of breast cancer and predictors of hospital resource utilisation, mortality and recurrence in a nationwide population of patients who have received surgery. This retrospective study analysed trends and outcomes in a Taiwan population of 77 971 patients after breast cancer surgery during 1996-2010. The Cox proportional hazards model was used for multivariate assessment of both mortality and recurrence predictors. The data analysis indicated that, during this period, the estimated mean hospital treatment cost and mean length of stay increased by 16.3% and 53.4%, respectively. The estimated mean overall survival time was 138.9 months (standard deviation 0.3 months) and the overall 1, 3, 5 and 10 year survival rates were 97.3, 89.2, 82.2 and 70.1%, respectively. The estimated mean overall recurrence time was 10.8 months (standard deviation 0.2 months) and the overall 1, 3, 5 and 10 year recurrence rates were 0.1, 18.8, 26.6 and 36.0%, respectively. Outcomes were significantly associated with age, Deyo-Charlson comorbidity index score, surgeon seniority, hospital volume, surgeon volume, surgery type, hospital level and baseline comorbidities (P<0.001). Analyses of these population-based data revealed simultaneous increases in the standard incidence of breast cancer surgery and its associated medical resource utilisation. Notably, healthcare providers and patients should recognise that both patient attributes and hospital attributes may affect breast cancer surgery outcomes. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

The influence of different error estimates in the detection of postoperative cognitive dysfunction using reliable change indices with correction for practice effects.

PubMed

Lewis, Matthew S; Maruff, Paul; Silbert, Brendan S; Evered, Lis A; Scott, David A

2007-02-01

The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of postoperative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week postoperatively using error and reliability data from a comparable healthy nonsurgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within-subject standard deviation (WSD), expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.

Comparison of Data on Serious Adverse Events and Mortality in ClinicalTrials.gov, Corresponding Journal Articles, and FDA Medical Reviews: Cross-Sectional Analysis.

PubMed

Pradhan, Richeek; Singh, Sonal

2018-04-11

Inconsistencies in data on serious adverse events (SAEs) and mortality in ClinicalTrials.gov and corresponding journal articles pose a challenge to research transparency. The objective of this study was to compare data on SAEs and mortality from clinical trials reported in ClinicalTrials.gov and corresponding journal articles with US Food and Drug Administration (FDA) medical reviews. We conducted a cross-sectional study of a randomly selected sample of new molecular entities approved during the study period 1 January 2013 to 31 December 2015. We extracted data on SAEs and mortality from 15 pivotal trials from ClinicalTrials.gov and corresponding journal articles (the two index resources), and FDA medical reviews (reference standard). We estimated the magnitude of deviations in rates of SAEs and mortality between the index resources and the reference standard. We found deviations in rates of SAEs (30% in ClinicalTrials.gov and 30% in corresponding journal articles) and mortality (72% in ClinicalTrials.gov and 53% in corresponding journal articles) when compared with the reference standard. The intra-class correlation coefficient between the three resources was 0.99 (95% confidence interval [CI] 0.98-0.99) for SAE rates and 0.99 (95% CI 0.97-0.99) for mortality rates. There are differences in data on rates of SAEs and mortality in randomized clinical trials in both ClinicalTrials.gov and journal articles compared with FDA reviews. Further efforts should focus on decreasing existing discrepancies to enhance the transparency and reproducibility of data reporting in clinical trials.

Computer simulation of schlieren images of rotationally symmetric plasma systems: a simple method.

PubMed

Noll, R; Haas, C R; Weikl, B; Herziger, G

1986-03-01

Schlieren techniques are commonly used methods for quantitative analysis of cylindrical or spherical index of refraction profiles. Many schlieren objects, however, are characterized by more complex geometries, so we have investigated the more general case of noncylindrical, rotationally symmetric distributions of index of refraction n(r,z). Assuming straight ray paths in the schlieren object we have calculated 2-D beam deviation profiles. It is shown that experimental schlieren images of the noncylindrical plasma generated by a plasma focus device can be simulated with these deviation profiles. The computer simulation allows a quantitative analysis of these schlieren images, which yields, for example, the plasma parameters, electron density, and electron density gradients.

Prepregnancy body mass index, gestational weight gain, and birth weight in the BRISA cohort.

PubMed

Lima, Raina Jansen Cutrim Propp; Batista, Rosângela Fernandes Lucena; Ribeiro, Marizélia Rodrigues Costa; Ribeiro, Cecília Cláudia Costa; Simões, Vanda Maria Ferreira; Lima Neto, Pedro Martins; Silva, Antônio Augusto Moura da; Bettiol, Heloisa

2018-01-01

OBJECTIVE To analyze the effects of maternal pre-pregnancy body mass index and weight gain during pregnancy on the baby's birth weight. METHODS We conducted a cross-sectional study with 5,024 mothers and their newborns using a Brazilian birth cohort study. In the proposed model, estimated by structural equation modeling, we tested socioeconomic status, age, marital status, pre-pregnancy body mass index, smoking habit and alcohol consumption during pregnancy, hypertension and gestational diabetes, gestational weight gain, and type of delivery as determinants of the baby's birth weight. RESULTS For a gain of 4 kg/m2 (1 Standard Deviation [SD]) in pre-pregnancy body mass index, there was a 0.126 SD increase in birth weight, corresponding to 68 grams (p < 0.001). A 6 kg increase (1 SD) in gestational weight gain represented a 0.280 SD increase in newborn weight, correponding to 151.2 grams (p < 0.001). The positive effect of pre-pregnancy body mass index on birth weight was direct (standardized coefficient [SC] = 0.202; p < 0.001), but the negative indirect effect was small (SC = -0.076, p < 0.001) and partially mediated by the lower weight gain during pregnancy (SC = -0.070, p < 0.001). The positive effect of weight gain during pregnany on birth weight was predominantly direct (SC = 0.269, p < 0.001), with a small indirect effect of cesarean delivery (SC = 0.011; p < 0.001). Women with a higher pre-pregnancy body mass index gained less weight during pregnancy (p < 0.001). CONCLUSIONS The effect of gestational weight gain on the increase in birth weight was greater than that of pre-pregnancy body mass index.

Comparisons between consumption estimates from bioenergetics simulations and field measurements for walleyes from Oneida Lake, New York

USGS Publications Warehouse

Lantry, B.F.; Rudstam, L. G.; Forney, J.L.; VanDeValk, A.J.; Mills, E.L.; Stewart, D.J.; Adams, J.V.

2008-01-01

Daily consumption was estimated from the stomach contents of walleyes Sander vitreus collected weekly from Oneida Lake, New York, during June-October 1975, 1992, 1993, and 1994 for one to four age-groups per year. Field rations were highly variable between weeks, and trends in ration size varied both seasonally and annually. The coefficient of variation for weekly field rations within years and ages ranged from 45% to 97%. Field estimates were compared with simulated consumption from a bioenergetics model. The simulation averages of daily ration deviated from those of the field estimates by -20.1% to +70.3%, with a mean across all simulations of +14.3%. The deviations for each time step were much greater than those for the simulation averages, ranging from -92.8% to +363.6%. A systematic trend in the deviations was observed, the model producing overpredictions at rations less than 3.7% of body weight. Analysis of variance indicated that the deviations were affected by sample year and week but not age. Multiple linear regression using backwards selection procedures and Akaike's information criterion indicated that walleye weight, walleye growth, lake temperature, prey energy density, and the proportion of gizzard shad Dorosoma cepedianum in the diet significantly affected the deviations between simulated and field rations and explained 32% of the variance. ?? Copyright by the American Fisheries Society 2008.

Comparison of age estimation between 15-25 years using a modified form of Demirjian’s ten stage method and two teeth regression formula

NASA Astrophysics Data System (ADS)

Amiroh; Priaminiarti, M.; Syahraini, S. I.

2017-08-01

Age estimation of individuals, both dead and living, is important for victim identification and legal certainty. The Demirjian method uses the third molar for age estimation of individuals above 15 years old. The aim is to compare age estimation between 15-25 years using two Demirjian methods. Development stage of third molars in panoramic radiographs of 50 male and female samples were assessed by two observers using Demirjian’s ten stages and two teeth regression formula. Reliability was calculated using Cohen’s kappa coefficient and the significance of the observations was obtained from Wilcoxon tests. Deviations of age estimation were calculated using various methods. The deviation of age estimation with the two teeth regression formula was ±1.090 years; with ten stages, it was ±1.191 years. The deviation of age estimation using the two teeth regression formula was less than with the ten stages method. The age estimations using the two teeth regression formula or the ten stages method are significantly different until the age of 25, but they can be applied up to the age of 22.

Comparison of estimators of standard deviation for hydrologic time series

USGS Publications Warehouse

Tasker, Gary D.; Gilroy, Edward J.

1982-01-01

Unbiasing factors as a function of serial correlation, ρ, and sample size, n for the sample standard deviation of a lag one autoregressive model were generated by random number simulation. Monte Carlo experiments were used to compare the performance of several alternative methods for estimating the standard deviation σ of a lag one autoregressive model in terms of bias, root mean square error, probability of underestimation, and expected opportunity design loss. Three methods provided estimates of σ which were much less biased but had greater mean square errors than the usual estimate of σ: s = (1/(n - 1) ∑ (xi −x¯)2)½. The three methods may be briefly characterized as (1) a method using a maximum likelihood estimate of the unbiasing factor, (2) a method using an empirical Bayes estimate of the unbiasing factor, and (3) a robust nonparametric estimate of σ suggested by Quenouille. Because s tends to underestimate σ, its use as an estimate of a model parameter results in a tendency to underdesign. If underdesign losses are considered more serious than overdesign losses, then the choice of one of the less biased methods may be wise.

38 CFR 36.4304 - Deviations; changes of identity.

Code of Federal Regulations, 2010 CFR

2010-07-01

... identity. 36.4304 Section 36.4304 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... Deviations; changes of identity. A deviation of more than 5 percent between the estimates upon which a... change in the identity of the property upon which the original appraisal was based, will invalidate the...

38 CFR 36.4304 - Deviations; changes of identity.

Code of Federal Regulations, 2012 CFR

2012-07-01

... identity. 36.4304 Section 36.4304 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... Deviations; changes of identity. A deviation of more than 5 percent between the estimates upon which a... change in the identity of the property upon which the original appraisal was based, will invalidate the...

38 CFR 36.4304 - Deviations; changes of identity.

Code of Federal Regulations, 2013 CFR

2013-07-01

... identity. 36.4304 Section 36.4304 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... Deviations; changes of identity. A deviation of more than 5 percent between the estimates upon which a... change in the identity of the property upon which the original appraisal was based, will invalidate the...

38 CFR 36.4304 - Deviations; changes of identity.

Code of Federal Regulations, 2011 CFR

2011-07-01

... identity. 36.4304 Section 36.4304 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... Deviations; changes of identity. A deviation of more than 5 percent between the estimates upon which a... change in the identity of the property upon which the original appraisal was based, will invalidate the...

38 CFR 36.4304 - Deviations; changes of identity.

Code of Federal Regulations, 2014 CFR

2014-07-01

... identity. 36.4304 Section 36.4304 Pensions, Bonuses, and Veterans' Relief DEPARTMENT OF VETERANS AFFAIRS... Deviations; changes of identity. A deviation of more than 5 percent between the estimates upon which a... change in the identity of the property upon which the original appraisal was based, will invalidate the...

Quantifying expert diagnosis variability when grading tumor-infiltrating lymphocytes

NASA Astrophysics Data System (ADS)

Toro, Paula; Corredor, Germán.; Wang, Xiangxue; Arias, Viviana; Velcheti, Vamsidhar; Madabhushi, Anant; Romero, Eduardo

2017-11-01

Tumor-infiltrating lymphocytes (TILs) have proved to play an important role in predicting prognosis, survival, and response to treatment in patients with a variety of solid tumors. Unfortunately, currently, there are not a standardized methodology to quantify the infiltration grade. The aim of this work is to evaluate variability among the reports of TILs given by a group of pathologists who examined a set of digitized Non-Small Cell Lung Cancer samples (n=60). 28 pathologists answered a different number of histopathological images. The agreement among pathologists was evaluated by computing the Kappa index coefficient and the standard deviation of their estimations. Furthermore, TILs reports were correlated with patient's prognosis and survival using the Pearson's correlation coefficient. General results show that the agreement among experts grading TILs in the dataset is low since Kappa values remain below 0.4 and the standard deviation values demonstrate that in none of the images there was a full consensus. Finally, the correlation coefficient for each pathologist also reveals a low association between the pathologists' predictions and the prognosis/survival data. Results suggest the need of defining standardized, objective, and effective strategies to evaluate TILs, so they could be used as a biomarker in the daily routine.

Tendency for interlaboratory precision in the GMO analysis method based on real-time PCR.

PubMed

Kodama, Takashi; Kurosawa, Yasunori; Kitta, Kazumi; Naito, Shigehiro

2010-01-01

The Horwitz curve estimates interlaboratory precision as a function only of concentration, and is frequently used as a method performance criterion in food analysis with chemical methods. The quantitative biochemical methods based on real-time PCR require an analogous criterion to progressively promote method validation. We analyzed the tendency of precision using a simplex real-time PCR technique in 53 collaborative studies of seven genetically modified (GM) crops. Reproducibility standard deviation (SR) and repeatability standard deviation (Sr) of the genetically modified organism (GMO) amount (%) was more or less independent of GM crops (i.e., maize, soybean, cotton, oilseed rape, potato, sugar beet, and rice) and evaluation procedure steps. Some studies evaluated whole steps consisting of DNA extraction and PCR quantitation, whereas others focused only on the PCR quantitation step by using DNA extraction solutions. Therefore, SR and Sr for GMO amount (%) are functions only of concentration similar to the Horwitz curve. We proposed S(R) = 0.1971C 0.8685 and S(r) = 0.1478C 0.8424, where C is the GMO amount (%). We also proposed a method performance index in GMO quantitative methods that is analogous to the Horwitz Ratio.

Analysis of the landscape complexity and heterogeneity of the Pantanal wetland.

PubMed

Miranda, C S; Gamarra, R M; Mioto, C L; Silva, N M; Conceição Filho, A P; Pott, A

2018-05-01

This is the first report on analysis of habitat complexity and heterogeneity of the Pantanal wetland. The Pantanal encompasses a peculiar mosaic of environments, being important to evaluate and monitor this area concerning conservation of biodiversity. Our objective was to indirectly measure the habitat complexity and heterogeneity of the mosaic forming the sub-regions of the Pantanal, by means of remote sensing. We obtained free images of Normalized Difference Vegetation Index (NDVI) from the sensor MODIS and calculated the mean value (complexity) and standard deviation (heterogeneity) for each sub-region in the years 2000, 2008 and 2015. The sub-regions of Poconé, Canoeira, Paraguai and Aquidauana presented the highest values of complexity (mean NDVI), between 0.69 and 0.64 in the evaluated years. The highest horizontal heterogeneity (NDVI standard deviation) was observed in the sub-region of Tuiuiú, with values of 0.19 in the years 2000 and 2015, and 0.21 in the year 2008. We concluded that the use of NDVI to estimate landscape parameters is an efficient tool for assessment and monitoring of the complexity and heterogeneity of the Pantanal habitats, applicable in other regions.

Potential Association of Triglyceride Glucose Index with Cardiac Autonomic Neuropathy in Type 2 Diabetes Mellitus Patients

PubMed Central

2017-01-01

Cardiac autonomic neuropathy (CAN) is a common and most neglected complication of diabetes, estimated to be roughly 8% in recently diagnosed patients and greater than 50% in patients with chronic disease history. The insulin resistance (IR) itself is bidirectionally associated with increased risk of type 2 diabetes mellitus (T2DM) and CAN is a predisposing factor. The primary objective of the present study was aimed to find a correlation of triglyceride glucose index (TyG index) in CAN patients along with the prevalence of CAN in T2DM patients as a secondary objective. This prevalence study was conducted on 202 patients visiting the diabetic clinic of Hamdard Institute of Medical Sciences and Research, Jamia Hamdard (HIMSR) teaching hospital in New Delhi, India who fulfilled the inclusion criteria. The Ewings autonomic function test was used for diagnosis of CAN. TyG index was calculated for patients based on fasting levels of glucose and triglyceride. The CAN was diagnosed in 62 participants out of 202 T2DM patients (overall prevalence 30.7%). The mean ± standard deviation (SD) for TyG index was 10.3 ± 0.2 and 9.5 ± 0.2 in CAN positive, T2DM patients, respectively. The difference of TyG index, in CAN positive and T2DM patients, was highly significant (P < 0.001). Further correlation analysis was performed to find an association of TyG index, duration, and age with patient groups. TyG index showed a positive correlation with heart rate during deep breathing (HRD), heart rate variation during standing (HRS), blood pressure (BP) response to handgrip and BP response to standing. Our finding highlights the TyG index, low-cost IR index, might be useful as an alternative tool for the early screening of patients at a high risk of diabetic neuropathy. PMID:28581270

Potential Association of Triglyceride Glucose Index with Cardiac Autonomic Neuropathy in Type 2 Diabetes Mellitus Patients.

PubMed

Akbar, Md; Bhandari, Uma; Habib, Anwar; Ahmad, Razi

2017-07-01

Cardiac autonomic neuropathy (CAN) is a common and most neglected complication of diabetes, estimated to be roughly 8% in recently diagnosed patients and greater than 50% in patients with chronic disease history. The insulin resistance (IR) itself is bidirectionally associated with increased risk of type 2 diabetes mellitus (T2DM) and CAN is a predisposing factor. The primary objective of the present study was aimed to find a correlation of triglyceride glucose index (TyG index) in CAN patients along with the prevalence of CAN in T2DM patients as a secondary objective. This prevalence study was conducted on 202 patients visiting the diabetic clinic of Hamdard Institute of Medical Sciences and Research, Jamia Hamdard (HIMSR) teaching hospital in New Delhi, India who fulfilled the inclusion criteria. The Ewings autonomic function test was used for diagnosis of CAN. TyG index was calculated for patients based on fasting levels of glucose and triglyceride. The CAN was diagnosed in 62 participants out of 202 T2DM patients (overall prevalence 30.7%). The mean ± standard deviation (SD) for TyG index was 10.3 ± 0.2 and 9.5 ± 0.2 in CAN positive, T2DM patients, respectively. The difference of TyG index, in CAN positive and T2DM patients, was highly significant (P < 0.001). Further correlation analysis was performed to find an association of TyG index, duration, and age with patient groups. TyG index showed a positive correlation with heart rate during deep breathing (HRD), heart rate variation during standing (HRS), blood pressure (BP) response to handgrip and BP response to standing. Our finding highlights the TyG index, low-cost IR index, might be useful as an alternative tool for the early screening of patients at a high risk of diabetic neuropathy. © 2017 The Korean Academy of Medical Sciences.

Deviation pattern approach for optimizing perturbative terms of QCD renormalization group invariant observables

NASA Astrophysics Data System (ADS)

Khellat, M. R.; Mirjalili, A.

2017-03-01

We first consider the idea of renormalization group-induced estimates, in the context of optimization procedures, for the Brodsky-Lepage-Mackenzie approach to generate higher-order contributions to QCD perturbative series. Secondly, we develop the deviation pattern approach (DPA) in which through a series of comparisons between lowerorder RG-induced estimates and the corresponding analytical calculations, one could modify higher-order RG-induced estimates. Finally, using the normal estimation procedure and DPA, we get estimates of αs4 corrections for the Bjorken sum rule of polarized deep-inelastic scattering and for the non-singlet contribution to the Adler function.

Dosimetric verification of lung cancer treatment using the CBCTs estimated from limited-angle on-board projections.

PubMed

Zhang, You; Yin, Fang-Fang; Ren, Lei

2015-08-01

Lung cancer treatment is susceptible to treatment errors caused by interfractional anatomical and respirational variations of the patient. On-board treatment dose verification is especially critical for the lung stereotactic body radiation therapy due to its high fractional dose. This study investigates the feasibility of using cone-beam (CB)CT images estimated by a motion modeling and free-form deformation (MM-FD) technique for on-board dose verification. Both digital and physical phantom studies were performed. Various interfractional variations featuring patient motion pattern change, tumor size change, and tumor average position change were simulated from planning CT to on-board images. The doses calculated on the planning CT (planned doses), the on-board CBCT estimated by MM-FD (MM-FD doses), and the on-board CBCT reconstructed by the conventional Feldkamp-Davis-Kress (FDK) algorithm (FDK doses) were compared to the on-board dose calculated on the "gold-standard" on-board images (gold-standard doses). The absolute deviations of minimum dose (ΔDmin), maximum dose (ΔDmax), and mean dose (ΔDmean), and the absolute deviations of prescription dose coverage (ΔV100%) were evaluated for the planning target volume (PTV). In addition, 4D on-board treatment dose accumulations were performed using 4D-CBCT images estimated by MM-FD in the physical phantom study. The accumulated doses were compared to those measured using optically stimulated luminescence (OSL) detectors and radiochromic films. Compared with the planned doses and the FDK doses, the MM-FD doses matched much better with the gold-standard doses. For the digital phantom study, the average (± standard deviation) ΔDmin, ΔDmax, ΔDmean, and ΔV100% (values normalized by the prescription dose or the total PTV) between the planned and the gold-standard PTV doses were 32.9% (±28.6%), 3.0% (±2.9%), 3.8% (±4.0%), and 15.4% (±12.4%), respectively. The corresponding values of FDK PTV doses were 1.6% (±1.9%), 1.2% (±0.6%), 2.2% (±0.8%), and 17.4% (±15.3%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.3% (±0.2%), 0.9% (±0.6%), 0.6% (±0.4%), and 1.0% (±0.8%), respectively. Similarly, for the physical phantom study, the average ΔDmin, ΔDmax, ΔDmean, and ΔV100% of planned PTV doses were 38.1% (±30.8%), 3.5% (±5.1%), 3.0% (±2.6%), and 8.8% (±8.0%), respectively. The corresponding values of FDK PTV doses were 5.8% (±4.5%), 1.6% (±1.6%), 2.0% (±0.9%), and 9.3% (±10.5%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.4% (±0.8%), 0.8% (±1.0%), 0.5% (±0.4%), and 0.8% (±0.8%), respectively. For the 4D dose accumulation study, the average (± standard deviation) absolute dose deviation (normalized by local doses) between the accumulated doses and the OSL measured doses was 3.3% (±2.7%). The average gamma index (3%/3 mm) between the accumulated doses and the radiochromic film measured doses was 94.5% (±2.5%). MM-FD estimated 4D-CBCT enables accurate on-board dose calculation and accumulation for lung radiation therapy. It can potentially be valuable for treatment quality assessment and adaptive radiation therapy.

Single-Trait and Antagonistic Index Selection for Litter Size and Body Weight in Mice

PubMed Central

Eisen, E. J.

1978-01-01

Individual selection based on female performance only was conducted in four lines of mice: L+ for increased litter size, W+ for increased 6-week body weight, L-W+ for a selection index aimed at decreasing litter size and increasing 6-week body weight and L+W- for a selection index aimed at increasing litter size and decreasing 6-week body weight. A fifth line (K) served as an unselected control. All litters were standardized to eight mice at one day of age. Expected heritability was based on twice the regression of offspring on dam (h2d), which contains additive genetic variance due to direct (σ2Ao) and maternal (σ2Am) effects and their covariance (σAoAm). Responses and correlated responses were measured either deviated (method 1) or not deviated (method 2) from the control line. Realized heritabilities (h2R) for litter size were 0.19 ± 0.04 (1) and 0.16 ± 0.03 (2), which were similar to h 2d of 0.17 ± 0.04. The h2 R for 6-week body weight of 0.55 ± 0.07 (1) and 0.44 ± 0.07 (2) agreed with h2d of 0.42 ± 0.02. Realized genetic correlations (r*GR) between litter size and 6-week body weight calculated from the double-selection experiment were 0.52 ± 0.10 (1) and 0.52 ± 0.13 (2), which were not significantly different from the base population estimate of r* Gd = 0.63 ± 0.14. Divergence (L-W + minus L+W-) in the antagonistic index selection lines was 0.21 ± 0.01 index units (I = 0.305 PW - 0.436 PL, where P W and PL are the phenotypic values for 6-week body weight and litter size, respectively.). The h2 R of index units of 0.14 ± 0.02 calculated from divergence agreed with h2d of 0.14 ± 0.04. Divergences in litter size (-0.19 ± 0.07) and 6-week body weight (0.46 ± 0.10) were in the expected direction. Antagonistic index selection yielded about one-half the expected divergence in litter size, while divergence in 6-week body weight was only slightly less than expected. Realized genetic correlations indicated that litter size, 6-week body weight and index units each showed positive pleiotropy with 3-week body weight, postweaning gain and weight at vaginal introitus and negative pleiotropy with age at vaginal introitus. Sex ratio and several components of fitness (days from joining to parturition, percent fertile matings and percent perinatal survival) did not change significantly in the selected lines. PMID:17248819

Estimation of inflation parameters for Perturbed Power Law model using recent CMB measurements

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

Mukherjee, Suvodip; Das, Santanu; Souradeep, Tarun

2015-01-01

Cosmic Microwave Background (CMB) is an important probe for understanding the inflationary era of the Universe. We consider the Perturbed Power Law (PPL) model of inflation which is a soft deviation from Power Law (PL) inflationary model. This model captures the effect of higher order derivative of Hubble parameter during inflation, which in turn leads to a non-zero effective mass m{sub eff} for the inflaton field. The higher order derivatives of Hubble parameter at leading order sources constant difference in the spectral index for scalar and tensor perturbation going beyond PL model of inflation. PPL model have two observable independentmore » parameters, namely spectral index for tensor perturbation ν{sub t} and change in spectral index for scalar perturbation ν{sub st} to explain the observed features in the scalar and tensor power spectrum of perturbation. From the recent measurements of CMB power spectra by WMAP, Planck and BICEP-2 for temperature and polarization, we estimate the feasibility of PPL model with standard ΛCDM model. Although BICEP-2 claimed a detection of r=0.2, estimates of dust contamination provided by Planck have left open the possibility that only upper bound on r will be expected in a joint analysis. As a result we consider different upper bounds on the value of r and show that PPL model can explain a lower value of tensor to scalar ratio (r<0.1 or r<0.01) for a scalar spectral index of n{sub s}=0.96 by having a non-zero value of effective mass of the inflaton field m{sup 2}{sub eff}/H{sup 2}. The analysis with WP + Planck likelihood shows a non-zero detection of m{sup 2}{sub eff}/H{sup 2} with 5.7 σ and 8.1 σ respectively for r<0.1 and r<0.01. Whereas, with BICEP-2 likelihood m{sup 2}{sub eff}/H{sup 2} = −0.0237 ± 0.0135 which is consistent with zero.« less

A Revaluation of Indexes of Residential Segregation

ERIC Educational Resources Information Center

Winship, Christopher

1977-01-01

Shows that there are at least two different perspectives from which residential segregation can be examined. Segregation can be measured as it deviates from a situation of complete desegregation or in terms of a situation in which there is random segregation in the city. New criteria for indexes of residential segregation are developed. (Author/JM)

Structure of Pine Stands in the Southeast

Treesearch

William A. Bechtold; Gregory A. Ruark

1988-01-01

Distributional and statistical information associated with stand age, site index, basal area per acre, number of stems per acre, and stand density index is reported for major pine cover types of the Southeastern United States. Means, standard deviations, and ranges of these variables are listed by State and physiographic region for loblolly, slash, longleaf, pond,...

A Malaria Ecology Index Predicted Spatial and Temporal Variation of Malaria Burden and Efficacy of Antimalarial Interventions Based on African Serological Data.

PubMed

McCord, Gordon C; Anttila-Hughes, Jesse K

2017-03-01

Reducing the global health burden of malaria is complicated by weak reporting systems for infectious diseases and a paucity of vital statistics registration. This limits our ability to predict changes in malaria health burden intensity, target antimalarial resources where needed, and identify malaria impacts in retrospective data. We refined and deployed a temporally and spatially varying Malaria Ecology Index (MEI) incorporating climatological and ecological data to estimate malaria transmission strength and validate it against cross-sectional serology data from 39,875 children from seven sub-Saharan African countries. The MEI is strongly associated with malaria burden; a 1 standard deviation higher MEI is associated with a 50-117% increase in malaria risk and a 3-5 g/dL lower level of Hg. Results show that the relationship between malaria ecology and disease burden is attenuated with sufficient coverage of insecticide treated nets (ITNs) or indoor residual spraying (IRS). Having both ITNs and IRS reduce the added risk from adverse malaria ecology conditions by half. Readily available climate and ecology data can be used to estimate the spatial and temporal variation in malaria disease burden, providing a feasible alternative to direct surveillance. This will help target resources for malaria programs in the absence of national coverage of active case detection systems, and facilitate malaria research using retrospective health data.

Breakeven costs for embryo transfer in a commercial dairy herd.

PubMed

Ferris, T A; Troyer, B W

1987-11-01

Differences in Estimated Breeding Values expressed in dollars were compared by simulation of two, 100-cow, closed herds. One herd practiced normal intensity of female selection. The other herd generated various herd replacements by embryo transfer by varying 1) selection rate of embryo transfer dams and 2) numbers of daughters per dam from which embryos were transferred, while varying the merit of mates of embryo transfer dams. Estimated Breeding Value dollars were compounded each generation and regressed to remove age adjustments and added feed and health costs. Beginning values in both herds included a standard deviation of 55 Cow Index dollars, herd average of -23 Cow Index dollars, and a 120 Predicted Difference dollars for mates of dams not embryo transferred. Average merit of all sires used increased $12 per year. Herd calving rate (.70), proportion females (.5), calf loss (.15), and heifer survival rate (.83) were used. Breakeven cost per embryo transfer cow entering the milking herd was computed by Net Present Value analysis using a 10% discount rate over 10 and 20 yr. Breakeven cost or the maximum expense that would allow a 10% return on the expenditure ranged from $135 to $510 per surviving cow, $24 to $125 per transfer, $47 to $178 per pregnancy, and $81 to $357 per female calf born. As the number of replacements resulting from embryo transfer increased, breakeven cost per embryo transfer cow decreased due to diminishing return.

Multiresolution analysis of characteristic length scales with high-resolution topographic data

NASA Astrophysics Data System (ADS)

Sangireddy, Harish; Stark, Colin P.; Passalacqua, Paola

2017-07-01

Characteristic length scales (CLS) define landscape structure and delimit geomorphic processes. Here we use multiresolution analysis (MRA) to estimate such scales from high-resolution topographic data. MRA employs progressive terrain defocusing, via convolution of the terrain data with Gaussian kernels of increasing standard deviation, and calculation at each smoothing resolution of (i) the probability distributions of curvature and topographic index (defined as the ratio of slope to area in log scale) and (ii) characteristic spatial patterns of divergent and convergent topography identified by analyzing the curvature of the terrain. The MRA is first explored using synthetic 1-D and 2-D signals whose CLS are known. It is then validated against a set of MARSSIM (a landscape evolution model) steady state landscapes whose CLS were tuned by varying hillslope diffusivity and simulated noise amplitude. The known CLS match the scales at which the distributions of topographic index and curvature show scaling breaks, indicating that the MRA can identify CLS in landscapes based on the scaling behavior of topographic attributes. Finally, the MRA is deployed to measure the CLS of five natural landscapes using meter resolution digital terrain model data. CLS are inferred from the scaling breaks of the topographic index and curvature distributions and equated with (i) small-scale roughness features and (ii) the hillslope length scale.

Environmental risk assessment of radioactivity and heavy metals in soil of Toplica region, South Serbia.

PubMed

Stevanović, Vladica; Gulan, Ljiljana; Milenković, Biljana; Valjarević, Aleksandar; Zeremski, Tijana; Penjišević, Ivana

2018-03-13

Activity levels of natural and artificial radionuclides and content of ten heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn and Hg) were investigated in 41 soil samples collected from Toplica region located in the south part of Serbia. Radioactivity was determined by gamma spectrometry using HPGe detector. The obtained mean activity concentrations ± standard deviations of radionuclides 226 Ra, 232 Th, 40 K and 137 Cs were 29.9 ± 9.4, 36.6 ± 11.5, 492 ± 181 and 13.4 ± 18.7 Bq kg -1 , respectively. According to Shapiro-Wilk normality test, activity concentrations of 226 Ra and 232 Th were consistent with normal distribution. External exposure from radioactivity was estimated through dose and radiation risk assessments. Concentrations of heavy metals were measured by using ICP-OES, and their health risks were then determined. Enrichment by heavy metals and pollution level in soils were evaluated using the enrichment factor, the geoaccumulation index (I geo ), pollution index and pollution load index. Based on GIS approach, the spatial distribution maps of radionuclides and heavy metal contents were made. Spearman correlation coefficient was used for correlation analysis between radionuclide activity concentrations and heavy metal contents.

Retirement effects on health in Europe.

PubMed

Coe, Norma B; Zamarro, Gema

2011-01-01

What are the health impacts of retirement? As talk of raising retirement ages in pensions and social security schemes continues around the world, it is important to know both the costs and benefits for the individual, as well as the governments' budgets. In this paper we use the Survey of Health, Ageing and Retirement in Europe (SHARE) dataset to address this question in a multi-country setting. We use country-specific early and full retirement ages as instruments for retirement behavior. These statutory retirement ages clearly induce retirement, but are not related to an individual's health. Exploiting the discontinuities in retirement behavior across countries, we find significant evidence that retirement has a health-preserving effect on overall general health. Our estimates indicate that retirement leads to a 35 percent decrease in the probability of reporting to be in fair, bad, or very bad health, and an almost one standard deviation improvement in the health index. While the self-reported health seems to be a temporary impact, the health index indicates there are long-lasting health differences. Copyright © 2010 Elsevier B.V. All rights reserved.

El Niño Southern Oscillation (ENSO) and dysentery in Shandong province, China.

PubMed

Zhang, Ying; Bi, Peng; Wang, Guoyong; Hiller, Janet E

2007-01-01

To investigate the impact of the El Niño Southern Oscillation (ENSO) on dysentery transmission, the relationship between monthly dysentery cases in Shandong Province of China and the monthly Southern Oscillation Index (SOI), a broad index of ENSO, was examined over the period 1991-2003. Spearman correlations and generalized linear models were calculated to detect the association between the SOI and dysentery cases. Data from 1991 to 2001 were used to estimate the parameters, while data from 2002 to 2003 were used to test the forecasting ability of the model. After controlling for seasonality, autocorrelation, and a time-lagged effect, the results indicate that there was a significant negative association between the number of dysentery cases and the SOI, with a lagged effect of 2 months. A one-standard-deviation decrease in the SOI might cause up to 207 more dysentery cases per month in Shandong Province. This is the first report of the impact of the Southern Oscillation on dysentery risk in China, indicating that the SOI may be a useful early indicator of potential dysentery risk in Shandong Province.

Modeling error PDF optimization based wavelet neural network modeling of dynamic system and its application in blast furnace ironmaking

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

Zhou, Ping; Wang, Chenyu; Li, Mingjie

In general, the modeling errors of dynamic system model are a set of random variables. The traditional performance index of modeling such as means square error (MSE) and root means square error (RMSE) can not fully express the connotation of modeling errors with stochastic characteristics both in the dimension of time domain and space domain. Therefore, the probability density function (PDF) is introduced to completely describe the modeling errors in both time scales and space scales. Based on it, a novel wavelet neural network (WNN) modeling method is proposed by minimizing the two-dimensional (2D) PDF shaping of modeling errors. First,more » the modeling error PDF by the tradional WNN is estimated using data-driven kernel density estimation (KDE) technique. Then, the quadratic sum of 2D deviation between the modeling error PDF and the target PDF is utilized as performance index to optimize the WNN model parameters by gradient descent method. Since the WNN has strong nonlinear approximation and adaptive capability, and all the parameters are well optimized by the proposed method, the developed WNN model can make the modeling error PDF track the target PDF, eventually. Simulation example and application in a blast furnace ironmaking process show that the proposed method has a higher modeling precision and better generalization ability compared with the conventional WNN modeling based on MSE criteria. Furthermore, the proposed method has more desirable estimation for modeling error PDF that approximates to a Gaussian distribution whose shape is high and narrow.« less

Modeling error PDF optimization based wavelet neural network modeling of dynamic system and its application in blast furnace ironmaking

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

Zhou, Ping; Wang, Chenyu; Li, Mingjie

In general, the modeling errors of dynamic system model are a set of random variables. The traditional performance index of modeling such as means square error (MSE) and root means square error (RMSE) cannot fully express the connotation of modeling errors with stochastic characteristics both in the dimension of time domain and space domain. Therefore, the probability density function (PDF) is introduced to completely describe the modeling errors in both time scales and space scales. Based on it, a novel wavelet neural network (WNN) modeling method is proposed by minimizing the two-dimensional (2D) PDF shaping of modeling errors. First, themore » modeling error PDF by the traditional WNN is estimated using data-driven kernel density estimation (KDE) technique. Then, the quadratic sum of 2D deviation between the modeling error PDF and the target PDF is utilized as performance index to optimize the WNN model parameters by gradient descent method. Since the WNN has strong nonlinear approximation and adaptive capability, and all the parameters are well optimized by the proposed method, the developed WNN model can make the modeling error PDF track the target PDF, eventually. Simulation example and application in a blast furnace ironmaking process show that the proposed method has a higher modeling precision and better generalization ability compared with the conventional WNN modeling based on MSE criteria. However, the proposed method has more desirable estimation for modeling error PDF that approximates to a Gaussian distribution whose shape is high and narrow.« less

Modeling error PDF optimization based wavelet neural network modeling of dynamic system and its application in blast furnace ironmaking

DOE PAGES

Zhou, Ping; Wang, Chenyu; Li, Mingjie; ...

2018-01-31

In general, the modeling errors of dynamic system model are a set of random variables. The traditional performance index of modeling such as means square error (MSE) and root means square error (RMSE) cannot fully express the connotation of modeling errors with stochastic characteristics both in the dimension of time domain and space domain. Therefore, the probability density function (PDF) is introduced to completely describe the modeling errors in both time scales and space scales. Based on it, a novel wavelet neural network (WNN) modeling method is proposed by minimizing the two-dimensional (2D) PDF shaping of modeling errors. First, themore » modeling error PDF by the traditional WNN is estimated using data-driven kernel density estimation (KDE) technique. Then, the quadratic sum of 2D deviation between the modeling error PDF and the target PDF is utilized as performance index to optimize the WNN model parameters by gradient descent method. Since the WNN has strong nonlinear approximation and adaptive capability, and all the parameters are well optimized by the proposed method, the developed WNN model can make the modeling error PDF track the target PDF, eventually. Simulation example and application in a blast furnace ironmaking process show that the proposed method has a higher modeling precision and better generalization ability compared with the conventional WNN modeling based on MSE criteria. However, the proposed method has more desirable estimation for modeling error PDF that approximates to a Gaussian distribution whose shape is high and narrow.« less

Comparing Standard Deviation Effects across Contexts

ERIC Educational Resources Information Center

Ost, Ben; Gangopadhyaya, Anuj; Schiman, Jeffrey C.

2017-01-01

Studies using tests scores as the dependent variable often report point estimates in student standard deviation units. We note that a standard deviation is not a standard unit of measurement since the distribution of test scores can vary across contexts. As such, researchers should be cautious when interpreting differences in the numerical size of…

Relationships between cold-temperature indices and all causes and cardiopulmonary morbidity and mortality in a subtropical island.

PubMed

Lin, Yu-Kai; Wang, Yu-Chun; Lin, Pay-Liam; Li, Ming-Hsu; Ho, Tsung-Jung

2013-09-01

This study aimed to identify optimal cold-temperature indices that are associated with the elevated risks of mortality from, and outpatient visits for all causes and cardiopulmonary diseases during the cold seasons (November to April) from 2000 to 2008 in Northern, Central and Southern Taiwan. Eight cold-temperature indices, average, maximum, and minimum temperatures, and the temperature humidity index, wind chill index, apparent temperature, effective temperature (ET), and net effective temperature and their standardized Z scores were applied to distributed lag non-linear models. Index-specific cumulative 26-day (lag 0-25) mortality risk, cumulative 8-day (lag 0-7) outpatient visit risk, and their 95% confidence intervals were estimated at 1 and 2 standardized deviations below the median temperature, comparing with the Z score of the lowest risks for mortality and outpatient visits. The average temperature was adequate to evaluate the mortality risk from all causes and circulatory diseases. Excess all-cause mortality increased for 17-24% when average temperature was at Z=-1, and for 27-41% at Z=-2 among study areas. The cold-temperature indices were inconsistent in estimating risk of outpatient visits. Average temperature and THI were appropriate indices for measuring risk for all-cause outpatient visits. Relative risk of all-cause outpatient visits increased slightly by 2-7% when average temperature was at Z=-1, but no significant risk at Z=-2. Minimum temperature estimated the strongest risk associated with outpatient visits of respiratory diseases. In conclusion, the relationships between cold temperatures and health varied among study areas, types of health event, and the cold-temperature indices applied. Mortality from all causes and circulatory diseases and outpatient visits of respiratory diseases has a strong association with cold temperatures in the subtropical island, Taiwan. Copyright © 2013 Elsevier B.V. All rights reserved.

Detecting chaos, determining the dimensions of tori and predicting slow diffusion in Fermi-Pasta-Ulam lattices by the Generalized Alignment Index method

NASA Astrophysics Data System (ADS)

Skokos, C.; Bountis, T.; Antonopoulos, C.

2008-12-01

The recently introduced GALI method is used for rapidly detecting chaos, determining the dimensionality of regular motion and predicting slow diffusion in multi-dimensional Hamiltonian systems. We propose an efficient computation of the GALIk indices, which represent volume elements of k randomly chosen deviation vectors from a given orbit, based on the Singular Value Decomposition (SVD) algorithm. We obtain theoretically and verify numerically asymptotic estimates of GALIs long-time behavior in the case of regular orbits lying on low-dimensional tori. The GALIk indices are applied to rapidly detect chaotic oscillations, identify low-dimensional tori of Fermi-Pasta-Ulam (FPU) lattices at low energies and predict weak diffusion away from quasiperiodic motion, long before it is actually observed in the oscillations.

Color reproducibility and dyestuff concentration

NASA Astrophysics Data System (ADS)

Csanyi, Sandor

2002-06-01

The purpose of this study was to develop a new sensitivity index connected with color matching, which makes it possible to investigate the effects of dyestuff concentration deviations in a larger part of the color space in a comprehensive manner. By the help of computer simulation and experimental design, we examined the color differences resulting from minor concentration changes in approximately 500 formulas of different compositions, altering their total concentration and the proportion of the individual dyes in them. The new sensitivity index makes it possible for the colorist to select the recipe that is the least sensitive to concentration deviations from among the computer color formulas, as well as to add a new aspect to the ranking applied in color matching so far.

Comparison of three NDVI time-series fitting methods in crop phenology detection in Northeast China

NASA Astrophysics Data System (ADS)

Wang, Meng; Tao, Fulu

2014-03-01

Phenological changes of cropland are the pivotal basis for farm management, agricultural production, and climate change research. Over the past decades, a range of methods have been used to extract phenological events based on satellite derived continuous vegetation index time series, however, large uncertainties still exist. In this study, three smoothing methods were compared to reduce the potential uncertainty and to quantify crop green-up dates over Northeast China. The results indicated that the crop spring onset dates estimated by three methods show variance in the dates, but with similar spatial pattern. In 60% of the study area, the standard deviation (SD) of the estimated starting date from different method is less than 10 days, while 39.5% of total pixels have SDs between 10days and 30 days. Through comparative analysis against the observation phenological data, we concluded that Asymmetric Gaussians produced the most approximative results of all, followed by Double Logistic algorithm, and Savizky-Glolay algorithm performed worst. The starting dates of crops occur mostly between May and June in this region. The Savitzky-Golay has the earliest estimates, while the Asymmetric Gaussians and Double logistic fitting method show similar and later estimates, which are more consistent with the observed data.

Task-oriented comparison of power spectral density estimation methods for quantifying acoustic attenuation in diagnostic ultrasound using a reference phantom method.

PubMed

Rosado-Mendez, Ivan M; Nam, Kibo; Hall, Timothy J; Zagzebski, James A

2013-07-01

Reported here is a phantom-based comparison of methods for determining the power spectral density (PSD) of ultrasound backscattered signals. Those power spectral density values are then used to estimate parameters describing α(f), the frequency dependence of the acoustic attenuation coefficient. Phantoms were scanned with a clinical system equipped with a research interface to obtain radiofrequency echo data. Attenuation, modeled as a power law α(f)= α0 f (β), was estimated using a reference phantom method. The power spectral density was estimated using the short-time Fourier transform (STFT), Welch's periodogram, and Thomson's multitaper technique, and performance was analyzed when limiting the size of the parameter-estimation region. Errors were quantified by the bias and standard deviation of the α0 and β estimates, and by the overall power-law fit error (FE). For parameter estimation regions larger than ~34 pulse lengths (~1 cm for this experiment), an overall power-law FE of 4% was achieved with all spectral estimation methods. With smaller parameter estimation regions as in parametric image formation, the bias and standard deviation of the α0 and β estimates depended on the size of the parameter estimation region. Here, the multitaper method reduced the standard deviation of the α0 and β estimates compared with those using the other techniques. The results provide guidance for choosing methods for estimating the power spectral density in quantitative ultrasound methods.

Retrospective database study to assess the economic impact of hip fracture in the United Kingdom.

PubMed

Lambrelli, Dimitra; Burge, Russel; Raluy-Callado, Mireia; Chen, Shih-Yin; Wu, Ning; Schoenfeld, Michael J

2014-11-01

Publications containing recent, real-world data on the economic impact of hip fractures in the UK are lacking. This retrospective electronic medical records database analysis assessed medication and healthcare resource use, direct healthcare costs, and factors predicting increased resource use and costs in adult UK hip fracture patients. Data were obtained from the Clinical Practice Research Datalink linked to the Hospital Episode Statistics for adult patients hospitalized for their first hip fracture between January 1, 2006 and March 31, 2011 (index event); healthcare costs were calculated from the National Health Service perspective using 2011-2012 cost data. Data from 8028 patients were analyzed. Resource use and costs were statistically significantly higher in the year following fracture (mean total [standard deviation (SD)] cost £7359 [£14,937]) compared with the year before fracture (mean total [SD] cost £3122 [£9435]; p < 0.001), and were similar to the total amount of the index hospitalization (mean total [SD] cost £8330 [£2627]). Multivariate regression analysis (using an estimated generalized linear model) showed that older age, male gender, higher comorbidity, osteoporosis, discharge to another institution compared with home, and pre-index hospitalization and outpatient visits were associated with increased post-index hospitalization healthcare costs (all p < 0.05). Although we did not capture all pre- and post-index costs and healthcare utilization, this study provides important insights regarding the characteristics of patients with hip fracture, and information that will be useful in burden-of-illness and economic analyses.

An activity index for geomagnetic paleosecular variation, excursions, and reversals

NASA Astrophysics Data System (ADS)

Panovska, S.; Constable, C. G.

2017-04-01

Magnetic indices provide quantitative measures of space weather phenomena that are widely used by researchers in geomagnetism. We introduce an index focused on the internally generated field that can be used to evaluate long term variations or climatology of modern and paleomagnetic secular variation, including geomagnetic excursions, polarity reversals, and changes in reversal rate. The paleosecular variation index, Pi, represents instantaneous or average deviation from a geocentric axial dipole field using normalized ratios of virtual geomagnetic pole colatitude and virtual dipole moment. The activity level of the index, σPi, provides a measure of field stability through the temporal standard deviation of Pi. Pi can be calculated on a global grid from geomagnetic field models to reveal large scale geographic variations in field structure. It can be determined for individual time series, or averaged at local, regional, and global scales to detect long term changes in geomagnetic activity, identify excursions, and transitional field behavior. For recent field models, Pi ranges from less than 0.05 to 0.30. Conventional definitions for geomagnetic excursions are characterized by Pi exceeding 0.5. Strong field intensities are associated with low Pi unless they are accompanied by large deviations from axial dipole field directions. σPi provides a measure of geomagnetic stability that is modulated by the level of PSV or frequency of excursional activity and reversal rate. We demonstrate uses of Pi for paleomagnetic observations and field models and show how it could be used to assess whether numerical simulations of the geodynamo exhibit Earth-like properties.

Aerodynamic roughness length estimation with lidar and imaging spectroscopy in a shrub-dominated dryland

USGS Publications Warehouse

Li, Aihua; Zhao, Wenguang; Mitchell, Jessica J; Glenn, Nancy F.; Germino, Matthew; Sankey, Joel B.; Allen, Richard G

2017-01-01

The aerodynamic roughness length (Z0 m) serves an important role in the flux exchange between the land surface and atmosphere. In this study, airborne lidar (ALS), terrestrial lidar (TLS), and imaging spectroscopy data were integrated to develop and test two approaches to estimate Z0 m over a shrub dominated dryland study area in south-central Idaho, USA. Sensitivity of the two parameterization methods to estimate Z0 m was analyzed. The comparison of eddy covariance-derived Z0 m and remote sensing-derived Z0 m showed that the accuracy of the estimated Z0 m heavily depends on the estimation model and the representation of shrub (e.g., Artemisia tridentata subsp. wyomingensis) height in the models. The geometrical method (RA1994) led to 9 percent (~0.5 cm) and 25% (~1.1 cm) errors at site 1 and site 2, respectively, which performed better than the height variability-based method (MR1994) with bias error of 20 percent and 48 percent at site 1 and site 2, respectively. The RA1994 model resulted in a larger range of Z0 m than the MR1994 method. We also found that the mean, median and 75th percentiles of heights (H75) from ALS provides the best Z0 m estimates in the MR1994 model, while the mean, median, and MLD (Median Absolute Deviation from Median Height), as well as AAD (Mean Absolute Deviation from Mean Height) heights from ALS provides the best Z0 m estimates in the RA1994 model. In addition, the fractional cover of shrub and grass, distinguished with ALS and imaging spectroscopy data, provided the opportunity to estimate the frontal area index at the pixel-level to assess the influence of grass and shrub on Z0m estimates in the RA1994 method. Results indicate that grass had little effect on Z0 m in the RA1994 method. The Z0 m estimations were tightly coupled with vegetation height and its local variance for the shrubs. Overall, the results demonstrate that the use of height and fractional cover from remote sensing data are promising for estimating Z0 m, and thus refining land surface models at regional scales in semiarid shrublands.

Assessment issues in the testing of children at school entry.

PubMed

Rock, Donald A; Stenner, A Jackson

2005-01-01

The authors introduce readers to the research documenting racial and ethnic gaps in school readiness. They describe the key tests, including the Peabody Picture Vocabulary Test (PPVT), the Early Childhood Longitudinal Study (ECLS), and several intelligence tests, and describe how they have been administered to several important national samples of children. Next, the authors review the different estimates of the gaps and discuss how to interpret these differences. In interpreting test results, researchers use the statistical term "standard deviation" to compare scores across the tests. On average, the tests find a gap of about 1 standard deviation. The ECLS-K estimate is the lowest, about half a standard deviation. The PPVT estimate is the highest, sometimes more than 1 standard deviation. When researchers adjust those gaps statistically to take into account different outside factors that might affect children's test scores, such as family income or home environment, the gap narrows but does not disappear. Why such different estimates of the gap? The authors consider explanations such as differences in the samples, racial or ethnic bias in the tests, and whether the tests reflect different aspects of school "readiness," and conclude that none is likely to explain the varying estimates. Another possible explanation is the Spearman Hypothesis-that all tests are imperfect measures of a general ability construct, g; the more highly a given test correlates with g, the larger the gap will be. But the Spearman Hypothesis, too, leaves questions to be investigated. A gap of 1 standard deviation may not seem large, but the authors show clearly how it results in striking disparities in the performance of black and white students and why it should be of serious concern to policymakers.

Multimode optical fibers: steady state mode exciter.

PubMed

Ikeda, M; Sugimura, A; Ikegami, T

1976-09-01

The steady state mode power distribution of the multimode graded index fiber was measured. A simple and effective steady state mode exciter was fabricated by an etching technique. Its insertion loss was 0.5 dB for an injection laser. Deviation in transmission characteristics of multimode graded index fibers can be avoided by using the steady state mode exciter.

Gait Deviations in Children With Osteogenesis Imperfecta Type I.

PubMed

Garman, Christina R; Graf, Adam; Krzak, Joseph; Caudill, Angela; Smith, Peter; Harris, Gerald

2017-08-02

Osteogenesis imperfecta (OI) is a congenital connective tissue disorder often characterized by orthopaedic complications that impact normal gait. As such, mobility is of particular interest in the OI population as it is associated with multiple aspects of participation and quality of life. The purpose of the current study was to identify and describe common gait deviations in a large sample of individuals with type I OI and speculate the etiology with a goal of improving function. Gait analysis was performed on 44 subjects with type I (11.7±3.08 y old) and 30 typically developing controls (9.54±3.1 y old ). Spatial temporal, kinematic, and kinetic gait data were calculated from the Vicon Plug-in-Gait Model. Musculoskeletal modeling of the muscle tendon lengths (MTL) was done in OpenSim 3.3 to evaluate the MTL of the gastrocnemius and gluteus maximus. The gait deviation index, a dimensionless parameter that evaluates the deviation of 9 kinematic gait parameters from a control database, was also calculated. Walking speed, single support time, stride, and step length were lower and double support time was higher in the OI group. The gait deviation index score was lower and external hip rotation angle was higher in the OI group. Peak hip flexor, knee extensor and ankle plantarflexor moments, and power generation at the ankle were lower in the OI group. MTL analysis revealed no significant length discrepancies between the OI group and the typically developing group. Together, these findings provide a comprehensive description of gait characteristics among a group of individuals with type I OI. Such data inform clinicians about specific gait deviations in this population allowing clinicians to recommend more focused interventions. Level III-case-control study.

Down-Looking Interferometer Study II, Volume I,

DTIC Science & Technology

1980-03-01

g(standard deviation of AN )(standard deviation of(3) where T’rm is the "reference spectrum", an estimate of the actual spectrum v gv T ’V Cgv . If jpj...spectrum T V . cgv . According to Eq. (2), Z is the standard deviation of the observed contrast spectral radiance AN divided by the effective rms system

Clinical Relevance of Differences in Glomerular Filtration Rate Estimations in Frail Older People by Creatinine- vs. Cystatin C-Based Formulae.

PubMed

Jacobs, Anne; Benraad, Carolien; Wetzels, Jack; Rikkert, Marcel Olde; Kramers, Cornelis

2017-06-01

The risk of incorrect medication dosing is high in frail older people. Therefore, accurate assessment of the glomerular filtration rate is important. The objective of this study was to compare the estimated glomerular filtration rate using creatinine- and cystatin C-based formulae, the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations, in frail older people. We hypothesized that frailty determines the difference between the creatinine- and cystatin C-based formulae. The mean difference between CKD-EPI creatinine and cystatin C was determined using (cross-sectional) data of 55 patients (mean age 73 years) admitted to a psychiatric ward for older adults. The level of agreement of these estimations was assessed by a Bland-Altman analysis. In all patients, the Rockwood's Frailty Index was derived and correlated with the mean difference between CKD-EPI creatinine and cystatin C. The mean difference between CKD-EPI creatinine (mean 71.2 mL/min/1.73 m 2 ) and CKD-EPI cystatin C (mean 57.6 mL/min/1.73 m 2 ) was 13.6 mL/min/1.73 m 2 (p < 0.0001). The two standard deviation limit in the Bland-Altman plot was large (43.2 mL/min/1.73 m 2 ), which represents a low level of agreement. The Frailty Index did not correlate with the mean difference between the creatinine- and cystatin C-based glomerular filtration rate (Pearson correlation coefficient 0.182, p = 0.184). There was a significant gap between a creatinine- and cystatin C-based estimation of glomerular filtration rate, irrespective of frailty. The range of differences between the commonly used estimated glomerular filtration rate formulae might result in clinically relevant differences in drug prescription and differences in chronic kidney disease staging.

Evaluating the Impact of Various Parameters on the Gamma Index Values of 2D Diode Array in IMRT Verification

PubMed Central

Jabbari, Keyvan; Pashaei, Fakhereh; Ay, Mohammad R.; Amouheidari, Alireza; Tavakoli, Mohammad B.

2018-01-01

Background: MapCHECK2 is a two-dimensional diode arrays planar dosimetry verification system. Dosimetric results are evaluated with gamma index. This study aims to provide comprehensive information on the impact of various factors on the gamma index values of MapCHECK2, which is mostly used for IMRT dose verification. Methods: Seven fields were planned for 6 and 18 MV photons. The azimuthal angle is defined as any rotation of collimators or the MapCHECK2 around the central axis, which was varied from 5 to −5°. The gantry angle was changed from −8 to 8°. Isodose sampling resolution was studied in the range of 0.5 to 4 mm. The effects of additional buildup on gamma index in three cases were also assessed. Gamma test acceptance criteria were 3%/3 mm. Results: The change of azimuthal angle in 5° interval reduced gamma index value by about 9%. The results of putting buildups of various thicknesses on the MapCHECK2 surface showed that gamma index was generally improved in thicker buildup, especially for 18 MV. Changing the sampling resolution from 4 to 2 mm resulted in an increase in gamma index by about 3.7%. The deviation of the gantry in 8° intervals in either directions changed the gamma index only by about 1.6% for 6 MV and 2.1% for 18 MV. Conclusion: Among the studied parameters, the azimuthal angle is one of the most effective factors on gamma index value. The gantry angle deviation and sampling resolution are less effective on gamma index value reduction. PMID:29535922

Influence of eye micromotions on spatially resolved refractometry

NASA Astrophysics Data System (ADS)

Chyzh, Igor H.; Sokurenko, Vyacheslav M.; Osipova, Irina Y.

2001-01-01

The influence eye micromotions on the accuracy of estimation of Zernike coefficients form eye transverse aberration measurements was investigated. By computer modeling, the following found eye aberrations have been examined: defocusing, primary astigmatism, spherical aberration of the 3rd and the 5th orders, as well as their combinations. It was determined that the standard deviation of estimated Zernike coefficients is proportional to the standard deviation of angular eye movements. Eye micromotions cause the estimation errors of Zernike coefficients of present aberrations and produce the appearance of Zernike coefficients of aberrations, absent in the eye. When solely defocusing is present, the biggest errors, cased by eye micromotions, are obtained for aberrations like coma and astigmatism. In comparison with other aberrations, spherical aberration of the 3rd and the 5th orders evokes the greatest increase of the standard deviation of other Zernike coefficients.

Parameter estimation method and updating of regional prediction equations for ungaged sites in the desert region of California

USGS Publications Warehouse

Barth, Nancy A.; Veilleux, Andrea G.

2012-01-01

The U.S. Geological Survey (USGS) is currently updating at-site flood frequency estimates for USGS streamflow-gaging stations in the desert region of California. The at-site flood-frequency analysis is complicated by short record lengths (less than 20 years is common) and numerous zero flows/low outliers at many sites. Estimates of the three parameters (mean, standard deviation, and skew) required for fitting the log Pearson Type 3 (LP3) distribution are likely to be highly unreliable based on the limited and heavily censored at-site data. In a generalization of the recommendations in Bulletin 17B, a regional analysis was used to develop regional estimates of all three parameters (mean, standard deviation, and skew) of the LP3 distribution. A regional skew value of zero from a previously published report was used with a new estimated mean squared error (MSE) of 0.20. A weighted least squares (WLS) regression method was used to develop both a regional standard deviation and a mean model based on annual peak-discharge data for 33 USGS stations throughout California’s desert region. At-site standard deviation and mean values were determined by using an expected moments algorithm (EMA) method for fitting the LP3 distribution to the logarithms of annual peak-discharge data. Additionally, a multiple Grubbs-Beck (MGB) test, a generalization of the test recommended in Bulletin 17B, was used for detecting multiple potentially influential low outliers in a flood series. The WLS regression found that no basin characteristics could explain the variability of standard deviation. Consequently, a constant regional standard deviation model was selected, resulting in a log-space value of 0.91 with a MSE of 0.03 log units. Yet drainage area was found to be statistically significant at explaining the site-to-site variability in mean. The linear WLS regional mean model based on drainage area had a Pseudo- 2 R of 51 percent and a MSE of 0.32 log units. The regional parameter estimates were then used to develop a set of equations for estimating flows with 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent annual exceedance probabilities for ungaged basins. The final equations are functions of drainage area.Average standard errors of prediction for these regression equations range from 214.2 to 856.2 percent.

Estimation of Tooth Size Discrepancies among Different Malocclusion Groups.

PubMed

Hasija, Narender; Bala, Madhu; Goyal, Virender

2014-05-01

Regards and Tribute: Late Dr Narender Hasija was a mentor and visionary in the light of knowledge and experience. We pay our regards with deepest gratitude to the departed soul to rest in peace. Bolton's ratios help in estimating overbite, overjet relationships, the effects of contemplated extractions on posterior occlusion, incisor relationships and identification of occlusal misfit produced by tooth size discrepancies. To determine any difference in tooth size discrepancy in anterior as well as overall ratio in different malocclusions and comparison with Bolton's study. After measuring the teeth on all 100 patients, Bolton's analysis was performed. Results were compared with Bolton's means and standard deviations. The results were also subjected to statistical analysis. Results show that the mean and standard deviations of ideal occlusion cases are comparable with those Bolton but, when the mean and standard deviation of malocclusion groups are compared with those of Bolton, the values of standard deviation are higher, though the mean is comparable. How to cite this article: Hasija N, Bala M, Goyal V. Estimation of Tooth Size Discrepancies among Different Malocclusion Groups. Int J Clin Pediatr Dent 2014;7(2):82-85.

Interplay between heritability, genetic correlation and economic weighting in a selection index with and without genomic information.

PubMed

Haberland, A M; Pimentel, E C G; Ytournel, F; Erbe, M; Simianer, H

2013-12-01

The availability of genomic information demands proper evaluation on how the kind (phenotypic versus genomic) and the amount of information influences the interplay of heritability (h(2)), genetic correlation (r(GiGj)) and economic weighting of traits with regard to the standard deviation of the index (σI). As σI is directly proportional to response to selection, it was the chosen parameter for comparing the indices. Three selection indices incorporating conventional and genomic information for a two trait (i and j) breeding goal were compared. Information sources were chosen corresponding to pig breeding applications. Index I incorporating an own performance in trait j served as reference scenario. In index II, additional information in both traits was contributed by a varying number of full-sibs (2, 7, 50). In index III, the conventional own performance in trait j was combined with genomic information for both traits. The number of animals in the reference population (NP = 1000, 5000, 10,000) and thus the accuracy of GBVs were varied. With more information included in the index, σI became more independent of r(GiGj), h(j)(2) and relative economic weighting. This applied for index II (more full-sibs) and for index III (more accurate GBVs). Standard deviations of index II with seven full-sibs and index III with NP = 1000 were similar when both traits had the same heritability. If the heritability of trait j was reduced (h(j)(2) = 0.1), σI of index III with NP = 1000 was clearly higher than for index II with seven full-sibs. When enhancing the relative economic weight of trait j, the decrease in σI of the conventional full-sib index was much stronger than for index III. Our results imply that NP = 1000 can be considered a minimum size for a reference population in pig breeding. These conclusions also hold for comparing the accuracies of the indices. © 2013 Blackwell Verlag GmbH.

Using the Method of Water Poverty Index (WPI) to Evaluate the Region Water Security

NASA Astrophysics Data System (ADS)

Fu, Q.; Kachanoski, G.

2008-12-01

Water security is a widely concerned issue in the world nowadays. A new method, water poverty index (WPI), has been used to evaluate the regional water security. Twelve state farms in Heilongjiang Province, Northeastern China were selected to evaluate water security status based on the data of 2006 by using WPI and mean deviation grading method. The method of WPI includes five key indexes, such as resources(R), access (A), capacity(C), utilization (U) and environment (E). Each key index includes several sub-indexes. According to the results of WPI, the grade of each farm has been calculated by using the method of mean deviation grading. Thus, the radar images can be protracted of each farm. From the radar images, the conclusions can be drawn that the WPI values of Farms 853 and Hongqiling were in very safe status, while that of Farm Raohe was in safe status, those of Farms Youyi, 597, 852, 291 and Jiangchuan were in moderate safe status, that of Farm Beixing was in low safe status and those of Farms Shuangyashan, Shuguang and Baoshan were in unsafe status. The results from this study can provide basic information for decision making on rational use of water resources and regulations for regional water safety guarantee system.

Far-ultraviolet refractive index of optical materials for solar blind channel (SBC) filters for the HST advanced camera for surveys (ACS)

NASA Astrophysics Data System (ADS)

Leviton, Douglas B.; Madison, Timothy J.; Petrone, Peter

1998-10-01

Refractive index measurements using the minimum deviation method have been carried out for prisms of a variety of far ultraviolet optical materials used in the manufacture of Solar Blind Channel (SBC) filters for the HST Advanced Camera for Surveys (ACS). Some of the materials measured are gaining popularity in a variety of high technology applications including high power excimer lasers and advanced microlithography optics operating in a wavelength region where high quality knowledge of optical material properties is sparse yet critical. Our measurements are of unusually high accuracy and precision for this wavelength region owing to advanced instrumentation in the large vacuum chamber of the Diffraction Grating Evaluation Facility (DGEF) at Goddard Space Flight Center (GSFC) used to implement a minimum deviation method refractometer. Index values for CaF2, BaF2, LiF, and far ultraviolet grades of synthetic sapphire and synthetic fused silica are reported and compared with values from the literature.

Iodine nutrition in elementary state schools of Queretaro, Mexico: correlations between urinary iodine concentration with global nutrition status and social gap index.

PubMed

García-Solís, Pablo; Solís-S, Juan Carlos; García-Gaytán, Ana Cristina; Reyes-Mendoza, Vanessa A; Robles-Osorio, Ludivina; Villarreal-Ríos, Enrique; Leal-García, Luisa; Hernández-Montiel, Hebert Luis

2013-08-01

To estimate median urinary iodine concentration (UIC), and to correlate it with global nutrition indicators and social gap index (SGI) in 50 elementary state schools from 10 municipalities in the State of Queretaro, Mexico. 1,544 students were enrolled and an above of requirements of iodine intake was found (median UIC of 297 µg/L). Iodine status was found as deficient, adequate, more than adequate and excessive in 2, 4, 19 and 25 schools, respectively. Seventy seven percent of table salt samples showed adequate iodine content (20-40 ppm), while 9.6% of the samples had low iodine content (< 15 ppm). Medians of UIC per school were positively correlated with medians of body mass index (BMI) by using the standard deviation score (SDS) (r = 0.47; p < 0.005), height SDS (r = 0.41; p < 0.05), and overweight and obesity prevalence (r = 0.41; p < 0.05). Medians of UIC per school were negatively correlated with stunting prevalence (r = -0.39; p = 005) and social gap index (r = -0.36; p < 0.05). Best multiple regression models showed that BMI SDS and height were significantly related with UIC (p < 0.05). There is coexistence between the two extremes of iodine intake (insufficient and excessive). To our knowledge, the observed positive correlation between UIC and overweight and obesity has not been described before, and could be explained by the availability and consumption of snack food rich in energy and iodized salt.

Monetary diet cost is positively associated with diet quality and obesity: an analysis of school-aged children in Southwest China.

PubMed

Zhang, Xiao; Gong, Yunhui; Jia, Peng; Zhang, Jieyi; Xue, Hongmei; Quan, Liming; Tian, Guo; Xiong, Jingyuan; Zhang, Lishi; Wang, Yu; Zhang, Lin; Cheng, Guo

2018-06-18

Little is known about the relationships between diet cost, dietary intake and obesity in Chinese populations. This study explored how diet cost was related to diet quality and obesity among school-aged children in Southwest China. Data from a cross-sectional study was analysed. Diet cost was estimated based on dietary intake assessed with 24-h dietary recalls and retail food prices. Diet quality was measured using the Chinese Children Dietary Index. Body height, weight, waist circumference and skinfold thicknesses were measured, and their body mass index standard deviation score (BMISDS), waist-to-height ratio (WHtR), fat mass index (FMI) and fat-free mass index (FFMI) were calculated. Multivariate regression models were used to explore the relevance of diet cost to diet quality and obesity. After adjustment for potential confounders, a positive association was observed between diet quality and energy-adjusted diet cost (β = 0.143, 95% confidence interval, CI: 0.014-0.285, Pfor-trend = 0.0006). Energy-adjusted diet cost also showed a positive association with FMI (β = 0.0354, 95% CI: 0.0001-0.0709, Pfor-trend = 0.01), BMISDS (β = 0.0200, 95% CI: 0.0006-0.0394, Pfor-trend = 0.002) and WHtR (β = 0.0010, 95% CI: 0.0003-0.0017, Pfor-trend = 0.02). Energy-adjusted diet cost was independently and positively associated with diet quality and obesity among Chinese school-aged children.

Spatial and temporal variability of the Aridity Index in Greece

NASA Astrophysics Data System (ADS)

Nastos, Panagiotis T.; Politi, Nadia; Kapsomenakis, John

2013-01-01

The objective of this paper is to study the spatial and temporal variability of the Aridity Index (AI) in Greece, per decade, during the 50-year period (1951-2000). Besides, the projected changes in ensemble mean AI between the period 1961-1990 (reference period) and the periods 2021-2050 (near future) and 2071-2100 (far future) along with the inter-model standard deviations were presented, based on the simulation results, derived from a number of Regional Climatic Models (RCMs), within the ENSEMBLE European Project. The projection of the future climate was done under SRES A1B. The climatic data used, concern monthly precipitation totals and air temperature from 28 meteorological stations (22 stations from the Hellenic National Meteorological Service and 6 stations from neighboring countries, taken from the Monthly Climatic Data for the World). The estimation of the AI was carried out based on the potential evapotranspiration (PET) defined by Thornthwaite (1948). The data processing was done by the application of the statistical package R-project and the Geographical Information Systems (GIS). The results of the analysis showed that, within the examined period (1951-2000), a progressive shift from the "humid" class, which characterized the wider area of Greece, towards the "sub-humid" and "semi-arid" classes appeared in the eastern Crete Island, the Cyclades complex, the Evia and Attica, that is mainly the eastern Greece. The most significant change appears during the period 1991-2000. The future projections at the end of twentieth century, using ensemble mean simulations from 8 RCMs, show that drier conditions are expected to establish in regions of Greece (Attica, eastern continental Greece, Cyclades, Dodecanese, eastern Crete Island and northern Aegean). The inter-model standard deviation over these regions ranges from 0.02 to 0.05 against high values (0.09-0.15) illustrated in western mountainous continental Greece, during 2021-2050. Higher values of inter-model standard deviation appear in the 2071-2100 ranging from 0.02 to 0.10 reaching even 0.50 over mountainous regions of the country.

Using Mathematical Algorithms to Modify Glomerular Filtration Rate Estimation Equations

PubMed Central

Zhu, Bei; Wu, Jianqing; Zhu, Jin; Zhao, Weihong

2013-01-01

Background The equations provide a rapid and low-cost method of evaluating glomerular filtration rate (GFR). Previous studies indicated that the Modification of Diet in Renal Disease (MDRD), Chronic Kidney Disease-Epidemiology (CKD-EPI) and MacIsaac equations need further modification for application in Chinese population. Thus, this study was designed to modify the three equations, and compare the diagnostic accuracy of the equations modified before and after. Methodology With the use of 99 mTc-DTPA renal dynamic imaging as the reference GFR (rGFR), the MDRD, CKD-EPI and MacIsaac equations were modified by two mathematical algorithms: the hill-climbing and the simulated-annealing algorithms. Results A total of 703 Chinese subjects were recruited, with the average rGFR 77.14±25.93 ml/min. The entire modification process was based on a random sample of 80% of subjects in each GFR level as a training sample set, the rest of 20% of subjects as a validation sample set. After modification, the three equations performed significant improvement in slop, intercept, correlated coefficient, root mean square error (RMSE), total deviation index (TDI), and the proportion of estimated GFR (eGFR) within 10% and 30% deviation of rGFR (P10 and P30). Of the three modified equations, the modified CKD-EPI equation showed the best accuracy. Conclusions Mathematical algorithms could be a considerable tool to modify the GFR equations. Accuracy of all the three modified equations was significantly improved in which the modified CKD-EPI equation could be the optimal one. PMID:23472113

The geomechanical strength of carbonate rock in Kinta valley, Ipoh, Perak Malaysia

NASA Astrophysics Data System (ADS)

Mazlan, Nur Amanina; Lai, Goh Thian; Razib, Ainul Mardhiyah Mohd; Rafek, Abdul Ghani; Serasa, Ailie Sofyiana; Simon, Norbert; Surip, Noraini; Ern, Lee Khai; Mohamed, Tuan Rusli

2018-04-01

The stability of both cut rocks and underground openings were influenced by the geomechanical strength of rock materials, while the strength characteristics are influenced by both material characteristics and the condition of weathering. This paper present a systematic approach to quantify the rock material strength characteristics for material failure and material & discontinuities failure by using uniaxial compressive strength, point load strength index and Brazilian tensile strength for carbonate rocks. Statistical analysis of the results at 95 percent confidence level showed that the mean value of compressive strength, point load strength index and Brazilian tensile strength for with material failure and material & discontinuities failure were 76.8 ± 4.5 and 41.2 ± 4.1 MPa with standard deviation of 15.2 and 6.5 MPa, respectively. The point load strength index for material failure and material & discontinuities failure were 3.1 ± 0.2 MPa and 1.8 ± 0.3 MPa with standard deviation of 0.9 and 0.6 MPa, respectively. The Brazilian tensile strength with material failure and material & discontinuities failure were 7.1 ± 0.3 MPa and 4.1 ± 0.3 MPa with standard deviation of 1.4 and 0.6 MPa, respectively. The results of this research revealed that the geomechanical strengths of rock material of carbonate rocks for material & discontinuities failure deteriorates approximately ½ from material failure.

Effects of Obstructive Sleep Apnea and Obesity on Cardiac Remodeling: The Wisconsin Sleep Cohort Study.

PubMed

Korcarz, Claudia E; Peppard, Paul E; Young, Terry B; Chapman, Carrie B; Hla, K Mae; Barnet, Jodi H; Hagen, Erika; Stein, James H

2016-06-01

To characterize the prospective associations of obstructive sleep apnea (OSA) with future echocardiographic measures of adverse cardiac remodeling. This was a prospective long-term observational study. Participants had overnight polysomnography followed by transthoracic echocardiography a mean (standard deviation) of 18.0 (3.7) y later. OSA was characterized by the apnea-hypopnea index (AHI, events/hour). Echocardiography was used to assess left ventricular (LV) systolic and diastolic function and mass, left atrial volume and pressure, cardiac output, systemic vascular resistance, and right ventricular (RV) systolic function, size, and hemodynamics. Multivariate regression models estimated associations between log10(AHI+1) and future echocardiographic findings. A secondary analysis looked at oxygen desaturation indices and future echocardiographic findings. At entry, the 601 participants were mean (standard deviation) 47 (8) y old (47% female). After adjustment for age, sex, and body mass index, baseline log10(AHI+1) was associated significantly with future reduced LV ejection fraction and tricuspid annular plane systolic excursion (TAPSE) ≤ 15 mm. After further adjustment for cardiovascular risk factors, participants with higher baseline log10(AHI+1) had lower future LV ejection fraction (β = -1.35 [standard error = 0.6]/log10(AHI+1), P = 0.03) and higher odds of TAPSE ≤ 15 mm (odds ratio = 6.3/log10(AHI+1), 95% confidence interval = 1.3-30.5, P = 0.02). SaO2 desaturation indices were associated independently with LV mass, LV wall thickness, and RV area (all P < 0.03). OSA is associated independently with decreasing LV systolic function and with reduced RV function. Echocardiographic measures of adverse cardiac remodeling are strongly associated with OSA but are confounded by obesity. Hypoxia may be a stimulus for hypertrophy in individuals with OSA. © 2016 Associated Professional Sleep Societies, LLC.

The storm-time assessment of GNSS-SBAS performance within low latitude African region using a testbed-like platform

NASA Astrophysics Data System (ADS)

Abe, O. E.; Paparini, C.; Ngaya, R. H.; Otero Villamide, X.; Radicella, S. M.; Nava, B.

2017-09-01

A Satellite Based Augmentation System (SBAS) is designed to improve Global Navigation Satellite Systems (GNSS) in terms of integrity, accuracy, availability and continuity. The main limitation to SBAS performance optimization is the ionosphere, and this is more critical in low latitude. During geomagnetically disturbed periods the role of storm-time winds is important because they modify the atmospheric composition toward low latitudes. An index of ionospheric disturbance, the relative percentage of deviation of the vertical Total Electron Content (TEC) from the quiet level (DvTEC) at each station was evaluated to study positive and negative phases of the geomagnetic storms. The rate of change of TEC index (ROTI) over all the GNSS stations was estimated to evaluate equatorial ionospheric gradients and irregularities. From the study it is observed that the positive deviations are more frequent than negative ones. The availability map, which is the mean of the combine Vertical Protection Level (VPL) and Horizontal Protection Level (HPL) are used for the SBAS performance. The cases of moderate and minor storms studied during the months of July and October 2013 showed that the SBAS system performance during the disturbed periods depends on the local time in which the storm occurs, geographic longitude and other phenomena that need further study. During the storm-time conditions considered, three out of seven geomagnetic storms indicated good SBAS performance and exceed monthly average of the availability map, three geomagnetic storms reduced the system performance below monthly average while one does not have effect on SBAS system performance in respect to monthly average. The present study indicates ROTI as a better proxy than geomagnetic indices for the assessment of storm-time effects on GNSS-SBAS performance.

Modeling of nutation-precession: Very long baseline interferometry results

NASA Astrophysics Data System (ADS)

Herring, T. A.; Mathews, P. M.; Buffett, B. A.

2002-04-01

Analysis of over 20 years of very long baseline interferometry data (VLBI) yields estimates of the coefficients of the nutation series with standard deviations ranging from 5 microseconds of arc (μas) for the terms with periods <400 days to 38 μas for the longest-period terms. The largest deviations between the VLBI estimates of the amplitudes of terms in the nutation series and the theoretical values from the Mathews-Herring-Buffett (MHB2000) nutation series are 56 +/- 38 μas (associated with two of the 18.6 year nutations). The amplitudes of nutational terms with periods <400 days deviate from the MHB2000 nutation series values at the level standard deviation. The estimated correction to the IAU-1976 precession constant is -2.997 +/- 0.008 mas yr-1 when the coefficients of the MHB2000 nutation series are held fixed and is consistent with that inferred from the MHB2000 nutation theory. The secular change in the obliquity of the ecliptic is estimated to be -0.252 +/- 0.003 mas yr-1. When the coefficients of the largest-amplitude terms in the nutation series are estimated, the precession constant correction and obliquity rate are estimated to be -2.960 +/- 0.030 and -0.237 +/- 0.012 mas yr-1. Significant variations in the freely excited retrograde free core nutation mode are observed over the 20 years. During this time the amplitude has decreased from ~300 +/- 50 μas in the mid-1980s to nearly zero by the year 2000. There is evidence that the amplitude of the mode in now increasing again.

Estimation of the measurement uncertainty in magnetic resonance velocimetry based on statistical models

NASA Astrophysics Data System (ADS)

Bruschewski, Martin; Freudenhammer, Daniel; Buchenberg, Waltraud B.; Schiffer, Heinz-Peter; Grundmann, Sven

2016-05-01

Velocity measurements with magnetic resonance velocimetry offer outstanding possibilities for experimental fluid mechanics. The purpose of this study was to provide practical guidelines for the estimation of the measurement uncertainty in such experiments. Based on various test cases, it is shown that the uncertainty estimate can vary substantially depending on how the uncertainty is obtained. The conventional approach to estimate the uncertainty from the noise in the artifact-free background can lead to wrong results. A deviation of up to -75 % is observed with the presented experiments. In addition, a similarly high deviation is demonstrated with the data from other studies. As a more accurate approach, the uncertainty is estimated directly from the image region with the flow sample. Two possible estimation methods are presented.

Trends in New U.S. Marine Corps Accessions During the Recent Conflicts in Iraq and Afghanistan

DTIC Science & Technology

2014-01-01

modest changes over the study period. Favorable trends included recent (2009-2010) improvernents in body mass index and physical activity levels...height, body mass index (BMI) in kg/m^ was calculated. Frequency of physical activity before service entry was assessed from self-report. Initial run...Test; BMI, body mass index; mph, miles per hour; SD, standard deviation. "Numbers (n) may not add up to 131,961 because of missing self-reported data for

T-wave axis deviation, metabolic syndrome and estimated cardiovascular risk--in men and women of the MOLI-SANI study.

PubMed

Rago, Livia; Di Castelnuovo, Augusto; Assanelli, Deodato; Badilini, Fabio; Vaglio, Martino; Gianfagna, Francesco; Salvetti, Massimo; Zito, Francesco; Alessandrini, Francesco; Donati, Maria Benedetta; de Gaetano, Giovanni; Iacoviello, Licia

2013-02-01

We aimed at investigating the association between T-wave axis deviation, metabolic syndrome (MetS), its components and estimated risk of cardiovascular disease (CVD) at 10 years in an adult Italian population. 11,143 women (54 ± 11 years) and 9742 men (55 ± 11 years) were analyzed from the Moli-sani cohort, randomly recruited from the general population. MetS was defined using the ATPIII criteria. T-wave axis deviation was measured from the standard 12-lead resting electrocardiogram. CVD risk in ten years was estimated by the CUORE score. 29% of men and 27% of women with MetS showed borderline or abnormal T-wave as compared to 24% and 17% without MetS (p < 0.0001 for both genders). Among components of MetS, elevated waist and blood pressure were strongly associated with T-wave axis deviation, whereas glucose, HDL and triglycerides were only marginally. The odds of having borderline or abnormal T-wave axis deviation in multivariable regression analysis, was 1.38 (95% CI:1.25-1.53) in MetS men and 1.68 (95% CI:1.51-1.87) in MetS women compared to those without. Further adjustment for MetS components completely abolished the associations. Abnormal T-wave axis deviation was associated with an increased risk of CVD in 10 years in men (OR = 4.4; 95% CI:1.10-17.9). T-wave axis deviation is strongly associated with components of the MetS, in particular high waist circumference and blood pressure and with an increased CVD risk, particularly in men. ECG monitoring to identify T-wave axis deviation in obese, hypertensive or MetS subjects can be an early indicator of vascular disease and help in reducing cardiac events. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Migration in the shearing sheet and estimates for young open cluster migration

NASA Astrophysics Data System (ADS)

Quillen, Alice C.; Nolting, Eric; Minchev, Ivan; De Silva, Gayandhi; Chiappini, Cristina

2018-04-01

Using tracer particles embedded in self-gravitating shearing sheet N-body simulations, we investigate the distance in guiding centre radius that stars or star clusters can migrate in a few orbital periods. The standard deviations of guiding centre distributions and maximum migration distances depend on the Toomre or critical wavelength and the contrast in mass surface density caused by spiral structure. Comparison between our simulations and estimated guiding radii for a few young supersolar metallicity open clusters, including NGC 6583, suggests that the contrast in mass surface density in the solar neighbourhood has standard deviation (in the surface density distribution) divided by mean of about 1/4 and larger than measured using COBE data by Drimmel and Spergel. Our estimate is consistent with a standard deviation of ˜0.07 dex in the metallicities measured from high-quality spectroscopic data for 38 young open clusters (<1 Gyr) with mean galactocentric radius 7-9 kpc.

Finite-time and finite-size scalings in the evaluation of large-deviation functions: Numerical approach in continuous time.

PubMed

Guevara Hidalgo, Esteban; Nemoto, Takahiro; Lecomte, Vivien

2017-06-01

Rare trajectories of stochastic systems are important to understand because of their potential impact. However, their properties are by definition difficult to sample directly. Population dynamics provides a numerical tool allowing their study, by means of simulating a large number of copies of the system, which are subjected to selection rules that favor the rare trajectories of interest. Such algorithms are plagued by finite simulation time and finite population size, effects that can render their use delicate. In this paper, we present a numerical approach which uses the finite-time and finite-size scalings of estimators of the large deviation functions associated to the distribution of rare trajectories. The method we propose allows one to extract the infinite-time and infinite-size limit of these estimators, which-as shown on the contact process-provides a significant improvement of the large deviation function estimators compared to the standard one.

Odds per Adjusted Standard Deviation: Comparing Strengths of Associations for Risk Factors Measured on Different Scales and Across Diseases and Populations

PubMed Central

Hopper, John L.

2015-01-01

How can the “strengths” of risk factors, in the sense of how well they discriminate cases from controls, be compared when they are measured on different scales such as continuous, binary, and integer? Given that risk estimates take into account other fitted and design-related factors—and that is how risk gradients are interpreted—so should the presentation of risk gradients. Therefore, for each risk factor X0, I propose using appropriate regression techniques to derive from appropriate population data the best fitting relationship between the mean of X0 and all the other covariates fitted in the model or adjusted for by design (X1, X2, … , Xn). The odds per adjusted standard deviation (OPERA) presents the risk association for X0 in terms of the change in risk per s = standard deviation of X0 adjusted for X1, X2, … , Xn, rather than the unadjusted standard deviation of X0 itself. If the increased risk is relative risk (RR)-fold over A adjusted standard deviations, then OPERA = exp[ln(RR)/A] = RRs. This unifying approach is illustrated by considering breast cancer and published risk estimates. OPERA estimates are by definition independent and can be used to compare the predictive strengths of risk factors across diseases and populations. PMID:26520360

Multiplicative Versus Additive Filtering for Spacecraft Attitude Determination

NASA Technical Reports Server (NTRS)

Markley, F. Landis

2003-01-01

The absence of a globally nonsingular three-parameter representation of rotations forces attitude Kalman filters to estimate either a singular or a redundant attitude representation. We compare two filtering strategies using simplified kinematics and measurement models. Our favored strategy estimates a three-parameter representation of attitude deviations from a reference attitude specified by a higher- dimensional nonsingular parameterization. The deviations from the reference are assumed to be small enough to avoid any singularity or discontinuity of the three-dimensional parameterization. We point out some disadvantages of the other strategy, which directly estimates the four-parameter quaternion representation.

Office and 24-hour heart rate and target organ damage in hypertensive patients

PubMed Central

2012-01-01

Background We investigated the association between heart rate and its variability with the parameters that assess vascular, renal and cardiac target organ damage. Methods A cross-sectional study was performed including a consecutive sample of 360 hypertensive patients without heart rate lowering drugs (aged 56 ± 11 years, 64.2% male). Heart rate (HR) and its standard deviation (HRV) in clinical and 24-hour ambulatory monitoring were evaluated. Renal damage was assessed by glomerular filtration rate and albumin/creatinine ratio; vascular damage by carotid intima-media thickness and ankle/brachial index; and cardiac damage by the Cornell voltage-duration product and left ventricular mass index. Results There was a positive correlation between ambulatory, but not clinical, heart rate and its standard deviation with glomerular filtration rate, and a negative correlation with carotid intima-media thickness, and night/day ratio of systolic and diastolic blood pressure. There was no correlation with albumin/creatinine ratio, ankle/brachial index, Cornell voltage-duration product or left ventricular mass index. In the multiple linear regression analysis, after adjusting for age, the association of glomerular filtration rate and intima-media thickness with ambulatory heart rate and its standard deviation was lost. According to the logistic regression analysis, the predictors of any target organ damage were age (OR = 1.034 and 1.033) and night/day systolic blood pressure ratio (OR = 1.425 and 1.512). Neither 24 HR nor 24 HRV reached statistical significance. Conclusions High ambulatory heart rate and its variability, but not clinical HR, are associated with decreased carotid intima-media thickness and a higher glomerular filtration rate, although this is lost after adjusting for age. Trial Registration ClinicalTrials.gov: NCT01325064 PMID:22439900

The retest distribution of the visual field summary index mean deviation is close to normal.

PubMed

Anderson, Andrew J; Cheng, Allan C Y; Lau, Samantha; Le-Pham, Anne; Liu, Victor; Rahman, Farahnaz

2016-09-01

When modelling optimum strategies for how best to determine visual field progression in glaucoma, it is commonly assumed that the summary index mean deviation (MD) is normally distributed on repeated testing. Here we tested whether this assumption is correct. We obtained 42 reliable 24-2 Humphrey Field Analyzer SITA standard visual fields from one eye of each of five healthy young observers, with the first two fields excluded from analysis. Previous work has shown that although MD variability is higher in glaucoma, the shape of the MD distribution is similar to that found in normal visual fields. A Shapiro-Wilks test determined any deviation from normality. Kurtosis values for the distributions were also calculated. Data from each observer passed the Shapiro-Wilks normality test. Bootstrapped 95% confidence intervals for kurtosis encompassed the value for a normal distribution in four of five observers. When examined with quantile-quantile plots, distributions were close to normal and showed no consistent deviations across observers. The retest distribution of MD is not significantly different from normal in healthy observers, and so is likely also normally distributed - or nearly so - in those with glaucoma. Our results increase our confidence in the results of influential modelling studies where a normal distribution for MD was assumed. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

A New Online Calibration Method Based on Lord's Bias-Correction.

PubMed

He, Yinhong; Chen, Ping; Li, Yong; Zhang, Shumei

2017-09-01

Online calibration technique has been widely employed to calibrate new items due to its advantages. Method A is the simplest online calibration method and has attracted many attentions from researchers recently. However, a key assumption of Method A is that it treats person-parameter estimates θ ^ s (obtained by maximum likelihood estimation [MLE]) as their true values θ s , thus the deviation of the estimated θ ^ s from their true values might yield inaccurate item calibration when the deviation is nonignorable. To improve the performance of Method A, a new method, MLE-LBCI-Method A, is proposed. This new method combines a modified Lord's bias-correction method (named as maximum likelihood estimation-Lord's bias-correction with iteration [MLE-LBCI]) with the original Method A in an effort to correct the deviation of θ ^ s which may adversely affect the item calibration precision. Two simulation studies were carried out to explore the performance of both MLE-LBCI and MLE-LBCI-Method A under several scenarios. Simulation results showed that MLE-LBCI could make a significant improvement over the ML ability estimates, and MLE-LBCI-Method A did outperform Method A in almost all experimental conditions.

Using the Standard Deviation of a Region of Interest in an Image to Estimate Camera to Emitter Distance

PubMed Central

Cano-García, Angel E.; Lazaro, José Luis; Infante, Arturo; Fernández, Pedro; Pompa-Chacón, Yamilet; Espinoza, Felipe

2012-01-01

In this study, a camera to infrared diode (IRED) distance estimation problem was analyzed. The main objective was to define an alternative to measures depth only using the information extracted from pixel grey levels of the IRED image to estimate the distance between the camera and the IRED. In this paper, the standard deviation of the pixel grey level in the region of interest containing the IRED image is proposed as an empirical parameter to define a model for estimating camera to emitter distance. This model includes the camera exposure time, IRED radiant intensity and the distance between the camera and the IRED. An expression for the standard deviation model related to these magnitudes was also derived and calibrated using different images taken under different conditions. From this analysis, we determined the optimum parameters to ensure the best accuracy provided by this alternative. Once the model calibration had been carried out, a differential method to estimate the distance between the camera and the IRED was defined and applied, considering that the camera was aligned with the IRED. The results indicate that this method represents a useful alternative for determining the depth information. PMID:22778608

Using the standard deviation of a region of interest in an image to estimate camera to emitter distance.

PubMed

Cano-García, Angel E; Lazaro, José Luis; Infante, Arturo; Fernández, Pedro; Pompa-Chacón, Yamilet; Espinoza, Felipe

2012-01-01

In this study, a camera to infrared diode (IRED) distance estimation problem was analyzed. The main objective was to define an alternative to measures depth only using the information extracted from pixel grey levels of the IRED image to estimate the distance between the camera and the IRED. In this paper, the standard deviation of the pixel grey level in the region of interest containing the IRED image is proposed as an empirical parameter to define a model for estimating camera to emitter distance. This model includes the camera exposure time, IRED radiant intensity and the distance between the camera and the IRED. An expression for the standard deviation model related to these magnitudes was also derived and calibrated using different images taken under different conditions. From this analysis, we determined the optimum parameters to ensure the best accuracy provided by this alternative. Once the model calibration had been carried out, a differential method to estimate the distance between the camera and the IRED was defined and applied, considering that the camera was aligned with the IRED. The results indicate that this method represents a useful alternative for determining the depth information.

Spectral solution of the inverse Mie problem

NASA Astrophysics Data System (ADS)

Romanov, Andrey V.; Konokhova, Anastasiya I.; Yastrebova, Ekaterina S.; Gilev, Konstantin V.; Strokotov, Dmitry I.; Chernyshev, Andrei V.; Maltsev, Valeri P.; Yurkin, Maxim A.

2017-10-01

We developed a fast method to determine size and refractive index of homogeneous spheres from the power Fourier spectrum of their light-scattering patterns (LSPs), measured with the scanning flow cytometer. Specifically, we used two spectral parameters: the location of the non-zero peak and zero-frequency amplitude, and numerically inverted the map from the space of particle characteristics (size and refractive index) to the space of spectral parameters. The latter parameters can be reliably resolved only for particle size parameter greater than 11, and the inversion is unique only in the limited range of refractive index with upper limit between 1.1 and 1.25 (relative to the medium) depending on the size parameter and particular definition of uniqueness. The developed method was tested on two experimental samples, milk fat globules and spherized red blood cells, and resulted in accuracy not worse than the reference method based on the least-square fit of the LSP with the Mie theory. Moreover, for particles with significant deviation from the spherical shape the spectral method was much closer to the Mie-fit result than the estimated uncertainty of the latter. The spectral method also showed adequate results for synthetic LSPs of spheroids with aspect ratios up to 1.4. Overall, we present a general framework, which can be used to construct an inverse algorithm for any other experimental signals.

Estimation of Tooth Size Discrepancies among Different Malocclusion Groups

PubMed Central

Bala, Madhu; Goyal, Virender

2014-01-01

ABSTRACT Regards and Tribute: Late Dr Narender Hasija was a mentor and visionary in the light of knowledge and experience. We pay our regards with deepest gratitude to the departed soul to rest in peace. Bolton’s ratios help in estimating overbite, overjet relationships, the effects of contemplated extractions on posterior occlusion, incisor relationships and identification of occlusal misfit produced by tooth size discrepancies. Aim: To determine any difference in tooth size discrepancy in anterior as well as overall ratio in different malocclusions and comparison with Bolton’s study. Materials and methods: After measuring the teeth on all 100 patients, Bolton’s analysis was performed. Results were compared with Bolton’s means and standard deviations. The results were also subjected to statistical analysis. Results show that the mean and standard deviations of ideal occlusion cases are comparable with those Bolton but, when the mean and standard deviation of malocclusion groups are compared with those of Bolton, the values of standard deviation are higher, though the mean is comparable. How to cite this article: Hasija N, Bala M, Goyal V. Estimation of Tooth Size Discrepancies among Different Malocclusion Groups. Int J Clin Pediatr Dent 2014;7(2):82-85. PMID:25356005

An estimator for the standard deviation of a natural frequency. I.

NASA Technical Reports Server (NTRS)

Schiff, A. J.; Bogdanoff, J. L.

1971-01-01

A brief review of mean-square approximate systems is given. The case in which the masses are deterministic is considered first in the derivation of an estimator for the upper bound of the standard deviation of a natural frequency. Two examples presented include a two-degree-of-freedom system and a case in which the disorder in the springs is perfectly correlated. For purposes of comparison, a Monte Carlo simulation was done on a digital computer.

Impact of Image Noise on Gamma Index Calculation

NASA Astrophysics Data System (ADS)

Chen, M.; Mo, X.; Parnell, D.; Olivera, G.; Galmarini, D.; Lu, W.

2014-03-01

Purpose: The Gamma Index defines an asymmetric metric between the evaluated image and the reference image. It provides a quantitative comparison that can be used to indicate sample-wised pass/fail on the agreement of the two images. The Gamma passing/failing rate has become an important clinical evaluation tool. However, the presence of noise in the evaluated and/or reference images may change the Gamma Index, hence the passing/failing rate, and further, clinical decisions. In this work, we systematically studied the impact of the image noise on the Gamma Index calculation. Methods: We used both analytic formulation and numerical calculations in our study. The numerical calculations included simulations and clinical images. Three different noise scenarios were studied in simulations: noise in reference images only, in evaluated images only, and in both. Both white and spatially correlated noises of various magnitudes were simulated. For clinical images of various noise levels, the Gamma Index of measurement against calculation, calculation against measurement, and measurement against measurement, were evaluated. Results: Numerical calculations for both the simulation and clinical data agreed with the analytic formulations, and the clinical data agreed with the simulations. For the Gamma Index of measurement against calculation, its distribution has an increased mean and an increased standard deviation as the noise increases. On the contrary, for the Gamma index of calculation against measurement, its distribution has a decreased mean and stabilized standard deviation as the noise increases. White noise has greater impact on the Gamma Index than spatially correlated noise. Conclusions: The noise has significant impact on the Gamma Index calculation and the impact is asymmetric. The Gamma Index should be reported along with the noise levels in both reference and evaluated images. Reporting of the Gamma Index with switched roles of the images as reference and evaluated images or some composite metrics would be a good practice.

Sarcopenia and its individual criteria are associated, in part, with mortality among patients on hemodialysis.

PubMed

Kittiskulnam, Piyawan; Chertow, Glenn M; Carrero, Juan J; Delgado, Cynthia; Kaysen, George A; Johansen, Kirsten L

2017-07-01

The relative importance of sarcopenia and its individual components as independent predictors of mortality in the dialysis population has not been determined. We estimated whole-body muscle mass using pre-dialysis bioimpedance spectroscopy measurements in 645 ACTIVE/ADIPOSE-enrolled prevalent hemodialysis patients from San Francisco and Atlanta. Low muscle mass was defined as two standard deviations below sex-specific means for young adults from NHANES and indexed to height 2 , body weight, body surface area, or body mass index. We evaluated the association of sarcopenia (low muscle mass) by four indexing methods, weak hand grip strength, and slow gait speed with mortality. Seventy-eight deaths were observed during a mean follow-up of 1.9 years. Sarcopenia was not significantly associated with mortality after adjusting for covariates. No muscle mass criteria were associated with death, regardless of indexing metrics. In contrast, having weak grip strength or slow walking speed was associated with mortality in the adjusted model. Only gait slowness significantly improved the predictive accuracy for death with an increase in C-statistic from 0.63 to 0.68. However, both gait slowness and hand grip weakness significantly improved the net reclassification index compared to models without performance measures (50.5% for slowness and 33.7% for weakness), whereas models with muscle size did not. Neither sarcopenia nor low muscle mass by itself was a better predictor of mortality than functional limitation alone in patients receiving hemodialysis. Thus, physical performance measures, including slow gait speed and weak hand grip strength, were associated with mortality even after adjustment for muscle size and other confounders. Published by Elsevier Inc.

A new validation technique for estimations of body segment inertia tensors: Principal axes of inertia do matter.

PubMed

Rossi, Marcel M; Alderson, Jacqueline; El-Sallam, Amar; Dowling, James; Reinbolt, Jeffrey; Donnelly, Cyril J

2016-12-08

The aims of this study were to: (i) establish a new criterion method to validate inertia tensor estimates by setting the experimental angular velocity data of an airborne objects as ground truth against simulations run with the estimated tensors, and (ii) test the sensitivity of the simulations to changes in the inertia tensor components. A rigid steel cylinder was covered with reflective kinematic markers and projected through a calibrated motion capture volume. Simulations of the airborne motion were run with two models, using inertia tensor estimated with geometric formula or the compound pendulum technique. The deviation angles between experimental (ground truth) and simulated angular velocity vectors and the root mean squared deviation angle were computed for every simulation. Monte Carlo analyses were performed to assess the sensitivity of simulations to changes in magnitude of principal moments of inertia within ±10% and to changes in orientation of principal axes of inertia within ±10° (of the geometric-based inertia tensor). Root mean squared deviation angles ranged between 2.9° and 4.3° for the inertia tensor estimated geometrically, and between 11.7° and 15.2° for the compound pendulum values. Errors up to 10% in magnitude of principal moments of inertia yielded root mean squared deviation angles ranging between 3.2° and 6.6°, and between 5.5° and 7.9° when lumped with errors of 10° in principal axes of inertia orientation. The proposed technique can effectively validate inertia tensors from novel estimation methods of body segment inertial parameter. Principal axes of inertia orientation should not be neglected when modelling human/animal mechanics. Copyright © 2016 Elsevier Ltd. All rights reserved.

Single isotope evaluation of pulmonary capillary protein leak (ARDS model) using computerized gamma scintigraphy

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

Tatum, J.L.; Strash, A.M.; Sugerman, H.J.

Using a canine oleic acid model, a computerized gamma scintigraphic technique was evaluated to determine 1) ability to detect pulmonary capillary protein leak in a model temporally consistent with clinical adult respiratory distress syndrome (ARDS), 2) the possibility of providing a quantitative index of leak, and 3) the feasibility of closely spaced repeat evaluations. Study animals received oleic acid (controls, n . 10; 0.05 ml/kg, n . 10; 0.10 ml/kg, n . 12; 0.15 ml/kg, n . 6) 3 hours prior to a tracer dose of technetium-99m (/sup 99/mTc) HSA. One animal in each dose group also received two repeatmore » tracer injections spaced a minimum of 45 minutes apart. Digital images were obtained with a conventional gamma camera interfaced to a dedicated medical computer. Lung: heart ratio versus time curves were generated, and a slope index was calculated for each curve. Slope index values for all doses were significantly greater than control values (P(t) less than 0.0001). Each incremental dose increase was also significantly greater than the previous dose level. Oleic acid dose versus slope index fitted a linear regression model with r . 0.94. Repeat dosing produced index values with standard deviations less than the group sample standard deviations. We feel this technique may have application in the clinical study of pulmonary permeability edema.« less

Measuring and Estimating GFR and Treatment Effect in ADPKD Patients: Results and Implications of a Longitudinal Cohort Study

PubMed Central

Cannata, Antonio; Carrara, Fabiola; Cella, Claudia; Ferrari, Silvia; Stucchi, Nadia; Prandini, Silvia; Ene-Iordache, Bogdan; Diadei, Olimpia; Perico, Norberto; Ondei, Patrizia; Pisani, Antonio; Buongiorno, Erasmo; Messa, Piergiorgio; Dugo, Mauro; Remuzzi, Giuseppe

2012-01-01

Trials failed to demonstrate protective effects of investigational treatments on glomerular filtration rate (GFR) reduction in Autosomal Dominant Polycystic Kidney Disease (ADPKD). To assess whether above findings were explained by unreliable GFR estimates, in this academic study we compared GFR values centrally measured by iohexol plasma clearance with corresponding values estimated by Chronic Kidney Disease Epidemiology Collaboration (CKD-Epi) and abbreviated Modification of Diet in Renal Disease (aMDRD) formulas in ADPKD patients retrieved from four clinical trials run by a Clinical Research Center and five Nephrology Units in Italy. Measured baseline GFRs and one-year GFR changes averaged 78.6±26.7 and 8.4±10.3 mL/min/1.73 m2 in 111 and 71 ADPKD patients, respectively. CKD-Epi significantly overestimated and aMDRD underestimated baseline GFRs. Less than half estimates deviated by <10% from measured values. One-year estimated GFR changes did not detect measured changes. Both formulas underestimated GFR changes by 50%. Less than 9% of estimates deviated <10% from measured changes. Extent of deviations even exceeded that of measured one-year GFR changes. In ADPKD, prediction formulas unreliably estimate actual GFR values and fail to detect their changes over time. Direct kidney function measurements by appropriate techniques are needed to adequately evaluate treatment effects in clinics and research. PMID:22393413

Estimated Kidney Function Based on Serum Cystatin C and Risk of Subsequent Coronary Artery Calcium in Young and Middle-aged Adults With Preserved Kidney Function: Results From the CARDIA Study

PubMed Central

Bansal, Nisha; Vittinghoff, Eric; Peralta, Carmen A.; Shlipak, Michael G.; Grubbs, Vanessa; Jacobs, David R.; Siscovick, David; Steffes, Michael; Carr, John Jeffrey; Bibbins-Domingo, Kirsten

2013-01-01

Whether kidney dysfunction is associated with coronary artery calcium (CAC) in young and middle-aged adults who have a cystatin C–derived estimated glomerular filtration rate (eGFRcys) greater than 60 mL/min/1.73 m2 is unknown. In the Coronary Artery Risk Development in Young Adults (CARDIA) cohort (recruited in 1985 and 1986 in Birmingham, Alabama; Chicago, Illinois; Minneapolis, Minnesota; and Oakland, California), we examined 1) the association of eGFRcys at years 10 and 15 and detectable CAC over the subsequent 5 years and 2) the association of change in eGFRcys and subsequent CAC, comparing those with stable eGFRcys to those whose eGFRcys increased (>3% annually over 5 years), declined moderately (3%–5%), or declined rapidly (>5%). Generalized estimating equation Poisson models were used, with adjustment for age, sex, race, educational level, income, family history of coronary artery disease, diabetes, body mass index, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and tobacco use. Among 3,070 participants (mean age 35.6 (standard deviation, 4.1) years and mean eGFRcys 106.7 (standard deviation, 18.5) mL/min/1.73 m2), 529 had detectable CAC. Baseline eGFRcys was not associated with CAC. Moderate eGFRcys decline was associated with a 33% greater relative risk of subsequent CAC (95% confidence interval: 5, 68; P = 0.02), whereas rapid decline was associated with a 51% higher relative risk (95% confidence interval: 10, 208; P = 0.01) in adjusted models. In conclusion, among young and middle-aged adults with eGFRcys greater than 60 mL/min/1.73 m2, annual decline in eGFRcys is an independent risk factor for subsequent CAC. PMID:23813702

Dust Optical Properties Over North Africa and Arabian Peninsula Derived from the AERONET Dataset

NASA Technical Reports Server (NTRS)

Kim, D.; Chin, M.; Yu, H.; Eck, T. F.; Sinyuk, A.; Smirnov, A.; Holben, B. N.

2011-01-01

Dust optical properties over North Africa and the Arabian Peninsula are extracted from the quality assured multi-year datasets obtained at 14 sites of the Aerosol Robotic Network (AERONET). We select the data with (a) large aerosol optical depth (AOD >= 0.4 at 440 nm) and (b) small Angstrom exponent (A(sub ext)<= 0.2) for retaining high accuracy and reducing interference of non-dust aerosols. The result indicates that the major fraction of high aerosol optical depth days are dominated by dust over these sites even though it varies depending on location and time. We have found that the annual mean and standard deviation of single scattering albedo, asymmetry parameter, real refractive index, and imaginary refractive index for Saharan and Arabian desert dust is 0.944 +/- 0.005, 0.752 +/- 0.014, 1.498 +/- 0.032, and 0.0024 +/- 0.0034 at 550 nm wavelength, respectively. Dust aerosol selected by this method is less absorbing than the previously reported values over these sites. The weaker absorption of dust from this study is consistent with the studies using remote sensing techniques from satellite. These results can help to constrain uncertainties in estimating global dust shortwave radiative forcing.

A Journal-Level Analysis of Progress in Transplantation.

PubMed

Feeley, Thomas; Lee, Seyoung; Moon, Shin-Il

2018-03-01

Citations to articles published in academic journals represent a proxy for influence in bibliometrics. To measure the journal impact factor for Progress in Transplantation over time and to also identify related journals indexed in transplantation and surgery. Data from Journal Citation Reports (ISI web of science) were used to rank Progress in Transplantation compared to peer journals using journal impact and journal relatedness measures. Social network analysis was used to measure relationships between pairs of journals in Progress in Transplantation's relatedness network. Journal impact factor and journal relatedness. Data from 2010 through 2015 indicate the average journal article in PIT was cited 0.87 times (standard deviation [SD] = 0.12) and this estimate was stable over time. Progress in Transplantation most often cited American Journal of Transplantation, Transplantation, American Journal of Kidney Diseases, and Liver Transplantation. In terms of cited data, the journal was most often referenced by Clinical Transplantation, Transplant International, and Current Opinion in Organ Transplantation. The journal is listed both in surgery and transplantation categories of Journal Citation Reports and its impact factors over time fare better with surgery journals than with transplant journals. Network data using betweenness centrality indicate Progress in Transplantation links transplantation-focused journals and journals indexed in health sciences categories.

Inbreeding and immigration in urban and rural zones of Chile, with an endogamy index.

PubMed

Lazo, B; Campusano, C; Figueroa, H; Pinto-Cisternas, J; Zambra, E

1978-01-01

In order to establish relationships among immigration, inbreeding, and age at marriage in urban and rural zones in Chile, and to formulate an endogamy index, ecclesiastical and civil data on consanguinity from 1865-1914 were analyzed, and a random mating deviation index was developed, with resulting values indicating deviation toward endogamy in both zones. Data grouped by zones and decades include means of population and density, nuptiality, consanguineous marriages (number, types, frequencies, and inbreeding coefficients), and frequencies of immigrants among consanguineous and nonconsanguineous couples. All of these values differ markedly between zones, with values in the rural zone double those in the urban zone. In the 2 zones, there are no clear differences in age at marriage between consanguineous and nonconsanguineous couples, and this is an important finding. From the point of view of fertility, one can expect a similar length period of fertility for both groups of couples. In this case, lower fertility might be expected in consanguineous marriages, only because of a higher probability of homozygosis of deleterious genes.

[Comparison between references of the overweight and obesity prevalence, through the Body Mass Index, in Argentinean children].

PubMed

Padula, Gisel; Salceda, Susana A

2008-12-01

The evaluation of child nutritional status is highly dependent on the growth charts used. The aim of this study was to compare different references assessing overweight and obesity in children population, through the Body Mass Index. A total of 737 healthy children born at term, aged 2-5 years, were included (cross-sectional study). The participation was voluntary and consent. Body Mass Index (kg/m2) was estimated. The measurements techniques were based on national guidelines. We compared three references: (1) Centers for Disease Control and Prevention (CDC) (> Pc85: overweight; > Pc95: obesity; (2) International Obesity Task Force (IOTF) (sex-age-specific body mass index cut-offs); (3) World Health Organization (WHO) (+2 standard deviation: overweight; +3: obesity). The Epi Info 6.0 software was used to the statistical evaluation (chi2, p < or = .05%). The prevalence of overweight was 1.1 and 2.33 times higher in CDC application respect to the IOTF and the WHO references respectively. The prevalence of overweight was 2.1 times higher in IOTF application respect to the WHO references (p = .00001). The prevalence of obesity was 5.4 and 23.9 times higher in CDC application respect to the IOTF and the WHO references respectively. The prevalence of obesity was 4.4 times higher in IOTF application respect to the WHO references (p = .0000001). The prevalence of overweight and obesity, calculated through the BMI, differs substantially according to the reference and cut-off points used. In the absence of even a single criterion, each of the references should be used with care.

Interrelationships Between Walkability, Air Pollution, Greenness, and Body Mass Index.

PubMed

James, Peter; Kioumourtzoglou, Marianthi-Anna; Hart, Jaime E; Banay, Rachel F; Kloog, Itai; Laden, Francine

2017-11-01

Recent studies have linked urban environmental factors and body mass index (BMI); however, such factors are often examined in isolation, ignoring correlations across exposures. Using data on Nurses' Health Study participants living in the Northeastern United States in 2006, we estimated associations between neighborhood walkability (a composite of population density, street connectivity, and business access), greenness (from satellite imagery), and ambient air pollution (from satellite-based spatiotemporally resolved PM2.5 predictions and weighted monthly average concentrations of NO2 from up to five nearest monitors) and self-reported BMI using generalized additive models, allowing for deviations from linearity using penalized splines. Among 23,435 women aged 60-87 years, we observed nonlinear associations between walkability and BMI and between PM2.5 and BMI in single-exposure models adjusted for age, race, and individual- and area-level socioeconomic status. When modeling all exposures simultaneously, only the association between walkability and BMI remained nonlinear and nonmonotonic. Increasing walkability was associated with increasing BMI at lower levels of walkability (walkability index <1.8), while increasing walkability was linked to lower BMI in areas of higher walkability (walkability index >1.8). A 10 percentile increase in walkability, right above 1.8 was associated with a 0.84% decrease in log BMI. The relationship between walkability and BMI existed only among younger participants (<71 years old). Neighborhood walkability was nonlinearly linked to lower BMI independent of air pollution and greenness. Our findings highlight the importance of accounting for nonlinear confounding by interrelated urban environmental factors when investigating associations between the environment and BMI.

Non-contact weight measurement of flat-faced pharmaceutical tablets using terahertz transmission pulse delay measurements.

PubMed

Bawuah, Prince; Silfsten, Pertti; Ervasti, Tuomas; Ketolainen, Jarkko; Zeitler, J Axel; Peiponen, Kai-Erik

2014-12-10

By measuring the time delay of a terahertz pulse traversing a tablet, and hence its effective refractive index, it is possible to non-invasively and non-destructively detect the weight of tablets made of microcrystalline cellulose (MCC). Two sets of MCC tablets were used in the study: Set A (training set) consisted of 13 tablets with nominally constant height but varying porosities, whereas Set B (test set) comprised of 21 tablets with nominally constant porosity but different heights. A linear correlation between the estimated absolute weight based on the terahertz measurement and the measured weight of both sets of MCC tablets was found. In addition, it was possible to estimate the height of the tablets by utilizing the estimated absolute weight and calculating the relative change of height of each tablet with respect to an ideal tablet. A good agreement between the experimental and the calculated results was found highlighting the potential of this technique for in-line sensing of the weight, porosity and the relative change in height of the tablets compared to a reference/ideal tablet. In this context, we propose a quantitative quality control method to assess the deviations in porosity of tablets immediately after compaction. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of economic insecurity on mental health: Recent evidence from Australian panel data.

PubMed

Rohde, Nicholas; Tang, K K; Osberg, Lars; Rao, Prasada

2016-02-01

This paper estimates the impact of economic insecurity on the mental health of Australian adults. Taking microdata from the 2001-2011 HILDA panel survey, we develop a conceptually diverse set of insecurity measures and explore their relationships with the SF-36 mental health index. By using fixed effects models that control for unobservable heterogeneity we produce estimates that correct for endogeneity more thoroughly than previous works. Our results show that exposure to economic risks has small but consistently detrimental mental health effects. The main contribution of the paper however comes from the breadth of risks that are found to be harmful. Job insecurity, financial dissatisfaction, reductions and volatility in income, an inability to meet standard expenditures and a lack of access to emergency funds all adversely affect health. This suggests that the common element of economic insecurity (rather than idiosyncratic phenomena associated with any specific risk) is likely to be hazardous. Our preferred estimates indicate that a standard deviation shock to economic insecurity lowers an individual's mental health score by about 1.4 percentage points. If applied uniformly across the Australian population such a shock would increase the morbidity rate of mental disorders by about 1.7%. Copyright © 2016 Elsevier Ltd. All rights reserved.

The influence of cooling forearm/hand and gender on estimation of handgrip strength.

PubMed

Cheng, Chih-Chan; Shih, Yuh-Chuan; Tsai, Yue-Jin; Chi, Chia-Fen

2014-01-01

Handgrip strength is essential in manual operations and activities of daily life, but the influence of forearm/hand skin temperature on estimation of handgrip strength is not well documented. Therefore, the present study intended to investigate the effect of local cooling of the forearm/hand on estimation of handgrip strength at various target force levels (TFLs, in percentage of MVC) for both genders. A cold pressor test was used to lower and maintain the hand skin temperature at 14°C for comparison with the uncooled condition. A total of 10 male and 10 female participants were recruited. The results indicated that females had greater absolute estimation deviations. In addition, both genders had greater absolute deviations in the middle range of TFLs. Cooling caused an underestimation of grip strength. Furthermore, a power function is recommended for establishing the relationship between actual and estimated handgrip force. Statement of relevance: Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the forearm/hand tended to cause underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Practitioner Summary: It is important to understand the effect of lowering the forearm/hand skin temperature on grip-strength estimation. A cold pressor was used to cool the hand. The cooling caused underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. Manipulation with grip strength is essential in daily life and the workplace, so it is important to understand the influence of lowering the forearm/hand skin temperature on grip-strength estimation. Females and the middle range of TFL had greater deviations. Cooling the forearm/hand tended to cause underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force. It is important to understand the effect of lowering the forearm/hand skin temperature on grip-strength estimation. A cold pressor was used to cool the hand. The cooling caused underestimation, and a power function is recommended for establishing the relationship between actual and estimated handgrip force

Genome-wide association analysis identifies three new susceptibility loci for childhood body mass index

PubMed Central

Felix, Janine F.; Bradfield, Jonathan P.; Monnereau, Claire; van der Valk, Ralf J.P.; Stergiakouli, Evie; Chesi, Alessandra; Gaillard, Romy; Feenstra, Bjarke; Thiering, Elisabeth; Kreiner-Møller, Eskil; Mahajan, Anubha; Pitkänen, Niina; Joro, Raimo; Cavadino, Alana; Huikari, Ville; Franks, Steve; Groen-Blokhuis, Maria M.; Cousminer, Diana L.; Marsh, Julie A.; Lehtimäki, Terho; Curtin, John A.; Vioque, Jesus; Ahluwalia, Tarunveer S.; Myhre, Ronny; Price, Thomas S.; Vilor-Tejedor, Natalia; Yengo, Loïc; Grarup, Niels; Ntalla, Ioanna; Ang, Wei; Atalay, Mustafa; Bisgaard, Hans; Blakemore, Alexandra I.; Bonnefond, Amelie; Carstensen, Lisbeth; Eriksson, Johan; Flexeder, Claudia; Franke, Lude; Geller, Frank; Geserick, Mandy; Hartikainen, Anna-Liisa; Haworth, Claire M.A.; Hirschhorn, Joel N.; Hofman, Albert; Holm, Jens-Christian; Horikoshi, Momoko; Hottenga, Jouke Jan; Huang, Jinyan; Kadarmideen, Haja N.; Kähönen, Mika; Kiess, Wieland; Lakka, Hanna-Maaria; Lakka, Timo A.; Lewin, Alexandra M.; Liang, Liming; Lyytikäinen, Leo-Pekka; Ma, Baoshan; Magnus, Per; McCormack, Shana E.; McMahon, George; Mentch, Frank D.; Middeldorp, Christel M.; Murray, Clare S.; Pahkala, Katja; Pers, Tune H.; Pfäffle, Roland; Postma, Dirkje S.; Power, Christine; Simpson, Angela; Sengpiel, Verena; Tiesler, Carla M. T.; Torrent, Maties; Uitterlinden, André G.; van Meurs, Joyce B.; Vinding, Rebecca; Waage, Johannes; Wardle, Jane; Zeggini, Eleftheria; Zemel, Babette S.; Dedoussis, George V.; Pedersen, Oluf; Froguel, Philippe; Sunyer, Jordi; Plomin, Robert; Jacobsson, Bo; Hansen, Torben; Gonzalez, Juan R.; Custovic, Adnan; Raitakari, Olli T.; Pennell, Craig E.; Widén, Elisabeth; Boomsma, Dorret I.; Koppelman, Gerard H.; Sebert, Sylvain; Järvelin, Marjo-Riitta; Hyppönen, Elina; McCarthy, Mark I.; Lindi, Virpi; Harri, Niinikoski; Körner, Antje; Bønnelykke, Klaus; Heinrich, Joachim; Melbye, Mads; Rivadeneira, Fernando; Hakonarson, Hakon; Ring, Susan M.; Smith, George Davey; Sørensen, Thorkild I.A.; Timpson, Nicholas J.; Grant, Struan F.A.; Jaddoe, Vincent W.V.

2016-01-01

A large number of genetic loci are associated with adult body mass index. However, the genetics of childhood body mass index are largely unknown. We performed a meta-analysis of genome-wide association studies of childhood body mass index, using sex- and age-adjusted standard deviation scores. We included 35 668 children from 20 studies in the discovery phase and 11 873 children from 13 studies in the replication phase. In total, 15 loci reached genome-wide significance (P-value < 5 × 10−8) in the joint discovery and replication analysis, of which 12 are previously identified loci in or close to ADCY3, GNPDA2, TMEM18, SEC16B, FAIM2, FTO, TFAP2B, TNNI3K, MC4R, GPR61, LMX1B and OLFM4 associated with adult body mass index or childhood obesity. We identified three novel loci: rs13253111 near ELP3, rs8092503 near RAB27B and rs13387838 near ADAM23. Per additional risk allele, body mass index increased 0.04 Standard Deviation Score (SDS) [Standard Error (SE) 0.007], 0.05 SDS (SE 0.008) and 0.14 SDS (SE 0.025), for rs13253111, rs8092503 and rs13387838, respectively. A genetic risk score combining all 15 SNPs showed that each additional average risk allele was associated with a 0.073 SDS (SE 0.011, P-value = 3.12 × 10−10) increase in childhood body mass index in a population of 1955 children. This risk score explained 2% of the variance in childhood body mass index. This study highlights the shared genetic background between childhood and adult body mass index and adds three novel loci. These loci likely represent age-related differences in strength of the associations with body mass index. PMID:26604143

Genome-wide association analysis identifies three new susceptibility loci for childhood body mass index.

PubMed

Felix, Janine F; Bradfield, Jonathan P; Monnereau, Claire; van der Valk, Ralf J P; Stergiakouli, Evie; Chesi, Alessandra; Gaillard, Romy; Feenstra, Bjarke; Thiering, Elisabeth; Kreiner-Møller, Eskil; Mahajan, Anubha; Pitkänen, Niina; Joro, Raimo; Cavadino, Alana; Huikari, Ville; Franks, Steve; Groen-Blokhuis, Maria M; Cousminer, Diana L; Marsh, Julie A; Lehtimäki, Terho; Curtin, John A; Vioque, Jesus; Ahluwalia, Tarunveer S; Myhre, Ronny; Price, Thomas S; Vilor-Tejedor, Natalia; Yengo, Loïc; Grarup, Niels; Ntalla, Ioanna; Ang, Wei; Atalay, Mustafa; Bisgaard, Hans; Blakemore, Alexandra I; Bonnefond, Amelie; Carstensen, Lisbeth; Eriksson, Johan; Flexeder, Claudia; Franke, Lude; Geller, Frank; Geserick, Mandy; Hartikainen, Anna-Liisa; Haworth, Claire M A; Hirschhorn, Joel N; Hofman, Albert; Holm, Jens-Christian; Horikoshi, Momoko; Hottenga, Jouke Jan; Huang, Jinyan; Kadarmideen, Haja N; Kähönen, Mika; Kiess, Wieland; Lakka, Hanna-Maaria; Lakka, Timo A; Lewin, Alexandra M; Liang, Liming; Lyytikäinen, Leo-Pekka; Ma, Baoshan; Magnus, Per; McCormack, Shana E; McMahon, George; Mentch, Frank D; Middeldorp, Christel M; Murray, Clare S; Pahkala, Katja; Pers, Tune H; Pfäffle, Roland; Postma, Dirkje S; Power, Christine; Simpson, Angela; Sengpiel, Verena; Tiesler, Carla M T; Torrent, Maties; Uitterlinden, André G; van Meurs, Joyce B; Vinding, Rebecca; Waage, Johannes; Wardle, Jane; Zeggini, Eleftheria; Zemel, Babette S; Dedoussis, George V; Pedersen, Oluf; Froguel, Philippe; Sunyer, Jordi; Plomin, Robert; Jacobsson, Bo; Hansen, Torben; Gonzalez, Juan R; Custovic, Adnan; Raitakari, Olli T; Pennell, Craig E; Widén, Elisabeth; Boomsma, Dorret I; Koppelman, Gerard H; Sebert, Sylvain; Järvelin, Marjo-Riitta; Hyppönen, Elina; McCarthy, Mark I; Lindi, Virpi; Harri, Niinikoski; Körner, Antje; Bønnelykke, Klaus; Heinrich, Joachim; Melbye, Mads; Rivadeneira, Fernando; Hakonarson, Hakon; Ring, Susan M; Smith, George Davey; Sørensen, Thorkild I A; Timpson, Nicholas J; Grant, Struan F A; Jaddoe, Vincent W V

2016-01-15

A large number of genetic loci are associated with adult body mass index. However, the genetics of childhood body mass index are largely unknown. We performed a meta-analysis of genome-wide association studies of childhood body mass index, using sex- and age-adjusted standard deviation scores. We included 35 668 children from 20 studies in the discovery phase and 11 873 children from 13 studies in the replication phase. In total, 15 loci reached genome-wide significance (P-value < 5 × 10(-8)) in the joint discovery and replication analysis, of which 12 are previously identified loci in or close to ADCY3, GNPDA2, TMEM18, SEC16B, FAIM2, FTO, TFAP2B, TNNI3K, MC4R, GPR61, LMX1B and OLFM4 associated with adult body mass index or childhood obesity. We identified three novel loci: rs13253111 near ELP3, rs8092503 near RAB27B and rs13387838 near ADAM23. Per additional risk allele, body mass index increased 0.04 Standard Deviation Score (SDS) [Standard Error (SE) 0.007], 0.05 SDS (SE 0.008) and 0.14 SDS (SE 0.025), for rs13253111, rs8092503 and rs13387838, respectively. A genetic risk score combining all 15 SNPs showed that each additional average risk allele was associated with a 0.073 SDS (SE 0.011, P-value = 3.12 × 10(-10)) increase in childhood body mass index in a population of 1955 children. This risk score explained 2% of the variance in childhood body mass index. This study highlights the shared genetic background between childhood and adult body mass index and adds three novel loci. These loci likely represent age-related differences in strength of the associations with body mass index. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Estimating extreme stream temperatures by the standard deviate method

NASA Astrophysics Data System (ADS)

Bogan, Travis; Othmer, Jonathan; Mohseni, Omid; Stefan, Heinz

2006-02-01

It is now widely accepted that global climate warming is taking place on the earth. Among many other effects, a rise in air temperatures is expected to increase stream temperatures indefinitely. However, due to evaporative cooling, stream temperatures do not increase linearly with increasing air temperatures indefinitely. Within the anticipated bounds of climate warming, extreme stream temperatures may therefore not rise substantially. With this concept in mind, past extreme temperatures measured at 720 USGS stream gauging stations were analyzed by the standard deviate method. In this method the highest stream temperatures are expressed as the mean temperature of a measured partial maximum stream temperature series plus its standard deviation multiplied by a factor KE (standard deviate). Various KE-values were explored; values of KE larger than 8 were found physically unreasonable. It is concluded that the value of KE should be in the range from 7 to 8. A unit error in estimating KE translates into a typical stream temperature error of about 0.5 °C. Using a logistic model for the stream temperature/air temperature relationship, a one degree error in air temperature gives a typical error of 0.16 °C in stream temperature. With a projected error in the enveloping standard deviate dKE=1.0 (range 0.5-1.5) and an error in projected high air temperature d Ta=2 °C (range 0-4 °C), the total projected stream temperature error is estimated as d Ts=0.8 °C.

Combined Use of Satellite Observations with Urban Surface Characteristics to Estimate PM Concentrations by Employing Mixed-Effects Models

NASA Astrophysics Data System (ADS)

Beloconi, Anton; Benas, Nikolaos; Chrysoulakis, Nektarios; Kamarianakis, Yiannis

2015-11-01

Linear mixed effects models were developed for the estimation of the average daily Particulate Matter (PM) concentration spatial distribution over the area of Greater London (UK). Both fine (PM2.5) and coarse (PM10) concentrations were predicted for the 2002- 2012 time period, based on satellite data. The latter included Aerosol Optical Thickness (AOT) at 3×3 km spatial resolution, as well as the Surface Relative Humidity, Surface Temperature and K-Index derived from MODIS (Moderate Resolution Imaging Spectroradiometer) sensor. For a meaningful interpretation of the association among these variables, all data were homogenized with regard to spatial support and geographic projection, thus addressing the change of support problem and leading to a valid statistical inference. To this end, spatial (2D) and spatio- temporal (3D) kriging techniques were applied to in-situ particulate matter concentrations and the leave-one- station-out cross-validation was performed on a daily level to gauge the quality of the predictions. Satellite- derived covariates displayed clear seasonal patterns; in order to work with data which is stationary in mean, for each covariate, deviations from its estimated annual profiles were computed using nonlinear least squares and nonlinear absolute deviations. High-resolution land- cover and morphology static datasets were additionally incorporated in the analysis in order to catch the effects of nearby emission sources and sequestration sites. For pairwise comparisons of the particulate matter concentration means at distinct land-cover classes, the pairwise comparisons method for unequal sample sizes, known as Tukey's method, was performed. The use of satellite-derived products allowed better assessment of space-time interactions of PM, since these daily spatial measurements were able to capture differences in PM concentrations between grid cells, while the use of high- resolution land-cover and morphology static datasets allowed accounting for local industrial, domestic and traffic related air pollution. The developed methods are expected to fully exploit ESA's new Sentinel-3 observations to estimate spatial distributions of both PM10 and PM2.5 concentrations in arbitrary cities.

Evaluation of Satellite and Model Precipitation Products Over Turkey

NASA Astrophysics Data System (ADS)

Yilmaz, M. T.; Amjad, M.

2017-12-01

Satellite-based remote sensing, gauge stations, and models are the three major platforms to acquire precipitation dataset. Among them satellites and models have the advantage of retrieving spatially and temporally continuous and consistent datasets, while the uncertainty estimates of these retrievals are often required for many hydrological studies to understand the source and the magnitude of the uncertainty in hydrological response parameters. In this study, satellite and model precipitation data products are validated over various temporal scales (daily, 3-daily, 7-daily, 10-daily and monthly) using in-situ measured precipitation observations from a network of 733 gauges from all over the Turkey. Tropical Rainfall Measurement Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) 3B42 version 7 and European Center of Medium-Range Weather Forecast (ECMWF) model estimates (daily, 3-daily, 7-daily and 10-daily accumulated forecast) are used in this study. Retrievals are evaluated for their mean and standard deviation and their accuracies are evaluated via bias, root mean square error, error standard deviation and correlation coefficient statistics. Intensity vs frequency analysis and some contingency table statistics like percent correct, probability of detection, false alarm ratio and critical success index are determined using daily time-series. Both ECMWF forecasts and TRMM observations, on average, overestimate the precipitation compared to gauge estimates; wet biases are 10.26 mm/month and 8.65 mm/month, respectively for ECMWF and TRMM. RMSE values of ECMWF forecasts and TRMM estimates are 39.69 mm/month and 41.55 mm/month, respectively. Monthly correlations between Gauges-ECMWF, Gauges-TRMM and ECMWF-TRMM are 0.76, 0.73 and 0.81, respectively. The model and the satellite error statistics are further compared against the gauges error statistics based on inverse distance weighting (IWD) analysis. Both the model and satellite data have less IWD errors (14.72 mm/month and 10.75 mm/month, respectively) compared to gauges IWD error (21.58 mm/month). These results show that, on average, ECMWF forecast data have higher skill than TRMM observations. Overall, both ECMWF forecast data and TRMM observations show good potential for catchment scale hydrological analysis.

Analysis of gait patterns pre- and post- Single Event Multilevel Surgery in children with Cerebral Palsy by means of Offset-Wise Movement Analysis Profile and Linear Fit Method.

PubMed

Ancillao, Andrea; van der Krogt, Marjolein M; Buizer, Annemieke I; Witbreuk, Melinda M; Cappa, Paolo; Harlaar, Jaap

2017-10-01

Gait analysis is used for the assessment of walking ability of children with cerebral palsy (CP), to inform clinical decision making and to quantify changes after treatment. To simplify gait analysis interpretation and to quantify deviations from normality, some quantitative synthetic descriptors were developed over the years, such as the Movement Analysis Profile (MAP) and the Linear Fit Method (LFM), but their interpretation is not always straightforward. The aims of this work were to: (i) study gait changes, by means of synthetic descriptors, in children with CP that underwent Single Event Multilevel Surgery; (ii) compare the MAP and the LFM on these patients; (iii) design a new index that may overcome the limitations of the previous methods, i.e. the lack of information about the direction of deviation or its source. Gait analysis exams of 10 children with CP, pre- and post-surgery, were collected and MAP and LFM were computed. A new index was designed asa modified version of the MAP by separating out changes in offset (named OC-MAP). MAP documented an improvement in the gait pattern after surgery. The highest effect was observed for the knee flexion/extension angle. However, a worsening was observed as an increase in anterior pelvic tilt. An important source of gait deviation was recognized in the offset between observed tracks and reference. OC-MAP allowed the assessment of the offset component versus the shape component of deviation. LFM provided results similar to OC-MAP offset analysis but could not be considered reliable due to intrinsic limitations. As offset in gait features played an important role in gait deviation, OC-MAP synthetic analysis was proposed as a novel approach to a meaningful parameterisation of global deviations in gait patterns of subjects with CP and gait changes after treatment. Copyright © 2017 Elsevier B.V. All rights reserved.

Reliability of temperatures measured at standard monitoring sites as an index of brain temperature during deep hypothermic cardiopulmonary bypass conducted for thoracic aortic reconstruction.

PubMed

Akata, Takashi; Setoguchi, Hidekazu; Shirozu, Kazuhiro; Yoshino, Jun

2007-06-01

It is essential to estimate the brain temperature of patients during deliberate deep hypothermia. Using jugular bulb temperature as a standard for brain temperature, we evaluated the accuracy and precision of 5 standard temperature monitoring sites (ie, pulmonary artery, nasopharynx, forehead deep-tissue, urinary bladder, and fingertip skin-surface tissue) during deep hypothermic cardiopulmonary bypass conducted for thoracic aortic reconstruction. In 20 adult patients with thoracic aortic aneurysms, the 5 temperature monitoring sites were recorded every 1 minute during deep hypothermic (<20 degrees C) cardiopulmonary bypass. The accuracy was evaluated by the difference from jugular bulb temperature, and the precision was evaluated by its standard deviation, as well as by the correlation with jugular bulb temperature. Pulmonary artery temperature and jugular bulb temperature began to change immediately after the start of cooling or rewarming, closely matching each other, and the other temperatures lagged behind these two temperatures. During either situation, the accuracy of pulmonary artery temperature measurement (0.3 degrees C-0.5 degrees C) was much superior to the other measurements, and its precision (standard deviation of the difference from jugular bulb temperature = 1.5 degrees C-1.8 degrees C; correlation coefficient = 0.94-0.95) was also best among the measurements, with its rank order being pulmonary artery > or = nasopharynx > forehead > bladder > fingertip. However, the accuracy and precision of pulmonary artery temperature measurement was significantly impaired during and for several minutes after infusion of cold cardioplegic solution. Pulmonary artery temperature measurement is recommended to estimate brain temperature during deep hypothermic cardiopulmonary bypass, even if it is conducted with the sternum opened; however, caution needs to be exercised in interpreting its measurements during periods of the cardioplegic solution infusion.

FIBER AND INTEGRATED OPTICS: Detection of the optical anisotropy in KTP:Rb waveguides

NASA Astrophysics Data System (ADS)

Buritskiĭ, K. S.; Dianov, Evgenii M.; Maslov, Vladislav A.; Chernykh, V. A.; Shcherbakov, E. A.

1990-10-01

The optical characteristics of channel waveguides made of rubidium-activated potassium titanyl phosphate (KTP:Rb) were determined. The refractive index increment of such waveguides was found to exhibit a considerable anisotropy: Δnx / Δnz approx 2. A deviation of the distribution of the refractive index in a channel waveguide from the model distribution was observed for ion-exchange times in excess of 1 h.

Path profiles of Cn2 derived from radiometer temperature measurements and geometrical ray tracing

NASA Astrophysics Data System (ADS)

Vyhnalek, Brian E.

2017-02-01

Atmospheric turbulence has significant impairments on the operation of Free-Space Optical (FSO) communication systems, in particular temporal and spatial intensity fluctuations at the receiving aperture resulting in power surges and fades, changes in angle of arrival, spatial coherence degradation, etc. The refractive index structure parameter C 2 n is a statistical measure of the strength of turbulence in the atmosphere and is highly dependent upon vertical height. Therefore to understand atmospheric turbulence effects on vertical FSO communication links such as space-to-ground links, it is necessary to specify C 2 n profiles along the atmospheric propagation path. To avoid the limitations on the applicability of classical approaches, propagation simulation through geometrical ray tracing is applied. This is achieved by considering the atmosphere along the optical propagation path as a spatial distribution of spherical bubbles with varying relative refractive index deviations representing turbulent eddies. The relative deviations of the refractive index are statistically determined from altitude-dependent and time varying temperature fluctuations, as measured by a microwave profiling radiometer. For each representative atmosphere ray paths are analyzed using geometrical optics, which is particularly advantageous in situations of strong turbulence where there is severe wavefront distortion and discontinuity. The refractive index structure parameter is then determined as a function of height and time.

Path Profiles of Cn2 Derived from Radiometer Temperature Measurements and Geometrical Ray Tracing

NASA Technical Reports Server (NTRS)

Vyhnalek, Brian E.

2017-01-01

Atmospheric turbulence has significant impairments on the operation of Free-Space Optical (FSO) communication systems, in particular temporal and spatial intensity fluctuations at the receiving aperture resulting in power surges and fades, changes in angle of arrival, spatial coherence degradation, etc. The refractive index structure parameter Cn2 is a statistical measure of the strength of turbulence in the atmosphere and is highly dependent upon vertical height. Therefore to understand atmospheric turbulence effects on vertical FSO communication links such as space-to-ground links, it is necessary to specify Cn2 profiles along the atmospheric propagation path. To avoid the limitations on the applicability of classical approaches, propagation simulation through geometrical ray tracing is applied. This is achieved by considering the atmosphere along the optical propagation path as a spatial distribution of spherical bubbles with varying relative refractive index deviations representing turbulent eddies. The relative deviations of the refractive index are statistically determined from altitude-dependent and time-varying temperature fluctuations, as measured by a microwave profiling radiometer. For each representative atmosphere ray paths are analyzed using geometrical optics, which is particularly advantageous in situations of strong turbulence where there is severe wavefront distortion and discontinuity. The refractive index structure parameter is then determined as a function of height and time.

Real-World Evaluation of Direct and Indirect Economic Burden Among Endometriosis Patients in the United States.

PubMed

Soliman, Ahmed M; Surrey, Eric; Bonafede, Machaon; Nelson, James K; Castelli-Haley, Jane

2018-03-01

The prevalence of endometriosis and the need for treatment in the USA has led to the need to explore the contemporary cost burden associated with the disease. This retrospective cohort study compared direct and indirect healthcare costs in patients with endometriosis to a control group without endometriosis. Women aged 18-49 years with endometriosis (date of initial diagnosis = index date) were identified in the Truven Health MarketScan ® Commercial database between 2010 and 2014 and female control patients without endometriosis were matched by age and index year. The following outcomes were compared: healthcare resource utilization (HRU) during the 12-month pre- and post-index periods (including inpatient admissions, pharmacy claims, emergency room visits, physician office visits, and obstetrics/gynecology visits), annual direct (medical and pharmacy) and indirect (absenteeism, short-term disability, and long-term disability) healthcare costs during the 12-month post-index period (in 2014 US$). Multivariate analyses were conducted to estimate annual total direct and indirect costs, controlling for demographics, pre-index clinical characteristics, and pre-index healthcare costs. Overall, 113,506 endometriosis patients and 927,599 controls were included. Endometriosis patients had significantly higher HRU during both the pre- and post-index periods compared to controls (p < 0.0001, all categories of HRU). Approximately two-thirds of endometriosis patients underwent an endometriosis-related surgical procedure (including laparotomy, laparoscopy, hysterectomy, oophorectomy, and other excision/ablation procedures) in the first 12 months post-index. Mean annual total adjusted direct costs per endometriosis patient during the 12-month post-index period was over three times higher than that for a non-endometriosis control [$16,573 (standard deviation (SD) = $21,336) vs. $4733 (SD = $14,833); p < 0.005]. On average, incremental direct and indirect 12-month costs per endometriosis patient were $10,002 and $2132 compared to their matched controls (p < 0.005). Endometriosis patients incurred significantly higher direct and indirect healthcare costs than non-endometriosis patients. AbbVie Inc.

Rotor Position Sensorless Control and Its Parameter Sensitivity of Permanent Magnet Motor Based on Model Reference Adaptive System

NASA Astrophysics Data System (ADS)

Ohara, Masaki; Noguchi, Toshihiko

This paper describes a new method for a rotor position sensorless control of a surface permanent magnet synchronous motor based on a model reference adaptive system (MRAS). This method features the MRAS in a current control loop to estimate a rotor speed and position by using only current sensors. This method as well as almost all the conventional methods incorporates a mathematical model of the motor, which consists of parameters such as winding resistances, inductances, and an induced voltage constant. Hence, the important thing is to investigate how the deviation of these parameters affects the estimated rotor position. First, this paper proposes a structure of the sensorless control applied in the current control loop. Next, it proves the stability of the proposed method when motor parameters deviate from the nominal values, and derives the relationship between the estimated position and the deviation of the parameters in a steady state. Finally, some experimental results are presented to show performance and effectiveness of the proposed method.

A method to estimate statistical errors of properties derived from charge-density modelling

PubMed Central

Lecomte, Claude

2018-01-01

Estimating uncertainties of property values derived from a charge-density model is not straightforward. A methodology, based on calculation of sample standard deviations (SSD) of properties using randomly deviating charge-density models, is proposed with the MoPro software. The parameter shifts applied in the deviating models are generated in order to respect the variance–covariance matrix issued from the least-squares refinement. This ‘SSD methodology’ procedure can be applied to estimate uncertainties of any property related to a charge-density model obtained by least-squares fitting. This includes topological properties such as critical point coordinates, electron density, Laplacian and ellipticity at critical points and charges integrated over atomic basins. Errors on electrostatic potentials and interaction energies are also available now through this procedure. The method is exemplified with the charge density of compound (E)-5-phenylpent-1-enylboronic acid, refined at 0.45 Å resolution. The procedure is implemented in the freely available MoPro program dedicated to charge-density refinement and modelling. PMID:29724964

ROBUST: an interactive FORTRAN-77 package for exploratory data analysis using parametric, ROBUST and nonparametric location and scale estimates, data transformations, normality tests, and outlier assessment

NASA Astrophysics Data System (ADS)

Rock, N. M. S.

ROBUST calculates 53 statistics, plus significance levels for 6 hypothesis tests, on each of up to 52 variables. These together allow the following properties of the data distribution for each variable to be examined in detail: (1) Location. Three means (arithmetic, geometric, harmonic) are calculated, together with the midrange and 19 high-performance robust L-, M-, and W-estimates of location (combined, adaptive, trimmed estimates, etc.) (2) Scale. The standard deviation is calculated along with the H-spread/2 (≈ semi-interquartile range), the mean and median absolute deviations from both mean and median, and a biweight scale estimator. The 23 location and 6 scale estimators programmed cover all possible degrees of robustness. (3) Normality: Distributions are tested against the null hypothesis that they are normal, using the 3rd (√ h1) and 4th ( b 2) moments, Geary's ratio (mean deviation/standard deviation), Filliben's probability plot correlation coefficient, and a more robust test based on the biweight scale estimator. These statistics collectively are sensitive to most usual departures from normality. (4) Presence of outliers. The maximum and minimum values are assessed individually or jointly using Grubbs' maximum Studentized residuals, Harvey's and Dixon's criteria, and the Studentized range. For a single input variable, outliers can be either winsorized or eliminated and all estimates recalculated iteratively as desired. The following data-transformations also can be applied: linear, log 10, generalized Box Cox power (including log, reciprocal, and square root), exponentiation, and standardization. For more than one variable, all results are tabulated in a single run of ROBUST. Further options are incorporated to assess ratios (of two variables) as well as discrete variables, and be concerned with missing data. Cumulative S-plots (for assessing normality graphically) also can be generated. The mutual consistency or inconsistency of all these measures helps to detect errors in data as well as to assess data-distributions themselves.

Use of instantaneous streamflow measurements to improve regression estimates of index flow for the summer month of lowest streamflow in Michigan

USGS Publications Warehouse

Holtschlag, David J.

2011-01-01

In Michigan, index flow Q50 is a streamflow characteristic defined as the minimum of median flows for July, August, and September. The state of Michigan uses index flow estimates to help regulate large (greater than 100,000 gallons per day) water withdrawals to prevent adverse effects on characteristic fish populations. At sites where long-term streamgages are located, index flows are computed directly from continuous streamflow records as GageQ50. In an earlier study, a multiple-regression equation was developed to estimate index flows IndxQ50 at ungaged sites. The index equation explains about 94 percent of the variability of index flows at 147 (index) streamgages by use of six explanatory variables describing soil type, aquifer transmissivity, land cover, and precipitation characteristics. This report extends the results of the previous study, by use of Monte Carlo simulations, to evaluate alternative flow estimators, DiscQ50, IntgQ50, SiteQ50, and AugmQ50. The Monte Carlo simulations treated each of the available index streamgages, in turn, as a miscellaneous site where streamflow conditions are described by one or more instantaneous measurements of flow. In the simulations, instantaneous flows were approximated by daily mean flows at the corresponding site. All estimators use information that can be obtained from instantaneous flow measurements and contemporaneous daily mean flow data from nearby long-term streamgages. The efficacy of these estimators was evaluated over a set of measurement intensities in which the number of simulated instantaneous flow measurements ranged from 1 to 100 at a site. The discrete measurement estimator DiscQ50 is based on a simple linear regression developed between information on daily mean flows at five or more streamgages near the miscellaneous site and their corresponding GageQ50 index flows. The regression relation then was used to compute a DiscQ50 estimate at the miscellaneous site by use of the simulated instantaneous flow measurement. This process was repeated to develop a set of DiscQ50 estimates for all simulated instantaneous measurements, a weighted DiscQ50 estimate was formed from this set. Results indicated that the expected value of this weighted estimate was more precise than the IndxQ50 estimate for all measurement intensities evaluated. The integrated index-flow estimator, IntgQ50, was formed by computing a weighted average of the index estimate IndxQ50 and the DiscQ50 estimate. Results indicated that the IntgQ50 estimator was more precise than the DiscQ50 estimator at low measurement intensities of one to two measurements. At greater measurement intensities, the precision of the IntgQ50 estimator converges to the DiscQ50 estimator. Neither the DiscQ50 nor the IntgQ50 estimators provided site-specific estimates. In particular, although expected values of DiscQ50 and IntgQ50 estimates converge with increasing measurement intensity, they do not necessarily converge to the site-specific value of Q50. The site estimator of flow, SiteQ50, was developed to facilitate this convergence at higher measurement intensities. This is accomplished by use of the median of simulated instantaneous flow values for each measurement intensity level. A weighted estimate of the median and information associated with the IntgQ50 estimate was used to form the SiteQ50 estimate. Initial simulations indicate that the SiteQ50 estimator generally has greater precision than the IntgQ50 estimator at measurement intensities greater than 3, however, additional analysis is needed to identify streamflow conditions under which instantaneous measurements will produce estimates that generally converge to the index flows. A preliminary augmented index regression equation was developed, which contains the index regression estimate and two additional variables associated with base-flow recession characteristics. When these recession variables were estimated as the medians of recession parameters compute

SU-F-P-56: On a New Approach to Reconstruct the Patient Dose From Phantom Measurements

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

Bangtsson, E; Vries, W de

Purpose: The development of complex radiation treatment schemes emphasizes the need for advanced QA analysis methods to ensure patient safety. One such tool is the Delta4 DVH Anatomy software, where the patient dose is reconstructed from phantom measurements. Deviations in the measured dose are transferred to the patient anatomy and their clinical impact is evaluated in situ. Results from the original algorithm revealed weaknesses that may introduce artefacts in the reconstructed dose. These can lead to false negatives or obscure the effects of minor dose deviations from delivery failures. Here, we will present results from a new patient dose reconstructionmore » algorithm. Methods: The main steps of the new algorithm are: (1) the dose delivered to a phantom is measured in a number of detector positions. (2) The measured dose is compared to an internally calculated dose distribution evaluated in said positions. The so-obtained dose difference is (3) used to calculate an energy fluence difference. This entity is (4) used as input to a patient dose correction calculation routine. Finally, the patient dose is reconstructed by adding said patient dose correction to the planned patient dose. The internal dose calculation in step (2) and (4) is based on the Pencil Beam algorithm. Results: The new patient dose reconstruction algorithm have been tested on a number of patients and the standard metrics dose deviation (DDev), distance-to-agreement (DTA) and Gamma index are improved when compared to the original algorithm. In a certain case the Gamma index (3%/3mm) increases from 72.9% to 96.6%. Conclusion: The patient dose reconstruction algorithm is improved. This leads to a reduction in non-physical artefacts in the reconstructed patient dose. As a consequence, the possibility to detect deviations in the dose that is delivered to the patient is improved. An increase in Gamma index for the PTV can be seen. The corresponding author is an employee of ScandiDos.« less

Assessment of smolt condition for travel time analysis. Annual report 1988

USGS Publications Warehouse

Rondorf, D.W.; Beeman, J.W.; Faler, J.C.; Free, M.E.; Wagner, E.J.

1989-01-01

Estimates of migration rates and travel times of juvenile salmonids within index reaches of the Columbia River basin are collected through the Smolt Monitoring Program for use by the Fish Passage Center. With increased reliance upon travel time estimates in 1988 by the Fish Passage Center, this study was implemented to monitor the biological attributes of juvenile chinook salmon Oncorhynchus tshawytscha and steelhead trout 0.- mykiss used for the travel time estimates, The physiological ability of fish to respond to stress was assessed by measuring levels of plasma cortisol, glucose, and chloride before and after a stress-challenge test. Most mid-Columbia and Snake river groups responded normally to the stress challenge exhibiting an increase in plasma glucose and cortisol and a slight decrease in chloride. Fish trucked to release sites were more stressed than those released directly from the hatchery, but most still responded to the stress challenge test normally. An abnormal or extreme stress response occurred when there were deviations from preferred protocol, disease problems at hatcheries, or when fish were trucked over long periods (7h). The development of smoltification was evaluated by measuring gill Na+K+-ATPase, plasma thyroxine, purines, and body morphology. Most groups were similar at the hatcheries but differed as the migration to McNary Dam proceeded. Gill ATPase activity increased 2-3 fold during the first 20 days of migration, after which it changed little. Fish with longer in-river travel times appeared to be more smolted than those which were in the river for a shorter period of time. The prevalence of bacterial kidney disease (BKD) in spring chinook salmon was evaluated using the enzyme linked immunosorbent assay (ELISA) and fluorescent antibody technique (FAT). Prevalence of BKD in groups tested using the ELISA method was as high as 99% at some downstream locations. A review of indices is presented as a guide, to the development of an index of smolt condition and preliminary data are presented. An index could be used as a tool to synthesize information on fish condition to assist with management and evaluation of the Water Budget.

Economic analysis of the link between diet quality and health: Evidence from Kosovo.

PubMed

Braha, Kushtrim; Cupák, Andrej; Pokrivčák, Ján; Qineti, Artan; Rizov, Marian

2017-11-01

We analyse the link between diet diversity, (which is a proxy of diet quality) and health outcomes measured by body-mass index (BMI) in a representative sample of Kosovar adults using household expenditure micro-data. Building on a household model of health production we devise a two-stage empirical strategy to estimate the determinants of diet diversity and its effect on BMI. Economic factors and demographic characteristics play an important role in the choice of balanced diets. Results from the BMI analysis support the hypothesis that diet diversity is associated with optimal BMI. One standard deviation increase in diet diversity leads to 2.3% increase in BMI of the underweight individuals and to 1.5% reduction in BMI of the obese individuals. The findings have important implications for food security policies aiming at enhancing the public health in Kosovo. Copyright © 2017 Elsevier B.V. All rights reserved.

Physical Fitness Index for Assess Fitness Speed Among Army Reserve Officer Training Unit Cadet in Malaysia

NASA Astrophysics Data System (ADS)

Rustam, Shahrulfadly; Kassim, Mohar

2018-05-01

The aim of this study is to develop physical fitness index (PFI) for physical fitness among Army Reserve Officer Training Unit Cadet Malaysia. This study use 30 meter speed run as a physical fitness test battery to develop physical fitness index (PFI) and to evaluate the subject fitness speed. 212 male respondent (N=212) was selected in this study including Army Reserve Officer Training Unit Cadet of National Defence University of Malaysia. 30 meter sprint was used as a instrument for this study. The methodology will be adopted for this study is quantitative research in the form of a quasi-experiment. Quasi-experimental methods is used to measure and evaluate the level of physical fitness and develop Physical Fitness Index especially in speed. The design of this study is quasi-experimental study design with pre-test and post-test. The study design is quasi-experimental research design in which the data is obtained through the practical test in the field. The data were analysed by using the SPSS software version 20 to calculate the mean, standard deviation and t-test for develop physical fitness index (PFI) and to evaluate the fitness speed level for Army Reserve Officers Training Unit Cadet Malaysia. The findings showed mean and standard deviation for develope physical fitness index is (M=4.84) and (SD=0.48). The t-test for evaluate fitness level in speed for pre-test and post-test is significantly difference (p ≤ 0.05). The implication at this study is that the develope of standard physical fitness index is able to identify the level of physical fitness among Army Reserve Officer Training Unit Cadet Malaysia.

Entanglement transitions induced by large deviations

NASA Astrophysics Data System (ADS)

Bhosale, Udaysinh T.

2017-12-01

The probability of large deviations of the smallest Schmidt eigenvalue for random pure states of bipartite systems, denoted as A and B , is computed analytically using a Coulomb gas method. It is shown that this probability, for large N , goes as exp[-β N2Φ (ζ ) ] , where the parameter β is the Dyson index of the ensemble, ζ is the large deviation parameter, while the rate function Φ (ζ ) is calculated exactly. Corresponding equilibrium Coulomb charge density is derived for its large deviations. Effects of the large deviations of the extreme (largest and smallest) Schmidt eigenvalues on the bipartite entanglement are studied using the von Neumann entropy. Effect of these deviations is also studied on the entanglement between subsystems 1 and 2, obtained by further partitioning the subsystem A , using the properties of the density matrix's partial transpose ρ12Γ. The density of states of ρ12Γ is found to be close to the Wigner's semicircle law with these large deviations. The entanglement properties are captured very well by a simple random matrix model for the partial transpose. The model predicts the entanglement transition across a critical large deviation parameter ζ . Log negativity is used to quantify the entanglement between subsystems 1 and 2. Analytical formulas for it are derived using the simple model. Numerical simulations are in excellent agreement with the analytical results.

Entanglement transitions induced by large deviations.

PubMed

Bhosale, Udaysinh T

2017-12-01

The probability of large deviations of the smallest Schmidt eigenvalue for random pure states of bipartite systems, denoted as A and B, is computed analytically using a Coulomb gas method. It is shown that this probability, for large N, goes as exp[-βN^{2}Φ(ζ)], where the parameter β is the Dyson index of the ensemble, ζ is the large deviation parameter, while the rate function Φ(ζ) is calculated exactly. Corresponding equilibrium Coulomb charge density is derived for its large deviations. Effects of the large deviations of the extreme (largest and smallest) Schmidt eigenvalues on the bipartite entanglement are studied using the von Neumann entropy. Effect of these deviations is also studied on the entanglement between subsystems 1 and 2, obtained by further partitioning the subsystem A, using the properties of the density matrix's partial transpose ρ_{12}^{Γ}. The density of states of ρ_{12}^{Γ} is found to be close to the Wigner's semicircle law with these large deviations. The entanglement properties are captured very well by a simple random matrix model for the partial transpose. The model predicts the entanglement transition across a critical large deviation parameter ζ. Log negativity is used to quantify the entanglement between subsystems 1 and 2. Analytical formulas for it are derived using the simple model. Numerical simulations are in excellent agreement with the analytical results.

Solvation free energies and partition coefficients with the coarse-grained and hybrid all-atom/coarse-grained MARTINI models.

PubMed

Genheden, Samuel

2017-10-01

We present the estimation of solvation free energies of small solutes in water, n-octanol and hexane using molecular dynamics simulations with two MARTINI models at different resolutions, viz. the coarse-grained (CG) and the hybrid all-atom/coarse-grained (AA/CG) models. From these estimates, we also calculate the water/hexane and water/octanol partition coefficients. More than 150 small, organic molecules were selected from the Minnesota solvation database and parameterized in a semi-automatic fashion. Using either the CG or hybrid AA/CG models, we find considerable deviations between the estimated and experimental solvation free energies in all solvents with mean absolute deviations larger than 10 kJ/mol, although the correlation coefficient is between 0.55 and 0.75 and significant. There is also no difference between the results when using the non-polarizable and polarizable water model, although we identify some improvements when using the polarizable model with the AA/CG solutes. In contrast to the estimated solvation energies, the estimated partition coefficients are generally excellent with both the CG and hybrid AA/CG models, giving mean absolute deviations between 0.67 and 0.90 log units and correlation coefficients larger than 0.85. We analyze the error distribution further and suggest avenues for improvements.

Solvation free energies and partition coefficients with the coarse-grained and hybrid all-atom/coarse-grained MARTINI models

NASA Astrophysics Data System (ADS)

Genheden, Samuel

2017-10-01

We present the estimation of solvation free energies of small solutes in water, n-octanol and hexane using molecular dynamics simulations with two MARTINI models at different resolutions, viz. the coarse-grained (CG) and the hybrid all-atom/coarse-grained (AA/CG) models. From these estimates, we also calculate the water/hexane and water/octanol partition coefficients. More than 150 small, organic molecules were selected from the Minnesota solvation database and parameterized in a semi-automatic fashion. Using either the CG or hybrid AA/CG models, we find considerable deviations between the estimated and experimental solvation free energies in all solvents with mean absolute deviations larger than 10 kJ/mol, although the correlation coefficient is between 0.55 and 0.75 and significant. There is also no difference between the results when using the non-polarizable and polarizable water model, although we identify some improvements when using the polarizable model with the AA/CG solutes. In contrast to the estimated solvation energies, the estimated partition coefficients are generally excellent with both the CG and hybrid AA/CG models, giving mean absolute deviations between 0.67 and 0.90 log units and correlation coefficients larger than 0.85. We analyze the error distribution further and suggest avenues for improvements.

Dosimetric verification of lung cancer treatment using the CBCTs estimated from limited-angle on-board projections

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

Zhang, You; Yin, Fang-Fang; Ren, Lei, E-mail: lei.ren@duke.edu

2015-08-15

Purpose: Lung cancer treatment is susceptible to treatment errors caused by interfractional anatomical and respirational variations of the patient. On-board treatment dose verification is especially critical for the lung stereotactic body radiation therapy due to its high fractional dose. This study investigates the feasibility of using cone-beam (CB)CT images estimated by a motion modeling and free-form deformation (MM-FD) technique for on-board dose verification. Methods: Both digital and physical phantom studies were performed. Various interfractional variations featuring patient motion pattern change, tumor size change, and tumor average position change were simulated from planning CT to on-board images. The doses calculated onmore » the planning CT (planned doses), the on-board CBCT estimated by MM-FD (MM-FD doses), and the on-board CBCT reconstructed by the conventional Feldkamp-Davis-Kress (FDK) algorithm (FDK doses) were compared to the on-board dose calculated on the “gold-standard” on-board images (gold-standard doses). The absolute deviations of minimum dose (ΔD{sub min}), maximum dose (ΔD{sub max}), and mean dose (ΔD{sub mean}), and the absolute deviations of prescription dose coverage (ΔV{sub 100%}) were evaluated for the planning target volume (PTV). In addition, 4D on-board treatment dose accumulations were performed using 4D-CBCT images estimated by MM-FD in the physical phantom study. The accumulated doses were compared to those measured using optically stimulated luminescence (OSL) detectors and radiochromic films. Results: Compared with the planned doses and the FDK doses, the MM-FD doses matched much better with the gold-standard doses. For the digital phantom study, the average (± standard deviation) ΔD{sub min}, ΔD{sub max}, ΔD{sub mean}, and ΔV{sub 100%} (values normalized by the prescription dose or the total PTV) between the planned and the gold-standard PTV doses were 32.9% (±28.6%), 3.0% (±2.9%), 3.8% (±4.0%), and 15.4% (±12.4%), respectively. The corresponding values of FDK PTV doses were 1.6% (±1.9%), 1.2% (±0.6%), 2.2% (±0.8%), and 17.4% (±15.3%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.3% (±0.2%), 0.9% (±0.6%), 0.6% (±0.4%), and 1.0% (±0.8%), respectively. Similarly, for the physical phantom study, the average ΔD{sub min}, ΔD{sub max}, ΔD{sub mean}, and ΔV{sub 100%} of planned PTV doses were 38.1% (±30.8%), 3.5% (±5.1%), 3.0% (±2.6%), and 8.8% (±8.0%), respectively. The corresponding values of FDK PTV doses were 5.8% (±4.5%), 1.6% (±1.6%), 2.0% (±0.9%), and 9.3% (±10.5%), respectively. In contrast, the corresponding values of MM-FD PTV doses were 0.4% (±0.8%), 0.8% (±1.0%), 0.5% (±0.4%), and 0.8% (±0.8%), respectively. For the 4D dose accumulation study, the average (± standard deviation) absolute dose deviation (normalized by local doses) between the accumulated doses and the OSL measured doses was 3.3% (±2.7%). The average gamma index (3%/3 mm) between the accumulated doses and the radiochromic film measured doses was 94.5% (±2.5%). Conclusions: MM-FD estimated 4D-CBCT enables accurate on-board dose calculation and accumulation for lung radiation therapy. It can potentially be valuable for treatment quality assessment and adaptive radiation therapy.« less

Inter-examination Precision of Magnitude-based Magnetic Resonance Imaging for Estimation of Segmental Hepatic Proton Density Fat Fraction (PDFF) in Obese Subjects

PubMed Central

Negrete, Lindsey M.; Middleton, Michael S.; Clark, Lisa; Wolfson, Tanya; Gamst, Anthony C.; Lam, Jessica; Changchien, Chris; Deyoung-Dominguez, Ivan M.; Hamilton, Gavin; Loomba, Rohit; Schwimmer, Jeffrey; Sirlin, Claude B.

2013-01-01

Purpose To prospectively describe magnitude-based multi-echo gradient-echo hepatic proton density fat fraction (PDFF) inter-examination precision at 3T. Materials and Methods In this prospective, IRB approved, HIPAA compliant study, written informed consent was obtained from 29 subjects (body mass indexes > 30kg/m2). Three 3T magnetic resonance imaging (MRI) examinations were obtained over 75-90 minutes. Segmental, lobar, and whole liver PDFF were estimated (using three, four, five, or six echoes) by magnitude-based multi-echo MRI in co-localized regions of interest (ROIs). For estimate (using three, four, five, or six echoes), at each anatomic level (segmental, lobar, whole liver), three inter-examination precision metrics were computed: intra-class correlation coefficient (ICC), standard deviation (SD), and range. Results Magnitude-based PDFF estimates using each reconstruction method showed excellent inter-examination precision for each segment (ICC ≥ 0.992; SD ≤ 0.66%; range ≤ 1.24%), lobe (ICC ≥ 0.998; SD ≤ 0.34%; range ≤ 0.64%), and the whole liver (ICC = 0.999; SD ≤ 0.24%; range ≤ 0.45%). Inter-examination precision was unaffected by whether PDFF was estimated using three, four, five, or six echoes. Conclusion Magnitude-based PDFF estimation shows high inter-examination precision at segmental, lobar, and whole liver anatomic levels, supporting its use in clinical care or clinical trials. The results of this study suggest that longitudinal hepatic PDFF change greater than 1.6% is likely to represent signal rather than noise. PMID:24136736

Estimating the geographical distribution of the prevalence of the metabolic syndrome in young Mexicans.

PubMed

Murguía-Romero, Miguel; Jiménez-Flores, Rafael; Villalobos-Molina, Rafael; Méndez-Cruz, Adolfo René

2012-09-01

The geographical distribution of the metabolic syndrome (MetS) prevalence in young Mexicans (aged 17-24 years) was estimated stepwise starting from its prevalence based on the body mass index (BMI) in a study of 3,176 undergraduate students of this age group from Mexico City. To estimate the number of people with MetS by state, we multiplied its prevalence derived from the BMI range found in the Mexico City sample by the BMI proportions (range and state) obtained from the Mexico 2006 national survey on health and nutrition. Finally, to estimate the total number of young people with MetS in Mexico, its prevalence by state was multiplied by the share of young population in each state according to the National Population and Housing Census 2010. Based on these figures, we estimated the national prevalence of MetS at 15.8%, the average BMI at 24.1 (standard deviation = 4.2), and the prevalence of overweight people (BMI ≥25) of that age group at 39.0%. These results imply that 2,588,414 young Mexicans suffered from MetS in 2010. The Yucatan peninsula in the south and the Sonora state in the north showed the highest rates of MetS prevalence. The calculation of the MetS prevalence by BMI range in a sample of the population, and extrapolating it using the BMI proportions by range of the total population, was found to be a useful approach. We conclude that the BMI is a valuable public health tool to estimate MetS prevalence in the whole country, including its geographical distribution.

Accuracy of Short Forms of the Dutch Wechsler Preschool and Primary Scale of Intelligence: Third Edition.

PubMed

Hurks, Petra; Hendriksen, Jos; Dek, Joelle; Kooij, Andress

2016-04-01

This article investigated the accuracy of six short forms of the Dutch Wechsler Preschool and Primary Scale of Intelligence-Third edition (WPPSI-III-NL) in estimating intelligent quotient (IQ) scores in healthy children aged 4 to 7 years (N = 1,037). Overall, accuracy for each short form was studied, comparing IQ equivalences based on the short forms with the original WPPSI-III-NL Full Scale IQ (FSIQ) scores. Next, our sample was divided into three groups: children performing below average, average, or above average, based on the WPPSI-III-NL FSIQ estimates of the original long form, to study the accuracy of WPPSI-III-NL short forms at the tails of the FSIQ distribution. While studying the entire sample, all IQ estimates of the WPPSI-III-NL short forms correlated highly with the FSIQ estimates of the original long form (all rs ≥ .83). Correlations decreased significantly while studying only the tails of the IQ distribution (rs varied between .55 and .83). Furthermore, IQ estimates of the short forms deviated significantly from the FSIQ score of the original long form, when the IQ estimates were based on short forms containing only two subtests. In contrast, unlike the short forms that contained two to four subtests, the Wechsler Abbreviated Scale of Intelligence short form (containing the subtests Vocabulary, Similarities, Block Design, and Matrix Reasoning) and the General Ability Index short form (containing the subtests Vocabulary, Similarities, Comprehension, Block Design, Matrix Reasoning, and Picture Concepts) produced less variations when compared with the original FSIQ score. © The Author(s) 2015.

Dynamics relationship between stock prices and economic variables in Malaysia

NASA Astrophysics Data System (ADS)

Chun, Ooi Po; Arsad, Zainudin; Huen, Tan Bee

2014-07-01

Knowledge on linkages between stock prices and macroeconomic variables are essential in the formulation of effective monetary policy. This study investigates the relationship between stock prices in Malaysia (KLCI) with four selected macroeconomic variables, namely industrial production index (IPI), quasi money supply (MS2), real exchange rate (REXR) and 3-month Treasury bill (TRB). The variables used in this study are monthly data from 1996 to 2012. Vector error correction (VEC) model and Kalman filter (KF) technique are utilized to assess the impact of macroeconomic variables on the stock prices. The results from the cointegration test revealed that the stock prices and macroeconomic variables are cointegrated. Different from the constant estimate from the static VEC model, the KF estimates noticeably exhibit time-varying attributes over the entire sample period. The varying estimates of the impact coefficients should be better reflect the changing economic environment. Surprisingly, IPI is negatively related to the KLCI with the estimates of the impact slowly increase and become positive in recent years. TRB is found to be generally negatively related to the KLCI with the impact fluctuating along the constant estimate of the VEC model. The KF estimates for REXR and MS2 show a mixture of positive and negative impact on the KLCI. The coefficients of error correction term (ECT) are negative in majority of the sample period, signifying the stock prices responded to stabilize any short term deviation in the economic system. The findings from the KF model indicate that any implication that is based on the usual static model may lead to authorities implementing less appropriate policies.

Remote sensing of water and nitrogen stress in broccoli

NASA Astrophysics Data System (ADS)

Elsheikha, Diael-Deen Mohamed

Remote sensing is being used in agriculture for crop management. Ground based remote sensing data acquisition system was used for collection of high spatial and temporal resolution data for irrigated broccoli crop. The system was composed of a small cart that ran back and forth on a rail system that was mounted on a linear move irrigation system. The cart was equipped with a sensor that had 4 discrete wavelengths; 550 nm, 660 nm, 720 nm, and 810 nm, and an infrared thermometer, all had 10 nm bandwidth. A global positioning system was used to indicate the cart position. The study consisted of two parts; the first was to evaluate remotely sensed reflectance and indices in broccoli during the growing season, and determine whether remotely sensed indices or standard deviation of indices can distinguish between nitrogen and water stress in broccoli, and the second part of the study was to evaluate remotely sensed indices and standard deviation of remotely sensed indices in broccoli during daily changes in solar zenith angle. Results indicated that nitrogen was detected using Ratio Vegetation index, RVI, Normalized Difference Vegetation Index, NDVI, Canopy Chlorophyll Concentration Index, CCCI, and also using the reflectance in the Near-Infrared, NIR, bands. The Red reflectance band capability of showing stress was not as clear as the previous indices and bands reflectance. The Canopy Chlorophyll Concentration Index, CCCI, was the most successful index. The Crop Water Stress Index was able to detect water stress but it was highly affected by the solar zenith angle change along the day.

Using an external gating signal to estimate noise in PET with an emphasis on tracer avid tumors

NASA Astrophysics Data System (ADS)

Schmidtlein, C. R.; Beattie, B. J.; Bailey, D. L.; Akhurst, T. J.; Wang, W.; Gönen, M.; Kirov, A. S.; Humm, J. L.

2010-10-01

The purpose of this study is to establish and validate a methodology for estimating the standard deviation of voxels with large activity concentrations within a PET image using replicate imaging that is immediately available for use in the clinic. To do this, ensembles of voxels in the averaged replicate images were compared to the corresponding ensembles in images derived from summed sinograms. In addition, the replicate imaging noise estimate was compared to a noise estimate based on an ensemble of voxels within a region. To make this comparison two phantoms were used. The first phantom was a seven-chamber phantom constructed of 1 liter plastic bottles. Each chamber of this phantom was filled with a different activity concentration relative to the lowest activity concentration with ratios of 1:1, 1:1, 2:1, 2:1, 4:1, 8:1 and 16:1. The second phantom was a GE Well-Counter phantom. These phantoms were imaged and reconstructed on a GE DSTE PET/CT scanner with 2D and 3D reprojection filtered backprojection (FBP), and with 2D- and 3D-ordered subset expectation maximization (OSEM). A series of tests were applied to the resulting images that showed that the region and replicate imaging methods for estimating standard deviation were equivalent for backprojection reconstructions. Furthermore, the noise properties of the FBP algorithms allowed scaling the replicate estimates of the standard deviation by a factor of 1/\\sqrt{N}, where N is the number of replicate images, to obtain the standard deviation of the full data image. This was not the case for OSEM image reconstruction. Due to nonlinearity of the OSEM algorithm, the noise is shown to be both position and activity concentration dependent in such a way that no simple scaling factor can be used to extrapolate noise as a function of counts. The use of the Well-Counter phantom contributed to the development of a heuristic extrapolation of the noise as a function of radius in FBP. In addition, the signal-to-noise ratio for high uptake objects was confirmed to be higher with backprojection image reconstruction methods. These techniques were applied to several patient data sets acquired in either 2D or 3D mode, with 18F (FLT and FDG). Images of the standard deviation and signal-to-noise ratios were constructed and the standard deviations of the tumors' uptake were determined. Finally, a radial noise extrapolation relationship deduced in this paper was applied to patient data.

Visual field progression in glaucoma: total versus pattern deviation analyses.

PubMed

Artes, Paul H; Nicolela, Marcelo T; LeBlanc, Raymond P; Chauhan, Balwantray C

2005-12-01

To compare visual field progression with total and pattern deviation analyses in a prospective longitudinal study of patients with glaucoma and healthy control subjects. A group of 101 patients with glaucoma (168 eyes) with early to moderately advanced visual field loss at baseline (average mean deviation [MD], -3.9 dB) and no clinical evidence of media opacity were selected from a prospective longitudinal study on visual field progression in glaucoma. Patients were examined with static automated perimetry at 6-month intervals for a median follow-up of 9 years. At each test location, change was established with event and trend analyses of total and pattern deviation. The event analyses compared each follow-up test to a baseline obtained from averaging the first two tests, and visual field progression was defined as deterioration beyond the 5th percentile of test-retest variability at three test locations, observed on three consecutive tests. The trend analyses were based on point-wise linear regression, and visual field progression was defined as statistically significant deterioration (P < 5%) worse than -1 dB/year at three locations, confirmed by independently omitting the last and the penultimate observation. The incidence and the time-to-progression were compared between total and pattern deviation analyses. To estimate the specificity of the progression analyses, identical criteria were applied to visual fields obtained in 102 healthy control subjects, and the rate of visual field improvement was established in the patients with glaucoma and the healthy control subjects. With both event and trend methods, pattern deviation analyses classified approximately 15% fewer eyes as having progressed than did the total deviation analyses. In eyes classified as progressing by both the total and pattern deviation methods, total deviation analyses tended to detect progression earlier than the pattern deviation analyses. A comparison of the changes observed in MD and the visual fields' general height (estimated by the 85th percentile of the total deviation values) confirmed that change in the glaucomatous eyes almost always comprised a diffuse component. Pattern deviation analyses of progression may therefore underestimate the true amount of glaucomatous visual field progression. Pattern deviation analyses of visual field progression may underestimate visual field progression in glaucoma, particularly when there is no clinical evidence of increasing media opacity. Clinicians should have access to both total and pattern deviation analyses to make informed decisions on visual field progression in glaucoma.

Mixed effects modelling for glass category estimation from glass refractive indices.

PubMed

Lucy, David; Zadora, Grzegorz

2011-10-10

520 Glass fragments were taken from 105 glass items. Each item was either a container, a window, or glass from an automobile. Each of these three classes of use are defined as glass categories. Refractive indexes were measured both before, and after a programme of re-annealing. Because the refractive index of each fragment could not in itself be observed before and after re-annealing, a model based approach was used to estimate the change in refractive index for each glass category. It was found that less complex estimation methods would be equivalent to the full model, and were subsequently used. The change in refractive index was then used to calculate a measure of the evidential value for each item belonging to each glass category. The distributions of refractive index change were considered for each glass category, and it was found that, possibly due to small samples, members of the normal family would not adequately model the refractive index changes within two of the use types considered here. Two alternative approaches to modelling the change in refractive index were used, one employed more established kernel density estimates, the other a newer approach called log-concave estimation. Either method when applied to the change in refractive index was found to give good estimates of glass category, however, on all performance metrics kernel density estimates were found to be slightly better than log-concave estimates, although the estimates from log-concave estimation prossessed properties which had some qualitative appeal not encapsulated in the selected measures of performance. These results and implications of these two methods of estimating probability densities for glass refractive indexes are discussed. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Development of a technique for estimating noise covariances using multiple observers

NASA Technical Reports Server (NTRS)

Bundick, W. Thomas

1988-01-01

Friedland's technique for estimating the unknown noise variances of a linear system using multiple observers has been extended by developing a general solution for the estimates of the variances, developing the statistics (mean and standard deviation) of these estimates, and demonstrating the solution on two examples.

Empirical behavior of a world stock index from intra-day to monthly time scales

NASA Astrophysics Data System (ADS)

Breymann, W.; Lüthi, D. R.; Platen, E.

2009-10-01

Most of the papers that study the distributional and fractal properties of financial instruments focus on stock prices or foreign exchange rates. This typically leads to mixed results concerning the distributions of log-returns and some multi-fractal properties of exchange rates, stock prices, and regional indices. This paper uses a well diversified world stock index as the central object of analysis. Such index approximates the growth optimal portfolio, which is demonstrated under the benchmark approach, it is the ideal reference unit for studying basic securities. When denominating this world index in units of a given currency, one measures the movements of the currency against the entire market. This provides a least disturbed observation of the currency dynamics. In this manner, one can expect to disentangle, e.g., the superposition of the two currencies involved in an exchange rate. This benchmark approach to the empirical analysis of financial data allows us to establish remarkable stylized facts. Most important is the observation that the repeatedly documented multi-fractal appearance of financial time series is very weak and much less pronounced than the deviation of the mono-scaling properties from Brownian-motion type scaling. The generalized Hurst exponent H(2) assumes typical values between 0.55 and 0.6. Accordingly, autocorrelations of log-returns decay according to a power law, and the quadratic variation vanishes when going to vanishing observation time step size. Furthermore, one can identify the Student t distribution as the log-return distribution of a well-diversified world stock index for long time horizons when a long enough data series is used for estimation. The study of dependence properties, finally, reveals that jumps at daily horizon originate primarily in the stock market while at 5min horizon they originate in the foreign exchange market. The principal message of the empirical analysis is that there is evidence that a diffusion model without multi-scaling could reasonably well model the dynamics of a broadly diversified world stock index. in here

Grasp and index finger reach zone during one-handed smartphone rear interaction: effects of task type, phone width and hand length.

PubMed

Lee, Songil; Kyung, Gyouhyung; Lee, Jungyong; Moon, Seung Ki; Park, Kyoung Jong

2016-11-01

Recently, some smartphones have introduced index finger interaction functions on the rear surface. The current study investigated the effects of task type, phone width, and hand length on grasp, index finger reach zone, discomfort, and muscle activation during such interaction. We considered five interaction tasks (neutral, comfortable, maximum, vertical, and horizontal strokes), two device widths (60 and 90 mm) and three hand lengths. Horizontal (vertical) strokes deviated from the horizontal axis in the range from -10.8° to -13.5° (81.6-88.4°). Maximum strokes appeared to be excessive as these caused 43.8% greater discomfort than did neutral strokes. The 90-mm width also appeared to be excessive as it resulted in 12.3% increased discomfort relative to the 60-mm width. The small-hand group reported 11.9-18.2% higher discomfort ratings, and the percent maximum voluntary exertion of their flexor digitorum superficialis muscle, pertaining to index finger flexion, was also 6.4% higher. These findings should be considered to make smartphone rear interaction more comfortable. Practitioner Summary: Among neutral, comfortable, maximum, horizontal, and vertical index finger strokes on smartphone rear surfaces, maximum vs. neutral strokes caused 43.8% greater discomfort. Horizontal (vertical) strokes deviated from the horizontal (vertical) axis. Discomfort increased by 12.3% with 90-mm- vs. 60-mm-wide devices. Rear interaction regions of five commercialised smartphones should be lowered 20 to 30 mm for more comfortable rear interaction.

Collinearity in Least-Squares Analysis

ERIC Educational Resources Information Center

de Levie, Robert

2012-01-01

How useful are the standard deviations per se, and how reliable are results derived from several least-squares coefficients and their associated standard deviations? When the output parameters obtained from a least-squares analysis are mutually independent, as is often assumed, they are reliable estimators of imprecision and so are the functions…

Use of thermal and visible imagery for estimating crop water status of irrigated grapevine.

PubMed

Möller, M; Alchanatis, V; Cohen, Y; Meron, M; Tsipris, J; Naor, A; Ostrovsky, V; Sprintsin, M; Cohen, S

2007-01-01

Achieving high quality wine grapes depends on the ability to maintain mild to moderate levels of water stress in the crop during the growing season. This study investigates the use of thermal imaging for monitoring water stress. Experiments were conducted on a wine-grape (Vitis vinifera cv. Merlot) vineyard in northern Israel. Irrigation treatments included mild, moderate, and severe stress. Thermal and visible (RGB) images of the crop were taken on four days at midday with a FLIR thermal imaging system and a digital camera, respectively, both mounted on a truck-crane 15 m above the canopy. Aluminium crosses were used to match visible and thermal images in post-processing and an artificial wet surface was used to estimate the reference wet temperature (T(wet)). Monitored crop parameters included stem water potential (Psi(stem)), leaf conductance (g(L)), and leaf area index (LAI). Meteorological parameters were measured at 2 m height. CWSI was highly correlated with g(L) and moderately correlated with Psi(stem). The CWSI-g(L) relationship was very stable throughout the season, but for that of CWSI-Psi(stem) both intercept and slope varied considerably. The latter presumably reflects the non-direct nature of the physiological relationship between CWSI and Psi(stem). The highest R(2) for the CWSI to g(L) relationship, 0.91 (n=12), was obtained when CWSI was computed using temperatures from the centre of the canopy, T(wet) from the artificial wet surface, and reference dry temperature from air temperature plus 5 degrees C. Using T(wet) calculated from the inverted Penman-Monteith equation and estimated from an artificially wetted part of the canopy also yielded crop water-stress estimates highly correlated with g(L) (R(2)=0.89 and 0.82, respectively), while a crop water-stress index using 'theoretical' reference temperatures computed from climate data showed significant deviations in the late season. Parameter variability and robustness of the different CWSI estimates are discussed. Future research should aim at developing thermal imaging into an irrigation scheduling tool applicable to different crops.

COPD exacerbations associated with the modified Medical Research Council scale and COPD assessment test among Humana Medicare members

PubMed Central

Pasquale, Margaret K; Xu, Yihua; Baker, Christine L; Zou, Kelly H; Teeter, John G; Renda, Andrew M; Davis, Cralen C; Lee, Theodore C; Bobula, Joel

2016-01-01

Background The Global initiative for chronic Obstructive Lung Disease guidelines recommend assessment of COPD severity, which includes symptomatology using the modified Medical Research Council (mMRC) or COPD assessment test (CAT) score in addition to the degree of airflow obstruction and exacerbation history. While there is great interest in incorporating symptomatology, little is known about how patient reported symptoms are associated with future exacerbations and exacerbation-related costs. Methods The mMRC and CAT were mailed to a randomly selected sample of 4,000 Medicare members aged >40 years, diagnosed with COPD (≥2 encounters with International Classification of Dis eases-9th Edition Clinical Modification: 491.xx, 492.xx, 496.xx, ≥30 days apart). The exacerbations and exacerbation-related costs were collected from claims data during 365-day post-survey after exclusion of members lost to follow-up or with cancer, organ transplant, or pregnancy. A logistic regression model estimated the predictive value of exacerbation history and symptomatology on exacerbations during follow-up, and a generalized linear model with log link and gamma distribution estimated the predictive value of exacerbation history and symptomatology on exacerbation-related costs. Results Among a total of 1,159 members who returned the survey, a 66% (765) completion rate was observed. Mean (standard deviation) age among survey completers was 72.0 (8.3), 53.7% female and 91.2% white. Odds ratios for having post-index exacerbations were 3.06, 4.55, and 16.28 times for members with 1, 2, and ≥3 pre-index exacerbations, respectively, relative to members with 0 pre-index exacerbations (P<0.001 for all). The odds ratio for high vs low symptoms using CAT was 2.51 (P<0.001). Similarly, exacerbation-related costs were 73% higher with each incremental pre-index exacerbation, and over four fold higher for high-vs low-symptom patients using CAT (each P<0.001). The symptoms using mMRC were not statistically significant in either model (P>0.10). Conclusion The patient-reported symptoms contribute important information related to future COPD exacerbations and exacerbation-related costs beyond that explained by exacerbation history. PMID:26834468

Factor structure and psychometric properties of the english version of the trier inventory for chronic stress (TICS-E).

PubMed

Petrowski, Katja; Kliem, Sören; Sadler, Michael; Meuret, Alicia E; Ritz, Thomas; Brähler, Elmar

2018-02-06

Demands placed on individuals in occupational and social settings, as well as imbalances in personal traits and resources, can lead to chronic stress. The Trier Inventory for Chronic Stress (TICS) measures chronic stress while incorporating domain-specific aspects, and has been found to be a highly reliable and valid research tool. The aims of the present study were to confirm the German version TICS factorial structure in an English translation of the instrument (TICS-E) and to report its psychometric properties. A random route sample of healthy participants (N = 483) aged 18-30 years completed the TICS-E. The robust maximum likelihood estimation with a mean-adjusted chi-square test statistic was applied due to the sample's significant deviation from the multivariate normal distribution. Goodness of fit, absolute model fit, and relative model fit were assessed by means of the root mean square error of approximation (RMSEA), the Comparative Fit Index (CFI) and the Tucker Lewis Index (TLI). Reliability estimates (Cronbach's α and adjusted split-half reliability) ranged from .84 to .92. Item-scale correlations ranged from .50 to .85. Measures of fit showed values of .052 for RMSEA (Cl = 0.50-.054) and .067 for SRMR for absolute model fit, and values of .846 (TLI) and .855 (CFI) for relative model-fit. Factor loadings ranged from .55 to .91. The psychometric properties and factor structure of the TICS-E are comparable to the German version of the TICS. The instrument therefore meets quality standards for an adequate measurement of chronic stress.

Odds per adjusted standard deviation: comparing strengths of associations for risk factors measured on different scales and across diseases and populations.

PubMed

Hopper, John L

2015-11-15

How can the "strengths" of risk factors, in the sense of how well they discriminate cases from controls, be compared when they are measured on different scales such as continuous, binary, and integer? Given that risk estimates take into account other fitted and design-related factors-and that is how risk gradients are interpreted-so should the presentation of risk gradients. Therefore, for each risk factor X0, I propose using appropriate regression techniques to derive from appropriate population data the best fitting relationship between the mean of X0 and all the other covariates fitted in the model or adjusted for by design (X1, X2, … , Xn). The odds per adjusted standard deviation (OPERA) presents the risk association for X0 in terms of the change in risk per s = standard deviation of X0 adjusted for X1, X2, … , Xn, rather than the unadjusted standard deviation of X0 itself. If the increased risk is relative risk (RR)-fold over A adjusted standard deviations, then OPERA = exp[ln(RR)/A] = RR(s). This unifying approach is illustrated by considering breast cancer and published risk estimates. OPERA estimates are by definition independent and can be used to compare the predictive strengths of risk factors across diseases and populations. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Hot topic: Definition and implementation of a breeding value for feed efficiency in dairy cows.

PubMed

Pryce, J E; Gonzalez-Recio, O; Nieuwhof, G; Wales, W J; Coffey, M P; Hayes, B J; Goddard, M E

2015-10-01

A new breeding value that combines the amount of feed saved through improved metabolic efficiency with predicted maintenance requirements is described. The breeding value includes a genomic component for residual feed intake (RFI) combined with maintenance requirements calculated from either a genomic or pedigree estimated breeding value (EBV) for body weight (BW) predicted using conformation traits. Residual feed intake is only available for genotyped Holsteins; however, BW is available for all breeds. The RFI component of the "feed saved" EBV has 2 parts: Australian calf RFI and Australian lactating cow RFI. Genomic breeding values for RFI were estimated from a reference population of 2,036 individuals in a multi-trait analysis including Australian calf RFI (n=843), Australian lactating cow RFI (n=234), and UK and Dutch lactating cow RFI (n=958). In all cases, the RFI phenotypes were deviations from a mean of 0, calculated by correcting dry matter intake for BW, growth, and milk yield (in the case of lactating cows). Single nucleotide polymorphism effects were calculated from the output of genomic BLUP and used to predict breeding values of 4,106 Holstein sires that were genotyped but did not have RFI phenotypes themselves. These bulls already had BW breeding values calculated from type traits, from which maintenance requirements in kilograms of feed per year were inferred. Finally, RFI and the feed required for maintenance (through BW) were used to calculate a feed saved breeding value and expressed as the predicted amount of feed saved per year. Animals that were 1 standard deviation above the mean were predicted to eat 66 kg dry matter less per year at the same level of milk production. In a data set of genotyped Holstein sires, the mean reliability of the feed saved breeding value was 0.37. For Holsteins that are not genotyped and for breeds other than Holsteins, feed saved is calculated using BW only. From April 2015, feed saved has been included as part of the Australian national selection index, the Balanced Performance Index (BPI). Selection on the BPI is expected to lead to modest gains in feed efficiency. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

"It is not guaranteed that you will benefit": True but misleading?

PubMed

Kim, Scott Y H; Wilson, Renee; De Vries, Raymond; Kim, H Myra; Holloway, Robert G; Kieburtz, Karl

2015-08-01

Participants of early-phase intervention trials for serious conditions provide high estimates of likelihood of benefit, even when informed consent forms do not promise such benefits. However, some technically correct, negatively stated benefits statements—such as "it is not guaranteed that you will benefit"—could play a role in raising expectations of benefit because in ordinary English usage such statements denote a likely but not a certain-to-occur event. An experimental online survey of 584 English-speaking adults recruited online. They were randomized to receive one of two benefit statements ("not guaranteed" vs "some but very small chance"), using a hypothetical scenario of an early-phase clinical trial testing an intervention to treat amyotrophic lateral sclerosis. We assessed respondents' willingness to consider participating in the amyotrophic lateral sclerosis trial, their estimates of likelihood of benefit, and their explanations for those estimates. The two arms did not differ in willingness to consider participation in the amyotrophic lateral sclerosis trial. Those receiving "not guaranteed" benefit statement had higher estimates of benefit than those receiving "some but very small chance" statement (35.7% (standard deviation 20.2) vs 28.3% (standard deviation 22.0), p < 0.0001). A total of 43% of all respondents chose expressions of positive sentiment (hope and need to stay positive) as explanations of their estimates; these respondents' estimates of benefit were higher than others but similar between the two arms. The effect of benefit statements was greatest among those who chose "Those are just the facts" as the explanation for their estimate (31.0% (standard deviation 22.4%) in "not guaranteed" arm vs 18.9% (standard deviation 21.0%) in comparison arm, p = 0.008). The use of "not guaranteed" language in benefit statements, when compared to "small but very small chance" language, appeared to increase the perception of likelihood of benefit of entering an early-phase trial, especially among those who view their estimates of benefits as "facts." Such "no guarantee" benefit statements may be misleading and should not be used in informed consent forms. © The Author(s) 2015.

Effects of a kindergarten-based, family-involved intervention on motor performance ability in 3- to 6-year-old children: the ToyBox-study.

PubMed

Birnbaum, Julia; Geyer, Christine; Kirchberg, Franca; Manios, Yannis; Koletzko, Berthold

2017-02-01

This study targeted to examine the effect of the ToyBox-intervention, a kindergarten-based, family-involved intervention, aiming to improve preschooler's energy-related behaviours (e.g., physical activity) on motor performance ability. Physical activity sessions, classroom activities, environmental changes and tools for parents were the components of the 1-year intervention. The intervention and control were cluster-randomised, and children's anthropometry and two motor test items (jumping from side to side, JSS and standing long jump, SLJ) were assessed. A total of 1293 (4.6 ± 0.69 years; 52% boys) from 45 kindergartens in Germany were included (intervention, n = 863; control, n = 430). The effect was assessed using generalised estimating equation. The intervention group showed a better improvement in JSS (Estimate 2.19 jumps, P = 0.01) and tended to improve better in SLJ (Estimate 2.73 cm, P = 0.08). The intervention was more effective in boys with respect to SLJ (P of interaction effect = 0.01). Children aged <4.5 years did not show a significant benefit while older children improved (JSS, Estimate 3.38 jumps, P = 0.004; SLJ, Estimate 4.18 cm, P = 0.04). Children with low socio-economic status improved in JSS (Estimate 5.98 jumps, P = 0.0001). The ToyBox-intervention offers an effective strategy to improve specific components of motor performance ability in early childhood. Future programmes should consider additional strategies specifically targeting girls and younger aged children. BMI: body mass index; SES: socio-economic status; JSS: jumping from side to side; SLJ: standing long jump; SD: standard deviation; GEE: generalised estimating equation.

Quantitative Evaluation for Differentiating Malignant and Benign Thyroid Nodules Using Histogram Analysis of Grayscale Sonograms.

PubMed

Nam, Se Jin; Yoo, Jaeheung; Lee, Hye Sun; Kim, Eun-Kyung; Moon, Hee Jung; Yoon, Jung Hyun; Kwak, Jin Young

2016-04-01

To evaluate the diagnostic value of histogram analysis using grayscale sonograms for differentiation of malignant and benign thyroid nodules. From July 2013 through October 2013, 579 nodules in 563 patients who had undergone ultrasound-guided fine-needle aspiration were included. For the grayscale histogram analysis, pixel echogenicity values in regions of interest were measured as 0 to 255 (0, black; 255, white) with in-house software. Five parameters (mean, skewness, kurtosis, standard deviation, and entropy) were obtained for each thyroid nodule. With principal component analysis, an index was derived. Diagnostic performance rates for the 5 histogram parameters and the principal component analysis index were calculated. A total of 563 patients were included in the study (mean age ± SD, 50.3 ± 12.3 years;range, 15-79 years). Of the 579 nodules, 431 were benign, and 148 were malignant. Among the 5 parameters and the principal component analysis index, the standard deviation (75.546 ± 14.153 versus 62.761 ± 16.01; P < .001), kurtosis (3.898 ± 2.652 versus 6.251 ± 9.102; P < .001), entropy (0.16 ± 0.135 versus 0.239 ± 0.185; P < .001), and principal component analysis index (-0.386±0.774 versus 0.134 ± 0.889; P < .001) were significantly different between the malignant and benign nodules. With the calculated cutoff values, the areas under the curve were 0.681 (95% confidence interval, 0.643-0.721) for standard deviation, 0.661 (0.620-0.703) for principal component analysis index, 0.651 (0.607-0.691) for kurtosis, 0.638 (0.596-0.681) for entropy, and 0.606 (0.563-0.647) for skewness. The subjective analysis of grayscale sonograms by radiologists alone showed an area under the curve of 0.861 (0.833-0.888). Grayscale histogram analysis was feasible for differentiating malignant and benign thyroid nodules but did not show better diagnostic performance than subjective analysis performed by radiologists. Further technical advances will be needed to objectify interpretations of thyroid grayscale sonograms. © 2016 by the American Institute of Ultrasound in Medicine.

47 CFR 61.3 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-10-01

...). (r) GDP Price Index (GDP-PI). The estimate of the Chain-Type Price Index for Gross Domestic Product... Price Index (GNP-PI). The estimate of the “Fixed-Weighted Price Index for Gross National Product, 1982...

A new look at the decomposition of agricultural productivity growth incorporating weather effects.

PubMed

Njuki, Eric; Bravo-Ureta, Boris E; O'Donnell, Christopher J

2018-01-01

Random fluctuations in temperature and precipitation have substantial impacts on agricultural output. However, the contribution of these changing configurations in weather to total factor productivity (TFP) growth has not been addressed explicitly in econometric analyses. Thus, the key objective of this study is to quantify and to investigate the role of changing weather patterns in explaining yearly fluctuations in TFP. For this purpose, we define TFP to be a measure of total output divided by a measure of total input. We estimate a stochastic production frontier model using U.S. state-level agricultural data incorporating growing season temperature and precipitation, and intra-annual standard deviations of temperature and precipitation for the period 1960-2004. We use the estimated parameters of the model to compute a TFP index that has good axiomatic properties. We then decompose TFP growth in each state into weather effects, technological progress, technical efficiency, and scale-mix efficiency changes. This approach improves our understanding of the role of different components of TFP in agricultural productivity growth. We find that annual TFP growth averaged 1.56% between 1960 and 2004. Moreover, we observe substantial heterogeneity in weather effects across states and over time.

A new look at the decomposition of agricultural productivity growth incorporating weather effects

PubMed Central

Bravo-Ureta, Boris E.; O’Donnell, Christopher J.

2018-01-01

Random fluctuations in temperature and precipitation have substantial impacts on agricultural output. However, the contribution of these changing configurations in weather to total factor productivity (TFP) growth has not been addressed explicitly in econometric analyses. Thus, the key objective of this study is to quantify and to investigate the role of changing weather patterns in explaining yearly fluctuations in TFP. For this purpose, we define TFP to be a measure of total output divided by a measure of total input. We estimate a stochastic production frontier model using U.S. state-level agricultural data incorporating growing season temperature and precipitation, and intra-annual standard deviations of temperature and precipitation for the period 1960–2004. We use the estimated parameters of the model to compute a TFP index that has good axiomatic properties. We then decompose TFP growth in each state into weather effects, technological progress, technical efficiency, and scale-mix efficiency changes. This approach improves our understanding of the role of different components of TFP in agricultural productivity growth. We find that annual TFP growth averaged 1.56% between 1960 and 2004. Moreover, we observe substantial heterogeneity in weather effects across states and over time. PMID:29466461

Are Study and Journal Characteristics Reliable Indicators of "Truth" in Imaging Research?

PubMed

Frank, Robert A; McInnes, Matthew D F; Levine, Deborah; Kressel, Herbert Y; Jesurum, Julia S; Petrcich, William; McGrath, Trevor A; Bossuyt, Patrick M

2018-04-01

Purpose To evaluate whether journal-level variables (impact factor, cited half-life, and Standards for Reporting of Diagnostic Accuracy Studies [STARD] endorsement) and study-level variables (citation rate, timing of publication, and order of publication) are associated with the distance between primary study results and summary estimates from meta-analyses. Materials and Methods MEDLINE was searched for meta-analyses of imaging diagnostic accuracy studies, published from January 2005 to April 2016. Data on journal-level and primary-study variables were extracted for each meta-analysis. Primary studies were dichotomized by variable as first versus subsequent publication, publication before versus after STARD introduction, STARD endorsement, or by median split. The mean absolute deviation of primary study estimates from the corresponding summary estimates for sensitivity and specificity was compared between groups. Means and confidence intervals were obtained by using bootstrap resampling; P values were calculated by using a t test. Results Ninety-eight meta-analyses summarizing 1458 primary studies met the inclusion criteria. There was substantial variability, but no significant differences, in deviations from the summary estimate between paired groups (P > .0041 in all comparisons). The largest difference found was in mean deviation for sensitivity, which was observed for publication timing, where studies published first on a topic demonstrated a mean deviation that was 2.5 percentage points smaller than subsequently published studies (P = .005). For journal-level factors, the greatest difference found (1.8 percentage points; P = .088) was in mean deviation for sensitivity in journals with impact factors above the median compared with those below the median. Conclusion Journal- and study-level variables considered important when evaluating diagnostic accuracy information to guide clinical decisions are not systematically associated with distance from the truth; critical appraisal of individual articles is recommended. © RSNA, 2017 Online supplemental material is available for this article.

Estimating accuracy of land-cover composition from two-stage cluster sampling

USGS Publications Warehouse

Stehman, S.V.; Wickham, J.D.; Fattorini, L.; Wade, T.D.; Baffetta, F.; Smith, J.H.

2009-01-01

Land-cover maps are often used to compute land-cover composition (i.e., the proportion or percent of area covered by each class), for each unit in a spatial partition of the region mapped. We derive design-based estimators of mean deviation (MD), mean absolute deviation (MAD), root mean square error (RMSE), and correlation (CORR) to quantify accuracy of land-cover composition for a general two-stage cluster sampling design, and for the special case of simple random sampling without replacement (SRSWOR) at each stage. The bias of the estimators for the two-stage SRSWOR design is evaluated via a simulation study. The estimators of RMSE and CORR have small bias except when sample size is small and the land-cover class is rare. The estimator of MAD is biased for both rare and common land-cover classes except when sample size is large. A general recommendation is that rare land-cover classes require large sample sizes to ensure that the accuracy estimators have small bias. ?? 2009 Elsevier Inc.

Space shuttle propulsion estimation development verification

NASA Technical Reports Server (NTRS)

Rogers, Robert M.

1989-01-01

The application of extended Kalman filtering to estimating the Space Shuttle Propulsion performance, i.e., specific impulse, from flight data in a post-flight processing computer program is detailed. The flight data used include inertial platform acceleration, SRB head pressure, SSME chamber pressure and flow rates, and ground based radar tracking data. The key feature in this application is the model used for the SRB's, which is a nominal or reference quasi-static internal ballistics model normalized to the propellant burn depth. Dynamic states of mass overboard and propellant burn depth are included in the filter model to account for real-time deviations from the reference model used. Aerodynamic, plume, wind and main engine uncertainties are also included for an integrated system model. Assuming uncertainty within the propulsion system model and attempts to estimate its deviations represent a new application of parameter estimation for rocket powered vehicles. Illustrations from the results of applying this estimation approach to several missions show good quality propulsion estimates.

A complex symbol signal-to-noise ratio estimator and its performance

NASA Technical Reports Server (NTRS)

Feria, Y.

1994-01-01

This article presents an algorithm for estimating the signal-to-noise ratio (SNR) of signals that contain data on a downconverted suppressed carrier or the first harmonic of a square-wave subcarrier. This algorithm can be used to determine the performance of the full-spectrum combiner for the Galileo S-band (2.2- to 2.3-GHz) mission by measuring the input and output symbol SNR. A performance analysis of the algorithm shows that the estimator can estimate the complex symbol SNR using 10,000 symbols at a true symbol SNR of -5 dB with a mean of -4.9985 dB and a standard deviation of 0.2454 dB, and these analytical results are checked by simulations of 100 runs with a mean of -5.06 dB and a standard deviation of 0.2506 dB.

Uncertainty Quantification of GEOS-5 L-band Radiative Transfer Model Parameters Using Bayesian Inference and SMOS Observations

NASA Technical Reports Server (NTRS)

DeLannoy, Gabrielle J. M.; Reichle, Rolf H.; Vrugt, Jasper A.

2013-01-01

Uncertainties in L-band (1.4 GHz) radiative transfer modeling (RTM) affect the simulation of brightness temperatures (Tb) over land and the inversion of satellite-observed Tb into soil moisture retrievals. In particular, accurate estimates of the microwave soil roughness, vegetation opacity and scattering albedo for large-scale applications are difficult to obtain from field studies and often lack an uncertainty estimate. Here, a Markov Chain Monte Carlo (MCMC) simulation method is used to determine satellite-scale estimates of RTM parameters and their posterior uncertainty by minimizing the misfit between long-term averages and standard deviations of simulated and observed Tb at a range of incidence angles, at horizontal and vertical polarization, and for morning and evening overpasses. Tb simulations are generated with the Goddard Earth Observing System (GEOS-5) and confronted with Tb observations from the Soil Moisture Ocean Salinity (SMOS) mission. The MCMC algorithm suggests that the relative uncertainty of the RTM parameter estimates is typically less than 25 of the maximum a posteriori density (MAP) parameter value. Furthermore, the actual root-mean-square-differences in long-term Tb averages and standard deviations are found consistent with the respective estimated total simulation and observation error standard deviations of m3.1K and s2.4K. It is also shown that the MAP parameter values estimated through MCMC simulation are in close agreement with those obtained with Particle Swarm Optimization (PSO).

Role of the standard deviation in the estimation of benchmark doses with continuous data.

PubMed

Gaylor, David W; Slikker, William

2004-12-01

For continuous data, risk is defined here as the proportion of animals with values above a large percentile, e.g., the 99th percentile or below the 1st percentile, for the distribution of values among control animals. It is known that reducing the standard deviation of measurements through improved experimental techniques will result in less stringent (higher) doses for the lower confidence limit on the benchmark dose that is estimated to produce a specified risk of animals with abnormal levels for a biological effect. Thus, a somewhat larger (less stringent) lower confidence limit is obtained that may be used as a point of departure for low-dose risk assessment. It is shown in this article that it is important for the benchmark dose to be based primarily on the standard deviation among animals, s(a), apart from the standard deviation of measurement errors, s(m), within animals. If the benchmark dose is incorrectly based on the overall standard deviation among average values for animals, which includes measurement error variation, the benchmark dose will be overestimated and the risk will be underestimated. The bias increases as s(m) increases relative to s(a). The bias is relatively small if s(m) is less than one-third of s(a), a condition achieved in most experimental designs.

Multiple Scale Analysis of the Dynamic State Index (DSI)

NASA Astrophysics Data System (ADS)

Müller, A.; Névir, P.

2016-12-01

The Dynamic State Index (DSI) is a novel parameter that indicates local deviations of the atmospheric flow field from a stationary, inviscid and adiabatic solution of the primitive equations of fluid mechanics. This is in contrast to classical methods, which often diagnose deviations from temporal or spatial mean states. We show some applications of the DSI to atmospheric flow phenomena on different scales. The DSI is derived from the Energy-Vorticity-Theory (EVT) which is based on two global conserved quantities, the total energy and Ertel's potential enstrophy. Locally, these global quantities lead to the Bernoulli function and the PV building together with the potential temperature the DSI.If the Bernoulli function and the PV are balanced, the DSI vanishes and the basic state is obtained. Deviations from the basic state provide an indication of diabatic and non-stationary weather events. Therefore, the DSI offers a tool to diagnose and even prognose different atmospheric events on different scales.On synoptic scale, the DSI can help to diagnose storms and hurricanes, where also the dipole structure of the DSI plays an important role. In the scope of the collaborative research center "Scaling Cascades in Complex Systems" we show high correlations between the DSI and precipitation on convective scale. Moreover, we compare the results with reduced models and different spatial resolutions.

Height intercept for estimating site index in young ponderosa pine plantations and natural stands

Treesearch

William W. Oliver

1972-01-01

Site index is difficult to estimate with any reliability in ponderosa pine (Pinus ponderosa Laws.) stands below 20 yeas old. A method of estimating site index based on 4-year height intercepts (total length of the first four internodes above breast height) is described. Equations based on two sets of published site-index curves were developed. They...

Relationship and significance of gait deviations associated with limb length discrepancy: A systematic review.

PubMed

Khamis, Sam; Carmeli, Eli

2017-09-01

Controversy still exists as to the clinical significance of leg length discrepancy (LLD) in spite of the fact that further evidence has been emerging regarding the relationship between several clinical conditions and LLD. The objectives of our study were to review the available research with regard to LLD as a cause of clinically significant gait deviations, to determine if there is a relationship between the magnitude of LLD and the presence of gait deviations and to identify the most common gait deviations associated with LLD. In line with the PRISMA guidelines, a literature search was carried out throughout the Medline, CINAHL and EMBASE databases. Twelve articles met the predetermined inclusion criteria and were included in the review. Quality assessment using the Methodological Index for Non-Randomized Studies (MINORS) scale was completed for all included studies. Two main methodologies were found in 4 studies evaluating gait asymmetry in patients or healthy participants with anatomic LLD and 8 studies evaluating gait deviations while simulating LLD by employing artificial lifts of 1-5cm on healthy subjects. A significant relationship was found between anatomic LLD and gait deviation. Evidence suggests that gait deviations may occur with discrepancies of >1cm, with greater impact seen as the discrepancy increases. Compensatory strategies were found to occur in both the shorter and longer limb, throughout the lower limb. As the discrepancy increases, more compensatory strategies occur. Sagittal plane deviations seem to be the most effective deviations, although, frontal plane compensations also occur in the pelvis, hip and foot. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantitative FLASH MRI at 3T using a rational approximation of the Ernst equation.

PubMed

Helms, Gunther; Dathe, Henning; Dechent, Peter

2008-03-01

From the half-angle substitution of trigonometric terms in the Ernst equation, rational approximations of the flip angle dependence of the FLASH signal can be derived. Even the rational function of the lowest order was in good agreement with the experiment for flip angles up to 20 degrees . Three-dimensional maps of the signal amplitude and longitudinal relaxation rates in human brain were obtained from eight subjects by dual-angle measurements at 3T (nonselective 3D-FLASH, 7 degrees and 20 degrees flip angle, TR = 30 ms, isotropic resolution of 0.95 mm, each 7:09 min). The corresponding estimates of T1 and signal amplitude are simple algebraic expressions and deviated about 1% from the exact solution. They are ill-conditioned to estimate the local flip angle deviation but can be corrected post hoc by division of squared RF maps obtained by independent measurements. Local deviations from the nominal flip angles strongly affected the relaxation estimates and caused considerable blurring of the T1 histograms. (c) 2008 Wiley-Liss, Inc.

[Estimating heavy metal concentrations in topsoil from vegetation reflectance spectra of Hyperion images: A case study of Yushu County, Qinghai, China.

PubMed

Yang, Ling Yu; Gao, Xiao Hong; Zhang, Wei; Shi, Fei Fei; He, Lin Hua; Jia, Wei

2016-06-01

In this study, we explored the feasibility of estimating the soil heavy metal concentrations using the hyperspectral satellite image. The concentration of As, Pb, Zn and Cd elements in 48 topsoil samples collected from the field in Yushu County of the Sanjiangyuan regions was measured in the laboratory. We then extracted 176 vegetation spectral reflectance bands of 48 soil samples as well as five vegetation indices from two Hyperion images. Following that, the partial least squares regression (PLSR) method was employed to estimate the soil heavy metal concentrations using the above two independent sets of Hyperion-derived variables, separately constructed the estimation model between the 176 vegetation spectral reflectance bands and the soil heavy metal concentrations (called the vegetation spectral reflectance-based estimation model), and between the five vegetation indices being used as the independent variable and the soil heavy metal concentrations (called synthetic vegetation index-based estimation model). Using RPD (the ratio of standard deviation from the 4 heavy metals measured values of the validation samples to RMSE) as the validation criteria, the RPDs of As and Pb concentrations from the two models were both less than 1.4, which suggested that both models were incapable of roughly estimating As and Pb concentrations; whereas the RPDs of Zn and Cd were 1.53, 1.46 and 1.46, 1.42, respectively, which implied that both models had the ability for rough estimation of Zn and Cd concentrations. Based on those results, the vegetation spectral-based estimation model was selected to obtain the spatial distribution map of Zn concentration in combination with the Hyperion image. The estimated Zn map showed that the zones with high Zn concentrations were distributed near the provincial road 308, national road 214 and towns, which could be influenced by human activities. Our study proved that the spectral reflectance of Hyperion image was useful in estimating the soil concentrations of Zn and Cd.

The Effective Dynamic Ranges for Glaucomatous Visual Field Progression With Standard Automated Perimetry and Stimulus Sizes III and V.

PubMed

Wall, Michael; Zamba, Gideon K D; Artes, Paul H

2018-01-01

It has been shown that threshold estimates below approximately 20 dB have little effect on the ability to detect visual field progression in glaucoma. We aimed to compare stimulus size V to stimulus size III, in areas of visual damage, to confirm these findings by using (1) a different dataset, (2) different techniques of progression analysis, and (3) an analysis to evaluate the effect of censoring on mean deviation (MD). In the Iowa Variability in Perimetry Study, 120 glaucoma subjects were tested every 6 months for 4 years with size III SITA Standard and size V Full Threshold. Progression was determined with three complementary techniques: pointwise linear regression (PLR), permutation of PLR, and linear regression of the MD index. All analyses were repeated on "censored'' datasets in which threshold estimates below a given criterion value were set to equal the criterion value. Our analyses confirmed previous observations that threshold estimates below 20 dB contribute much less to visual field progression than estimates above this range. These findings were broadly similar with stimulus sizes III and V. Censoring of threshold values < 20 dB has relatively little impact on the rates of visual field progression in patients with mild to moderate glaucoma. Size V, which has lower retest variability, performs at least as well as size III for longitudinal glaucoma progression analysis and appears to have a larger useful dynamic range owing to the upper sensitivity limit being higher.

Associations of infant subcutaneous fat mass with total and abdominal fat mass at school-age. The Generation R Study

PubMed Central

Santos, Susana; Gaillard, Romy; Oliveira, Andreia; Barros, Henrique; Abrahamse-Berkeveld, Marieke; van der Beek, Eline M; Hofman, Albert; Jaddoe, Vincent WV

2017-01-01

Background Skinfold thickness enables the measurement of overall and regional subcutaneous fatness in infancy and may be associated with total and abdominal body fat in later childhood. We examined the associations of subcutaneous fat in infancy with total and abdominal fat at school-age. Methods In a population-based prospective cohort study among 821 children, we calculated total subcutaneous fat (sum of biceps, triceps, suprailiacal and subscapular skinfold thicknesses) and central-to-total subcutaneous fat ratio (sum of suprailiacal and subscapular skinfold thicknesses/total subcutaneous fat) at 1.5 and 24 months. At 6 years, we measured fat mass index (total fat/height3), central-to-total fat ratio (trunk fat/total fat) and android-to-gynoid fat ratio (android fat/gynoid fat) by dual-energy X-ray absorptiometry and preperitoneal fat mass area by abdominal ultrasound. Results Central-to-total subcutaneous fat ratio at 1.5 months was positively associated with fat mass index and central-to-total fat ratio at 6 years, whereas both total and central-to-total subcutaneous fat ratio at 24 months were positively associated with all childhood adiposity measures (p<0.05). A 1-standard-deviation scores higher total subcutaneous fat at 24 months was associated with an increased risk of childhood overweight (Odds Ratio 1.70 [95% Confidence Interval 1.36, 2.12]). These associations were weaker than those for body mass index and stronger among girls than boys. Conclusions Subcutaneous fat in infancy is positively associated with total and abdominal fat at school-age. Our results also suggest that skinfold thicknesses add little value to estimate later body fat, as compared to body mass index. PMID:27225335

Associations of Infant Subcutaneous Fat Mass with Total and Abdominal Fat Mass at School-Age: The Generation R Study.

PubMed

Santos, Susana; Gaillard, Romy; Oliveira, Andreia; Barros, Henrique; Abrahamse-Berkeveld, Marieke; van der Beek, Eline M; Hofman, Albert; Jaddoe, Vincent W V

2016-09-01

Skinfold thickness enables the measurement of overall and regional subcutaneous fatness in infancy and may be associated with total and abdominal body fat in later childhood. We examined the associations of subcutaneous fat in infancy with total and abdominal fat at school-age. In a population-based prospective cohort study among 821 children, we calculated total subcutaneous fat (sum of biceps, triceps, suprailiacal, and subscapular skinfold thicknesses) and central-to-total subcutaneous fat ratio (sum of suprailiacal and subscapular skinfold thicknesses/total subcutaneous fat) at 1.5 and 24 months. At 6 years, we measured fat mass index (total fat/height(3) ), central-to-total fat ratio (trunk fat/total fat), and android-to-gynoid fat ratio (android fat/gynoid fat) by dual-energy X-ray absorptiometry and preperitoneal fat mass area by abdominal ultrasound. Central-to-total subcutaneous fat ratio at 1.5 months was positively associated with fat mass index and central-to-total fat ratio at 6 years, whereas both total and central-to-total subcutaneous fat ratio at 24 months were positively associated with all childhood adiposity measures. A 1-standard-deviation scores higher total subcutaneous fat at 24 months was associated with an increased risk of childhood overweight (odds ratio 1.70, 95% confidence interval 1.36, 2.12). These associations were weaker than those for body mass index and stronger among girls than boys. Subcutaneous fat in infancy is positively associated with total and abdominal fat at school-age. Our results also suggest that skinfold thicknesses add little value to estimate later body fat, as compared with body mass index. © 2016 John Wiley & Sons Ltd.

Adherence to dietary guidelines and cardiovascular disease risk in the EPIC-NL cohort.

PubMed

Struijk, Ellen A; May, Anne M; Wezenbeek, Nick L W; Fransen, Heidi P; Soedamah-Muthu, Sabita S; Geelen, Anouk; Boer, Jolanda M A; van der Schouw, Yvonne T; Bueno-de-Mesquita, H Bas; Beulens, Joline W J

2014-09-20

Global and national dietary guidelines have been created to lower chronic disease risk. The aim of this study was to assess whether greater adherence to the WHO guidelines (Healthy Diet Indicator (HDI)); the Dutch guidelines for a healthy diet (Dutch Healthy Diet-index (DHD-index)); and the Dietary Approaches to Stop Hypertension (DASH) diet was associated with a lower risk of cardiovascular disease (CVD), coronary heart disease (CHD) or stroke. A prospective cohort study was conducted among 33,671 healthy Dutch men and women aged 20-70 years recruited into the EPIC-NL study during 1993-1997. We used Cox regression adjusted for relevant confounders to estimate the hazard ratios per standard deviation increase in score and 95% confidence intervals (CI) of the associations between the dietary guidelines and CVD, CHD and stroke risk. After an average follow-up of 12.2 years, 2752 CVD cases were documented, including 1630 CHD cases and 527 stroke cases. We found no association between the HDI (0.98, 95% CI 0.94; 1.02) or DHD-index (0.96, 95% CI 0.92; 1.00) and CVD incidence. Similar results were found for these guidelines and CHD or stroke incidence. Higher adherence to the DASH diet was significantly associated with a lower CVD (0.92, 95% CI 0.89; 0.96), CHD (0.91, 95% CI 0.86; 0.95), and stroke (0.90, 95% CI 0.82; 0.99) risk. The HDI and the DHD-index were not associated with CVD risk, while the DASH diet was significantly associated with a lower risk of developing CVD, CHD and stroke. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

The Calibration of the Corneal Light Reflex to Estimate the Degree of an Angle of Deviation.

PubMed

Tengtrisorn, Supaporn; Tangkijwongpaisarn, Sitthi; Burachokvivat, Somporn

2015-12-01

To measure the conversion factor for the size of an angle of deviation from the clinical photographs of the corneal light reflex. In this cross-sectional study, 19 normal subjects with 20/20 visual acuity were photographed with a digital camera while staring at targets placed five prism diopters (PD) apart from one another on a screen. The subjects were tested at a distance of 1 meter (m) and 4 m from a screen. Measurement of the corneal light reflex displacement for each fixed target was obtained from the photographs. The calibration of the corneal light reflex displacement in millimeters (mm) against the angle of deviation in PD was then analyzed with repeated measure linear regression analysis. At 1 m, the values of 0.047 mm/PD and 0.058 mm/PD were obtained as the conversion factor from reflex displacement to deviated angle for the nasal side and temporal side respectively. At 4 m, the values were 0.050 mm/PD and 0.064 mm/PD for the nasal side and the temporal side respectively. There were significant differences between the values obtained at the different distances, regardless of nasal or temporal side. Conversion factors were presented for estimating the strabismic angle at different distances and gazes. For clinical practice, the use of photographs to estimate the strabismic angle should use different values for different distances and strabismic types.

Asynchronous arterial systolic expansion as a marker of vascular aging: assessment of the carotid artery with velocity vector imaging.

PubMed

Yang, Woo-In; Shim, Chi Y; Bang, Woo D; Oh, Chang M; Chang, Hyuk J; Chung, Namsik; Ha, Jong-Won

2011-12-01

Arterial elastic properties change with aging. Measurements of pulse wave velocity and augmentation index are useful for the evaluation of arterial stiffness. However, they likely represent only global characteristics of the arterial tree rather than local vascular alterations. The aim of this study was to evaluate whether local vascular properties assessed by velocity vector imaging differed with aging. Vascular properties of carotid arteries with ages were assessed in 100 healthy volunteers (52 men) ranging from 20 to 68 years using velocity vector imaging. The peak circumferential strain and strain rate of the six segments in left common carotid arteries were analyzed and the standard deviation of the time to peak circumferential strain and strain rate of the six segments, representing the synchronicity of the arterial expansion, were calculated. Central blood pressure, augmentation index and pulse wave velocity were assessed by commercially available radial artery tonometry, the SphygmoCor system (AtCor Medical, West Ryde, Australia). A validated generalized transfer function was used to acquire the central aortic pressures and pressure waveforms. Pulse wave velocity, augmentation index and velocity vector imaging parameters showed significant changes with age. However, the age-related changes in pulse wave velocity, augmentation index and velocity vector imaging parameters were different. The increase in pulse wave velocity was more prominent in older individuals, whereas the changes in augmentation index and carotid strain and strain rate were evident earlier, at the age of 30 years. Unlike augmentation index, which showed little change in older individuals, the standard deviation of time to peak strain and strain rate showed a steady increase from younger to older individuals. Asynchronous arterial expansion could be a useful discriminative marker of vascular aging independent of individual's age.

Academic productivity among fellowship associated adult total joint reconstruction surgeons.

PubMed

Khan, Adam Z; Kelley, Benjamin V; Patel, Ankur D; McAllister, David R; Leong, Natalie L

2017-12-01

The Hirsch index (h-index) is a measure that evaluates both research volume and quality-taking into consideration both publications and citations of a single author. No prior work has evaluated academic productivity and contributions to the literature of adult total joint replacement surgeons. This study uses h-index to benchmark the academic impact and identify characteristics associated with productivity of faculty members at joint replacement fellowships. Adult reconstruction fellowship programs were obtained via the American Association of Hip and Knee Surgeons website. Via the San Francisco match and program-specific websites, program characteristics (Accreditation Council for Graduate Medical Education approval, academic affiliation, region, number of fellows, fellow research requirement), associated faculty members, and faculty-specific characteristics (gender, academic title, formal fellowship training, years in practice) were obtained. H-index and total faculty publications served as primary outcome measures. Multivariable linear regression determined statistical significance. Sixty-six adult total joint reconstruction fellowship programs were identified: 30% were Accreditation Council for Graduate Medical Education approved and 73% had an academic affiliation. At these institutions, 375 adult reconstruction surgeons were identified; 98.1% were men and 85.3% had formal arthroplasty fellowship training. Average number of publications per faculty member was 50.1 (standard deviation 76.8; range 0-588); mean h-index was 12.8 (standard deviation 13.8; range 0-67). Number of fellows, faculty academic title, years in practice, and formal fellowship training had a significant ( P < .05) positive correlation with both h-index and total publications. The statistical overview presented in this work can help total joint surgeons quantitatively benchmark their academic performance against that of their peers.

Long-Term Melatonin Therapy for Adolescents and Young Adults with Chronic Sleep Onset Insomnia and Late Melatonin Onset: Evaluation of Sleep Quality, Chronotype, and Lifestyle Factors Compared to Age-Related Randomly Selected Population Cohorts.

PubMed

Zwart, Tom C; Smits, Marcel G; Egberts, Toine C G; Rademaker, Carin M A; van Geijlswijk, Ingeborg M

2018-03-02

The extent of continuance of melatonin therapy initiated in pre-pubertal children with chronic sleep onset insomnia (CSOI) was investigated in young adult life. Sleep timing, sleep quality, adverse events, reasons for cessation of therapy, and patient characteristics with regard to therapy regimen, chronotype and lifestyle factors possibly influencing sleeping behavior were assessed. With an online survey using questionnaires (Pittsburgh Sleep Quality Index, Insomnia Severity Index, Morningness-Eveningness Questionnaire, and Munich Chronotype Questionnaire), outcomes were measured and compared with age-related controls. These controls were extracted from published epidemiological research programs applying the same questionnaires. At the moment of the survey, melatonin was still continued by 27.3% of the patients, with a mean treatment duration of 10.8 years. The overall average treatment duration was 7.1 years. Sleep quality of both discontinued and persistent melatonin users did not deviate from controls. Sleep timing and chronotype scores indicated evening type preference in all responders. Adverse events were scarce but the perceived timing of pubertal development suggested a tendency towards delayed puberty in former and current users of melatonin. This study may underestimate the number of children that are able to stop using melatonin due to the response rate (47.8%) and appeal for continuing users. Sleep timing parameters were based on self-reported estimates. Control populations were predominantly students and were of varying nationalities. The statistical power of this study is low due to the limited sample size. Melatonin therapy sustained for 7.1 years does not result in substantial deviations of sleep quality as compared to controls and appears to be safe. The evening type preference suggests a causal relation with CSOI. This study shows that ten years after initiation of treatment with melatonin for CSOI, approximately 75% of the patients will have normal sleep quality without medication.

Marsh collapse thresholds for coastal Louisiana estimated using elevation and vegetation index data

USGS Publications Warehouse

Couvillion, Brady R.; Beck, Holly

2013-01-01

Forecasting marsh collapse in coastal Louisiana as a result of changes in sea-level rise, subsidence, and accretion deficits necessitates an understanding of thresholds beyond which inundation stress impedes marsh survival. The variability in thresholds at which different marsh types cease to occur (i.e., marsh collapse) is not well understood. We utilized remotely sensed imagery, field data, and elevation data to help gain insight into the relationships between vegetation health and inundation. A Normalized Difference Vegetation Index (NDVI) dataset was calculated using remotely sensed data at peak biomass (August) and used as a proxy for vegetation health and productivity. Statistics were calculated for NDVI values by marsh type for intermediate, brackish, and saline marsh in coastal Louisiana. Marsh-type specific NDVI values of 1.5 and 2 standard deviations below the mean were used as upper and lower limits to identify conditions indicative of collapse. As marshes seldom occur beyond these values, they are believed to represent a range within which marsh collapse is likely to occur. Inundation depth was selected as the primary candidate for evaluation of marsh collapse thresholds. Elevation relative to mean water level (MWL) was calculated by subtracting MWL from an elevation dataset compiled from multiple data types including light detection and ranging (lidar) and bathymetry. A polynomial cubic regression was used to examine a random subset of pixels to determine the relationship between elevation (relative to MWL) and NDVI. The marsh collapse uncertainty range values were found by locating the intercept of the regression line with the 1.5 and 2 standard deviations below the mean NDVI value for each marsh type. Results indicate marsh collapse uncertainty ranges of 30.7–35.8 cm below MWL for intermediate marsh, 20–25.6 cm below MWL for brackish marsh, and 16.9–23.5 cm below MWL for saline marsh. These values are thought to represent the ranges of inundation depths within which marsh collapse is probable.

Air displacement plethysmography versus dual-energy x-ray absorptiometry in underweight, normal-weight, and overweight/obese individuals.

PubMed

Lowry, David W; Tomiyama, A Janet

2015-01-01

Accurately estimating fat percentage is important for assessing health and determining treatment course. Methods of estimating body composition such as hydrostatic weighing or dual-energy x-ray absorptiometry (DXA), however, can be expensive, require extensive operator training, and, in the case of hydrostatic weighing, be highly burdensome for patients. Our objective was to evaluate air displacement plethysmography via the Bod Pod, a less burdensome method of estimating body fat percentage. In particular, we filled a gap in the literature by testing the Bod Pod at the lower extreme of the Body Mass Index (BMI) distribution. Three BMI groups were recruited and underwent both air displacement plethysmography and dual-energy x-ray absorptiometry. We recruited 30 healthy adults at the lower BMI distribution from the Calorie Restriction (CR) Society and followers of the CR Way. We also recruited 15 normal weight and 19 overweight/obese healthy adults from the general population. Both Siri and Brozek equations derived body fat percentage from the Bod Pod, and Bland-Altman analyses assessed agreement between the Bod Pod and DXA. Compared to DXA, the Bod Pod overestimated body fat percentage in thinner participants and underestimated body fat percentage in heavier participants, and the magnitude of difference was larger for underweight BMI participants, reaching 13% in some. The Bod Pod and DXA had smaller discrepancies in normal weight and overweight/obese participants. While less burdensome, clinicians should be aware that Bod Pod estimates may deviate from DXA estimates particularly at the lower end of the BMI distribution.

Air Displacement Plethysmography versus Dual-Energy X-Ray Absorptiometry in Underweight, Normal-Weight, and Overweight/Obese Individuals

PubMed Central

Lowry, David W.; Tomiyama, A. Janet

2015-01-01

Background Accurately estimating fat percentage is important for assessing health and determining treatment course. Methods of estimating body composition such as hydrostatic weighing or dual-energy x-ray absorptiometry (DXA), however, can be expensive, require extensive operator training, and, in the case of hydrostatic weighing, be highly burdensome for patients. Our objective was to evaluate air displacement plethysmography via the Bod Pod, a less burdensome method of estimating body fat percentage. In particular, we filled a gap in the literature by testing the Bod Pod at the lower extreme of the Body Mass Index (BMI) distribution. Findings Three BMI groups were recruited and underwent both air displacement plethysmography and dual-energy x-ray absorptiometry. We recruited 30 healthy adults at the lower BMI distribution from the Calorie Restriction (CR) Society and followers of the CR Way. We also recruited 15 normal weight and 19 overweight/obese healthy adults from the general population. Both Siri and Brozek equations derived body fat percentage from the Bod Pod, and Bland-Altman analyses assessed agreement between the Bod Pod and DXA. Compared to DXA, the Bod Pod overestimated body fat percentage in thinner participants and underestimated body fat percentage in heavier participants, and the magnitude of difference was larger for underweight BMI participants, reaching 13% in some. The Bod Pod and DXA had smaller discrepancies in normal weight and overweight/obese participants. Conclusions While less burdensome, clinicians should be aware that Bod Pod estimates may deviate from DXA estimates particularly at the lower end of the BMI distribution. PMID:25607661

Quantifying prosthetic gait deviation using simple outcome measures

PubMed Central

Kark, Lauren; Odell, Ross; McIntosh, Andrew S; Simmons, Anne

2016-01-01

AIM: To develop a subset of simple outcome measures to quantify prosthetic gait deviation without needing three-dimensional gait analysis (3DGA). METHODS: Eight unilateral, transfemoral amputees and 12 unilateral, transtibial amputees were recruited. Twenty-eight able-bodied controls were recruited. All participants underwent 3DGA, the timed-up-and-go test and the six-minute walk test (6MWT). The lower-limb amputees also completed the Prosthesis Evaluation Questionnaire. Results from 3DGA were summarised using the gait deviation index (GDI), which was subsequently regressed, using stepwise regression, against the other measures. RESULTS: Step-length (SL), self-selected walking speed (SSWS) and the distance walked during the 6MWT (6MWD) were significantly correlated with GDI. The 6MWD was the strongest, single predictor of the GDI, followed by SL and SSWS. The predictive ability of the regression equations were improved following inclusion of self-report data related to mobility and prosthetic utility. CONCLUSION: This study offers a practicable alternative to quantifying kinematic deviation without the need to conduct complete 3DGA. PMID:27335814

Revisiting the synoptic-scale predictability of severe European winter storms using ECMWF ensemble reforecasts

NASA Astrophysics Data System (ADS)

Pantillon, Florian; Knippertz, Peter; Corsmeier, Ulrich

2017-10-01

New insights into the synoptic-scale predictability of 25 severe European winter storms of the 1995-2015 period are obtained using the homogeneous ensemble reforecast dataset from the European Centre for Medium-Range Weather Forecasts. The predictability of the storms is assessed with different metrics including (a) the track and intensity to investigate the storms' dynamics and (b) the Storm Severity Index to estimate the impact of the associated wind gusts. The storms are well predicted by the whole ensemble up to 2-4 days ahead. At longer lead times, the number of members predicting the observed storms decreases and the ensemble average is not clearly defined for the track and intensity. The Extreme Forecast Index and Shift of Tails are therefore computed from the deviation of the ensemble from the model climate. Based on these indices, the model has some skill in forecasting the area covered by extreme wind gusts up to 10 days, which indicates a clear potential for early warnings. However, large variability is found between the individual storms. The poor predictability of outliers appears related to their physical characteristics such as explosive intensification or small size. Longer datasets with more cases would be needed to further substantiate these points.

Interventions with children and parents to improve physical activity and body mass index: a meta-analysis.

PubMed

Dellert, Jane Cerruti; Johnson, Portia

2014-01-01

Examine the effect of interventions with parents and children on children's physical activity and body mass index (BMI). Computerized searches for intervention studies published between 1990 and 2011 used multiple ProQuest databases, including unpublished dissertations and theses to minimize publication bias. English-language, intervention-testing studies of children, parents, or families with outcomes of physical activity or BMI were retrieved from peer-reviewed journals, dissertations, and theses. Eliminated studies had no control or comparison group; had no continuous outcome variable; had no physical activity/exercise and/or BMI as outcomes; or had incomplete statistics necessary for meta-analysis (means, standard deviations, or confidence intervals). Twenty-one studies met inclusion criteria. Quality criteria were control group, objective outcome variable measure, clarity of variable definitions, and number and reason for subject withdrawal. Meta-analysis on the raw difference of means estimated mean weighted effect size (MWES) assessed dispersion of effects and computed a summary effect. MWES for interventions with parents and children on physical activity (Z = 2.92; confidence interval [CI] = .09 to .48; p = .002) and on BMI for interventions with children alone (Z = -2.10; CI = -.16 to -.01; p = .02) was significant. A significant effect on physical activity but not on BMI was found when interventions included both parents and their children.

Age-dependence of the average and equivalent refractive indices of the crystalline lens

PubMed Central

Charman, W. Neil; Atchison, David A.

2013-01-01

Lens average and equivalent refractive indices are required for purposes such as lens thickness estimation and optical modeling. We modeled the refractive index gradient as a power function of the normalized distance from lens center. Average index along the lens axis was estimated by integration. Equivalent index was estimated by raytracing through a model eye to establish ocular refraction, and then backward raytracing to determine the constant refractive index yielding the same refraction. Assuming center and edge indices remained constant with age, at 1.415 and 1.37 respectively, average axial refractive index increased (1.408 to 1.411) and equivalent index decreased (1.425 to 1.420) with age increase from 20 to 70 years. These values agree well with experimental estimates based on different techniques, although the latter show considerable scatter. The simple model of index gradient gives reasonable estimates of average and equivalent lens indices, although refinements in modeling and measurements are required. PMID:24466474

A total merit selection index for Ontario organic dairy farmers.

PubMed

Rozzi, P; Miglior, F; Hand, K J

2007-03-01

Organic standards require changes in management practices so that health, fertility, and overall fitness are more important than on conventional dairy farms and require different selection objectives. A survey involving 18 (40%) Ontario organic dairy farms was carried out to collect data on their production systems, breeding policies, and concerns. Compared with conventional farms, organic farms had lower milk production, lower replacement rate, higher somatic cell count, and a much higher rate of crossbreeding. Actual culling rate was 21%, and the main causes were fertility, mastitis, feet and legs, production, and old age. The major areas of concern expressed by organic dairy farmers were related to grazing traits, fertility, health, and longevity. An organic total merit index was developed based on the subjective scores for traits with a genetic evaluation in Canada. The relative weights of production to fitness traits (28:72) were substantially different from those in the Canadian Lifetime Profit Index (54:46), but similar to those used in conventional indices in Sweden and Denmark and in the Swiss organic index. The overall weight on health traits was 2.5 times higher in the organic index and, among fitness traits, the emphasis was substantially higher for lactation persistency, somatic cell score, and body capacity. Correlations between the organic index and Lifetime Profit Index were 0.88 for all bulls proven in Canada, 0.70 for the top 1,000, and 0.65 for the top 100, indicating that a different group of bulls would rank at the top of these 2 indices. When the top 100 bulls for either index were compared, those selected for the organic index were about 0.5 standard deviations lower for all yield traits, but were much better for body capacity and somatic cell score, and 0.25 standard deviations higher for herd life, feet and legs, udder conformation, and lactation persistency. Given the small population size, a separate breeding program for an organic management system is not viable in the foreseeable future. However, the organic index would allow producers to rank proven bulls in accordance with their perceived needs.

An empirical analysis of the distribution of the duration of overshoots in a stationary gaussian stochastic process

NASA Technical Reports Server (NTRS)

Parrish, R. S.; Carter, M. C.

1974-01-01

This analysis utilizes computer simulation and statistical estimation. Realizations of stationary gaussian stochastic processes with selected autocorrelation functions are computer simulated. Analysis of the simulated data revealed that the mean and the variance of a process were functionally dependent upon the autocorrelation parameter and crossing level. Using predicted values for the mean and standard deviation, by the method of moments, the distribution parameters was estimated. Thus, given the autocorrelation parameter, crossing level, mean, and standard deviation of a process, the probability of exceeding the crossing level for a particular length of time was calculated.

Comparison of spectral estimators for characterizing fractionated atrial electrograms

PubMed Central

2013-01-01

Background Complex fractionated atrial electrograms (CFAE) acquired during atrial fibrillation (AF) are commonly assessed using the discrete Fourier transform (DFT), but this can lead to inaccuracy. In this study, spectral estimators derived by averaging the autocorrelation function at lags were compared to the DFT. Method Bipolar CFAE of at least 16 s duration were obtained from pulmonary vein ostia and left atrial free wall sites (9 paroxysmal and 10 persistent AF patients). Power spectra were computed using the DFT and three other methods: 1. a novel spectral estimator based on signal averaging (NSE), 2. the NSE with harmonic removal (NSH), and 3. the autocorrelation function average at lags (AFA). Three spectral parameters were calculated: 1. the largest fundamental spectral peak, known as the dominant frequency (DF), 2. the DF amplitude (DA), and 3. the mean spectral profile (MP), which quantifies noise floor level. For each spectral estimator and parameter, the significance of the difference between paroxysmal and persistent AF was determined. Results For all estimators, mean DA and mean DF values were higher in persistent AF, while the mean MP value was higher in paroxysmal AF. The differences in means between paroxysmals and persistents were highly significant for 3/3 NSE and NSH measurements and for 2/3 DFT and AFA measurements (p<0.001). For all estimators, the standard deviation in DA and MP values were higher in persistent AF, while the standard deviation in DF value was higher in paroxysmal AF. Differences in standard deviations between paroxysmals and persistents were highly significant in 2/3 NSE and NSH measurements, in 1/3 AFA measurements, and in 0/3 DFT measurements. Conclusions Measurements made from all four spectral estimators were in agreement as to whether the means and standard deviations in three spectral parameters were greater in CFAEs acquired from paroxysmal or in persistent AF patients. Since the measurements were consistent, use of two or more of these estimators for power spectral analysis can be assistive to evaluate CFAE more objectively and accurately, which may lead to improved clinical outcome. Since the most significant differences overall were achieved using the NSE and NSH estimators, parameters measured from their spectra will likely be the most useful for detecting and discerning electrophysiologic differences in the AF substrate based upon frequency analysis of CFAE. PMID:23855345

Error Estimates of the Ares I Computed Turbulent Ascent Longitudinal Aerodynamic Analysis

NASA Technical Reports Server (NTRS)

Abdol-Hamid, Khaled S.; Ghaffari, Farhad

2012-01-01

Numerical predictions of the longitudinal aerodynamic characteristics for the Ares I class of vehicles, along with the associated error estimate derived from an iterative convergence grid refinement, are presented. Computational results are based on an unstructured grid, Reynolds-averaged Navier-Stokes analysis. The validity of the approach to compute the associated error estimates, derived from a base grid to an extrapolated infinite-size grid, was first demonstrated on a sub-scaled wind tunnel model at representative ascent flow conditions for which the experimental data existed. Such analysis at the transonic flow conditions revealed a maximum deviation of about 23% between the computed longitudinal aerodynamic coefficients with the base grid and the measured data across the entire roll angles. This maximum deviation from the wind tunnel data was associated with the computed normal force coefficient at the transonic flow condition and was reduced to approximately 16% based on the infinite-size grid. However, all the computed aerodynamic coefficients with the base grid at the supersonic flow conditions showed a maximum deviation of only about 8% with that level being improved to approximately 5% for the infinite-size grid. The results and the error estimates based on the established procedure are also presented for the flight flow conditions.

Evaluation of association between psychological stress and serum cortisol levels in patients with chronic periodontitis - Estimation of relationship between psychological stress and periodontal status.

PubMed

Jaiswal, Roshni; Shenoy, Nina; Thomas, Biju

2016-01-01

Stress classically describes a destructive notion that can have a bearing on one's physical and mental health. It may also add to an increased propensity to periodontal disease. To investigate the association between psychological stress and serum cortisol levels in patients with chronic periodontitis. Forty subjects were recruited from the outpatient department at the Department of Periodontics, from a college in Mangalore, divided into two groups, i.e., twenty as healthy controls and twenty were stressed subjects with chronic periodontitis. The clinical examination included the assessment of probing pocket depth, clinical attachment level and oral hygiene index-simplified. Serum cortisol levels were estimated biochemically using the enzyme-linked immunosorbent assay method and the estimation of psychological stress was done by a questionnaire. Descriptive statistics such as mean and standard deviation was used to review the collected data. Independent sample t -test was used for comparison and correlation was evaluation using Pearson's correlation test. As per our observation, high serum cortisol levels and psychological stress are positively linked with chronic periodontitis establishing a risk profile showing a significant correlation ( P < 0.05). Routine serum cortisol assessment may be a reasonable and a valuable investigative indicator to rule out stress in periodontitis patients as it should be considered as an imperative risk factor for periodontal disease.

Evaluation of association between psychological stress and serum cortisol levels in patients with chronic periodontitis - Estimation of relationship between psychological stress and periodontal status

PubMed Central

Jaiswal, Roshni; Shenoy, Nina; Thomas, Biju

2016-01-01

Background: Stress classically describes a destructive notion that can have a bearing on one's physical and mental health. It may also add to an increased propensity to periodontal disease. Aim: To investigate the association between psychological stress and serum cortisol levels in patients with chronic periodontitis. Materials and Methods: Forty subjects were recruited from the outpatient department at the Department of Periodontics, from a college in Mangalore, divided into two groups, i.e., twenty as healthy controls and twenty were stressed subjects with chronic periodontitis. The clinical examination included the assessment of probing pocket depth, clinical attachment level and oral hygiene index-simplified. Serum cortisol levels were estimated biochemically using the enzyme-linked immunosorbent assay method and the estimation of psychological stress was done by a questionnaire. Results: Descriptive statistics such as mean and standard deviation was used to review the collected data. Independent sample t-test was used for comparison and correlation was evaluation using Pearson's correlation test. As per our observation, high serum cortisol levels and psychological stress are positively linked with chronic periodontitis establishing a risk profile showing a significant correlation (P < 0.05). Conclusion: Routine serum cortisol assessment may be a reasonable and a valuable investigative indicator to rule out stress in periodontitis patients as it should be considered as an imperative risk factor for periodontal disease. PMID:28298818

Discrepancies between leg-to-leg bioelectrical Impedance analysis and computerized tomography in abdominal visceral fat measurement.

PubMed

Lu, Hsueh-Kuan; Chen, Yu-Yawn; Yeh, Chinagwen; Chuang, Chih-Lin; Chiang, Li-Ming; Lai, Chung-Liang; Casebolt, Kevin M; Huang, Ai-Chun; Lin, Wen-Long; Hsieh, Kuen-Chang

2017-08-22

The aim of this study was to evaluate leg-to-leg bioelectrical impedance analysis (LBIA) using a four-contact electrode system for measuring abdominal visceral fat area (VFA). The present study recruited 381 (240 male and 141 female) Chinese participants to compare VFA measurements estimated by a standing LBIA system (VFALBIA) with computerized tomography (CT) scanned at the L4-L5 vertebrae (VFA CT ). The total mean body mass index (BMI) was 24.7 ± 4.2 kg/m 2 . Correlation analysis, regression analysis, Bland-Altman plot, and paired sample t-tests were used to analyze the accuracy of the VFA LBIA . For the total subjects, the regression line was VFA LBIA  = 0.698 VFA CT  + 29.521, (correlation coefficient (r) = 0.789, standard estimate of error (SEE) = 24.470 cm 2 , p < 0.001), Lin's correlation coefficient (CCC) was 0.785; and the limit of agreement (LOA; mean difference ±2 standard deviation) ranged from -43.950 to 67.951 cm 2 , LOA% (given as a percentage of mean value measured by the CT) was 48.2%. VFA LBIA and VFA CT showed significant difference (p < 0.001). Collectively, the current study indicates that LBIA has limited potential to accurately estimate visceral fat in a clinical setting.

Asymmetries and Visual Field Summaries as Predictors of Glaucoma in the Ocular Hypertension Treatment Study

PubMed Central

Levine, Richard A.; Demirel, Shaban; Fan, Juanjuan; Keltner, John L.; Johnson, Chris A.; Kass, Michael A.

2007-01-01

Purpose To evaluate whether baseline visual field data and asymmetries between eyes predict the onset of primary open-angle glaucoma (POAG) in Ocular Hypertension Treatment Study (OHTS) participants. Methods A new index, mean prognosis (MP), was designed for optimal combination of visual field thresholds, to discriminate between eyes that developed POAG from eyes that did not. Baseline intraocular pressure (IOP) in fellow eyes was used to construct measures of IOP asymmetry. Age-adjusted baseline thresholds were used to develop indicators of visual field asymmetry and summary measures of visual field defects. Marginal multivariate failure time models were constructed that relate the new index MP, IOP asymmetry, and visual field asymmetry to POAG onset for OHTS participants. Results The marginal multivariate failure time analysis showed that the MP index is significantly related to POAG onset (P < 0.0001) and appears to be a more highly significant predictor of POAG onset than either mean deviation (MD; P = 0.17) or pattern standard deviation (PSD; P = 0.046). A 1-mm Hg increase in IOP asymmetry between fellow eyes is associated with a 17% increase in risk for development of POAG. When threshold asymmetry between eyes existed, the eye with lower thresholds was at a 37% greater risk of development of POAG, and this feature was more predictive of POAG onset than the visual field index MD, though not as strong a predictor as PSD. Conclusions The MP index, IOP asymmetry, and binocular test point asymmetry can assist in clinical evaluation of eyes at risk of development of POAG. PMID:16936102

Comparing industry compensation of cardiothoracic surgeons and interventional cardiologists.

PubMed

Parreco, Joshua; Donath, Elie; Kozol, Robert; Faber, Cristiano

2017-02-01

The purpose of this study was to compare payment trends between cardiothoracic surgeons and interventional cardiologists using the Open Payments website made available for the public by the Center for Medicare and Medicaid Services. Data were extracted from the second release of the Open Payments database, which includes payments made between August 1, 2013 and December 31, 2014. Total payments to individual physicians were aggregated based on specialty, region of the country, and payment type. The Gini index was calculated for each specialty to measure income disparity. A Gini index of 1 indicates all the payments went to one individual, whereas a Gini index of 0 indicates all individuals received equal payments. During the study period of interest, data were made available for 3587 (80%) cardiothoracic surgeons compared with 2957 (99%) interventional cardiologists. Mean total payments to cardiothoracic surgeons were $7770 (standard deviation, $52,608) compared with a mean of $15,221 (standard deviation, $98,828) for interventional cardiologists. The median total payments to cardiothoracic surgeons was $1050 (interquartile range, $233-$3612) compared with $1851 (interquartile range, $607-$5462) for interventional cardiologists. The overall Gini index was 0.932, whereas the Gini index was 0.862 for interventional cardiologists and 0.860 for cardiothoracic surgeons. The vast majority of interventional cardiologists and cardiothoracic surgeons received payments from drug and device manufacturers. The mean total payments to interventional cardiologists were higher than any other specialty. However, like cardiothoracic surgery, they were among the most equitably distributed compared with other specialties. Copyright © 2016 Elsevier Inc. All rights reserved.

Diffuse ultraviolet erythemal irradiance on inclined planes: a comparison of experimental and modeled data.

PubMed

Utrillas, María P; Marín, María J; Esteve, Anna R; Estellés, Victor; Tena, Fernando; Cañada, Javier; Martínez-Lozano, José A

2009-01-01

Values of measured and modeled diffuse UV erythemal irradiance (UVER) for all sky conditions are compared on planes inclined at 40 degrees and oriented north, south, east and west. The models used for simulating diffuse UVER are of the geometric-type, mainly the Isotropic, Klucher, Hay, Muneer, Reindl and Schauberger models. To analyze the precision of the models, some statistical estimators were used such as root mean square deviation, mean absolute deviation and mean bias deviation. It was seen that all the analyzed models reproduce adequately the diffuse UVER on the south-facing plane, with greater discrepancies for the other inclined planes. When the models are applied to cloud-free conditions, the errors obtained are higher because the anisotropy of the sky dome acquires more importance and the models do not provide the estimation of diffuse UVER accurately.

Specification of ISS Plasma Environment Variability

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Neergaard, Linda F.; Bui, Them H.; Mikatarian, Ronald R.; Barsamian, H.; Koontz, Steven L.

2004-01-01

Quantifying spacecraft charging risks and associated hazards for the International Space Station (ISS) requires a plasma environment specification for the natural variability of ionospheric temperature (Te) and density (Ne). Empirical ionospheric specification and forecast models such as the International Reference Ionosphere (IRI) model typically only provide long term (seasonal) mean Te and Ne values for the low Earth orbit environment. This paper describes a statistical analysis of historical ionospheric low Earth orbit plasma measurements from the AE-C, AE-D, and DE-2 satellites used to derive a model of deviations of observed data values from IRI-2001 estimates of Ne, Te parameters for each data point to provide a statistical basis for modeling the deviations of the plasma environment from the IRI model output. Application of the deviation model with the IRI-2001 output yields a method for estimating extreme environments for the ISS spacecraft charging analysis.

Bayesian Estimation Supersedes the "t" Test

ERIC Educational Resources Information Center

Kruschke, John K.

2013-01-01

Bayesian estimation for 2 groups provides complete distributions of credible values for the effect size, group means and their difference, standard deviations and their difference, and the normality of the data. The method handles outliers. The decision rule can accept the null value (unlike traditional "t" tests) when certainty in the estimate is…

Lactation persistency as a component trait of the selection index and increase in reliability by using single nucleotide polymorphism in net merit defined as the first five lactation milk yields and herd life.

PubMed

Togashi, K; Hagiya, K; Osawa, T; Nakanishi, T; Yamazaki, T; Nagamine, Y; Lin, C Y; Matsumoto, S; Aihara, M; Hayasaka, K

2012-08-01

We first sought to clarify the effects of discounted rate, survival rate, and lactation persistency as a component trait of the selection index on net merit, defined as the first five lactation milks and herd life (HL) weighted by 1 and 0.389 (currently used in Japan), respectively, in units of genetic standard deviation. Survival rate increased the relative economic importance of later lactation traits and the first five lactation milk yields during the first 120 months from the start of the breeding scheme. In contrast, reliabilities of the estimated breeding value (EBV) in later lactation traits are lower than those of earlier lactation traits. We then sought to clarify the effects of applying single nucleotide polymorphism (SNP) on net merit to improve the reliability of EBV of later lactation traits to maximize their increased economic importance due to increase in survival rate. Net merit, selection accuracy, and HL increased by adding lactation persistency to the selection index whose component traits were only milk yields. Lactation persistency of the second and (especially) third parities contributed to increasing HL while maintaining the first five lactation milk yields compared with the selection index whose only component traits were milk yields. A selection index comprising the first three lactation milk yields and persistency accounted for 99.4% of net merit derived from a selection index whose components were identical to those for net merit. We consider that the selection index comprising the first three lactation milk yields and persistency is a practical method for increasing lifetime milk yield in the absence of data regarding HL. Applying SNP to the second- and third-lactation traits and HL increased net merit and HL by maximizing the increased economic importance of later lactation traits, reducing the effect of first-lactation milk yield on HL (genetic correlation (rG) = -0.006), and by augmenting the effects of the second- and third-lactation milk yields on HL (rG = 0.118 and 0.257, respectively).

Screen Twice, Cut Once: Assessing the Predictive Validity of Teacher Selection Tools

ERIC Educational Resources Information Center

Goldhaber, Dan; Grout, Cyrus; Huntington-Klein, Nick

2015-01-01

It is well documented that teachers can have profound effects on student outcomes. Empirical estimates find that a one standard deviation increase in teacher quality raises student test achievement by 10 to 25 percent of a standard deviation. More recent evidence shows that the effectiveness of teachers can affect long-term student outcomes, such…

Evaluating the sensitivity of EQ-5D in a sample of patients with type 2 diabetes mellitus in two tertiary health care facilities in Nigeria.

PubMed

Ekwunife, Obinna Ikechukwu; Ezenduka, Charles C; Uzoma, Bede Emeka

2016-01-12

The EQ-5D instrument is arguably the most well-known and commonly used generic measure of health status internationally. Although the instrument has been employed in outcomes studies of diabetes mellitus in many countries, it has not yet been used in Nigeria. This study was carried out to assess the sensitivity of the EQ-5D instrument in a sample of Nigerian patients with type 2 diabetes mellitus (T2DM). A cross-sectional study was conducted using the EQ-5D instrument to assess the self-reported quality of life of patients with T2DM attending two tertiary healthcare facilities in south eastern Nigeria consenting patients completed the questionnaire while waiting to see a doctor. A priori hypotheses were examined using multiple regression analysis to model the relationship between the dependent variables (EQ VAS and EQ-5D Index) and hypothesized independent variables. A total of 226 patients with T2DM participated in the study. The average age of participants was 57 years (standard deviation 10 years) and 61.1% were male. The EQ VAS score and EQ-5D index averaged 66.19 (standard deviation 15.42) and 0.78 (standard deviation 0.21) respectively. Number of diabetic complications, number of co-morbidities, patient's age and being educated predicted EQ VAS score by -6.76, -6.15, -0.22, and 4.51 respectively. Also, number of diabetic complications, number of co-morbidities, patient's age and being educated predicted EQ-5D index by -0.12, -0.07, -0.003, and 0.06 respectively.. Our findings indicate that the EQ-5D could adequately capture the burden of type 2 diabetes and related complications among Nigerian patients.

KSC Construction Cost Index

NASA Technical Reports Server (NTRS)

Brown, J. A.

1983-01-01

Kennedy Space Center cost Index aids in conceptual design cost estimates. Report discusses development of KSC Cost Index since January 1974. Index since January 1974. Index provides management, design engineers, and estimators an up-to-data reference for local labor and material process. Also provides mount and rate of change in these costs used to predict future construction costs.

Crystallographic parameters of compounds and solid solutions in binary systems Cu-Pt and Ga-Pt

NASA Astrophysics Data System (ADS)

Potekaev, Alexandr; Probova, Svetlana; Klopotov, Anatolii; Vlasov, Viktor; Markov, Tatiana; Klopotov, Vladimir

2015-10-01

The study establishes that the packing index in compounds of the system Cu-Pt is close to the value 0.74 against a slight deviation from the Zen law of atomic volumes. The compounds in the system Ga-Pt have the highest values of the packing index in the range of the equiatomic composition, which greatly exceed ψ for close-packed structures based on FCC and HCP lattices for compounds made of the same kind of atoms. A correlation between singular points on the phase diagram of the system Ga-Pt and high values of the packing index in compounds is established.

SU-E-I-59: Investigation of the Usefulness of a Standard Deviation and Mammary Gland Density as Indexes for Mammogram Classification.

PubMed

Takarabe, S; Yabuuchi, H; Morishita, J

2012-06-01

To investigate the usefulness of the standard deviation of pixel values in a whole mammary glands region and the percentage of a high- density mammary glands region to a whole mammary glands region as features for classification of mammograms into four categories based on the ACR BI-RADS breast composition. We used 36 digital mediolateral oblique view mammograms (18 patients) approved by our IRB. These images were classified into the four categories of breast compositions by an experienced breast radiologist and the results of the classification were regarded as a gold standard. First, a whole mammary region in a breast was divided into two regions such as a high-density mammary glands region and a low/iso-density mammary glands region by using a threshold value that was obtained from the pixel values corresponding to a pectoral muscle region. Then the percentage of a high-density mammary glands region to a whole mammary glands region was calculated. In addition, as a new method, the standard deviation of pixel values in a whole mammary glands region was calculated as an index based on the intermingling of mammary glands and fats. Finally, all mammograms were classified by using the combination of the percentage of a high-density mammary glands region and the standard deviation of each image. The agreement rates of the classification between our proposed method and gold standard was 86% (31/36). This result signified that our method has the potential to classify mammograms. The combination of the standard deviation of pixel values in a whole mammary glands region and the percentage of a high-density mammary glands region to a whole mammary glands region was available as features to classify mammograms based on the ACR BI- RADS breast composition. © 2012 American Association of Physicists in Medicine.

Refractivity of Molten Nitrates and Chlorides: Binary Mixtures Containing Cesium Ions

NASA Astrophysics Data System (ADS)

Uchiyama, Yohji; Karawacki, Ernest

1981-05-01

By using an interferometric technique, the refractive index of some molten salt mixtures containing Cs+ ions was measured with high accuracy: (Li-Cs)NO3, (Na-Cs)NO3, (Ag-Cs)NO3, (Li-Cs)Cl, and also pure RbCl. The isotherms of molar refractivity show a small negative deviation from additivity in the (Li-Cs)NO3 and (Li-Cs)Cl systems and a positive deviation in the (Ag-Cs)NO3 mixture. A tentative attempt was made to relate the excess molar refractivities with the absorption bands of the ions.

A posteriori noise estimation in variable data sets. With applications to spectra and light curves

NASA Astrophysics Data System (ADS)

Czesla, S.; Molle, T.; Schmitt, J. H. M. M.

2018-01-01

Most physical data sets contain a stochastic contribution produced by measurement noise or other random sources along with the signal. Usually, neither the signal nor the noise are accurately known prior to the measurement so that both have to be estimated a posteriori. We have studied a procedure to estimate the standard deviation of the stochastic contribution assuming normality and independence, requiring a sufficiently well-sampled data set to yield reliable results. This procedure is based on estimating the standard deviation in a sample of weighted sums of arbitrarily sampled data points and is identical to the so-called DER_SNR algorithm for specific parameter settings. To demonstrate the applicability of our procedure, we present applications to synthetic data, high-resolution spectra, and a large sample of space-based light curves and, finally, give guidelines to apply the procedure in situation not explicitly considered here to promote its adoption in data analysis.

Complex index of refraction estimation from degree of polarization with diffuse scattering consideration.

PubMed

Zhan, Hanyu; Voelz, David G; Cho, Sang-Yeon; Xiao, Xifeng

2015-11-20

The estimation of the refractive index from optical scattering off a target's surface is an important task for remote sensing applications. Optical polarimetry is an approach that shows promise for refractive index estimation. However, this estimation often relies on polarimetric models that are limited to specular targets involving single surface scattering. Here, an analytic model is developed for the degree of polarization (DOP) associated with reflection from a rough surface that includes the effect of diffuse scattering. A multiplicative factor is derived to account for the diffuse component and evaluation of the model indicates that diffuse scattering can significantly affect the DOP values. The scattering model is used in a new approach for refractive index estimation from a series of DOP values that involves jointly estimating n, k, and ρ(d)with a nonlinear equation solver. The approach is shown to work well with simulation data and additive noise. When applied to laboratory-measured DOP values, the approach produces significantly improved index estimation results relative to reference values.

Evaluating the potential of vegetation indices for winter wheat LAI estimation under different fertilization and water conditions

NASA Astrophysics Data System (ADS)

Xie, Qiaoyun; Huang, Wenjiang; Dash, Jadunandan; Song, Xiaoyu; Huang, Linsheng; Zhao, Jinling; Wang, Renhong

2015-12-01

Leaf area index (LAI) is an important indicator for monitoring crop growth conditions and forecasting grain yield. Many algorithms have been developed for remote estimation of the leaf area index of vegetation, such as using spectral vegetation indices, inversion of radiative transfer models, and supervised learning techniques. Spectral vegetation indices, mathematical combination of reflectance bands, are widely used for LAI estimation due to their computational simplicity and their applications ranged from the leaf scale to the entire globe. However, in many cases, their applicability is limited to specific vegetation types or local conditions due to species specific nature of the relationship used to transfer the vegetation indices to LAI. The overall objective of this study is to investigate the most suitable vegetation index for estimating winter wheat LAI under eight different types of fertilizer and irrigation conditions. Regression models were used to estimate LAI using hyperspectral reflectance data from the Pushbroom Hyperspectral Imager (PHI) and in-situ measurements. Our results showed that, among six vegetation indices investigated, the modified soil-adjusted vegetation index (MSAVI) and the normalized difference vegetation index (NDVI) exhibited strong and significant relationships with LAI, and thus were sensitive across different nitrogen and water treatments. The modified triangular vegetation index (MTVI2) confirmed its potential on crop LAI estimation, although second to MSAVI and NDVI in our study. The enhanced vegetation index (EVI) showed moderate performance. However, the ratio vegetation index (RVI) and the modified simple ratio index (MSR) predicted the least accurate estimations of LAI, exposing the simple band ratio index's weakness under different treatment conditions. The results support the use of vegetation indices for a quick and effective LAI mapping procedure that is suitable for winter wheat under different management practices.

Quality of life in patients with vitiligo: a cross-sectional study based on Vitiligo Quality of Life index (VitiQoL).

PubMed

Hedayat, Kosar; Karbakhsh, Mojgan; Ghiasi, Maryam; Goodarzi, Azadeh; Fakour, Yousef; Akbari, Zahra; Ghayoumi, Afsaneh; Ghandi, Narges

2016-06-07

Vitiligo is a multi-factorial pigmentary skin disorder. Recently, the importance of emotional and psychological issues is proposed in incidence, progression, relapse and remission of vitiligo. There are limited studies conducted in developing countries, which assess life quality of patients with vitiligo. The aim of this study was the application and evaluation of a disease-specific quality of life index in Iranian patients, for the first time. This cross-sectional biphasic study was conducted on 25 patients as a pilot and another 173 patients as the main study group, in Razi Hospital, Tehran, Iran, 2013-2014. Persian version of Vitiligo Quality of Life index (VitiQoL) was developed with backward-forward method. Based on the pilot study, the validity and reliability were assessed. The Vitiligo Area and Score Index (VASI), VitiQoL, and their relationship, demographic and clinical characteristic of patients were measured. The Mean and standard deviation of the VitiQoL score was 30.5 ± 14.5 (range 0-60 in Persian version). There was a significant relationship between VASI score and VitiQoL (p = 0.015, r = 0.187). Confirmatory factor analysis revealed three important factors within VitiQoL: participation limitation, stigma, and behavior. In subscale analysis based on behavior factor, female patients had poorer quality of life (p = 0.02). Concomitant psychiatric problems, e.g. anxiety and depression, were not associated with QOL; however, they were near to being meaningful (p = 0.06, r = 0.14). VitiQoL is a valid index in estimating life quality of vitiligo patients and has proper relation to disease severity. Focusing on patient's life quality is an important entity in the management of vitiligo patients; relevant supportive group-based consultations and therapies are also important arms when approaching vitiligo.

Two-station comparison of peak flows to improve flood-frequency estimates for seven streamflow-gaging stations in the Salmon and Clearwater River Basins, Central Idaho

USGS Publications Warehouse

Berenbrock, Charles

2003-01-01

Improved flood-frequency estimates for short-term (10 or fewer years of record) streamflow-gaging stations were needed to support instream flow studies by the U.S. Forest Service, which are focused on quantifying water rights necessary to maintain or restore productive fish habitat. Because peak-flow data for short-term gaging stations can be biased by having been collected during an unusually wet, dry, or otherwise unrepresentative period of record, the data may not represent the full range of potential floods at a site. To test whether peak-flow estimates for short-term gaging stations could be improved, the two-station comparison method was used to adjust the logarithmic mean and logarithmic standard deviation of peak flows for seven short-term gaging stations in the Salmon and Clearwater River Basins, central Idaho. Correlation coefficients determined from regression of peak flows for paired short-term and long-term (more than 10 years of record) gaging stations over a concurrent period of record indicated that the mean and standard deviation of peak flows for all short-term gaging stations would be improved. Flood-frequency estimates for seven short-term gaging stations were determined using the adjusted mean and standard deviation. The original (unadjusted) flood-frequency estimates for three of the seven short-term gaging stations differed from the adjusted estimates by less than 10 percent, probably because the data were collected during periods representing the full range of peak flows. Unadjusted flood-frequency estimates for four short-term gaging stations differed from the adjusted estimates by more than 10 percent; unadjusted estimates for Little Slate Creek and Salmon River near Obsidian differed from adjusted estimates by nearly 30 percent. These large differences probably are attributable to unrepresentative periods of peak-flow data collection.

Multivariable analysis of tests for the diagnosis of intrauterine growth restriction.

PubMed

Bachmann, L M; Khan, K S; Ogah, J; Owen, P

2003-04-01

To describe how data from antenatal fetal ultrasound biometry, amniotic fluid index and umbilical artery Doppler can be appropriately combined using multivariable models and to investigate how the addition of these ultrasound parameters influences the ability to predict intrauterine growth restriction (IUGR). This was a prospective cohort study involving 274 low-risk pregnancies undergoing serial ultrasound examination at predetermined intervals. Standard deviation (Z) scores of the last values for fetal abdominal area (FAA), growth velocity of the FAA, amniotic fluid index (AFI) and umbilical artery Doppler pulsatility index prior to delivery were calculated for 260 fetuses. Customized estimated fetal weight (cEFW) centiles were also calculated using the last EFW before delivery after adjustment for fetal gender, gestational age, birth order and maternal weight, height and ethnic origin. Following delivery the neonatal ponderal index was calculated and centile position obtained. A neonatal ponderal index <25(th) centile served as the main outcome measure for diagnosis of IUGR. Logistic regression analysis was used to delineate the predictive value of the three fetal growth tests FAA, FAA growth velocity and cEFW and the additional values of AFI and pulsatility index of the umbilical artery. The areas under the receiver-operating characteristics (ROC) curves (95% confidence interval) for FAA, FAA growth velocity and cEFW alone were 0.819 (0.748-0.891), 0.784 (0.699-0.869) and 0.74 (0.643-0.837), respectively, in the prediction of a neonatal ponderal index <25(th) centile. The addition of both the AFI and pulsatility index to FAA, FAA growth velocity and cEFW generated small increases in the areas, to 0.831 (0.758-0.904), 0.817 (0.735-0.899) and 0.766 (0.672-0.859), respectively. These improvements in diagnostic prediction were not statistically significant. The addition of AFI and umbilical artery pulsatility index to the fetal biometry parameters did not significantly increase the ROC areas in the study population. The approach applied in this study is useful in the context of hypothesis generation. Further studies using larger data sets and other predictors should be carried out using the analytical techniques outlined in this paper to determine the contribution of various antenatal tests in the prediction of IUGR. Copyright 2003 ISUOG. Published by John Wiley & Sons, Ltd.

Growth Intercept as an Indicator of Site Index in Natural Stands of White Pine in the Southern Appalachians

Treesearch

Donald E. Beck

1971-01-01

Equations are presented for estimating site index from periodic height growth in natural, even-aged stands of white pine in the Southern Appalachians. Site index can be estimated from height growth during both 3-year and 5-year periods, beginning with the year in which breast height was reached. In stands less than 15 years old, estimates of site index from 5-year...

The biologic error in gestational length related to the use of the first day of last menstrual period as a proxy for the start of pregnancy.

PubMed

Nakling, Jakob; Buhaug, Harald; Backe, Bjorn

2005-10-01

In a large unselected population of normal spontaneous pregnancies, to estimate the biologic variation of the interval from the first day of the last menstrual period to start of pregnancy, and the biologic variation of gestational length to delivery; and to estimate the random error of routine ultrasound assessment of gestational age in mid-second trimester. Cohort study of 11,238 singleton pregnancies, with spontaneous onset of labour and reliable last menstrual period. The day of delivery was predicted with two independent methods: According to the rule of Nägele and based on ultrasound examination in gestational weeks 17-19. For both methods, the mean difference between observed and predicted day of delivery was calculated. The variances of the differences were combined to estimate the variances of the two partitions of pregnancy. The biologic variation of the time from last menstrual period to pregnancy start was estimated to 7.0 days (standard deviation), and the standard deviation of the time to spontaneous delivery was estimated to 12.4 days. The estimate of the standard deviation of the random error of ultrasound assessed foetal age was 5.2 days. Even when the last menstrual period is reliable, the biologic variation of the time from last menstrual period to the real start of pregnancy is substantial, and must be taken into account. Reliable information about the first day of the last menstrual period is not equivalent with reliable information about the start of pregnancy.

[Noninvasive total hemoglobin monitoring based on multiwave spectrophotometry in obstetrics and gynecology].

PubMed

Pyregov, A V; Ovechkin, A Iu; Petrov, S V

2012-01-01

Results of prospective randomized comparative research of 2 total hemoglobin estimation methods are presented. There were laboratory tests and continuous noninvasive technique with multiwave spectrophotometry on the Masimo Rainbow SET. Research was carried out in two stages. At the 1st stage (gynecology)--67 patients were included and in second stage (obstetrics)--44 patients during and after Cesarean section. The standard deviation of noninvasive total hemoglobin estimation from absolute values (invasive) was 7.2 and 4.1%, an standard deviation in a sample--5.2 and 2.7 % in gynecologic operations and surgical delivery respectively, that confirms lack of reliable indicators differences. The method of continuous noninvasive total hemoglobin estimation with multiwave spectrophotometry on the Masimo Rainbow SET technology can be recommended for use in obstetrics and gynecology.

Solar cell angle of incidence corrections

NASA Technical Reports Server (NTRS)

Burger, Dale R.; Mueller, Robert L.

1995-01-01

Literature on solar array angle of incidence corrections was found to be sparse and contained no tabular data for support. This lack along with recent data on 27 GaAs/Ge 4 cm by 4 cm cells initiated the analysis presented in this paper. The literature cites seven possible contributors to angle of incidence effects: cosine, optical front surface, edge, shadowing, UV degradation, particulate soiling, and background color. Only the first three are covered in this paper due to lack of sufficient data. The cosine correction is commonly used but is not sufficient when the incident angle is large. Fresnel reflection calculations require knowledge of the index of refraction of the coverglass front surface. The absolute index of refraction for the coverglass front surface was not known nor was it measured due to lack of funds. However, a value for the index of refraction was obtained by examining how the prediction errors varied with different assumed indices and selecting the best fit to the set of measured values. Corrections using front surface Fresnel reflection along with the cosine correction give very good predictive results when compared to measured data, except there is a definite trend away from predicted values at the larger incident angles. This trend could be related to edge effects and is illustrated by a use of a box plot of the errors and by plotting the deviation of the mean against incidence angle. The trend is for larger deviations at larger incidence angles and there may be a fourth order effect involved in the trend. A chi-squared test was used to determine if the measurement errors were normally distributed. At 10 degrees the chi-squared test failed, probably due to the very small numbers involved or a bias from the measurement procedure. All other angles showed a good fit to the normal distribution with increasing goodness-of-fit as the angles increased which reinforces the very small numbers hypothesis. The contributed data only went to 65 degrees from normal which prevented any firm conclusions about extreme angle effects although a trend in the right direction was seen. Measurement errors were estimated and found to be consistent with the conclusions that were drawn. A controlled experiment using coverglasses and cells from the same lots and extending to larger incidence angles would probably lead to further insight into the subject area.

Echocardiographic variables after left ventricular assist device implantation associated with adverse outcome.

PubMed

Topilsky, Yan; Hasin, Tal; Oh, Jae K; Borgeson, Daniel D; Boilson, Barry A; Schirger, John A; Clavell, Alfredo L; Frantz, Robert P; Tsutsui, Rayji; Liu, Mingya; Maltais, Simon; Kushwaha, Sudhir S; Pereira, Naveen L; Park, Soon J

2011-11-01

Operative mortality after left ventricular assist device (LVAD) implantation is heavily influenced by patient selection and the technical difficulty of surgery. However, how we treat our patients and LVAD setting may affect the patient outcome beyond this period. We postulated that the presence of echocardiographic variables 1 month after surgery suggesting appropriate degree of LV unloading and an adequate forward flow would be important in determining clinical outcomes after the initial successful LVAD implantation. We retrospectively analyzed various variables in echocardiographic examinations performed 30 days after LVAD implant in 76 consecutive patients receiving continuous flow device for their association with a compound end point (90-day mortality, readmission for heart failure, or New York Heart Association class III or higher at the end of the 90-day period). The echocardiographic associations examined included estimated LVAD flow, with and without native LV contribution, interventricular septal position, the status of aortic valve opening, an estimated left atrial pressure (ELAP), the mitral flow E-wave deceleration time, and the ratio of deceleration time to E-wave velocity (mitral deceleration index [MDI]). Four patients died during the 30- to 90-day period, 6 patients were readmitted for heart failure, and 25 patients were considered to have New York Heart Association class III or higher at the end of the 90-day period. Variables associated with adverse outcome included increased ELAP (odds ratio, 1.30 [1.16-1.48]; P<0.0001), MDI <2 ms/[cm/s] (odds ratio, 4.4 implantation [1.22-18]; P=0.02) and decreased tricuspid lateral annulus velocity (odds ratio, 0.70 implantation [0.48-0.95]; P=0.02). A leftward deviation of interventricular septum was associated with a worse outcome (odds ratio, 3.03 implantation [1.21-13.3]; P=0.01). Mortality and heart failure after LVAD surgery appear to be predominantly determined by echocardiographic evidence of inefficient unloading of the left ventricle and persistence of right ventricular dysfunction. Increased estimated LA pressure and short MDI are associated with worse mid term outcome. Leftward deviation of the septum is associated with worse outcome as well.

Photometric Selection of a Massive Galaxy Catalog with z ≥ 0.55

NASA Astrophysics Data System (ADS)

Núñez, Carolina; Spergel, David N.; Ho, Shirley

2017-02-01

We present the development of a photometrically selected massive galaxy catalog, targeting Luminous Red Galaxies (LRGs) and massive blue galaxies at redshifts of z≥slant 0.55. Massive galaxy candidates are selected using infrared/optical color-color cuts, with optical data from the Sloan Digital Sky Survey (SDSS) and infrared data from “unWISE” forced photometry derived from the Wide-field Infrared Survey Explorer (WISE). The selection method is based on previously developed techniques to select LRGs with z> 0.5, and is optimized using receiver operating characteristic curves. The catalog contains 16,191,145 objects, selected over the full SDSS DR10 footprint. The redshift distribution of the resulting catalog is estimated using spectroscopic redshifts from the DEEP2 Galaxy Redshift Survey and photometric redshifts from COSMOS. Restframe U - B colors from DEEP2 are used to estimate LRG selection efficiency. Using DEEP2, the resulting catalog has an average redshift of z = 0.65, with a standard deviation of σ =2.0, and an average restframe of U-B=1.0, with a standard deviation of σ =0.27. Using COSMOS, the resulting catalog has an average redshift of z = 0.60, with a standard deviation of σ =1.8. We estimate 34 % of the catalog to be blue galaxies with z≥slant 0.55. An estimated 9.6 % of selected objects are blue sources with redshift z< 0.55. Stellar contamination is estimated to be 1.8%.

Estimation of Local Bone Loads for the Volume of Interest.

PubMed

Kim, Jung Jin; Kim, Youkyung; Jang, In Gwun

2016-07-01

Computational bone remodeling simulations have recently received significant attention with the aid of state-of-the-art high-resolution imaging modalities. They have been performed using localized finite element (FE) models rather than full FE models due to the excessive computational costs of full FE models. However, these localized bone remodeling simulations remain to be investigated in more depth. In particular, applying simplified loading conditions (e.g., uniform and unidirectional loads) to localized FE models have a severe limitation in a reliable subject-specific assessment. In order to effectively determine the physiological local bone loads for the volume of interest (VOI), this paper proposes a novel method of estimating the local loads when the global musculoskeletal loads are given. The proposed method is verified for the three VOI in a proximal femur in terms of force equilibrium, displacement field, and strain energy density (SED) distribution. The effect of the global load deviation on the local load estimation is also investigated by perturbing a hip joint contact force (HCF) in the femoral head. Deviation in force magnitude exhibits the greatest absolute changes in a SED distribution due to its own greatest deviation, whereas angular deviation perpendicular to a HCF provides the greatest relative change. With further in vivo force measurements and high-resolution clinical imaging modalities, the proposed method will contribute to the development of reliable patient-specific localized FE models, which can provide enhanced computational efficiency for iterative computing processes such as bone remodeling simulations.

Adjusting head circumference for covariates in autism: clinical correlates of a highly heritable continuous trait.

PubMed

Chaste, Pauline; Klei, Lambertus; Sanders, Stephan J; Murtha, Michael T; Hus, Vanessa; Lowe, Jennifer K; Willsey, A Jeremy; Moreno-De-Luca, Daniel; Yu, Timothy W; Fombonne, Eric; Geschwind, Daniel; Grice, Dorothy E; Ledbetter, David H; Lord, Catherine; Mane, Shrikant M; Lese Martin, Christa; Martin, Donna M; Morrow, Eric M; Walsh, Christopher A; Sutcliffe, James S; State, Matthew W; Devlin, Bernie; Cook, Edwin H; Kim, Soo-Jeong

2013-10-15

Brain development follows a different trajectory in children with autism spectrum disorders (ASD) than in typically developing children. A proxy for neurodevelopment could be head circumference (HC), but studies assessing HC and its clinical correlates in ASD have been inconsistent. This study investigates HC and clinical correlates in the Simons Simplex Collection cohort. We used a mixed linear model to estimate effects of covariates and the deviation from the expected HC given parental HC (genetic deviation). After excluding individuals with incomplete data, 7225 individuals in 1891 families remained for analysis. We examined the relationship between HC/genetic deviation of HC and clinical parameters. Gender, age, height, weight, genetic ancestry, and ASD status were significant predictors of HC (estimate of the ASD effect = .2 cm). HC was approximately normally distributed in probands and unaffected relatives, with only a few outliers. Genetic deviation of HC was also normally distributed, consistent with a random sampling of parental genes. Whereas larger HC than expected was associated with ASD symptom severity and regression, IQ decreased with the absolute value of the genetic deviation of HC. Measured against expected values derived from covariates of ASD subjects, statistical outliers for HC were uncommon. HC is a strongly heritable trait, and population norms for HC would be far more accurate if covariates including genetic ancestry, height, and age were taken into account. The association of diminishing IQ with absolute deviation from predicted HC values suggests HC could reflect subtle underlying brain development and warrants further investigation. © 2013 Society of Biological Psychiatry.

Adjusting head circumference for covariates in autism: clinical correlates of a highly heritable continuous trait

PubMed Central

Chaste, Pauline; Klei, Lambertus; Sanders, Stephan J.; Murtha, Michael T.; Hus, Vanessa; Lowe, Jennifer K.; Willsey, A. Jeremy; Moreno-De-Luca, Daniel; Yu, Timothy W.; Fombonne, Eric; Geschwind, Daniel; Grice, Dorothy E.; Ledbetter, David H.; Lord, Catherine; Mane, Shrikant M.; Martin, Christa Lese; Martin, Donna M.; Morrow, Eric M.; Walsh, Christopher A.; Sutcliffe, James S.; State, Matthew W.; Devlin, Bernie; Cook, Edwin H.; Kim, Soo-Jeong

2013-01-01

BACKGROUND Brain development follows a different trajectory in children with Autism Spectrum Disorders (ASD) than in typically developing children. A proxy for neurodevelopment could be head circumference (HC), but studies assessing HC and its clinical correlates in ASD have been inconsistent. This study investigates HC and clinical correlates in the Simons Simplex Collection cohort. METHODS We used a mixed linear model to estimate effects of covariates and the deviation from the expected HC given parental HC (genetic deviation). After excluding individuals with incomplete data, 7225 individuals in 1891 families remained for analysis. We examined the relationship between HC/genetic deviation of HC and clinical parameters. RESULTS Gender, age, height, weight, genetic ancestry and ASD status were significant predictors of HC (estimate of the ASD effect=0.2cm). HC was approximately normally distributed in probands and unaffected relatives, with only a few outliers. Genetic deviation of HC was also normally distributed, consistent with a random sampling of parental genes. Whereas larger HC than expected was associated with ASD symptom severity and regression, IQ decreased with the absolute value of the genetic deviation of HC. CONCLUSIONS Measured against expected values derived from covariates of ASD subjects, statistical outliers for HC were uncommon. HC is a strongly heritable trait and population norms for HC would be far more accurate if covariates including genetic ancestry, height and age were taken into account. The association of diminishing IQ with absolute deviation from predicted HC values suggests HC could reflect subtle underlying brain development and warrants further investigation. PMID:23746936

Tree morphologic plasticity explains deviation from metabolic scaling theory in semi-arid conifer forests, southwestern USA

Treesearch

Tyson L. Swetnam; Christopher D. O' Connor; Ann M. Lynch

2016-01-01

A significant concern about Metabolic Scaling Theory (MST) in real forests relates to consistent differences between the values of power law scaling exponents of tree primary size measures used to estimate mass and those predicted by MST. Here we consider why observed scaling exponents for diameter and height relationships deviate from MST predictions across...

The Effects of Prepregnancy Body Mass Index and Gestational Weight Gain on Fetal Macrosomia Among American Indian/Alaska Native Women.

PubMed

Rockhill, Karilynn; Dorfman, Haley; Srinath, Meghna; Hogue, Carol

2015-11-01

The American Indian/Alaska Native (AI/AN) population is a high-risk group across many health indicators, including fetal macrosomia. We aimed to investigate the effects of prepregnancy body mass index (BMI) and gestational weight gain (GWG) on macrosomia and explore possible racial and geographical variations among AI/AN women. This retrospective cohort study was conducted from the Pregnancy Risk Assessment Monitoring System in eight states (2004-2011) among live, singleton, term births to AI/AN women 20 years or older. Prevalence of macrosomia (birth weight ≥ 4000 g) by select characteristics were estimated; differences were assessed with Chi-squares. Multivariable logistic regression was conducted to calculate adjusted odds ratios (aOR) for effects on macrosomia of BMI and GWG (enumerating the pounds women deviated from the Institute of Medicine guidelines for GWG) controlling for other factors in the total sample and stratified by race and state of residence. The prevalence of macrosomia was 14 %, ranging from 8 to 21 % (Utah-Alaska). Among AI/AN women, 30 % were obese prepregnancy and 50 % had excess GWG. Significant independent effects were found for macrosomia of prepregnancy overweight (aOR 1.27; 95 % Confidence Interval 1.01-1.59), obesity (aOR 1.63; 1.29-2.07), and excess GWG (aOR 1.16; 1.13-1.20 per five pounds gained beyond appropriate). Adjusted estimates varied between race and state. Prepregnancy BMI and GWG are independent factors for macrosomia among AI/AN women. Future research should prioritize development, testing, and implementation of weight management programs, which account for variations among AI/AN women, both before and during pregnancy for BMI regulation and GWG control.

Finger muscle attachments for an OpenSim upper-extremity model.

PubMed

Lee, Jong Hwa; Asakawa, Deanna S; Dennerlein, Jack T; Jindrich, Devin L

2015-01-01

We determined muscle attachment points for the index, middle, ring and little fingers in an OpenSim upper-extremity model. Attachment points were selected to match both experimentally measured locations and mechanical function (moment arms). Although experimental measurements of finger muscle attachments have been made, models differ from specimens in many respects such as bone segment ratio, joint kinematics and coordinate system. Likewise, moment arms are not available for all intrinsic finger muscles. Therefore, it was necessary to scale and translate muscle attachments from one experimental or model environment to another while preserving mechanical function. We used a two-step process. First, we estimated muscle function by calculating moment arms for all intrinsic and extrinsic muscles using the partial velocity method. Second, optimization using Simulated Annealing and Hooke-Jeeves algorithms found muscle-tendon paths that minimized root mean square (RMS) differences between experimental and modeled moment arms. The partial velocity method resulted in variance accounted for (VAF) between measured and calculated moment arms of 75.5% on average (range from 48.5% to 99.5%) for intrinsic and extrinsic index finger muscles where measured data were available. RMS error between experimental and optimized values was within one standard deviation (S.D) of measured moment arm (mean RMS error = 1.5 mm < measured S.D = 2.5 mm). Validation of both steps of the technique allowed for estimation of muscle attachment points for muscles whose moment arms have not been measured. Differences between modeled and experimentally measured muscle attachments, averaged over all finger joints, were less than 4.9 mm (within 7.1% of the average length of the muscle-tendon paths). The resulting non-proprietary musculoskeletal model of the human fingers could be useful for many applications, including better understanding of complex multi-touch and gestural movements.

Finger Muscle Attachments for an OpenSim Upper-Extremity Model

PubMed Central

Lee, Jong Hwa; Asakawa, Deanna S.; Dennerlein, Jack T.; Jindrich, Devin L.

2015-01-01

We determined muscle attachment points for the index, middle, ring and little fingers in an OpenSim upper-extremity model. Attachment points were selected to match both experimentally measured locations and mechanical function (moment arms). Although experimental measurements of finger muscle attachments have been made, models differ from specimens in many respects such as bone segment ratio, joint kinematics and coordinate system. Likewise, moment arms are not available for all intrinsic finger muscles. Therefore, it was necessary to scale and translate muscle attachments from one experimental or model environment to another while preserving mechanical function. We used a two-step process. First, we estimated muscle function by calculating moment arms for all intrinsic and extrinsic muscles using the partial velocity method. Second, optimization using Simulated Annealing and Hooke-Jeeves algorithms found muscle-tendon paths that minimized root mean square (RMS) differences between experimental and modeled moment arms. The partial velocity method resulted in variance accounted for (VAF) between measured and calculated moment arms of 75.5% on average (range from 48.5% to 99.5%) for intrinsic and extrinsic index finger muscles where measured data were available. RMS error between experimental and optimized values was within one standard deviation (S.D) of measured moment arm (mean RMS error = 1.5 mm < measured S.D = 2.5 mm). Validation of both steps of the technique allowed for estimation of muscle attachment points for muscles whose moment arms have not been measured. Differences between modeled and experimentally measured muscle attachments, averaged over all finger joints, were less than 4.9 mm (within 7.1% of the average length of the muscle-tendon paths). The resulting non-proprietary musculoskeletal model of the human fingers could be useful for many applications, including better understanding of complex multi-touch and gestural movements. PMID:25853869

An easy-to-use tool for the evaluation of leachate production at landfill sites.

PubMed

Grugnaletti, Matteo; Pantini, Sara; Verginelli, Iason; Lombardi, Francesco

2016-09-01

A simulation program for the evaluation of leachate generation at landfill sites is herein presented. The developed tool is based on a water balance model that accounts for all the key processes influencing leachate generation through analytical and empirical equations. After a short description of the tool, different simulations on four Italian landfill sites are shown. The obtained results revealed that when literature values were assumed for the unknown input parameters, the model provided a rough estimation of the leachate production measured in the field. In this case, indeed, the deviations between observed and predicted data appeared, in some cases, significant. Conversely, by performing a preliminary calibration for some of the unknown input parameters (e.g. initial moisture content of wastes, compression index), in nearly all cases the model performances significantly improved. These results although showed the potential capability of a water balance model to estimate the leachate production at landfill sites also highlighted the intrinsic limitation of a deterministic approach to accurately forecast the leachate production over time. Indeed, parameters such as the initial water content of incoming waste and the compression index, that have a great influence on the leachate production, may exhibit temporal variation due to seasonal changing of weather conditions (e.g. rainfall, air humidity) as well as to seasonal variability in the amount and type of specific waste fractions produced (e.g. yard waste, food, plastics) that make their prediction quite complicated. In this sense, we believe that a tool such as the one proposed in this work that requires a limited number of unknown parameters, can be easier handled to quantify the uncertainties. Copyright © 2016 Elsevier Ltd. All rights reserved.

Influence of early life factors on body mass index trajectory during childhood: a population-based longitudinal analysis in the Western Brazilian Amazon.

PubMed

Lourenço, Barbara H; Villamor, Eduardo; Augusto, Rosângela A; Cardoso, Marly A

2015-04-01

Low- to middle-income countries may experience the occurrence of a dual burden of under and overnutrition. To better understand the overall progression of body mass index (BMI) during childhood, we estimated average BMI-for-age z-score (BAZ) growth curves in a population-based longitudinal study of 255 children living in the Brazilian Amazon. Children were aged 0.1-5.5 years at recruitment (2003). We collected data on socio-economic and maternal characteristics, children's birthweight and infant feeding practices. Child anthropometric measurements were taken in 2003, 2007 and 2009. BAZ differences among categories of exposure variables were calculated at 6 and 12 months, and 2, 7 and 10 years. At baseline, the mean (standard deviation) age was 2.6 (1.4) years; 12.9% were overweight and 3.9% thin. After adjustment, mean BAZ estimates were mostly negative. Boys were close to the median value for BAZ until 12 months, whereas girls were below the median (P=0.05). Children from households above the wealth median were 0.36 z- and 0.49 z-less underweight than poorer children at 7 and 10 years, respectively (P<0.01). Maternal BMI was positively associated with children's BAZ since 12 months old; BAZ in children from overweight mothers was higher by 0.69 compared with their counterparts at 10 years (P<0.01). Birthweight was positively related to BAZ up until 2 years (P=0.01). Socio-economic background and maternal nutritional status are important predictors of BAZ throughout childhood. Although excessive weight gain is a public health concern, it is critical to restrict inequities, while promoting healthier growth in developing countries. © 2012 Blackwell Publishing Ltd.

Design of a device for sky light polarization measurements.

PubMed

Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

2014-08-14

Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky.

Design of a Device for Sky Light Polarization Measurements

PubMed Central

Wang, Yujie; Hu, Xiaoping; Lian, Junxiang; Zhang, Lilian; Xian, Zhiwen; Ma, Tao

2014-01-01

Sky polarization patterns can be used both as indicators of atmospheric turbidity and as a sun compass for navigation. The objective of this study is to improve the precision of sky light polarization measurements by optimal design of the device used. The central part of the system is composed of a Charge Coupled Device (CCD) camera; a fish-eye lens and a linear polarizer. Algorithms for estimating parameters of the polarized light based on three images are derived and the optimal alignments of the polarizer are analyzed. The least-squares estimation is introduced for sky light polarization pattern measurement. The polarization patterns of sky light are obtained using the designed system and they follow almost the same patterns of the single-scattering Rayleigh model. Deviations of polarization angles between observation and the theory are analyzed. The largest deviations occur near the sun and anti-sun directions. Ninety percent of the deviations are less than 5° and 40% percent of them are less than 1°. The deviations decrease evidently as the degree of polarization increases. It also shows that the polarization pattern of the cloudy sky is almost identical as in the blue sky. PMID:25196003

Evaluating Hyperspectral Vegetation Indices for Leaf Area Index Estimation of Oryza sativa L. at Diverse Phenological Stages

PubMed Central

Din, Mairaj; Zheng, Wen; Rashid, Muhammad; Wang, Shanqin; Shi, Zhihua

2017-01-01

Hyperspectral reflectance derived vegetation indices (VIs) are used for non-destructive leaf area index (LAI) monitoring for precise and efficient N nutrition management. This study tested the hypothesis that there is potential for using various hyperspectral VIs for estimating LAI at different growth stages of rice under varying N rates. Hyperspectral reflectance and crop canopy LAI measurements were carried out over 2 years (2015 and 2016) in Meichuan, Hubei, China. Different N fertilization, 0, 45, 82, 127, 165, 210, 247, and 292 kg ha-1, were applied to generate various scales of VIs and LAI values. Regression models were used to perform quantitative analyses between spectral VIs and LAI measured under different phenological stages. In addition, the coefficient of determination and RMSE were employed to evaluate these models. Among the nine VIs, the ratio vegetation index, normalized difference vegetation index (NDVI), modified soil-adjusted vegetation index (MSAVI), modified triangular vegetation index (MTVI2) and exhibited strong and significant relationships with the LAI estimation at different phenological stages. The enhanced vegetation index performed moderately. However, the green normalized vegetation index and blue normalized vegetation index confirmed that there is potential for crop LAI estimation at early phenological stages; the soil-adjusted vegetation index and optimized soil-adjusted vegetation index were more related to the soil optical properties, which were predicted to be the least accurate for LAI estimation. The noise equivalent accounted for the sensitivity of the VIs and MSAVI, MTVI2, and NDVI for the LAI estimation at phenological stages. The results note that LAI at different crop phenological stages has a significant influence on the potential of hyperspectral derived VIs under different N management practices. PMID:28588596

The Role of Inflation and Price Escalation Adjustments in Properly Estimating Program Costs: F-35 Case Study

DTIC Science & Technology

2016-04-30

costs of new defense systems. An inappropriate price index can introduce errors in both development of cost estimating relationships ( CERs ) and in...indexes derived from CERs . These indexes isolate changes in price due to factors other than changes in quality over time. We develop a “Baseline” CER ...The hedonic index application has commonalities with cost estimating relationships ( CERs ), which also model system costs as a function of quality

Does standard deviation matter? Using "standard deviation" to quantify security of multistage testing.

PubMed

Wang, Chun; Zheng, Yi; Chang, Hua-Hua

2014-01-01

With the advent of web-based technology, online testing is becoming a mainstream mode in large-scale educational assessments. Most online tests are administered continuously in a testing window, which may post test security problems because examinees who take the test earlier may share information with those who take the test later. Researchers have proposed various statistical indices to assess the test security, and one most often used index is the average test-overlap rate, which was further generalized to the item pooling index (Chang & Zhang, 2002, 2003). These indices, however, are all defined as the means (that is, the expected proportion of common items among examinees) and they were originally proposed for computerized adaptive testing (CAT). Recently, multistage testing (MST) has become a popular alternative to CAT. The unique features of MST make it important to report not only the mean, but also the standard deviation (SD) of test overlap rate, as we advocate in this paper. The standard deviation of test overlap rate adds important information to the test security profile, because for the same mean, a large SD reflects that certain groups of examinees share more common items than other groups. In this study, we analytically derived the lower bounds of the SD under MST, with the results under CAT as a benchmark. It is shown that when the mean overlap rate is the same between MST and CAT, the SD of test overlap tends to be larger in MST. A simulation study was conducted to provide empirical evidence. We also compared the security of MST under the single-pool versus the multiple-pool designs; both analytical and simulation studies show that the non-overlapping multiple-pool design will slightly increase the security risk.

Effect Sizes for Growth-Modeling Analysis for Controlled Clinical Trials in the Same Metric as for Classical Analysis

PubMed Central

Feingold, Alan

2009-01-01

The use of growth-modeling analysis (GMA)--including Hierarchical Linear Models, Latent Growth Models, and General Estimating Equations--to evaluate interventions in psychology, psychiatry, and prevention science has grown rapidly over the last decade. However, an effect size associated with the difference between the trajectories of the intervention and control groups that captures the treatment effect is rarely reported. This article first reviews two classes of formulas for effect sizes associated with classical repeated-measures designs that use the standard deviation of either change scores or raw scores for the denominator. It then broadens the scope to subsume GMA, and demonstrates that the independent groups, within-subjects, pretest-posttest control-group, and GMA designs all estimate the same effect size when the standard deviation of raw scores is uniformly used. Finally, it is shown that the correct effect size for treatment efficacy in GMA--the difference between the estimated means of the two groups at end of study (determined from the coefficient for the slope difference and length of study) divided by the baseline standard deviation--is not reported in clinical trials. PMID:19271847

Flux or speed? Examining speckle contrast imaging of vascular flows

PubMed Central

Kazmi, S. M. Shams; Faraji, Ehssan; Davis, Mitchell A.; Huang, Yu-Yen; Zhang, Xiaojing J.; Dunn, Andrew K.

2015-01-01

Speckle contrast imaging enables rapid mapping of relative blood flow distributions using camera detection of back-scattered laser light. However, speckle derived flow measures deviate from direct measurements of erythrocyte speeds by 47 ± 15% (n = 13 mice) in vessels of various calibers. Alternatively, deviations with estimates of volumetric flux are on average 91 ± 43%. We highlight and attempt to alleviate this discrepancy by accounting for the effects of multiple dynamic scattering with speckle imaging of microfluidic channels of varying sizes and then with red blood cell (RBC) tracking correlated speckle imaging of vascular flows in the cerebral cortex. By revisiting the governing dynamic light scattering models, we test the ability to predict the degree of multiple dynamic scattering across vessels in order to correct for the observed discrepancies between relative RBC speeds and multi-exposure speckle imaging estimates of inverse correlation times. The analysis reveals that traditional speckle contrast imagery of vascular flows is neither a measure of volumetric flux nor particle speed, but rather the product of speed and vessel diameter. The corrected speckle estimates of the relative RBC speeds have an average 10 ± 3% deviation in vivo with those obtained from RBC tracking. PMID:26203384

Flux or speed? Examining speckle contrast imaging of vascular flows.

PubMed

Kazmi, S M Shams; Faraji, Ehssan; Davis, Mitchell A; Huang, Yu-Yen; Zhang, Xiaojing J; Dunn, Andrew K

2015-07-01

Speckle contrast imaging enables rapid mapping of relative blood flow distributions using camera detection of back-scattered laser light. However, speckle derived flow measures deviate from direct measurements of erythrocyte speeds by 47 ± 15% (n = 13 mice) in vessels of various calibers. Alternatively, deviations with estimates of volumetric flux are on average 91 ± 43%. We highlight and attempt to alleviate this discrepancy by accounting for the effects of multiple dynamic scattering with speckle imaging of microfluidic channels of varying sizes and then with red blood cell (RBC) tracking correlated speckle imaging of vascular flows in the cerebral cortex. By revisiting the governing dynamic light scattering models, we test the ability to predict the degree of multiple dynamic scattering across vessels in order to correct for the observed discrepancies between relative RBC speeds and multi-exposure speckle imaging estimates of inverse correlation times. The analysis reveals that traditional speckle contrast imagery of vascular flows is neither a measure of volumetric flux nor particle speed, but rather the product of speed and vessel diameter. The corrected speckle estimates of the relative RBC speeds have an average 10 ± 3% deviation in vivo with those obtained from RBC tracking.

Experimental determination of the navigation error of the 4-D navigation, guidance, and control systems on the NASA B-737 airplane

NASA Technical Reports Server (NTRS)

Knox, C. E.

1978-01-01

Navigation error data from these flights are presented in a format utilizing three independent axes - horizontal, vertical, and time. The navigation position estimate error term and the autopilot flight technical error term are combined to form the total navigation error in each axis. This method of error presentation allows comparisons to be made between other 2-, 3-, or 4-D navigation systems and allows experimental or theoretical determination of the navigation error terms. Position estimate error data are presented with the navigation system position estimate based on dual DME radio updates that are smoothed with inertial velocities, dual DME radio updates that are smoothed with true airspeed and magnetic heading, and inertial velocity updates only. The normal mode of navigation with dual DME updates that are smoothed with inertial velocities resulted in a mean error of 390 m with a standard deviation of 150 m in the horizontal axis; a mean error of 1.5 m low with a standard deviation of less than 11 m in the vertical axis; and a mean error as low as 252 m with a standard deviation of 123 m in the time axis.

Influence of genetic variants associated with body mass index on eating behavior in childhood

PubMed Central

Monnereau, Claire; Jansen, Pauline W; Tiemeier, Henning; Jaddoe, Vincent WV; Felix, Janine F

2017-01-01

Objective Childhood eating behaviors are associated with body mass index (BMI). Recent genome-wide association studies have identified many single nucleotide polymorphisms (SNPs) associated with adult and childhood BMI. We hypothesized that these SNPs also influence eating behavior. Methods In a population-based prospective cohort study among 3,179 children (mean age (standard deviation): 4.0 (0.1) years), we tested two weighted genetic risk scores, based on 15 childhood and 97 adult BMI SNPs, and ten individual appetite and/or satiety related SNPs for association with food fussiness, food responsiveness, enjoyment of food, satiety responsiveness, slowness in eating. Results The 15 SNP-based childhood BMI genetic risk score was not associated with the eating behavior subscales. The 97 SNP-based adult BMI genetic risk score was nominally associated with satiety responsiveness (β: -0.007 standard deviation, 95% confidence interval (CI) -0.013, 0.000). Of the ten individual SNPs, rs11030104 in BDNF and rs10733682 in LMX1B were nominally associated with satiety responsiveness (β: -0.057 standard deviation, 95% CI -0.112, -0.002). Conclusion Our findings do not strongly support the hypothesis that BMI associated SNPs also influence eating behavior at this age. A potential role for BMI SNPs in satiety responsiveness during childhood was observed, however, no associations with the other eating behavior subscales. PMID:28245097

Functional condition of masseters muscles of patients with class ?? subdivision.

PubMed

Kuroyedova, Vera D; Makarova, Alexandra N; Chicor, Tatyana A

Main functional characteristics of masticator muscles in patients with class ?? malocclusions is activity dominance of m. temporalis in comparison with m. ?asseter. We have not found datum about functional status of the masticators in patients with class II subdivision. The purpose of our study was to investigate the functional characteristics of m. ?asseter, m. temporalis in adult patients with class II subdivision malocclusion. There have been carried out the surface electromyographic study of m. masseter, m. temporalis in 17 adult patients with class II subdivision. It was realized quantitative analysis of 271 electromyogram, it was determined the average bioelectric activity, index activity, symmetry and torsion index. It was observed predominance of the bioelectrical activity of m. temporales on m. masseter for all persons with class II subdivision. Bioelectrical activity for m. masseter was bigger on side of distal ratio and for m. temporales on side of neutral ratio. In class ?? subdivision right, the mandible was deviated to the left side and in class ?? subdivision left is deviated to the right side. Thus, rotational moment generated during compression of the jaws, causes deviation of the lower jaw to the side, with a neutral molar ratio. During voluntary chewing bioelectrical activity of m. masseter and m. temporalis was higher in the right side. In accordance with the functional condition of the masticatory muscles of class II subdivision is characterized with functional features of distal occlusion.

Coffee Consumption and Heart Rate Variability: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) Cohort Study.

PubMed

de Oliveira, Rackel Aguiar Mendes; Araújo, Larissa Fortunato; de Figueiredo, Roberta Carvalho; Goulart, Alessandra C; Schmidt, Maria Ines; Barreto, Sandhi Maria; Ribeiro, Antonio Luiz Pinho

2017-07-13

Studies have shown that acute coffee ingestion can affect cardiovascular autonomic activity, although the chronic effects on heart rate variability (HRV) remain controversial. A cross-sectional study with baseline data (2008-2010) from ELSA-Brasil cohort of 15,105 (aged 35-74), based in six Brazilian states. Coffee consumption in the previous 12 months was measured using the semi-quantitative food frequency questionnaire, and HRV was obtained through electrocardiographic tracings during 10 min at rest. Independent association between the frequency of coffee consumption "never or almost never", "≤1 cup/day", "2-3 cups/day", "≥3 cups/day", and HRV was estimated using generalized linear regression, adjusting for socio-demographic characteristics, health-related behavior, markers of abnormal metabolism, and the presence of coronary artery disease. Further, we applied Bonferroni correction in the full models. The mean age was 52 years (standard deviation (SD) = 9.1), and 52% was female; 9.5% never/almost never consumed coffee. In univariate analysis, coffee consumers had reduced values of HRV indexes, but after full adjustments and correction for multiple comparisons, these associations disappeared. A trend of reduction in HRV vagal indexes was observed in those that consumed ≥3 cups of coffee/day. Most of the effects attributed to the chronic use of coffee on the HRV indexes is related to the higher prevalence of unhealthy habits in coffee users, such as smoking and alcohol use. Adjustment for confounding factors weaken this association, making it non-significant. The effect of higher daily doses of coffee on the autonomic system should be evaluated in further studies.

Target organ damage in primary hypertensive patients: role of the morning heart rate surge.

PubMed

Zhan, Yuliang; Kang, Ting; Wei, Yunfeng

The morning heart rate surge (MHRS) and morning blood pressure surge (MBPS) may be responsible for the high prevalence of cardiovascular events during the morning period. The clinical significance of the MBPS has been well established, but that of the MHRS remains unclear. Thus, we evaluated the association between the MHRS and target organ damage (TOD). A cross-sectional study of 580 hypertensive patients was performed. MHRS and heart rate variability (HRV) were analyzed by 24 h electrocardiogram. TOD was assessed by estimated glomerular filtration rate, carotid intima-media thickness (IMT), and left ventricular mass index. The prevalence of TOD tended to decrease with sleep-trough MHRS (first to fourth quartiles: 71%, 70.3%, 58.6%, and 52.7%, respectively) or prewaking MHRS quartiles (first to fourth quartiles: 65.3%, 73.6%, 61.4%, and 54.2%, respectively), whereas the opposite trend was observed for standard deviation of all normal NN intervals (SDNN). Moreover, sleep-trough MHRS, prewaking MHRS, SDNN, and SDNN index were significantly lower in patients with TOD than in those without TOD. According to four logistic regression models, the associations of prewaking MHRS, SDNN, and SDNN index with TOD were lost after adjustment for age and BP. Patients in the first (≤11.125 bpm) and second sleep-trough MHRS quartiles (11.125-15.75 bpm) had a 1.95-2.06-fold increased risk of TOD compared with those in the fourth quartile (p < 0.05). A blunted sleep-trough MHRS, which may serve as a surrogate marker for autonomic imbalance, was independently associated with TOD in primary hypertensive patients.

Simple Refractometers for Index Measurements by Minimum Deviation Method from Far-ultraviolet to Near Infrared

NASA Technical Reports Server (NTRS)

Leviton, Douglas B.; Madison, Timothy J.; Petrone, Peter

1998-01-01

The focal shift of an optical filter used in non-collimated light depends directly on substrate thickness and index of refraction. The HST Advanced Camera for Surveys (ACS) requires a set of filters whose focal shifts are tightly matched. Knowing the index of refraction for substrate glasses allows precise substrate thicknesses to be specified. Two refractometers have been developed at the Goddard Space Flight Center (GSFC) to determine the indices of refraction of materials from which ACS filters are made. Modem imaging detectors for the near infrared, visible, and far ultraviolet spectral regions make these simple yet sophisticated refractometers possible. A new technology, high accuracy, angular encoder also developed at GSFC makes high precision index measurement possible in the vacuum ultraviolet.

A Functional Varying-Coefficient Single-Index Model for Functional Response Data

PubMed Central

Li, Jialiang; Huang, Chao; Zhu, Hongtu

2016-01-01

Motivated by the analysis of imaging data, we propose a novel functional varying-coefficient single index model (FVCSIM) to carry out the regression analysis of functional response data on a set of covariates of interest. FVCSIM represents a new extension of varying-coefficient single index models for scalar responses collected from cross-sectional and longitudinal studies. An efficient estimation procedure is developed to iteratively estimate varying coefficient functions, link functions, index parameter vectors, and the covariance function of individual functions. We systematically examine the asymptotic properties of all estimators including the weak convergence of the estimated varying coefficient functions, the asymptotic distribution of the estimated index parameter vectors, and the uniform convergence rate of the estimated covariance function and their spectrum. Simulation studies are carried out to assess the finite-sample performance of the proposed procedure. We apply FVCSIM to investigating the development of white matter diffusivities along the corpus callosum skeleton obtained from Alzheimer’s Disease Neuroimaging Initiative (ADNI) study. PMID:29200540

A Functional Varying-Coefficient Single-Index Model for Functional Response Data.

PubMed

Li, Jialiang; Huang, Chao; Zhu, Hongtu

2017-01-01

Motivated by the analysis of imaging data, we propose a novel functional varying-coefficient single index model (FVCSIM) to carry out the regression analysis of functional response data on a set of covariates of interest. FVCSIM represents a new extension of varying-coefficient single index models for scalar responses collected from cross-sectional and longitudinal studies. An efficient estimation procedure is developed to iteratively estimate varying coefficient functions, link functions, index parameter vectors, and the covariance function of individual functions. We systematically examine the asymptotic properties of all estimators including the weak convergence of the estimated varying coefficient functions, the asymptotic distribution of the estimated index parameter vectors, and the uniform convergence rate of the estimated covariance function and their spectrum. Simulation studies are carried out to assess the finite-sample performance of the proposed procedure. We apply FVCSIM to investigating the development of white matter diffusivities along the corpus callosum skeleton obtained from Alzheimer's Disease Neuroimaging Initiative (ADNI) study.

Causes of systematic over- or underestimation of low streamflows by use of index-streamgage approaches in the United States

USGS Publications Warehouse

Eng, K.; Kiang, J.E.; Chen, Y.-Y.; Carlisle, D.M.; Granato, G.E.

2011-01-01

Low-flow characteristics can be estimated by multiple linear regressions or the index-streamgage approach. The latter transfers streamflow information from a hydrologically similar, continuously gaged basin ('index streamgage') to one with a very limited streamflow record, but often results in biased estimates. The application of the index-streamgage approach can be generalized into three steps: (1) selection of streamflow information of interest, (2) definition of hydrologic similarity and selection of index streamgage, and (3) application of an information-transfer approach. Here, we explore the effects of (1) the range of streamflow values, (2) the areal density of streamgages, and (3) index-streamgage selection criteria on the bias of three information-transfer approaches on estimates of the 7-day, 10-year minimum streamflow (Q7, 10). The three information-transfer approaches considered are maintenance of variance extension, base-flow correlation, and ratio of measured to concurrent gaged streamflow (Q-ratio invariance). Our results for 1120 streamgages throughout the United States suggest that only a small portion of the total bias in estimated streamflow values is explained by the areal density of the streamgages and the hydrologic similarity between the two basins. However, restricting the range of streamflow values used in the index-streamgage approach reduces the bias of estimated Q7, 10 values substantially. Importantly, estimated Q7, 10 values are heavily biased when the observed Q7, 10 values are near zero. Results of the analysis also showed that Q7, 10 estimates from two of the three index-streamgage approaches have lower root-mean-square error values than estimates derived from multiple regressions for the large regions considered in this study.

Physicochemical characterization of Lavandula spp. honey with FT-Raman spectroscopy.

PubMed

Anjos, Ofélia; Santos, António J A; Paixão, Vasco; Estevinho, Letícia M

2018-02-01

This study aimed to evaluate the potential of FT-Raman spectroscopy in the prediction of the chemical composition of Lavandula spp. monofloral honey. Partial Least Squares (PLS) regression models were performed for the quantitative estimation and the results were correlated with those obtained using reference methods. Good calibration models were obtained for electrical conductivity, ash, total acidity, pH, reducing sugars, hydroxymethylfurfural (HMF), proline, diastase index, apparent sucrose, total flavonoids content and total phenol content. On the other hand, the model was less accurate for pH determination. The calibration models had high r 2 (ranging between 92.8% and 99.9%), high residual prediction deviation - RPD (ranging between 4.2 and 26.8) and low root mean square errors. These results confirm the hypothesis that FT-Raman is a useful technique for the quality control and chemical properties' evaluation of Lavandula spp honey. Its application may allow improving the efficiency, speed and cost of the current laboratory analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

Bayesian estimation of seasonal course of canopy leaf area index from hyperspectral satellite data

NASA Astrophysics Data System (ADS)

Varvia, Petri; Rautiainen, Miina; Seppänen, Aku

2018-03-01

In this paper, Bayesian inversion of a physically-based forest reflectance model is investigated to estimate of boreal forest canopy leaf area index (LAI) from EO-1 Hyperion hyperspectral data. The data consist of multiple forest stands with different species compositions and structures, imaged in three phases of the growing season. The Bayesian estimates of canopy LAI are compared to reference estimates based on a spectral vegetation index. The forest reflectance model contains also other unknown variables in addition to LAI, for example leaf single scattering albedo and understory reflectance. In the Bayesian approach, these variables are estimated simultaneously with LAI. The feasibility and seasonal variation of these estimates is also examined. Credible intervals for the estimates are also calculated and evaluated. The results show that the Bayesian inversion approach is significantly better than using a comparable spectral vegetation index regression.

MRI-guided procedures in various regions of the body using a robotic assistance system in a closed-bore scanner: preliminary clinical experience and limitations.

PubMed

Moche, Michael; Zajonz, Dirk; Kahn, Thomas; Busse, Harald

2010-04-01

To present the clinical setup and workflow of a robotic assistance system for image-guided interventions in a conventional magnetic resonance imaging (MRI) environment and to report our preliminary clinical experience with percutaneous biopsies in various body regions. The MR-compatible, servo-pneumatically driven, robotic device (Innomotion) fits into the 60-cm bore of a standard MR scanner. The needle placement (n = 25) accuracy was estimated by measuring the 3D deviation between needle tip and prescribed target point in a phantom. Percutaneous biopsies in six patients and different body regions were planned by graphically selecting entry and target points on intraoperatively acquired roadmap MR data. For insertion depths between 29 and 95 mm, the average 3D needle deviation was 2.2 +/- 0.7 mm (range 0.9-3.8 mm). Patients with a body mass index of up to approximately 30 kg/m(2) fitted into the bore with the device. Clinical work steps and limitations are reported for the various applications. All biopsies were diagnostic and could be completed without any major complications. Median planning and intervention times were 25 (range 20-36) and 44 (36-68) minutes, respectively. Preliminary clinical results in a standard MRI environment suggest that the presented robotic device provides accurate guidance for percutaneous procedures in various body regions. Shorter procedure times may be achievable by optimizing technical and workflow aspects. (c) 2010 Wiley-Liss, Inc.

Association of black carbon with cognition among children in a prospective birth cohort study.

PubMed

Suglia, S Franco; Gryparis, A; Wright, R O; Schwartz, J; Wright, R J

2008-02-01

While studies show that ultrafine and fine particles can be translocated from the lungs to the central nervous system, the possible neurodegenerative effect of air pollution remains largely unexplored. The authors examined the relation between black carbon, a marker for traffic particles, and cognition among 202 Boston, Massachusetts, children (mean age = 9.7 years (standard deviation, 1.7)) in a prospective birth cohort study (1986-2001). Local black carbon levels were estimated using a validated spatiotemporal land-use regression model (mean predicted annual black carbon level, 0.56 mug/m(3) (standard deviation, 0.13)). The Wide Range Assessment of Memory and Learning and the Kaufman Brief Intelligence Test were administered for assessment of cognitive constructs. In analysis adjusting for sociodemographic factors, birth weight, blood lead level, and tobacco smoke exposure, black carbon (per interquartile-range increase) was associated with decreases in the vocabulary (-2.2, 95% confidence interval (CI): -5.5, 1.1), matrices (-4.0, 95% CI: -7.6, -0.5), and composite intelligence quotient (-3.4, 95% CI: -6.6, -0.3) scores of the Kaufman Brief Intelligence Test and with decreases on the visual subscale (-5.4, 95% CI: -8.9, -1.9) and general index (-3.9, 95% CI: -7.5, -0.3) of the Wide Range Assessment of Memory and Learning. Higher levels of black carbon predicted decreased cognitive function across assessments of verbal and nonverbal intelligence and memory constructs.

Quantitative evaluation of dual-flip-angle T1 mapping on DCE-MRI kinetic parameter estimation in head and neck

PubMed Central

Chow, Steven Kwok Keung; Yeung, David Ka Wai; Ahuja, Anil T; King, Ann D

2012-01-01

Purpose To quantitatively evaluate the kinetic parameter estimation for head and neck (HN) dynamic contrast-enhanced (DCE) MRI with dual-flip-angle (DFA) T1 mapping. Materials and methods Clinical DCE-MRI datasets of 23 patients with HN tumors were included in this study. T1 maps were generated based on multiple-flip-angle (MFA) method and different DFA combinations. Tofts model parameter maps of kep, Ktrans and vp based on MFA and DFAs were calculated and compared. Fitted parameter by MFA and DFAs were quantitatively evaluated in primary tumor, salivary gland and muscle. Results T1 mapping deviations by DFAs produced remarkable kinetic parameter estimation deviations in head and neck tissues. In particular, the DFA of [2º, 7º] overestimated, while [7º, 12º] and [7º, 15º] underestimated Ktrans and vp, significantly (P<0.01). [2º, 15º] achieved the smallest but still statistically significant overestimation for Ktrans and vp in primary tumors, 32.1% and 16.2% respectively. kep fitting results by DFAs were relatively close to the MFA reference compared to Ktrans and vp. Conclusions T1 deviations induced by DFA could result in significant errors in kinetic parameter estimation, particularly Ktrans and vp, through Tofts model fitting. MFA method should be more reliable and robust for accurate quantitative pharmacokinetic analysis in head and neck. PMID:23289084

Specifying the ISS Plasma Environment

NASA Technical Reports Server (NTRS)

Minow, Joseph I.; Diekmann, Anne; Neergaard, Linda; Bui, Them; Mikatarian, Ronald; Barsamian, Hagop; Koontz, Steven

2002-01-01

Quantifying the spacecraft charging risks and corresponding hazards for the International Space Station (ISS) requires a plasma environment specification describing the natural variability of ionospheric temperature (Te) and density (Ne). Empirical ionospheric specification and forecast models such as the International Reference Ionosphere (IN) model typically only provide estimates of long term (seasonal) mean Te and Ne values for the low Earth orbit environment. Knowledge of the Te and Ne variability as well as the likelihood of extreme deviations from the mean values are required to estimate both the magnitude and frequency of occurrence of potentially hazardous spacecraft charging environments for a given ISS construction stage and flight configuration. This paper describes the statistical analysis of historical ionospheric low Earth orbit plasma measurements used to estimate Ne, Te variability in the ISS flight environment. The statistical variability analysis of Ne and Te enables calculation of the expected frequency of occurrence of any particular values of Ne and Te, especially those that correspond to possibly hazardous spacecraft charging environments. The database used in the original analysis included measurements from the AE-C, AE-D, and DE-2 satellites. Recent work on the database has added additional satellites to the database and ground based incoherent scatter radar observations as well. Deviations of the data values from the IRI estimated Ne, Te parameters for each data point provide a statistical basis for modeling the deviations of the plasma environment from the IRI model output.

Spatial and Temporal Spread of Acute Viral Respiratory Infections in Young Children Living in High-Altitude Rural Communities: A Prospective Household-Based Study

PubMed Central

Cherry, Charlotte Buehler; Griffin, Marie R.; Edwards, Kathryn M.; Williams, John V.; Gil, Ana I.; Verastegui, Hector; Lanata, Claudio F.; Grijalva, Carlos G

2016-01-01

Background Few studies have described patterns of transmission of viral acute respiratory infections (ARI) in children in developing countries. We examined the spatial and temporal spread of viral ARI among young children in rural Peruvian highland communities. Previous work has described intense social interactions in those communities, which could influence the transmission of viral infections. Methods We enrolled and followed children <3 years of age for detection of ARI during the 2009–2011 respiratory seasons in a rural setting with relatively wide geographic dispersion of households and communities. Viruses detected included influenza, respiratory syncytial virus (RSV), human metapneumovirus (MPV), and parainfluenza 2 and 3 viruses (PIV2; PIV3). We used geospatial analyses to identify specific viral infection hot spots with high ARI incidence. We also explored the local spread of ARI from index cases using standard deviational ellipses. Results Geospatial analyses revealed hot spots of high ARI incidence around the index cases of influenza outbreaks and RSV outbreak in 2010. Although PIV3 in 2009 and PIV2 in 2010 showed distinct spatial hot spots, clustering was not in proximity to their respective index cases. No significant aggregation around index cases was noted for other viruses. Standard deviational ellipse analyses suggested that influenza B and RSV in 2010, and MPV in 2011 spread temporally in alignment with the major road network. Conclusions Despite the geographic dispersion of communities in this rural setting, we observed a rapid spread of viral ARI among young children. Influenza strains and RSV in 2010 had distinctive outbreaks arising from their index cases. PMID:27404599

Bayesian Non-Stationary Flood Frequency Estimation at Ungauged Basins Using Climate Information and a Scaling Model

NASA Astrophysics Data System (ADS)

Lima, C. H.; Lall, U.

2010-12-01

Flood frequency statistical analysis most often relies on stationary assumptions, where distribution moments (e.g. mean, standard deviation) and associated flood quantiles do not change over time. In this sense, one expects that flood magnitudes and their frequency of occurrence will remain constant as observed in the historical information. However, evidence of inter-annual and decadal climate variability and anthropogenic change as well as an apparent increase in the number and magnitude of flood events across the globe have made the stationary assumption questionable. Here, we show how to estimate flood quantiles (e.g. 100-year flood) at ungauged basins without needing to consider stationarity. A statistical model based on the well known flow-area scaling law is proposed to estimate flood flows at ungauged basins. The slope and intercept scaling law coefficients are assumed time varying and a hierarchical Bayesian model is used to include climate information and reduce parameter uncertainties. Cross-validated results from 34 streamflow gauges located in a nested Basin in Brazil show that the proposed model is able to estimate flood quantiles at ungauged basins with remarkable skills compared with data based estimates using the full record. The model as developed in this work is also able to simulate sequences of flood flows considering global climate changes provided an appropriate climate index developed from the General Circulation Model is used as a predictor. The time varying flood frequency estimates can be used for pricing insurance models, and in a forecast mode for preparations for flooding, and finally, for timing infrastructure investments and location. Non-stationary 95% interval estimation for the 100-year Flood (shaded gray region) and 95% interval for the 100-year flood estimated from data (horizontal dashed and solid lines). The average distribution of the 100-year flood is shown in green in the right side.

Historical baselines of coral cover on tropical reefs as estimated by expert opinion

PubMed Central

Cheung, William W.L.; Bruno, John F.

2018-01-01

Coral reefs are important habitats that represent global marine biodiversity hotspots and provide important benefits to people in many tropical regions. However, coral reefs are becoming increasingly threatened by climate change, overfishing, habitat destruction, and pollution. Historical baselines of coral cover are important to understand how much coral cover has been lost, e.g., to avoid the ‘shifting baseline syndrome’. There are few quantitative observations of coral reef cover prior to the industrial revolution, and therefore baselines of coral reef cover are difficult to estimate. Here, we use expert and ocean-user opinion surveys to estimate baselines of global coral reef cover. The overall mean estimated baseline coral cover was 59% (±19% standard deviation), compared to an average of 58% (±18% standard deviation) estimated by professional scientists. We did not find evidence of the shifting baseline syndrome, whereby respondents who first observed coral reefs more recently report lower estimates of baseline coral cover. These estimates of historical coral reef baseline cover are important for scientists, policy makers, and managers to understand the extent to which coral reefs have become depleted and to set appropriate recovery targets. PMID:29379692

Historical baselines of coral cover on tropical reefs as estimated by expert opinion.

PubMed

Eddy, Tyler D; Cheung, William W L; Bruno, John F

2018-01-01

Coral reefs are important habitats that represent global marine biodiversity hotspots and provide important benefits to people in many tropical regions. However, coral reefs are becoming increasingly threatened by climate change, overfishing, habitat destruction, and pollution. Historical baselines of coral cover are important to understand how much coral cover has been lost, e.g., to avoid the 'shifting baseline syndrome'. There are few quantitative observations of coral reef cover prior to the industrial revolution, and therefore baselines of coral reef cover are difficult to estimate. Here, we use expert and ocean-user opinion surveys to estimate baselines of global coral reef cover. The overall mean estimated baseline coral cover was 59% (±19% standard deviation), compared to an average of 58% (±18% standard deviation) estimated by professional scientists. We did not find evidence of the shifting baseline syndrome, whereby respondents who first observed coral reefs more recently report lower estimates of baseline coral cover. These estimates of historical coral reef baseline cover are important for scientists, policy makers, and managers to understand the extent to which coral reefs have become depleted and to set appropriate recovery targets.

Density estimation in wildlife surveys

Treesearch

Jonathan Bart; Sam Droege; Paul Geissler; Bruce Peterjohn; C. John Ralph

2004-01-01

Several authors have recently discussed the problems with using index methods to estimate trends in population size. Some have expressed the view that index methods should virtually never be used. Others have responded by defending index methods and questioning whether better alternatives exist. We suggest that index methods are often a costeffective component of valid...

Attitude Estimation or Quaternion Estimation?

NASA Technical Reports Server (NTRS)

Markley, F. Landis

2003-01-01

The attitude of spacecraft is represented by a 3x3 orthogonal matrix with unity determinant, which belongs to the three-dimensional special orthogonal group SO(3). The fact that all three-parameter representations of SO(3) are singular or discontinuous for certain attitudes has led to the use of higher-dimensional nonsingular parameterizations, especially the four-component quaternion. In attitude estimation, we are faced with the alternatives of using an attitude representation that is either singular or redundant. Estimation procedures fall into three broad classes. The first estimates a three-dimensional representation of attitude deviations from a reference attitude parameterized by a higher-dimensional nonsingular parameterization. The deviations from the reference are assumed to be small enough to avoid any singularity or discontinuity of the three-dimensional parameterization. The second class, which estimates a higher-dimensional representation subject to enough constraints to leave only three degrees of freedom, is difficult to formulate and apply consistently. The third class estimates a representation of SO(3) with more than three dimensions, treating the parameters as independent. We refer to the most common member of this class as quaternion estimation, to contrast it with attitude estimation. We analyze the first and third of these approaches in the context of an extended Kalman filter with simplified kinematics and measurement models.

Increasing market efficiency in the stock markets

NASA Astrophysics Data System (ADS)

Yang, Jae-Suk; Kwak, Wooseop; Kaizoji, Taisei; Kim, In-Mook

2008-01-01

We study the temporal evolutions of three stock markets; Standard and Poor's 500 index, Nikkei 225 Stock Average, and the Korea Composite Stock Price Index. We observe that the probability density function of the log-return has a fat tail but the tail index has been increasing continuously in recent years. We have also found that the variance of the autocorrelation function, the scaling exponent of the standard deviation, and the statistical complexity decrease, but that the entropy density increases as time goes over time. We introduce a modified microscopic spin model and simulate the model to confirm such increasing and decreasing tendencies in statistical quantities. These findings indicate that these three stock markets are becoming more efficient.

Association of auricular pressing and heart rate variability in pre-exam anxiety students.

PubMed

Wu, Wocao; Chen, Junqi; Zhen, Erchuan; Huang, Huanlin; Zhang, Pei; Wang, Jiao; Ou, Yingyi; Huang, Yong

2013-03-25

A total of 30 students scoring between 12 and 20 on the Test Anxiety Scale who had been exhibiting an anxious state > 24 hours, and 30 normal control students were recruited. Indices of heart rate variability were recorded using an Actiheart electrocardiogram recorder at 10 minutes before auricular pressing, in the first half of stimulation and in the second half of stimulation. The results revealed that the standard deviation of all normal to normal intervals and the root mean square of standard deviation of normal to normal intervals were significantly increased after stimulation. The heart rate variability triangular index, very-low-frequency power, low-frequency power, and the ratio of low-frequency to high-frequency power were increased to different degrees after stimulation. Compared with normal controls, the root mean square of standard deviation of normal to normal intervals was significantly increased in anxious students following auricular pressing. These results indicated that auricular pressing can elevate heart rate variability, especially the root mean square of standard deviation of normal to normal intervals in students with pre-exam anxiety.

Association of auricular pressing and heart rate variability in pre-exam anxiety students

PubMed Central

Wu, Wocao; Chen, Junqi; Zhen, Erchuan; Huang, Huanlin; Zhang, Pei; Wang, Jiao; Ou, Yingyi; Huang, Yong

2013-01-01

A total of 30 students scoring between 12 and 20 on the Test Anxiety Scale who had been exhibiting an anxious state > 24 hours, and 30 normal control students were recruited. Indices of heart rate variability were recorded using an Actiheart electrocardiogram recorder at 10 minutes before auricular pressing, in the first half of stimulation and in the second half of stimulation. The results revealed that the standard deviation of all normal to normal intervals and the root mean square of standard deviation of normal to normal intervals were significantly increased after stimulation. The heart rate variability triangular index, very-low-frequency power, low-frequency power, and the ratio of low-frequency to high-frequency power were increased to different degrees after stimulation. Compared with normal controls, the root mean square of standard deviation of normal to normal intervals was significantly increased in anxious students following auricular pressing. These results indicated that auricular pressing can elevate heart rate variability, especially the root mean square of standard deviation of normal to normal intervals in students with pre-exam anxiety. PMID:25206734

Comparison of the Lund and Browder table to computed tomography scan three-dimensional surface area measurement for a pediatric cohort.

PubMed

Rumpf, R Wolfgang; Stewart, William C L; Martinez, Stephen K; Gerrard, Chandra Y; Adolphi, Natalie L; Thakkar, Rajan; Coleman, Alan; Rajab, Adrian; Ray, William C; Fabia, Renata

2018-01-01

Treating burns effectively requires accurately assessing the percentage of the total body surface area (%TBSA) affected by burns. Current methods for estimating %TBSA, such as Lund and Browder (L&B) tables, rely on historic body statistics. An increasingly obese population has been blamed for increasing errors in %TBSA estimates. However, this assumption has not been experimentally validated. We hypothesized that errors in %TBSA estimates using L&B were due to differences in the physical proportions of today's children compared with children in the early 1940s when the chart was developed and that these differences would appear as body mass index (BMI)-associated systematic errors in the L&B values versus actual body surface areas. We measured the TBSA of human pediatric cadavers using computed tomography scans. Subjects ranged from 9 mo to 15 y in age. We chose outliers of the BMI distribution (from the 31st percentile at the low through the 99th percentile at the high). We examined surface area proportions corresponding to L&B regions. Measured regional proportions based on computed tomography scans were in reasonable agreement with L&B, even with subjects in the tails of the BMI range. The largest deviation was 3.4%, significantly less than the error seen in real-world %TBSA estimates. While today's population is more obese than those studied by L&B, their body region proportions scale surprisingly well. The primary error in %TBSA estimation is not due to changing physical proportions of today's children and may instead lie in the application of the L&B table. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Drone based estimation of actual evapotranspiration over different forest types

NASA Astrophysics Data System (ADS)

Marzahn, Philip; Gampe, David; Castro, Saulo; Vega-Araya, Mauricio; Sanchez-Azofeifa, Arturo; Ludwig, Ralf

2017-04-01

Actual evapotranspiration (Eta) plays an important role in surface-atmosphere interactions. Traditionally, Eta is measured by means of lysimeters, eddy-covariance systems or fiber optics, providing estimates which are spatially restricted to a footprint from a few square meters up to several hectares . In the past, several methods have been developed to derive Eta by means of multi-spectral remote sensing data using thermal and VIS/NIR satellite imagery of the land surface. As such approaches do have their justification on coarser scales, they do not provide Eta information on the fine resolution plant level over large areas which is mandatory for the detection of water stress or tree mortality. In this study, we present a comparison of a drone based assessment of Eta with eddy-covariance measurements over two different forest types - a deciduous forest in Alberta, Canada and a tropical dry forest in Costa Rica. Drone based estimates of Eta were calculated applying the Triangle-Method proposed by Jiang and Islam (1999). The Triangle-Method estimates actual evapotranspiration (Eta) by means of the Normalized Difference Vegetation Index (NDVI) and land surface temperature (LST) provided by two camera systems (MicaSense RedEdge, FLIR TAU2 640) flown simultaneously on an octocopter. . Results indicate a high transferability of the original approach from Jiang and Islam (1999) developed for coarse to medium resolution satellite imagery tothe high resolution drone data, leading to a deviation in Eta estimates of 10% compared to the eddy-covariance measurements. In addition, the spatial footprint of the eddy-covariance measurement can be detected with this approach, by showing the spatial heterogeneities of Eta due to the spatial distribution of different trees and understory vegetation.

Estimation of the peak entrance surface air kerma for patients undergoing computed tomography-guided procedures.

PubMed

Avilés Lucas, P; Dance, D R; Castellano, I A; Vañó, E

2005-01-01

The purpose of this work was to develop a method for estimating the patient peak entrance surface air kerma from measurements using a pencil ionisation chamber on dosimetry phantoms exposed in a computed tomography (CT) scanner. The method described is especially relevant for CT fluoroscopy and CT perfusion procedures where the peak entrance surface air kerma is the risk-related quantity of primary concern. Pencil ionisation chamber measurements include scattered radiation, which is outside the primary radiation field, and that must be subtracted in order to derive the peak entrance surface air kerma. A Monte Carlo computer model has therefore been used to calculate correction factors, which may be applied to measurements of the CT dose index obtained using a pencil ionisation chamber in order to estimate the peak entrance surface air kerma. The calculations were made for beam widths of 5, 7, 10 and 20 mm, for seven positions of the phantom, and for the geometry of a GE HiSpeed CT/i scanner. The program was validated by comparing measurements and calculations of CTDI for various vertical positions of the phantom and by directly estimating the peak ESAK using the program. Both validations showed agreement within statistical uncertainties (standard deviation of 2.3% or less). For the GE machine, the correction factors vary by approximately 10% with slice width for a fixed phantom position, being largest for the 20 mm beam width, and at that beam width range from 0.87 when the phantom surface is at the isocentre to 1.23 when it is displaced vertically by 24 cm.

Using ARM Observations to Evaluate Climate Model Simulations of Land-Atmosphere Coupling on the U.S. Southern Great Plains

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

Phillips, Thomas J.; Klein, Stephen A.; Ma, Hsi -Yen

Several independent measurements of warm-season soil moisture and surface atmospheric variables recorded at the ARM Southern Great Plains (SGP) research facility are used to estimate the terrestrial component of land-atmosphere coupling (LAC) strength and its regional uncertainty. The observations reveal substantial variation in coupling strength, as estimated from three soil moisture measurements at a single site, as well as across six other sites having varied soil and land cover types. The observational estimates then serve as references for evaluating SGP terrestrial coupling strength in the Community Atmospheric Model coupled to the Community Land Model. These coupled model components are operatedmore » in both a free-running mode and in a controlled configuration, where the atmospheric and land states are reinitialized daily, so that they do not drift very far from observations. Although the controlled simulation deviates less from the observed surface climate than its free-running counterpart, the terrestrial LAC in both configurations is much stronger and displays less spatial variability than the SGP observational estimates. Preliminary investigation of vegetation leaf area index (LAI) substituted for soil moisture suggests that the overly strong coupling between model soil moisture and surface atmospheric variables is associated with too much evaporation from bare ground and too little from the vegetation cover. Lastly, these results imply that model surface characteristics such as LAI, as well as the physical parameterizations involved in the coupling of the land and atmospheric components, are likely to be important sources of the problematical LAC behaviors.« less

Using ARM Observations to Evaluate Climate Model Simulations of Land-Atmosphere Coupling on the U.S. Southern Great Plains

DOE PAGES

Phillips, Thomas J.; Klein, Stephen A.; Ma, Hsi -Yen; ...

2017-10-13

Several independent measurements of warm-season soil moisture and surface atmospheric variables recorded at the ARM Southern Great Plains (SGP) research facility are used to estimate the terrestrial component of land-atmosphere coupling (LAC) strength and its regional uncertainty. The observations reveal substantial variation in coupling strength, as estimated from three soil moisture measurements at a single site, as well as across six other sites having varied soil and land cover types. The observational estimates then serve as references for evaluating SGP terrestrial coupling strength in the Community Atmospheric Model coupled to the Community Land Model. These coupled model components are operatedmore » in both a free-running mode and in a controlled configuration, where the atmospheric and land states are reinitialized daily, so that they do not drift very far from observations. Although the controlled simulation deviates less from the observed surface climate than its free-running counterpart, the terrestrial LAC in both configurations is much stronger and displays less spatial variability than the SGP observational estimates. Preliminary investigation of vegetation leaf area index (LAI) substituted for soil moisture suggests that the overly strong coupling between model soil moisture and surface atmospheric variables is associated with too much evaporation from bare ground and too little from the vegetation cover. Lastly, these results imply that model surface characteristics such as LAI, as well as the physical parameterizations involved in the coupling of the land and atmospheric components, are likely to be important sources of the problematical LAC behaviors.« less

The Effective Dynamic Ranges for Glaucomatous Visual Field Progression With Standard Automated Perimetry and Stimulus Sizes III and V

PubMed Central

Zamba, Gideon K. D.; Artes, Paul H.

2018-01-01

Purpose It has been shown that threshold estimates below approximately 20 dB have little effect on the ability to detect visual field progression in glaucoma. We aimed to compare stimulus size V to stimulus size III, in areas of visual damage, to confirm these findings by using (1) a different dataset, (2) different techniques of progression analysis, and (3) an analysis to evaluate the effect of censoring on mean deviation (MD). Methods In the Iowa Variability in Perimetry Study, 120 glaucoma subjects were tested every 6 months for 4 years with size III SITA Standard and size V Full Threshold. Progression was determined with three complementary techniques: pointwise linear regression (PLR), permutation of PLR, and linear regression of the MD index. All analyses were repeated on “censored'' datasets in which threshold estimates below a given criterion value were set to equal the criterion value. Results Our analyses confirmed previous observations that threshold estimates below 20 dB contribute much less to visual field progression than estimates above this range. These findings were broadly similar with stimulus sizes III and V. Conclusions Censoring of threshold values < 20 dB has relatively little impact on the rates of visual field progression in patients with mild to moderate glaucoma. Size V, which has lower retest variability, performs at least as well as size III for longitudinal glaucoma progression analysis and appears to have a larger useful dynamic range owing to the upper sensitivity limit being higher. PMID:29356822

Sample Size and Item Parameter Estimation Precision When Utilizing the One-Parameter "Rasch" Model

ERIC Educational Resources Information Center

Custer, Michael

2015-01-01

This study examines the relationship between sample size and item parameter estimation precision when utilizing the one-parameter model. Item parameter estimates are examined relative to "true" values by evaluating the decline in root mean squared deviation (RMSD) and the number of outliers as sample size increases. This occurs across…

Spectral combination of spherical gravitational curvature boundary-value problems

NASA Astrophysics Data System (ADS)

PitoÅák, Martin; Eshagh, Mehdi; Šprlák, Michal; Tenzer, Robert; Novák, Pavel

2018-04-01

Four solutions of the spherical gravitational curvature boundary-value problems can be exploited for the determination of the Earth's gravitational potential. In this article we discuss the combination of simulated satellite gravitational curvatures, i.e., components of the third-order gravitational tensor, by merging these solutions using the spectral combination method. For this purpose, integral estimators of biased- and unbiased-types are derived. In numerical studies, we investigate the performance of the developed mathematical models for the gravitational field modelling in the area of Central Europe based on simulated satellite measurements. Firstly, we verify the correctness of the integral estimators for the spectral downward continuation by a closed-loop test. Estimated errors of the combined solution are about eight orders smaller than those from the individual solutions. Secondly, we perform a numerical experiment by considering the Gaussian noise with the standard deviation of 6.5× 10-17 m-1s-2 in the input data at the satellite altitude of 250 km above the mean Earth sphere. This value of standard deviation is equivalent to a signal-to-noise ratio of 10. Superior results with respect to the global geopotential model TIM-r5 are obtained by the spectral downward continuation of the vertical-vertical-vertical component with the standard deviation of 2.104 m2s-2, but the root mean square error is the largest and reaches 9.734 m2s-2. Using the spectral combination of all gravitational curvatures the root mean square error is more than 400 times smaller but the standard deviation reaches 17.234 m2s-2. The combination of more components decreases the root mean square error of the corresponding solutions while the standard deviations of the combined solutions do not improve as compared to the solution from the vertical-vertical-vertical component. The presented method represents a weight mean in the spectral domain that minimizes the root mean square error of the combined solutions and improves standard deviation of the solution based only on the least accurate components.

Characteristics and Impact Factors of Parameter Alpha in the Nonlinear Advection-Aridity Method for Estimating Evapotranspiration at Interannual Scale in the Loess Plateau

NASA Astrophysics Data System (ADS)

Zhou, H.; Liu, W.; Ning, T.

2017-12-01

Land surface actual evapotranspiration plays a key role in the global water and energy cycles. Accurate estimation of evapotranspiration is crucial for understanding the interactions between the land surface and the atmosphere, as well as for managing water resources. The nonlinear advection-aridity approach was formulated by Brutsaert to estimate actual evapotranspiration in 2015. Subsequently, this approach has been verified, applied and developed by many scholars. The estimation, impact factors and correlation analysis of the parameter alpha (αe) of this approach has become important aspects of the research. According to the principle of this approach, the potential evapotranspiration (ETpo) (taking αe as 1) and the apparent potential evapotranspiration (ETpm) were calculated using the meteorological data of 123 sites of the Loess Plateau and its surrounding areas. Then the mean spatial values of precipitation (P), ETpm and ETpo for 13 catchments were obtained by a CoKriging interpolation algorithm. Based on the runoff data of the 13 catchments, actual evapotranspiration was calculated using the catchment water balance equation at the hydrological year scale (May to April of the following year) by ignoring the change of catchment water storage. Thus, the parameter was estimated, and its relationships with P, ETpm and aridity index (ETpm/P) were further analyzed. The results showed that the general range of annual parameter value was 0.385-1.085, with an average value of 0.751 and a standard deviation of 0.113. The mean annual parameter αe value showed different spatial characteristics, with lower values in northern and higher values in southern. The annual scale parameter linearly related with annual P (R2=0.89) and ETpm (R2=0.49), while it exhibited a power function relationship with the aridity index (R2=0.83). Considering the ETpm is a variable in the nonlinear advection-aridity approach in which its effect has been incorporated, the relationship of precipitation and parameter (αe=1.0×10-3*P+0.301) was developed. The value of αe in this study is lower than those in the published literature. The reason is unclear at this point and yet need further investigation. The preliminary application of the nonlinear advection-aridity approach in the Loess Plateau has shown promising results.

Estimating Mixed Broadleaves Forest Stand Volume Using Dsm Extracted from Digital Aerial Images

NASA Astrophysics Data System (ADS)

Sohrabi, H.

2012-07-01

In mixed old growth broadleaves of Hyrcanian forests, it is difficult to estimate stand volume at plot level by remotely sensed data while LiDar data is absent. In this paper, a new approach has been proposed and tested for estimating stand forest volume. The approach is based on this idea that forest volume can be estimated by variation of trees height at plots. In the other word, the more the height variation in plot, the more the stand volume would be expected. For testing this idea, 120 circular 0.1 ha sample plots with systematic random design has been collected in Tonekaon forest located in Hyrcanian zone. Digital surface model (DSM) measure the height values of the first surface on the ground including terrain features, trees, building etc, which provides a topographic model of the earth's surface. The DSMs have been extracted automatically from aerial UltraCamD images so that ground pixel size for extracted DSM varied from 1 to 10 m size by 1m span. DSMs were checked manually for probable errors. Corresponded to ground samples, standard deviation and range of DSM pixels have been calculated. For modeling, non-linear regression method was used. The results showed that standard deviation of plot pixels with 5 m resolution was the most appropriate data for modeling. Relative bias and RMSE of estimation was 5.8 and 49.8 percent, respectively. Comparing to other approaches for estimating stand volume based on passive remote sensing data in mixed broadleaves forests, these results are more encouraging. One big problem in this method occurs when trees canopy cover is totally closed. In this situation, the standard deviation of height is low while stand volume is high. In future studies, applying forest stratification could be studied.

Evaluation of a Wipe Surface Sample Method for Collection of Bacillus Spores from Nonporous Surfaces▿

PubMed Central

Brown, Gary S.; Betty, Rita G.; Brockmann, John E.; Lucero, Daniel A.; Souza, Caroline A.; Walsh, Kathryn S.; Boucher, Raymond M.; Tezak, Mathew; Wilson, Mollye C.; Rudolph, Todd

2007-01-01

Polyester-rayon blend wipes were evaluated for efficiency of extraction and recovery of powdered Bacillus atrophaeus spores from stainless steel and painted wallboard surfaces. Method limits of detection were also estimated for both surfaces. The observed mean efficiency of polyester-rayon blend wipe recovery from stainless steel was 0.35 with a standard deviation of ±0.12, and for painted wallboard it was 0.29 with a standard deviation of ±0.15. Evaluation of a sonication extraction method for the polyester-rayon blend wipes produced a mean extraction efficiency of 0.93 with a standard deviation of ±0.09. Wipe recovery quantitative limits of detection were estimated at 90 CFU per unit of stainless steel sample area and 105 CFU per unit of painted wallboard sample area. The method recovery efficiency and limits of detection established in this work provide useful guidance for the planning of incident response environmental sampling following the release of a biological agent such as Bacillus anthracis. PMID:17122390

Evaluation of a wipe surface sample method for collection of Bacillus spores from nonporous surfaces.

PubMed

Brown, Gary S; Betty, Rita G; Brockmann, John E; Lucero, Daniel A; Souza, Caroline A; Walsh, Kathryn S; Boucher, Raymond M; Tezak, Mathew; Wilson, Mollye C; Rudolph, Todd

2007-02-01

Polyester-rayon blend wipes were evaluated for efficiency of extraction and recovery of powdered Bacillus atrophaeus spores from stainless steel and painted wallboard surfaces. Method limits of detection were also estimated for both surfaces. The observed mean efficiency of polyester-rayon blend wipe recovery from stainless steel was 0.35 with a standard deviation of +/-0.12, and for painted wallboard it was 0.29 with a standard deviation of +/-0.15. Evaluation of a sonication extraction method for the polyester-rayon blend wipes produced a mean extraction efficiency of 0.93 with a standard deviation of +/-0.09. Wipe recovery quantitative limits of detection were estimated at 90 CFU per unit of stainless steel sample area and 105 CFU per unit of painted wallboard sample area. The method recovery efficiency and limits of detection established in this work provide useful guidance for the planning of incident response environmental sampling following the release of a biological agent such as Bacillus anthracis.

Growth Patterns in the Irish Pyridoxine Nonresponsive Homocystinuria Population and the Influence of Metabolic Control and Protein Intake

PubMed Central

Coughlan, Aoife; Grant, Tim; McNulty, Jenny; Clark, Anne; Deverell, Deirdre; Mayne, Philip; Hughes, Joanne; Monavari, Ahmad; Knerr, Ina; Crushell, Ellen

2017-01-01

A low methionine diet is the mainstay of treatment for pyridoxine nonresponsive homocystinuria (HCU). There are various guidelines for recommended protein intakes for HCU and clinical practice varies. Poor growth has been associated with low cystine levels. This retrospective review of 48 Irish pyridoxine nonresponsive HCU patients assessed weight, height, body mass index (BMI), protein intake, and metabolic control up to 18 years at nine set time points. Patients diagnosed through newborn screening (NBS) were compared to late diagnosed (LD) patients. At 18 years the LD group (n = 12, mean age at diagnosis 5.09 years) were heavier (estimated effect +4.97 Kg, P = 0.0058) and taller (estimated effect +7.97 cm P = 0.0204) than the NBS group (n = 36). There was no difference in growth rate between the groups after 10 years of age. The HCU population were heavier and taller than the general population by one standard deviation with no difference in BMI. There was no association between intermittently low cystine levels and height. Three protein intake guidelines were compared; there was no difference in adult height between those who met the lowest of the guidelines (Genetic Metabolic Dietitians International) and those with a higher protein intake. PMID:29270317

The BGS magnetic field candidate models for the 12th generation IGRF

NASA Astrophysics Data System (ADS)

Hamilton, Brian; Ridley, Victoria A.; Beggan, Ciarán D.; Macmillan, Susan

2015-05-01

We describe the candidate models submitted by the British Geological Survey for the 12th generation International Geomagnetic Reference Field. These models are extracted from a spherical harmonic `parent model' derived from vector and scalar magnetic field data from satellite and observatory sources. These data cover the period 2009.0 to 2014.7 and include measurements from the recently launched European Space Agency (ESA) Swarm satellite constellation. The parent model's internal field time dependence for degrees 1 to 13 is represented by order 6 B-splines with knots at yearly intervals. The parent model's degree 1 external field time dependence is described by periodic functions for the annual and semi-annual signals and by dependence on the 20-min Vector Magnetic Disturbance index. Signals induced by these external fields are also parameterized. Satellite data are weighted by spatial density and by two different noise estimators: (a) by standard deviation along segments of the satellite track and (b) a larger-scale noise estimator defined in terms of a measure of vector activity at the geographically closest magnetic observatories to the sample point. Forecasting of the magnetic field secular variation beyond the span of data is by advection of the main field using core surface flows.

STOCK MARKET CRASH AND EXPECTATIONS OF AMERICAN HOUSEHOLDS*

PubMed Central

HUDOMIET, PÉTER; KÉZDI, GÁBOR; WILLIS, ROBERT J.

2011-01-01

SUMMARY This paper utilizes data on subjective probabilities to study the impact of the stock market crash of 2008 on households’ expectations about the returns on the stock market index. We use data from the Health and Retirement Study that was fielded in February 2008 through February 2009. The effect of the crash is identified from the date of the interview, which is shown to be exogenous to previous stock market expectations. We estimate the effect of the crash on the population average of expected returns, the population average of the uncertainty about returns (subjective standard deviation), and the cross-sectional heterogeneity in expected returns (disagreement). We show estimates from simple reduced-form regressions on probability answers as well as from a more structural model that focuses on the parameters of interest and separates survey noise from relevant heterogeneity. We find a temporary increase in the population average of expectations and uncertainty right after the crash. The effect on cross-sectional heterogeneity is more significant and longer lasting, which implies substantial long-term increase in disagreement. The increase in disagreement is larger among the stockholders, the more informed, and those with higher cognitive capacity, and disagreement co-moves with trading volume and volatility in the market. PMID:21547244

Site index curves for young-growth California white fir on the western slopes of the Sierra Nevada

Treesearch

K. Leroy Dolph

1987-01-01

Site index curves for young-growth California white fir were developed by using stem analysis data from 77 dominant and codominant trees growing in mixed-coniferstands on the western slopes of the Sierra Nevada. Site index reference age is 50 years at breast height. A family of 11 curves is presented for site index estimation. For more precise estimates, the site index...

Using a laser source to measure the refractive index of glass beads and Debye theory analysis.

PubMed

Li, Shui-Yan; Qin, Shuang; Li, Da-Hai; Wang, Qiong-Hua

2015-11-20

Using a monochromatic laser beam to illuminate a homogeneous glass bead, some rainbows will appear around it. This paper concentrates on the study of the scattering intensity distribution and the method of measuring the refractive index for glass beads based on the Debye theory. It is found that the first rainbow due to the scattering superposition of backward light of the low-refractive-index glass beads can be explained approximately with the diffraction, the external reflection plus the one internal reflection, while the second rainbow of high-refractive-index glass beads is due to the contribution from the diffraction, the external reflection, the direct transmission, and the two internal reflections. The scattering intensity distribution is affected by the refractive index, the radius of the glass bead, and the incident beam width. The effects of the refractive index and the glass bead size on the first and second minimum deviation angle position are analyzed in this paper. The results of the measurements agree very well with the specifications.

Determining site index accurately in even-aged stands

Treesearch

Gayne G. Erdmann; Ralph M., Jr. Peterson

1992-01-01

Good site index estimates are necessary for intensive forest management. To get tree age used in determining site index, increment cores are commonly used. The diffuse-porous rings of northern hardwoods, though, are difficult to count in cores, so many site index estimates are imprecise. Also, measuring the height of standing trees is more difficult and less accurate...

Borehole deviation and correction factor data for selected wells in the eastern Snake River Plain aquifer at and near the Idaho National Laboratory, Idaho

USGS Publications Warehouse

Twining, Brian V.

2016-11-29

The U.S. Geological Survey (USGS), in cooperation with the U.S. Department of Energy, has maintained a water-level monitoring program at the Idaho National Laboratory (INL) since 1949. The purpose of the program is to systematically measure and report water-level data to assess the eastern Snake River Plain aquifer and long term changes in groundwater recharge, discharge, movement, and storage. Water-level data are commonly used to generate potentiometric maps and used to infer increases and (or) decreases in the regional groundwater system. Well deviation is one component of water-level data that is often overlooked and is the result of the well construction and the well not being plumb. Depending on measured slant angle, where well deviation generally increases linearly with increasing slant angle, well deviation can suggest artificial anomalies in the water table. To remove the effects of well deviation, the USGS INL Project Office applies a correction factor to water-level data when a well deviation survey indicates a change in the reference elevation of greater than or equal to 0.2 ft.Borehole well deviation survey data were considered for 177 wells completed within the eastern Snake River Plain aquifer, but not all wells had deviation survey data available. As of 2016, USGS INL Project Office database includes: 57 wells with gyroscopic survey data; 100 wells with magnetic deviation survey data; 11 wells with erroneous gyroscopic data that were excluded; and, 68 wells with no deviation survey data available. Of the 57 wells with gyroscopic deviation surveys, correction factors for 16 wells ranged from 0.20 to 6.07 ft and inclination angles (SANG) ranged from 1.6 to 16.0 degrees. Of the 100 wells with magnetic deviation surveys, a correction factor for 21 wells ranged from 0.20 to 5.78 ft and SANG ranged from 1.0 to 13.8 degrees, not including the wells that did not meet the correction factor criteria of greater than or equal to 0.20 ft.Forty-seven wells had gyroscopic and magnetic deviation survey data for the same well. Datasets for both survey types were compared for the same well to determine whether magnetic survey data were consistent with gyroscopic survey data. Of those 47 wells, 96 percent showed similar correction factor estimates (≤ 0.20 ft) for both magnetic and gyroscopic well deviation surveys. A linear comparison of correction factor estimates for both magnetic and gyroscopic deviation well surveys for all 47 wells indicate good linear correlation, represented by an r-squared of 0.88. The correction factor difference between the gyroscopic and magnetic surveys for 45 of 47 wells ranged from 0.00 to 0.18 ft, not including USGS 57 and USGS 125. Wells USGS 57 and USGS 125 show a correction factor difference of 2.16 and 0.36 ft, respectively; however, review of the data files suggest erroneous SANG data for both magnetic deviation well surveys. The difference in magnetic and gyroscopic well deviation SANG measurements, for all wells, ranged from 0.0 to 0.9 degrees. These data indicate good agreement between SANG data measured using the magnetic deviation survey methods and SANG data measured using gyroscopic deviation survey methods, even for surveys collected years apart.

Estimates of site index and height growth for Douglas-fir in high-elevation forests of the Oregon-Washington Cascade Range: curves and tables for field application.

Treesearch

Donald J. DeMars; Francis R. Herman

1987-01-01

Estimation equations for height growth and site index were derived from stem-analysis data of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) in the highelevation forests of the Cascade Range in Oregon and Washington. Two sets of height-growth and site-index estimation curves and tables produced from...

Temporal variability of spectro-temporal receptive fields in the anesthetized auditory cortex.

PubMed

Meyer, Arne F; Diepenbrock, Jan-Philipp; Ohl, Frank W; Anemüller, Jörn

2014-01-01

Temporal variability of neuronal response characteristics during sensory stimulation is a ubiquitous phenomenon that may reflect processes such as stimulus-driven adaptation, top-down modulation or spontaneous fluctuations. It poses a challenge to functional characterization methods such as the receptive field, since these often assume stationarity. We propose a novel method for estimation of sensory neurons' receptive fields that extends the classic static linear receptive field model to the time-varying case. Here, the long-term estimate of the static receptive field serves as the mean of a probabilistic prior distribution from which the short-term temporally localized receptive field may deviate stochastically with time-varying standard deviation. The derived corresponding generalized linear model permits robust characterization of temporal variability in receptive field structure also for highly non-Gaussian stimulus ensembles. We computed and analyzed short-term auditory spectro-temporal receptive field (STRF) estimates with characteristic temporal resolution 5-30 s based on model simulations and responses from in total 60 single-unit recordings in anesthetized Mongolian gerbil auditory midbrain and cortex. Stimulation was performed with short (100 ms) overlapping frequency-modulated tones. Results demonstrate identification of time-varying STRFs, with obtained predictive model likelihoods exceeding those from baseline static STRF estimation. Quantitative characterization of STRF variability reveals a higher degree thereof in auditory cortex compared to midbrain. Cluster analysis indicates that significant deviations from the long-term static STRF are brief, but reliably estimated. We hypothesize that the observed variability more likely reflects spontaneous or state-dependent internal fluctuations that interact with stimulus-induced processing, rather than experimental or stimulus design.

Brain mass estimation by head circumference and body mass methods in neonatal glycaemic modelling and control.

PubMed

Gunn, Cameron Allan; Dickson, Jennifer L; Pretty, Christopher G; Alsweiler, Jane M; Lynn, Adrienne; Shaw, Geoffrey M; Chase, J Geoffrey

2014-07-01

Hyperglycaemia is a common complication of stress and prematurity in extremely low-birth-weight infants. Model-based insulin therapy protocols have the ability to safely improve glycaemic control for this group. Estimating non-insulin-mediated brain glucose uptake by the central nervous system in these models is typically done using population-based body weight models, which may not be ideal. A head circumference-based model that separately treats small-for-gestational-age (SGA) and appropriate-for-gestational-age (AGA) infants is compared to a body weight model in a retrospective analysis of 48 patients with a median birth weight of 750g and median gestational age of 25 weeks. Estimated brain mass, model-based insulin sensitivity (SI) profiles, and projected glycaemic control outcomes are investigated. SGA infants (5) are also analyzed as a separate cohort. Across the entire cohort, estimated brain mass deviated by a median 10% between models, with a per-patient median difference in SI of 3.5%. For the SGA group, brain mass deviation was 42%, and per-patient SI deviation 13.7%. In virtual trials, 87-93% of recommended insulin rates were equal or slightly reduced (Δ<0.16mU/h) under the head circumference method, while glycaemic control outcomes showed little change. The results suggest that body weight methods are not as accurate as head circumference methods. Head circumference-based estimates may offer improved modelling accuracy and a small reduction in insulin administration, particularly for SGA infants. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Type I Error Rates and Power Estimates of Selected Parametric and Nonparametric Tests of Scale.

ERIC Educational Resources Information Center

Olejnik, Stephen F.; Algina, James

1987-01-01

Estimated Type I Error rates and power are reported for the Brown-Forsythe, O'Brien, Klotz, and Siegal-Tukey procedures. The effect of aligning the data using deviations from group means or group medians is investigated. (RB)

How does spatial and temporal resolution of vegetation index impact crop yield estimation?

USDA-ARS?s Scientific Manuscript database

Timely and accurate estimation of crop yield before harvest is critical for food market and administrative planning. Remote sensing data have long been used in crop yield estimation for decades. The process-based approach uses light use efficiency model to estimate crop yield. Vegetation index (VI) ...

Measurement-based estimates of direct radiative effects of absorbing aerosols above clouds

NASA Astrophysics Data System (ADS)

Feng, Nan; Christopher, Sundar A.

2015-07-01

The elevated layers of absorbing smoke aerosols from western African (e.g., Gabon and Congo) biomass burning activities have been frequently observed above low-level stratocumulus clouds off the African coast, which presents an excellent natural laboratory for studying the effects of aerosols above clouds (AAC) on regional energy balance in tropical and subtropical environments. Using spatially and temporally collocated Moderate Resolution Imaging Spectroradiometer, Ozone Monitoring Instrument (OMI), and Clouds and the Earth's Radiant Energy System data sets, the top-of-atmosphere shortwave aerosol direct shortwave radiative effects (ARE) of absorbing aerosols above low-level water clouds in the southeast Atlantic Ocean was examined in this study. The regional averaged instantaneous ARE has been estimated to be 36.7 ± 20.5 Wm-2 (regional mean ± standard deviation) along with a mean positive OMI Aerosol Index at 1.3 in August 2006 based on multisensors measurements. The highest magnitude of instantaneous ARE can even reach 138.2 Wm-2. We assess that the 660 nm cloud optical depth (COD) values of 8-12 is the critical value above (below) which aerosol absorption (scattering) effect dominates and further produces positive (negative) ARE values. The results further show that ARE values are more sensitive to aerosols above lower COD values than cases for higher COD values. This is among the first studies to provide quantitative estimates of shortwave ARE due to AAC events from an observational perspective.

Tests of a habitat suitability model for black-capped chickadees

USGS Publications Warehouse

Schroeder, Richard L.

1990-01-01

The black-capped chickadee (Parus atricapillus) Habitat Suitability Index (HSI) model provides a quantitative rating of the capability of a habitat to support breeding, based on measures related to food and nest site availability. The model assumption that tree canopy volume can be predicted from measures of tree height and canopy closure was tested using data from foliage volume studies conducted in the riparian cottonwood habitat along the South Platte River in Colorado. Least absolute deviations (LAD) regression showed that canopy cover and over story tree height yielded volume predictions significantly lower than volume estimated by more direct methods. Revisions to these model relations resulted in improved predictions of foliage volume. The relation between the HSI and estimates of black-capped chickadee population densities was examined using LAD regression for both the original model and the model with the foliage volume revisions. Residuals from these models were compared to residuals from both a zero slope model and an ideal model. The fit model for the original HSI differed significantly from the ideal model, whereas the fit model for the original HSI did not differ significantly from the ideal model. However, both the fit model for the original HSI and the fit model for the revised HSI did not differ significantly from a model with a zero slope. Although further testing of the revised model is needed, its use is recommended for more realistic estimates of tree canopy volume and habitat suitability.

Mapping between 6 Multiattribute Utility Instruments.

PubMed

Chen, Gang; Khan, Munir A; Iezzi, Angelo; Ratcliffe, Julie; Richardson, Jeff

2016-02-01

Cost-utility analyses commonly employ a multiattribute utility (MAU) instrument to estimate the health state utilities, which are needed to calculate quality-adjusted life years. Different MAU instruments predict significantly different utilities, which makes comparison of results from different evaluation studies problematical. This article presents mapping functions ("crosswalks") from 6 MAU instruments (EQ-5D-5L, SF-6D, Health Utilities Index 3 [HUI 3], 15D, Quality of Well-Being [QWB], and Assessment of Quality of Life 8D [AQoL-8D]) to each of the other 5 instruments in the study: a total of 30 mapping functions. Data were obtained from a multi-instrument comparison survey of the public and patients in 7 disease areas conducted in 6 countries (Australia, Canada, Germany, Norway, United Kingdom, and United States). The 8022 respondents were administered each of the 6 study instruments. Mapping equations between each instrument pair were estimated using 4 econometric techniques: ordinary least squares, generalized linear model, censored least absolute deviations, and, for the first time, a robust MM-estimator. Goodness-of-fit indicators for each of the results are within the range of published studies. Transformations reduced discrepancies between predicted utilities. Incremental utilities, which determine the value of quality-related health benefits, are almost perfectly aligned at the sample means. Transformations presented here align the measurement scales of MAU instruments. Their use will increase confidence in the comparability of evaluation studies, which have employed different MAU instruments. © The Author(s) 2015.

Index/Ring Finger Ratio, Hand and Foot Index: Gender Estimation Tools.

PubMed

Gupta, Sonia; Gupta, Vineeta; Tyagi, Nutan; Ettishree; Bhagat, Sinthia; Dadu, Mohit; Anthwal, Nishita; Ashraf, Tahira

2017-06-01

Gender estimation from dismembered human body parts and skeletal remains in cases of mass disasters, explosions, and assaults cases is an imperative element of any medico-legal investigations and has been a major challenge for forensic scientists. The aim of the present study was to estimate the gender by using index and ring finger length ratio, hand and foot index along with the correlation of both the hand and foot index to determine the vital role of all the indices in establishing gender identity. A descriptive cross-sectional study was done on 300 subjects (150 males and 150 females). Various anthropometric measurements like hand length, hand breadth and hand index, Index Finger Length (IFL), Ring Finger Length (RFL) and IFL/RFL ratio as well as foot length, foot breadth and foot index were estimated in millimeters (mm) with the help of sliding-anthropometric caliper. The data was analysed using independent t-test and Pearson correlation coefficient test. A probability value (p) of ≤ 0.05 was considered statistically significant. The index and ring finger ratio was found to be higher in females as compared to males. The hand and foot index was more in males than in females. The index and ring finger length ratio, hand and foot index between males and females was found to be statistically significant for both hands and feet. A statistically significant correlation was determined between hand indexes versus foot index. This study can be useful to establish the gender of a dismembered hand or foot when subjected for medicolegal examination.

Advancing Underwater Acoustic Communication for Autonomous Distributed Networks via Sparse Channel Sensing, Coding, and Navigation Support

DTIC Science & Technology

2012-09-30

Estimation Methods for Underwater OFDM 5) Two Iterative Receivers for Distributed MIMO - OFDM with Large Doppler Deviations. 6) Asynchronous Multiuser...multi-input multi-output ( MIMO ) OFDM is also pursued, where it is shown that the proposed hybrid initialization enables drastically improved receiver...are investigated. 5) Two Iterative Receivers for Distributed MIMO - OFDM with Large Doppler Deviations. This work studies a distributed system with

A critical assessment of two types of personal UV dosimeters.

PubMed

Seckmeyer, Gunther; Klingebiel, Marcus; Riechelmann, Stefan; Lohse, Insa; McKenzie, Richard L; Liley, J Ben; Allen, Martin W; Siani, Anna-Maria; Casale, Giuseppe R

2012-01-01

Doses of erythemally weighted irradiances derived from polysulphone (PS) and electronic ultraviolet (EUV) dosimeters have been compared with measurements obtained using a reference spectroradiometer. PS dosimeters showed mean absolute deviations of 26% with a maximum deviation of 44%, the calibrated EUV dosimeters showed mean absolute deviations of 15% (maximum 33%) around noon during several test days in the northern hemisphere autumn. In the case of EUV dosimeters, measurements with various cut-off filters showed that part of the deviation from the CIE erythema action spectrum was due to a small, but significant sensitivity to visible radiation that varies between devices and which may be avoided by careful preselection. Usually the method of calibrating UV sensors by direct comparison to a reference instrument leads to reliable results. However, in some circumstances the quality of measurements made with simple sensors may be over-estimated. In the extreme case, a simple pyranometer can be used as a UV instrument, providing acceptable results for cloudless skies, but very poor results under cloudy conditions. It is concluded that while UV dosimeters are useful for their design purpose, namely to estimate personal UV exposures, they should not be regarded as an inexpensive replacement for meteorological grade instruments. © 2011 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2011 The American Society of Photobiology.

Estimating search engine index size variability: a 9-year longitudinal study.

PubMed

van den Bosch, Antal; Bogers, Toine; de Kunder, Maurice

One of the determining factors of the quality of Web search engines is the size of their index. In addition to its influence on search result quality, the size of the indexed Web can also tell us something about which parts of the WWW are directly accessible to the everyday user. We propose a novel method of estimating the size of a Web search engine's index by extrapolating from document frequencies of words observed in a large static corpus of Web pages. In addition, we provide a unique longitudinal perspective on the size of Google and Bing's indices over a nine-year period, from March 2006 until January 2015. We find that index size estimates of these two search engines tend to vary dramatically over time, with Google generally possessing a larger index than Bing. This result raises doubts about the reliability of previous one-off estimates of the size of the indexed Web. We find that much, if not all of this variability can be explained by changes in the indexing and ranking infrastructure of Google and Bing. This casts further doubt on whether Web search engines can be used reliably for cross-sectional webometric studies.

Estimation of genetic variance for macro- and micro-environmental sensitivity using double hierarchical generalized linear models.

PubMed

Mulder, Han A; Rönnegård, Lars; Fikse, W Freddy; Veerkamp, Roel F; Strandberg, Erling

2013-07-04

Genetic variation for environmental sensitivity indicates that animals are genetically different in their response to environmental factors. Environmental factors are either identifiable (e.g. temperature) and called macro-environmental or unknown and called micro-environmental. The objectives of this study were to develop a statistical method to estimate genetic parameters for macro- and micro-environmental sensitivities simultaneously, to investigate bias and precision of resulting estimates of genetic parameters and to develop and evaluate use of Akaike's information criterion using h-likelihood to select the best fitting model. We assumed that genetic variation in macro- and micro-environmental sensitivities is expressed as genetic variance in the slope of a linear reaction norm and environmental variance, respectively. A reaction norm model to estimate genetic variance for macro-environmental sensitivity was combined with a structural model for residual variance to estimate genetic variance for micro-environmental sensitivity using a double hierarchical generalized linear model in ASReml. Akaike's information criterion was constructed as model selection criterion using approximated h-likelihood. Populations of sires with large half-sib offspring groups were simulated to investigate bias and precision of estimated genetic parameters. Designs with 100 sires, each with at least 100 offspring, are required to have standard deviations of estimated variances lower than 50% of the true value. When the number of offspring increased, standard deviations of estimates across replicates decreased substantially, especially for genetic variances of macro- and micro-environmental sensitivities. Standard deviations of estimated genetic correlations across replicates were quite large (between 0.1 and 0.4), especially when sires had few offspring. Practically, no bias was observed for estimates of any of the parameters. Using Akaike's information criterion the true genetic model was selected as the best statistical model in at least 90% of 100 replicates when the number of offspring per sire was 100. Application of the model to lactation milk yield in dairy cattle showed that genetic variance for micro- and macro-environmental sensitivities existed. The algorithm and model selection criterion presented here can contribute to better understand genetic control of macro- and micro-environmental sensitivities. Designs or datasets should have at least 100 sires each with 100 offspring.

Standardized Precipitation Index (SPI) over the Mediterranean region based on high resolution gridded data.

NASA Astrophysics Data System (ADS)

Polychroni, Iliana; Nastos, Panagiotis

2017-04-01

Mediterranean water resource system is heavily influenced by changes in climate conditions, which in turns affect significantly the socioeconomic development, specifically over coastal areas. Taking into consideration that the surface temperature is projected to rise over the 21st century and the mean precipitation is likely to decrease in mid-latitude dry regions, according to IPCC 2014, we confronted the challenge to study the drought over the Mediterranean region by means of the Standardized Precipitation Index (SPI), defined as the difference from the mean for a specified time period divided by the standard deviation, where the mean and standard deviation are determined from past records. Drought is a long-range phenomenon that affects the Mediterranean. The drought not only affects food production but also has severe environmental, economic and social impacts. The objective of this study is to assess and analyze the spatio-temporal evolution of the SPI for 3-, 6-, 9-, 12- month timescales, during the period 1950-2015. For this purpose, we processed high resolution gridded daily precipitation datasets (0.25° x 0.25°), based on the E-OBS dataset from ECA&D. Mean SPI patterns and trends for the whole examined period, as well as successive 30-year periods, were assessed by using R-project. Moreover, the influence of the well-known atmospheric circulation index of the wider region of Europe, namely the North Atlantic Oscillation Index (NAOI), on the SPI over the Mediterranean was considered necessary to evaluate, because NAOI strongly modulates precipitation over Europe and the Mediterranean.

Childhood body weight in relation to morbidity from cardiovascular disease and cancer in older adulthood: 67-year follow-up of participants in the 1947 Scottish Mental Survey.

PubMed

Batty, G David; Calvin, Catherine M; Brett, Caroline E; Čukić, Iva; Deary, Ian J

2015-11-01

Although it has been well documented that elevated body weight in middle- and older-aged populations is associated with multiple morbidities, the influence of childhood body weight on health endpoints other than coronary heart disease is not well understood. Accordingly, using a subsample of 4,620 participants (2,288 women) from the Scottish Mental Survey of 1947, we examined the association between body mass index measured at 11 years of age and future risk of 9 independent health endpoints as ascertained from national hospital admissions and cancer registers until 2014 (up to age 77 years). Although there was some evidence of a relationship between elevated childhood body mass index and higher rates of peripheral vascular disease (per each 1-standard deviation increase in body mass index, hazard ratio = 1.21, 95% confidence interval: 1.07, 1.37) and smoking-related cancers (per each 1-standard deviation increase in body mass index, hazard ratio = 1.09, 95% confidence interval: 1.01, 1.17), there was no apparent association with coronary heart disease, stroke (including ischemic stroke), heart failure, or carcinomas of the colorectum, stomach, lung, prostate, or breast. In conclusion, a relationship between childhood body weight and later morbidity was largely lacking in the present study. © The Author 2015. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

A refractometry-based glucose analysis of body fluids.

PubMed

Zirk, Kai; Poetzschke, Harald

2007-05-01

In principle, refractometry appears to be a suitable method for the measurement of glucose concentrations in body fluids (such as blood and the intercellular fluid), even though the refractive index of the measured samples, as an additive property, is not specific. But, if certain conditions are fulfilled, the glucose content can be calculated using the refractive index in combination with values from a further measurement. This study describes the determination of the glucose content using refractometry in human blood serum derivates, which were selected - due to their ready availability - to be used as a model for interstitial fluid. Refractometry of body fluids requires the elimination of disturbing components from the measurement sample. First of all, a homogenous fluid (i.e. consisting of one phase) is required, so that all cells and components in suspension need to be separated out. Furthermore, certain dissolved macromolecular components which are known to disturb the measurement process must also be removed. In human serum samples which had been ultrafiltrated with a range of ultrafilters of different pore sizes, a comparative evaluation showed that only ultrafiltration through a filter with a separation limit of between 3 and 30kDa resulted in maximal reduction of the refractive index (compared to native serum), whereas ultrafilters with greater separation limits did not. The total content of osmotically active solutes (the tonicity) also exerts a clear influence. However, exemplary measurements in blood plasma fluid from one volunteer showed that the electrical conductivity is (without an additive component) directly proportional to the osmolality: physiological changes in the state of body hydration (hyperhydration and dehydration) do not lead to any considerable changes in the relation between ionised and uncharged solute particles, but instead result in a sufficiently clear dilution or concentration of the blood fluid's low molecular components. This finding allows the use of the--technically easy to measure--electrical conductivity as a measure for the tonicity of the measurement samples. Using measurements of these two parameters--refractive index and electrical conductivity--in blood serum obtained from a healthy volunteer, a two-dimensional calibration function (calibration matrix) for the assessment of the glucose content of ultrafiltrated human blood serum was constructed, and the measurement of blood glucose levels in non-diabetic (four females and four males) volunteers in comparison to a reference method was evaluated showing (as a proof of concept) a linear association. Assessment of the inaccuracy of these measurements made with the described measuring devices and methods showed a deviation from the reference values of less than 10%. An estimation of the maximum possible error showed relative deviations (maximum measurement uncertainties) of up to 20%.

Rapid assessment of mid-infrared refractive index anisotropy using a prism coupler: chemical vapor deposited ZnS

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

Qiao, Hong; Lipschultz, Kristen A.; Anheier, Norman C.

2012-04-01

A state-of-the-art mid-infrared prism coupler was used to study the refractive index properties of forward-looking-infrared (FLIR) grade zinc sulfide samples prepared with unique planar grain orientations and locations with respect to the CVD growth axis. This study was motivated by prior photoluminescence and x-ray diffraction measurements that suggested refractive index may vary according to grain orientation. Measurements were conducted to provide optical dispersion and thermal index (dn/dT) data at discrete laser wavelengths between 0.633 and 10.591 {mu}m at two temperature set points (30 C and 90 C). Refractive index measurements between samples exhibited an average standard deviation comparable to themore » uncertainty of the prism coupler measurement (0.0004 refractive index units), suggesting that the variation in refractive index as a function of planar grain orientation and CVD deposition time is negligible, and should have no impact on subsequent optical designs. Measured dispersion data at mid-infrared wavelengths was found to agree well with prior published measurements.« less

Closed-form confidence intervals for functions of the normal mean and standard deviation.

PubMed

Donner, Allan; Zou, G Y

2012-08-01

Confidence interval methods for a normal mean and standard deviation are well known and simple to apply. However, the same cannot be said for important functions of these parameters. These functions include the normal distribution percentiles, the Bland-Altman limits of agreement, the coefficient of variation and Cohen's effect size. We present a simple approach to this problem by using variance estimates recovered from confidence limits computed for the mean and standard deviation separately. All resulting confidence intervals have closed forms. Simulation results demonstrate that this approach performs very well for limits of agreement, coefficients of variation and their differences.

Grassland Aboveground Biomass in Inner Mongolia: Dynamics (2001-2016) and Driving force

NASA Astrophysics Data System (ADS)

Li, F.; Zeng, Y.; Chen, J.; Wu, B.

2017-12-01

Plant biomass is the most critical measure of carbon stored in an ecosystem, yet it remains imprecisely modeled for many terrestrial biomes. This lack of modeling capacity for biomass and its change through time and space has impeded scientists from making headway concerning issues in the geographic and social sciences. Satellite remote sensing techniques excel at detecting changes in the Earth's surface; however, accurate estimates of biomass for the heterogeneous biome landscapes based on remote sensing techniques are few and far between, which has led to many repetitive studies. Here, we argued that our ability to assess biomass in a heterogeneous landscape using satellite remote sensing techniques would be effectively enhanced through a stratification of landscapes, i.e homogenizing landscapes. Specifically, above-ground biomass (AGB) for an extended heterogeneous grassland biome over the entirety of Inner Mongolia during the past 16 years (2001-2016) was explored using remote sensing time series data from the Moderate Resolution Imaging Spectroradiometer (MODIS). Massive and extensive in-situ measurement AGB data and pure vegetation index (PVI) models, developed from normal remote sensing vegetation indices such as the normalized difference vegetation index (NDVI) and the enhanced vegetation index (EVI), were highlighted in the accomplishment of this study. Taking into full consideration the landscape heterogeneity for the grassland biome over Inner Mongolia, we achieved a series of AGB models with high R2 (>0.85) and low RMSE ( 20.85 g/m2). The total average amount of fresh AGB for the entirety of Inner Mongolia grasslands over the past 16 years was estimated as 87 Tg with an inter-annual standard deviation of 9 Tg. Overall, the grassland AGB for Inner Mongolia increased sporadically. We found that the dynamics of AGB in the grassland biome of Inner Mongolia were substantially dominated by variation in precipitation despite the accommodation of a huge population of livestock in this area over the past few decades. Concerning the production of grassland AGB for the future, we emphasized that the impacts of the frequently warming-drying climate associated with climate change across the Mongolia Plateau should be paid more attention.

The impact of individual materials parameters on color temperature reproducibility among phosphor converted LED sources

NASA Astrophysics Data System (ADS)

Schweitzer, Susanne; Nemitz, Wolfgang; Sommer, Christian; Hartmann, Paul; Fulmek, Paul; Nicolics, Johann; Pachler, Peter; Hoschopf, Hans; Schrank, Franz; Langer, Gregor; Wenzl, Franz P.

2014-09-01

For a systematic approach to improve the white light quality of phosphor converted light-emitting diodes (LEDs) for general lighting applications it is imperative to get the individual sources of error for color temperature reproducibility under control. In this regard, it is imperative to understand how compositional, optical and materials properties of the color conversion element (CCE), which typically consists of phosphor particles embedded in a transparent matrix material, affect the constancy of a desired color temperature of a white LED source. In this contribution we use an LED assembly consisting of an LED die mounted on a printed circuit board (PCB) by chip-on-board technology and a CCE with a glob-top configuration as a model system and discuss the impact of potential sources for color temperature deviation among individual devices. Parameters that are investigated include imprecisions in the amount of materials deposition, deviations from the target value for the phosphor concentration in the matrix material, deviations from the target value for the particle sizes of the phosphor material, deviations from the target values for the refractive indexes of phosphor and matrix material as well as deviations from the reflectivity of the substrate surface. From these studies, some general conclusions can be drawn which of these parameters have the largest impact on color deviation and have to be controlled most precisely in a fabrication process in regard of color temperature reproducibility among individual white LED sources.

Extreme statistics and index distribution in the classical 1d Coulomb gas

NASA Astrophysics Data System (ADS)

Dhar, Abhishek; Kundu, Anupam; Majumdar, Satya N.; Sabhapandit, Sanjib; Schehr, Grégory

2018-07-01

We consider a 1D gas of N charged particles confined by an external harmonic potential and interacting via the 1D Coulomb potential. For this system we show that in equilibrium the charges settle, on an average, uniformly and symmetrically on a finite region centred around the origin. We study the statistics of the position of the rightmost particle and show that the limiting distribution describing its typical fluctuations is different from the Tracy–Widom distribution found in the 1D log-gas. We also compute the large deviation functions which characterise the atypical fluctuations of far away from its mean value. In addition, we study the gap between the two rightmost particles as well as the index N + , i.e. the number of particles on the positive semi-axis. We compute the limiting distributions associated to the typical fluctuations of these observables as well as the corresponding large deviation functions. We provide numerical supports to our analytical predictions. Part of these results were announced in a recent letter, Dhar et al (2017 Phys. Rev. Lett. 119 060601).

Current organ allocation disadvantages kidney alone recipients over combined organ recipients.

PubMed

Martin, Michael S; Hagan, Michael E; Granger, Darla K

2016-03-01

The United Network for Organ Sharing began including the Kidney Donor Profile Index (KDPI) March 26, 2012 and began a new allocation scheme December 1, 2014. Kidney donors from our organ procurement organization from March 2012 to December 2014 were reviewed. The KDPIs of all 919 kidney only transplants were compared with all 102 kidney/extrarenal transplants. The average KDPI for kidney alone allografts was 47 (range 1 to 100) (standard deviation = 25.83) vs 27 for kidney/extrarenal kidneys (range 1 to 82) (standard deviation = 20.16) (P < .001, t test). Multivariate analysis including in- vs out-of-state recipient, donor body mass index, and donation after cardiac death vs brain-dead donor showed significantly lower KDPI for kidney/extrarenal transplants. Kidney/extrarenal organs have decreased graft survival compared with kidneys transplanted alone. In this sample, 21% of lower KDPI kidneys were allocated as kidney/extrarenal organs. This disadvantages those waiting for a kidney alone. Attention to the outcomes of kidneys transplanted with extrarenal organs is needed. Copyright © 2016 Elsevier Inc. All rights reserved.

Derivation of an analytic expression for the error associated with the noise reduction rating

NASA Astrophysics Data System (ADS)

Murphy, William J.

2005-04-01

Hearing protection devices are assessed using the Real Ear Attenuation at Threshold (REAT) measurement procedure for the purpose of estimating the amount of noise reduction provided when worn by a subject. The rating number provided on the protector label is a function of the mean and standard deviation of the REAT results achieved by the test subjects. If a group of subjects have a large variance, then it follows that the certainty of the rating should be correspondingly lower. No estimate of the error of a protector's rating is given by existing standards or regulations. Propagation of errors was applied to the Noise Reduction Rating to develop an analytic expression for the hearing protector rating error term. Comparison of the analytic expression for the error to the standard deviation estimated from Monte Carlo simulation of subject attenuations yielded a linear relationship across several protector types and assumptions for the variance of the attenuations.

Estimating Stability Class in the Field

Treesearch

Leonidas G. Lavdas

1997-01-01

A simple and easily remembered method is described for estimating cloud ceiling height in the field. Estimating ceiling height provides the means to estimate stability class, a parameter used to help determine Dispersion Index and Low Visibility Occurrence Risk Index, indices used as smoke management aids. Stability class is also used as an input to VSMOKE, an...

Processing arctic eddy-flux data using a simple carbon-exchange model embedded in the ensemble Kalman filter.

PubMed

Rastetter, Edward B; Williams, Mathew; Griffin, Kevin L; Kwiatkowski, Bonnie L; Tomasky, Gabrielle; Potosnak, Mark J; Stoy, Paul C; Shaver, Gaius R; Stieglitz, Marc; Hobbie, John E; Kling, George W

2010-07-01

Continuous time-series estimates of net ecosystem carbon exchange (NEE) are routinely made using eddy covariance techniques. Identifying and compensating for errors in the NEE time series can be automated using a signal processing filter like the ensemble Kalman filter (EnKF). The EnKF compares each measurement in the time series to a model prediction and updates the NEE estimate by weighting the measurement and model prediction relative to a specified measurement error estimate and an estimate of the model-prediction error that is continuously updated based on model predictions of earlier measurements in the time series. Because of the covariance among model variables, the EnKF can also update estimates of variables for which there is no direct measurement. The resulting estimates evolve through time, enabling the EnKF to be used to estimate dynamic variables like changes in leaf phenology. The evolving estimates can also serve as a means to test the embedded model and reconcile persistent deviations between observations and model predictions. We embedded a simple arctic NEE model into the EnKF and filtered data from an eddy covariance tower located in tussock tundra on the northern foothills of the Brooks Range in northern Alaska, USA. The model predicts NEE based only on leaf area, irradiance, and temperature and has been well corroborated for all the major vegetation types in the Low Arctic using chamber-based data. This is the first application of the model to eddy covariance data. We modified the EnKF by adding an adaptive noise estimator that provides a feedback between persistent model data deviations and the noise added to the ensemble of Monte Carlo simulations in the EnKF. We also ran the EnKF with both a specified leaf-area trajectory and with the EnKF sequentially recalibrating leaf-area estimates to compensate for persistent model-data deviations. When used together, adaptive noise estimation and sequential recalibration substantially improved filter performance, but it did not improve performance when used individually. The EnKF estimates of leaf area followed the expected springtime canopy phenology. However, there were also diel fluctuations in the leaf-area estimates; these are a clear indication of a model deficiency possibly related to vapor pressure effects on canopy conductance.

A Robust and Affordable Table Indexing Approach for Multi-isocenter Dosimetrically Matched Fields.

PubMed

Yu, Amy; Fahimian, Benjamin; Million, Lynn; Hsu, Annie

2017-05-23

Purpose  Radiotherapy treatment planning of extended volume typically necessitates the utilization of multiple field isocenters and abutting dosimetrically matched fields in order to enable coverage beyond the field size limits. A common example includes total lymphoid irradiation (TLI) treatments, which are conventionally planned using dosimetric matching of the mantle, para-aortic/spleen, and pelvic fields. Due to the large irradiated volume and system limitations, such as field size and couch extension, a combination of couch shifts and sliding of patients are necessary to be correctly executed for accurate delivery of the plan. However, shifting of patients presents a substantial safety issue and has been shown to be prone to errors ranging from minor deviations to geometrical misses warranting a medical event. To address this complex setup and mitigate the safety issues relating to delivery, a practical technique for couch indexing of TLI treatments has been developed and evaluated through a retrospective analysis of couch position. Methods The indexing technique is based on the modification of the commonly available slide board to enable indexing of the patient position. Modifications include notching to enable coupling with indexing bars, and the addition of a headrest used to fixate the head of the patient relative to the slide board. For the clinical setup, a Varian Exact Couch TM (Varian Medical Systems, Inc, Palo Alto, CA) was utilized. Two groups of patients were treated: 20 patients with table indexing and 10 patients without. The standard deviations (SDs) of the couch positions in longitudinal, lateral, and vertical directions through the entire treatment cycle for each patient were calculated and differences in both groups were analyzed with Student's t-test. Results The longitudinal direction showed the largest improvement. In the non-indexed group, the positioning SD ranged from 2.0 to 7.9 cm. With the indexing device, the positioning SD was reduced to a range of 0.4 to 1.3 cm (p < 0.05 with 95% confidence level). The lateral positioning was slightly improved (p < 0.05 with 95% confidence level), while no improvement was observed in the vertical direction. Conclusions The conventional matched field TLI treatment is error-prone to geometrical setup error. The feasibility of full indexing TLI treatments was validated and shown to result in a significant reduction of positioning and shifting errors.

Variance component and breeding value estimation for genetic heterogeneity of residual variance in Swedish Holstein dairy cattle.

PubMed

Rönnegård, L; Felleki, M; Fikse, W F; Mulder, H A; Strandberg, E

2013-04-01

Trait uniformity, or micro-environmental sensitivity, may be studied through individual differences in residual variance. These differences appear to be heritable, and the need exists, therefore, to fit models to predict breeding values explaining differences in residual variance. The aim of this paper is to estimate breeding values for micro-environmental sensitivity (vEBV) in milk yield and somatic cell score, and their associated variance components, on a large dairy cattle data set having more than 1.6 million records. Estimation of variance components, ordinary breeding values, and vEBV was performed using standard variance component estimation software (ASReml), applying the methodology for double hierarchical generalized linear models. Estimation using ASReml took less than 7 d on a Linux server. The genetic standard deviations for residual variance were 0.21 and 0.22 for somatic cell score and milk yield, respectively, which indicate moderate genetic variance for residual variance and imply that a standard deviation change in vEBV for one of these traits would alter the residual variance by 20%. This study shows that estimation of variance components, estimated breeding values and vEBV, is feasible for large dairy cattle data sets using standard variance component estimation software. The possibility to select for uniformity in Holstein dairy cattle based on these estimates is discussed. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A study on body weight perception and weight control behaviours among adolescents in Hong Kong.

PubMed

Cheung, Patrick C H; Ip, Patricia L S; Lam, S T; Bibby, Helen

2007-02-01

To examine the relationships between body weight perceptions, estimated body mass index, gender, and weight control behaviours. Cross-sectional survey. Three secondary schools in Hong Kong. A total of 1132 secondary school forms 1 and 3 students. The strength of agreement between perceived weight and estimated body mass index, and the association between perceived weight, estimated body mass index, and weight control behaviours. A total of 14% of students were estimated to be overweight or obese. The agreement between actual (estimated) body mass index and perceived weight was poor in females and fair in males (Kappa 0.137 and 0.225, respectively). In females, there was no evidence of a relationship between body mass index and weight control behaviours. However, there was a relationship between perceived weight and weight control behaviours such that females who perceived themselves as overweight were more likely to exercise, restrict caloric intake, self medicate with diet pills, purge, or use laxatives. In males, there was evidence of a relationship between perceived weight, body mass index, and weight control behaviours. Males who perceived themselves as overweight or were overweight, were more likely to exercise or restrict caloric intake. Body weight perceptions are not in agreement with actual weight in adolescents. This discrepancy is more marked in females who use a variety of weight control behaviours. These behaviours are motivated by perceived weight rather than actual (estimated) body mass index. Overweight adolescents should be encouraged to adopt appropriate weight control behaviours for their health needs.

Importance sampling large deviations in nonequilibrium steady states. I.

PubMed

Ray, Ushnish; Chan, Garnet Kin-Lic; Limmer, David T

2018-03-28

Large deviation functions contain information on the stability and response of systems driven into nonequilibrium steady states and in such a way are similar to free energies for systems at equilibrium. As with equilibrium free energies, evaluating large deviation functions numerically for all but the simplest systems is difficult because by construction they depend on exponentially rare events. In this first paper of a series, we evaluate different trajectory-based sampling methods capable of computing large deviation functions of time integrated observables within nonequilibrium steady states. We illustrate some convergence criteria and best practices using a number of different models, including a biased Brownian walker, a driven lattice gas, and a model of self-assembly. We show how two popular methods for sampling trajectory ensembles, transition path sampling and diffusion Monte Carlo, suffer from exponentially diverging correlations in trajectory space as a function of the bias parameter when estimating large deviation functions. Improving the efficiencies of these algorithms requires introducing guiding functions for the trajectories.

Importance sampling large deviations in nonequilibrium steady states. I

NASA Astrophysics Data System (ADS)

Ray, Ushnish; Chan, Garnet Kin-Lic; Limmer, David T.

2018-03-01

Large deviation functions contain information on the stability and response of systems driven into nonequilibrium steady states and in such a way are similar to free energies for systems at equilibrium. As with equilibrium free energies, evaluating large deviation functions numerically for all but the simplest systems is difficult because by construction they depend on exponentially rare events. In this first paper of a series, we evaluate different trajectory-based sampling methods capable of computing large deviation functions of time integrated observables within nonequilibrium steady states. We illustrate some convergence criteria and best practices using a number of different models, including a biased Brownian walker, a driven lattice gas, and a model of self-assembly. We show how two popular methods for sampling trajectory ensembles, transition path sampling and diffusion Monte Carlo, suffer from exponentially diverging correlations in trajectory space as a function of the bias parameter when estimating large deviation functions. Improving the efficiencies of these algorithms requires introducing guiding functions for the trajectories.

Sensitivity factor of the axial-symmetric transmission gauge: Deviation and long-term variation

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

Takahashi, N.; Tuzi, Y.; Arakawa, I.

2007-07-15

The deviation of the sensitivity factors for about 50 sensors of the axial-symmetric transmission gauge (ATG) was examined. The deviation has been compared with that for about 30 sensors of the B-A gauge and for about 30 sensors of the extractor gauge. Almost the same deviations are found for the above three types of gauges. The long-term variations of the sensitivity factors for two sensors of the ATG were also measured during four years. After the initial change with operating time, the sensitivity factor stabilized after long-term operation. The room temperature effect of the sensitivity factor plays an important rolemore » on the total pressure measurement by an ionization gauge, but the change of the sensitivity factor was larger than the room temperature effect. The reason for the change of the factor is estimated in connection with the annealing and the alignment of the filament and with the deviation of the place of electron emission on the filament.« less

The concordance index C and the Mann-Whitney parameter Pr(X>Y) with randomly censored data.

PubMed

Koziol, James A; Jia, Zhenyu

2009-06-01

Harrell's c-index or concordance C has been widely used as a measure of separation of two survival distributions. In the absence of censored data, the c-index estimates the Mann-Whitney parameter Pr(X>Y), which has been repeatedly utilized in various statistical contexts. In the presence of randomly censored data, the c-index no longer estimates Pr(X>Y); rather, a parameter that involves the underlying censoring distributions. This is in contrast to Efron's maximum likelihood estimator of the Mann-Whitney parameter, which is recommended in the setting of random censorship.

Estimation of confidence limits for descriptive indexes derived from autoregressive analysis of time series: Methods and application to heart rate variability.

PubMed

Beda, Alessandro; Simpson, David M; Faes, Luca

2017-01-01

The growing interest in personalized medicine requires making inferences from descriptive indexes estimated from individual recordings of physiological signals, with statistical analyses focused on individual differences between/within subjects, rather than comparing supposedly homogeneous cohorts. To this end, methods to compute confidence limits of individual estimates of descriptive indexes are needed. This study introduces numerical methods to compute such confidence limits and perform statistical comparisons between indexes derived from autoregressive (AR) modeling of individual time series. Analytical approaches are generally not viable, because the indexes are usually nonlinear functions of the AR parameters. We exploit Monte Carlo (MC) and Bootstrap (BS) methods to reproduce the sampling distribution of the AR parameters and indexes computed from them. Here, these methods are implemented for spectral and information-theoretic indexes of heart-rate variability (HRV) estimated from AR models of heart-period time series. First, the MS and BC methods are tested in a wide range of synthetic HRV time series, showing good agreement with a gold-standard approach (i.e. multiple realizations of the "true" process driving the simulation). Then, real HRV time series measured from volunteers performing cognitive tasks are considered, documenting (i) the strong variability of confidence limits' width across recordings, (ii) the diversity of individual responses to the same task, and (iii) frequent disagreement between the cohort-average response and that of many individuals. We conclude that MC and BS methods are robust in estimating confidence limits of these AR-based indexes and thus recommended for short-term HRV analysis. Moreover, the strong inter-individual differences in the response to tasks shown by AR-based indexes evidence the need of individual-by-individual assessments of HRV features. Given their generality, MC and BS methods are promising for applications in biomedical signal processing and beyond, providing a powerful new tool for assessing the confidence limits of indexes estimated from individual recordings.

Estimation of confidence limits for descriptive indexes derived from autoregressive analysis of time series: Methods and application to heart rate variability

PubMed Central

2017-01-01

The growing interest in personalized medicine requires making inferences from descriptive indexes estimated from individual recordings of physiological signals, with statistical analyses focused on individual differences between/within subjects, rather than comparing supposedly homogeneous cohorts. To this end, methods to compute confidence limits of individual estimates of descriptive indexes are needed. This study introduces numerical methods to compute such confidence limits and perform statistical comparisons between indexes derived from autoregressive (AR) modeling of individual time series. Analytical approaches are generally not viable, because the indexes are usually nonlinear functions of the AR parameters. We exploit Monte Carlo (MC) and Bootstrap (BS) methods to reproduce the sampling distribution of the AR parameters and indexes computed from them. Here, these methods are implemented for spectral and information-theoretic indexes of heart-rate variability (HRV) estimated from AR models of heart-period time series. First, the MS and BC methods are tested in a wide range of synthetic HRV time series, showing good agreement with a gold-standard approach (i.e. multiple realizations of the "true" process driving the simulation). Then, real HRV time series measured from volunteers performing cognitive tasks are considered, documenting (i) the strong variability of confidence limits' width across recordings, (ii) the diversity of individual responses to the same task, and (iii) frequent disagreement between the cohort-average response and that of many individuals. We conclude that MC and BS methods are robust in estimating confidence limits of these AR-based indexes and thus recommended for short-term HRV analysis. Moreover, the strong inter-individual differences in the response to tasks shown by AR-based indexes evidence the need of individual-by-individual assessments of HRV features. Given their generality, MC and BS methods are promising for applications in biomedical signal processing and beyond, providing a powerful new tool for assessing the confidence limits of indexes estimated from individual recordings. PMID:28968394

Development of a local-scale urban stream assessment method using benthic macroinvertebrates: An example from the Santa Clara Basin, California

USGS Publications Warehouse

Carter, J.L.; Purcell, A.H.; Fend, S.V.; Resh, V.H.

2009-01-01

Research that explores the biological response to urbanization on a site-specific scale is necessary for management of urban basins. Recent studies have proposed a method to characterize the biological response of benthic macroinvertebrates along an urban gradient for several climatic regions in the USA. Our study demonstrates how this general framework can be refined and applied on a smaller scale to an urbanized basin, the Santa Clara Basin (surrounding San Jose, California, USA). Eighty-four sampling sites on 14 streams in the Santa Clara Basin were used for assessing local stream conditions. First, an urban index composed of human population density, road density, and urban land cover was used to determine the extent of urbanization upstream from each sampling site. Second, a multimetric biological index was developed to characterize the response of macroinvertebrate assemblages along the urban gradient. The resulting biological index included metrics from 3 ecological categories: taxonomic composition ( Ephemeroptera, Plecoptera, and Trichoptera), functional feeding group (shredder richness), and habit ( clingers). The 90th-quantile regression line was used to define the best available biological conditions along the urban gradient, which we define as the predicted biological potential. This descriptor was then used to determine the relative condition of sites throughout the basin. Hierarchical partitioning of variance revealed that several site-specific variables (dissolved O2 and temperature) were significantly related to a site's deviation from its predicted biological potential. Spatial analysis of each site's deviation from its biological potential indicated geographic heterogeneity in the distribution of impaired sites. The presence and operation of local dams optimize water use, but modify natural flow regimes, which in turn influence stream habitat, dissolved O2, and temperature. Current dissolved O2 and temperature regimes deviate from natural conditions and appear to affect benthic macroinvertebrate assemblages. The assessment methods presented in our study provide finer-scale assessment tools for managers in urban basins. ?? North American Benthological Society.

Utility of CT classifications to predict unfavorable outcomes in children with acute pancreatitis.

PubMed

Izquierdo, Yojhan E; Fonseca, Eileen V; Moreno, Luz-Ángela; Montoya, Rubén D; Guerrero Lozano, Rafael

2018-02-21

Computed tomography (CT) is useful for the diagnosis of local complications in children with acute pancreatitis but its role as a prognostic tool remains controversial. To establish the correlation between the CT Severity Index and the Revised Atlanta Classification regarding unfavorable outcomes such as severe acute pancreatitis and need for Pediatric Special Care Unit attention in children with acute pancreatitis. We conducted a retrospective and concordance cohort study in which we obtained abdominal CT scans from 30 patients ages 0 to 18 years with acute pancreatitis. Two pediatric radiologists interpreted the results using the CT Severity Index and the Revised Atlanta Classification. The kappa coefficient was determined for each scale. The association among severe acute pancreatitis, need for admission to the Pediatric Special Care Unit and CT systems were established using chi-square or Mann-Whitney U tests. The best CT Severity Index value to predict the need for admission to the Pediatric Special Care Unit was estimated through a receiver operating characteristic (ROC) curve. Mean CT Severity Index was 5.1±2.8 (mean ± standard deviation on a scale of 0 to 10) for the severe acute pancreatitis group vs. 3.8±2.7 for the mild acute pancreatitis group (P=0.230). The CT Severity Index for the children who were not hospitalized at the Pediatric Special Care Unit was 2.2±2.2 vs. 5.6±2.4 for the group hospitalized at the Pediatric Special Care Unit (P=0.001). Only parenchymal necrosis >30% was associated with severe acute pancreatitis (P=0.021). A CT Severity Index ≥3 has a sensitivity of 89% and specificity of 72% to predict need for admission to the Pediatric Special Care Unit. None of the Revised Atlanta Classification categories was associated with severe acute pancreatitis or admission to the Pediatric Special Care Unit. A CT Severity Index ≥3 in children with acute pancreatitis who require CT assessment based on clinical criteria is associated with the need for admission to the Pediatric Special Care Unit. We found that pancreatic necrosis greater than 30% is the only tomographic parameter related to severe acute pancreatitis. New studies with a greater sample size are necessary to confirm this result.

What Is the Long-Run Impact of Learning Mathematics during Preschool?

ERIC Educational Resources Information Center

Watts, Tyler W.; Duncan, Greg J.; Clements, Douglas H.; Sarama, Julie

2018-01-01

The current study estimated the causal links between preschool mathematics learning and late elementary school mathematics achievement using variation in treatment assignment to an early mathematics intervention as an instrument for preschool mathematics change. Estimates indicate (n = 410) that a standard deviation of intervention-produced change…

Measurement variability error for estimates of volume change

Treesearch

James A. Westfall; Paul L. Patterson

2007-01-01

Using quality assurance data, measurement variability distributions were developed for attributes that affect tree volume prediction. Random deviations from the measurement variability distributions were applied to 19381 remeasured sample trees in Maine. The additional error due to measurement variation and measurement bias was estimated via a simulation study for...

Correlation between indexes of autonomic maneuvers and heart rate variability in hemodialysis patients.

PubMed

Vieira, Carlos Felipe Delmondes; Lima, Márcia Maria Oliveira; Costa, Henrique Silveira; Diniz, Karen Marina Alves; Guião, João Paulo Lemos; Alves, Frederico Lopes; Maciel, Emílio Henrique; Brandao, Vanessa Gomes; Figueiredo, Pedro Henrique Scheidt

2016-06-01

The autonomic maneuvers are simple methods to evaluate autonomic balance, but the association between autonomic maneuvers and heart rate variability (HRV) in hemodialysis patients remains unknown. This study aimed to evaluate the correlation between HRV and respiratory sinus arrhythmia (RSA) and Valsalva maneuver (VM) indexes in hemodialysis patients and to compare two methods for RSA indexes acquisitions. Forty-eight volunteers on hemodialysis (66.7 % men) were evaluated by VM, RSA, and 24 h Holter monitoring. At the VM, the Valsalva index (VI) was the variable considered. In the RSA, the ratio and difference between the RR intervals of inspiratory and expiratory phase (E:I and E-I, respectively) were considered by traditional form (average of respiratory cycles) and independent respiratory cycles (E:Iindep and E-Iindep). The HRV indexes evaluated were standard deviation of all normal RR intervals (SDNN), standard deviation of sequential 5-min RR interval means (SDANN), root mean square of the successive differences (rMSSD) and percentage of adjacent RR intervals with difference of duration greater than 50 ms (pNN50). The SDNN, SDANN showed significant correlation with all classic indexes of RSA (E:I: r = 0.62, 0.55, respectively, E-I: r = 0.64, 0.57, respectively), E:Iindep (r = 0.59, 0.54, respectively), E-Iindep (r = 0.47, 0.43, respectively) and VI (r = 0.42, 0.34, respectively). Significant correlation of rMSSD with E:I (r = 0.37), E-I (r = 0.41) and E:Iindep (r = 0.34) was also observed. There was no association of any variable with pNN50. Have been show high values for all variables of independent cycles method (p < 0.05). The autonomic maneuvers, especially RSA, are useful methods to evaluate cardiac autonomic function in hemodialysis patients. The acquisition of the RSA index by independent cycles should not be used in this population.

Estimating red pine site index in northern Minnesota.

Treesearch

1976-01-01

Methods are presented for estimating red pine site index from the height growth of red pine, site index of several associated species (jack pine, white pine, white spruce, or quaking aspen), and from easily measured soil properties. The restrictions and limitations of each method and their relative precision are discussed.

Cerebrovascular Pressure Reactivity in Children With Traumatic Brain Injury.

PubMed

Lewis, Philip M; Czosnyka, Marek; Carter, Bradley G; Rosenfeld, Jeffrey V; Paul, Eldho; Singhal, Nitesh; Butt, Warwick

2015-10-01

Traumatic brain injury is a significant cause of morbidity and mortality in children. Cerebral autoregulation disturbance after traumatic brain injury is associated with worse outcome. Pressure reactivity is a fundamental component of cerebral autoregulation that can be estimated using the pressure-reactivity index, a correlation between slow arterial blood pressure, and intracranial pressure fluctuations. Pressure-reactivity index has shown prognostic value in adult traumatic brain injury, with one study confirming this in children. Pressure-reactivity index can identify a cerebral perfusion pressure range within which pressure reactivity is optimal. An increasing difference between optimal cerebral perfusion pressure and cerebral perfusion pressure is associated with worse outcome in adult traumatic brain injury; however, this has not been investigated in children. Our objective was to study pressure-reactivity index and optimal cerebral perfusion pressure in pediatric traumatic brain injury, including associations with outcome, age, and cerebral perfusion pressure. Prospective observational study. ICU, Royal Children's Hospital, Melbourne, Australia. Patients with traumatic brain injury who are 6 months to 16 years old, are admitted to the ICU, and require arterial blood pressure and intracranial pressure monitoring. None. Arterial blood pressure, intracranial pressure, and end-tidal CO2 were recorded electronically until ICU discharge or monitoring cessation. Pressure-reactivity index and optimal cerebral perfusion pressure were computed according to previously published methods. Clinical data were collected from electronic medical records. Outcome was assessed 6 months post discharge using the modified Glasgow Outcome Score. Thirty-six patients were monitored, with 30 available for follow-up. Pressure-reactivity index correlated with modified Glasgow Outcome Score (Spearman ρ = 0.42; p = 0.023) and was higher in patients with unfavorable outcome (0.23 vs -0.09; p = 0.0009). A plot of pressure-reactivity index averaged within 5 mm Hg cerebral perfusion pressure bins showed a U-shape, reaffirming the concept of cerebral perfusion pressure optimization in children. Optimal cerebral perfusion pressure increased with age (ρ = 0.40; p = 0.02). Both the duration and magnitude of negative deviations in the difference between cerebral perfusion pressure and optimal cerebral perfusion pressure were associated with unfavorable outcome. In pediatric patients with traumatic brain injury, pressure-reactivity index has prognostic value and can identify cerebral perfusion pressure targets that may differ from treatment protocols. Our results suggest but do not confirm that cerebral perfusion pressure targeting using pressure-reactivity index as a guide may positively impact on outcome. This question should be addressed by a prospective clinical study.

Development of bioelectrical impedance-derived indices of fat and fat-free mass for assessment of nutritional status in childhood.

PubMed

Wright, C M; Sherriff, A; Ward, S C G; McColl, J H; Reilly, J J; Ness, A R

2008-02-01

(1) To develop a method of manipulating bioelectrical impedance (BIA) that gives indices of lean and fat adjusted for body size, using a large normative cohort of children. (2) To assess the discriminant validity of the method in a group of children likely to have abnormal body composition. Two prospective cohort studies. Normative data: Avon Longitudinal Study of Parents and Children (ALSPAC), population based cohort; proof of concept study: tertiary feeding clinic and special needs schools. Normative data: 7576 children measured aged between 7.25 and 8.25 (mean 7.5) (s.d.=0.2) years; proof of concept study: 29 children with either major neurodisability or receiving artificial feeding, or both, mean age 7.6 (s.d.=2) years. Leg-to-leg (Z (T)) and arm-to-leg (Z (B)) BIA, weight and height. Total body water (TBW) was estimated from the resistance index (RI=height(2)/Z), and fat-free mass was linearly related to TBW. Fat mass was obtained by subtracting fat-free mass from total weight. Fat-free mass was log-transformed and the reciprocal transform was taken for fat mass to satisfy parametric model assumptions. Lean and fat mass were then adjusted for height and age using multiple linear regression models. The resulting standardized residuals gave the lean index and fat index, respectively. In the normative cohort, the lean index was higher and fat index lower in boys. The lean index rose steeply to the middle of the normal range of body mass index (BMI) and then slowly for higher BMI values, whereas the fat index rose linearly through and above the normal range. In the proof of concept study, the children as a group had low lean indices (mean (s.d.) -1.5 (1.7)) with average fat indices (+0.21 (2.0)) despite relatively low BMI standard deviation scores (-0.60 (2.3)), but for any given BMI, individual children had extremely wide ranges of fat indices. The lean index proved more stable and repeatable than BMI. This clinical method of handling BIA reveals important variations in nutritional status that would not be detected using anthropometry alone. BIA used in this way would allow more accurate assessment of energy sufficiency in children with neurodisability and may provide a more valid identification of children at risk of underweight or obesity in field and clinical settings.

The Solar Spectral Irradiance as a Function of the Mg II Index for Atmosphere and Climate Modelling

NASA Technical Reports Server (NTRS)

Thuillier, Gerard; DeLand, Matthew; Shapiro, Alexander; Schmutz, Werner; Bolsee, David; Melo, Stella

2011-01-01

In this paper we present a new method to reconstruct the solar spectrum irradiance in the Ly alpha-400 nm region, and its variability, based on the Mg II index and neutron monitor. Measurements of the solar spectral irradiance available in the literature have been made with different instruments at different times and different spectral ranges. However, climate studies require harmonized data sets. This new approach has the advantage of being independent of the absolute calibration and aging of the instruments. First, the Mg II index is derived using solar spectra from Ly alpha (121 nm) to 410 nm measured from 1978 to 2010 by several space missions. The variability of the spectra with respect to a chosen reference spectrum as a function of time and wavelength is scaled to the derived Mg II index. The set of coefficients expressing the spectral variability can be applied to the chosen reference spectrum to reconstruct the solar spectra within a given time frame or Mg II index values. The accuracy of this method is estimated using two approaches: by direct comparison with particular cases where solar spectra are available from independent measurements, and by calculating the standard deviation between the measured spectra and their reconstruction. From direct comparisons with measurements we obtain an accuracy of about 1 to 2 %, which degrades towards Ly alpha. In a further step, we extend our solar spectral irradiance reconstruction back to the Maunder Minimum introducing the relationship between the Mg II index and the neutron monitor data. Consistent measurements of the Mg II index are not available prior to 1978. However, we observe that over the last three solar cycles, the Mg II index shows strong correlation with the modulation potential determined from the neutron monitor data. Assuming that this correlation can be applied to the past, we reconstruct the Mg II index from the modulation potential back to the Maunder Minimum, and obtain the corresponding solar spectral irradiance reconstruction back to that period. As there is no direct measurement of the spectral irradiance for this period we discuss this methodology in light of the other proposed approaches available in the literature. The use of the cosmogenic isotope data provides a major advantage: it provides information about the solar activity over several thousands years. Using technology of today we can calibrate the solar irradiance against the activity and thus reconstruct it for the times when cosmogenic isotope data are available. This calibration can be re-accessed at any time, if necessary.

Inference of pCO2 Levels during the Late Cretaceous Using Fossil Lauraceae

NASA Astrophysics Data System (ADS)

Richey, J. D.; Upchurch, G. R.

2011-12-01

Botanical estimates of pCO2 for the Late Cretaceous have most commonly used Stomatal Index (SI) in fossil Ginkgo. Recently, SI in fossil Lauraceae has been used to infer changes in pCO2 across the Cenomanian-Turonian boundary, based on the relation between SI and pCO2 in extant Laurus and Hypodaphnis. To provide a broad-scale picture of pCO2 based on fossil Lauraceae, we examined dispersed cuticle of the leaf macrofossil genus Pandemophyllum from: 1) the early to middle Cenomanian of the Potomac Group of Maryland (Mauldin Mountain locality, lower Zone III) and 2) the Maastrichtian of southern Colorado (Raton Basin, Starkville South and Berwind Canyon localities). These samples fall within the Late Cretaceous decline in pCO2 inferred from geochemical modeling and other proxies. SI was calculated from fossil cuticle fragments using ImageJ and counts of up to 56,000 cells per sample, a far greater number of cells than are counted in most studies. CO2 levels were estimated using the relation between SI and CO2 published for Laurus nobilis and Hypodaphnis zenkeri. Early to middle Cenomanian atmospheric pCO2 is estimated at 362-536 parts per million (ppm). This represents the absolute minimum and maximum estimated CO2 levels from the ±95% confidence intervals (CI) of the relation between SI and CO2 for the modern equivalents, and SI ± 1 Standard Deviation (SD) in the fossil genus Pandemophyllum. Late Maastrichtian atmospheric pCO2 is estimated at 358-534 ppm. The Maastrichtian estimates falls within the range of published estimates from other proxies. The Cenomanian estimate, in contrast, is low relative to most other estimates. The 95% confidence intervals of our pCO2 estimates overlap each other and many of the assemblages published by Barclay et al. (2010) for Lauraceae across the Cenomanian-Turonian boundary. This could indicate that 1) pCO2 did not undergo a major long-term decline during the Late Cretaceous, 2) Lauraceae show low sensitivity to high pCO2, or 3) additional sampling is necessary to find the mid-Cretaceous pCO2 maximum inferred by other proxy methods.

Coffee Consumption and Heart Rate Variability: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) Cohort Study

PubMed Central

de Oliveira, Rackel Aguiar Mendes; Araújo, Larissa Fortunato; de Figueiredo, Roberta Carvalho; Goulart, Alessandra C.; Schmidt, Maria Ines; Barreto, Sandhi Maria; Ribeiro, Antonio Luiz Pinho

2017-01-01

Studies have shown that acute coffee ingestion can affect cardiovascular autonomic activity, although the chronic effects on heart rate variability (HRV) remain controversial. Method: A cross-sectional study with baseline data (2008–2010) from ELSA-Brasil cohort of 15,105 (aged 35–74), based in six Brazilian states. Coffee consumption in the previous 12 months was measured using the semi-quantitative food frequency questionnaire, and HRV was obtained through electrocardiographic tracings during 10 min at rest. Independent association between the frequency of coffee consumption “never or almost never”, “≤1 cup/day”, “2–3 cups/day”, “≥3 cups/day”, and HRV was estimated using generalized linear regression, adjusting for socio-demographic characteristics, health-related behavior, markers of abnormal metabolism, and the presence of coronary artery disease. Further, we applied Bonferroni correction in the full models. Results: The mean age was 52 years (standard deviation (SD) = 9.1), and 52% was female; 9.5% never/almost never consumed coffee. In univariate analysis, coffee consumers had reduced values of HRV indexes, but after full adjustments and correction for multiple comparisons, these associations disappeared. A trend of reduction in HRV vagal indexes was observed in those that consumed ≥3 cups of coffee/day. Conclusion: Most of the effects attributed to the chronic use of coffee on the HRV indexes is related to the higher prevalence of unhealthy habits in coffee users, such as smoking and alcohol use. Adjustment for confounding factors weaken this association, making it non-significant. The effect of higher daily doses of coffee on the autonomic system should be evaluated in further studies. PMID:28703735

Dietary diversity decreases the risk of cognitive decline among Japanese older adults.

PubMed

Otsuka, Rei; Nishita, Yukiko; Tange, Chikako; Tomida, Makiko; Kato, Yuki; Nakamoto, Mariko; Imai, Tomoko; Ando, Fujiko; Shimokata, Hiroshi

2017-06-01

To clarify the effectiveness of dietary diversity, calculated by dietary records, on cognitive decline. Data were derived from the National Institute for Longevity Sciences - Longitudinal Study of Aging. Participants comprised 298 men and 272 women aged 60-81 years at baseline (second wave) who participated in the follow-up study (third to seventh wave) at least once. Cognitive function was assessed with the Mini-Mental State Examination in all study waves. Dietary diversity was determined using the Quantitative Index for Dietary Diversity based on a 3-day dietary record in the second wave. Cumulative data among participants with a Mini-Mental State Examination score >27 in the second wave were analyzed using a generalized estimating equation. Multivariate adjusted odds ratios and 95% confidence intervals for Mini-Mental State Examination scores ≤27 in each study wave according to a 1 standard deviation (increase), or quartiles of the Quantitative Index for Dietary Diversity at baseline, were adjusted for sex, age, follow-up time, baseline Mini-Mental State Examination score, education, body mass index, annual household income, current smoking status, energy intake and disease history. Multivariate adjusted odds ratio for a decline in Mini-Mental State Examination score was 0.79 (95% CI 0.70-0.89; P < 0.001) with a 1 SD increase in dietary diversity score, or 1.00 (reference), 0.99 (95% CI 0.70-1.43), 0.68 (95% CI 0.46-0.99) and 0.56 (95% CI 0.38-0.83) according to the lowest through highest quartiles of dietary diversity score, respectively (trend P = 0.001). Daily intake of various kinds of food might be a protective factor against cognitive decline in community-dwelling Japanese older adults. Geriatr Gerontol Int 2017; 17: 937-944. © 2016 Japan Geriatrics Society.

Film-based delivery quality assurance for robotic radiosurgery: Commissioning and validation.

PubMed

Blanck, Oliver; Masi, Laura; Damme, Marie-Christin; Hildebrandt, Guido; Dunst, Jürgen; Siebert, Frank-Andre; Poppinga, Daniela; Poppe, Björn

2015-07-01

Robotic radiosurgery demands comprehensive delivery quality assurance (DQA), but guidelines for commissioning of the DQA method is missing. We investigated the stability and sensitivity of our film-based DQA method with various test scenarios and routine patient plans. We also investigated the applicability of tight distance-to-agreement (DTA) Gamma-Index criteria. We used radiochromic films with multichannel film dosimetry and re-calibration and our analysis was performed in four steps: 1) Film-to-plan registration, 2) Standard Gamma-Index criteria evaluation (local-pixel-dose-difference ≤2%, distance-to-agreement ≤2 mm, pass-rate ≥90%), 3) Dose distribution shift until maximum pass-rate (Maxγ) was found (shift acceptance <1 mm), and 4) Final evaluation with tight DTA criteria (≤1 mm). Test scenarios consisted of purposefully introduced phantom misalignments, dose miscalibrations, and undelivered MU. Initial method evaluation was done on 30 clinical plans. Our method showed similar sensitivity compared to the standard End-2-End-Test and incorporated an estimate of global system offsets in the analysis. The simulated errors (phantom shifts, global robot misalignment, undelivered MU) were detected by our method while standard Gamma-Index criteria often did not reveal these deviations. Dose miscalibration was not detected by film alone, hence simultaneous ion-chamber measurement for film calibration is strongly recommended. 83% of the clinical patient plans were within our tight DTA tolerances. Our presented methods provide additional measurements and quality references for film-based DQA enabling more sensitive error detection. We provided various test scenarios for commissioning of robotic radiosurgery DQA and demonstrated the necessity to use tight DTA criteria. Copyright © 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

GRACE score predicts heart failure admission following acute coronary syndrome.

PubMed

McAllister, David A; Halbesma, Nynke; Carruthers, Kathryn; Denvir, Martin; Fox, Keith A

2015-04-01

Congestive heart failure (CHF) is a common and preventable complication of acute coronary syndrome (ACS). Nevertheless, ACS risk scores have not been shown to predict CHF risk. We investigated whether the at-discharge Global Registry of Acute Coronary Events (GRACE) score predicts heart failure admission following ACS. Five-year mortality and hospitalization data were obtained for patients admitted with ACS from June 1999 to September 2009 to a single centre of the GRACE registry. CHF was defined as any admission assigned WHO International Classification of Diseases 10 diagnostic code I50. The hazard ratio (HR) for CHF according to GRACE score was estimated in Cox models adjusting for age, gender and the presence of CHF on index admission. Among 1,956 patients, CHF was recorded on index admission in 141 patients (7%), and 243 (12%) were admitted with CHF over 3.8 median years of follow-up. Compared to the lowest quintile, patients in the highest GRACE score quintile had more CHF admissions (116 vs 17) and a shorter time to first admission (1.2 vs 2.0 years, HR 9.87, 95% CI 5.93-16.43). Per standard deviation increment in GRACE score, the instantaneous risk was more than two-fold higher (HR 2.28; 95% CI 2.02-2.57), including after adjustment for CHF on index admission, age and gender (HR 2.49; 95% CI 2.06-3.02). The C-statistic for CHF admission at 1-year was 0.74 (95% CI 0.70-0.79). The GRACE score predicts CHF admission, and may therefore be used to target ACS patients at high risk of CHF with clinical monitoring and therapies. © The European Society of Cardiology 2014.

Correlation of 18F-FDG uptake on PET/CT with Ki67 immunohistochemistry in pre-treatment epithelial ovarian cancer.

PubMed

Mayoral, M; Paredes, P; Saco, A; Fusté, P; Perlaza, P; Tapias, A; Fernandez-Martinez, A; Vidal, L; Ordi, J; Pavia, J; Martinez-Roman, S; Lomeña, F

Standardised uptake value (SUV) and volumetric parameters such as metabolic tumour volume (MTV) and total lesion glycolysis (TLG) from 18 F-FDG PET/CT are useful criteria for disease prognosis in pre-operative and post-treatment epithelial ovarian cancer (EOC). Ki67 is another prognostic biomarker in EOC, associated with tumour aggressiveness. The aim of this study is to evaluate the association between 18 F-FDG PET/CT measurements and Ki67 in pre-treatment EOC to determine if PET/CT parameters could non-invasively predict tumour aggressiveness. A pre-treatment PET/CT was performed on 18 patients with suspected or newly diagnosed EOC. Maximum SUV (SUVmax), mean SUV (SUVmean), whole-body MTV (wbMTV), and whole-body TLG (wbTLG) with a threshold of 30% and 40% of the SUVmax were obtained. Furthermore, Ki67 index (mean and hotspot) was estimated in tumour tissue specimens. Immunohistochemical findings were correlated with PET parameters. The mean age was 57.0 years old (standard deviation 13.6 years). A moderate correlation was observed between mean Ki67 index and SUVmax (r=0.392), SUVmean 30% (r=0.437), and SUVmean 40% (r=0.443), and also between hotspot Ki67 index and SUVmax (r=0.360), SUVmean 30% (r=0.362) and SUVmean 40% (r=0.319). There was a weaker correlation, which was inversely negative, between mean and hotspot Ki67 and volumetric PET parameters. However, no statistical significant differences were found for any correlations. SUVmax and SUVmean were moderately correlated with Ki67 index, whereas volumetric PET parameters overall, showed a weaker correlation. Thus, SUVmax and SUVmean could be used to assess tumour aggressiveness in pre-treatment EOC. Copyright © 2017 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

Impact of sarcopenia on the outcomes of elective total arch replacement in the elderly†.

PubMed

Ikeno, Yuki; Koide, Yutaka; Abe, Noriyuki; Matsueda, Takashi; Izawa, Naoto; Yamazato, Takahiro; Miyahara, Shunsuke; Nomura, Yoshikatsu; Sato, Shunsuke; Takahashi, Hiroaki; Inoue, Takeshi; Matsumori, Masamichi; Tanaka, Hiroshi; Ishihara, Satoshi; Nakayama, Shinichi; Sugimoto, Koji; Okita, Yutaka

2017-06-01

The purpose of this study was to identify the cut-off value of sarcopenia based on the psoas muscle area index and evaluate early and late outcomes following elective total arch replacement in the elderly. Sarcopenia was assessed by the psoas muscle area index [defined as the psoas muscle area at the L3 level on computed tomography (cm 2 )/body surface area (m 2 )]. The cut-off value for sarcopenia was defined as > 2 standard deviations below the mean psoas muscle area index value obtained from 464 normal control patients. Between October 1999 and July 2015, 266 patients who were ≥ 65 years and had undergone psoas muscle area index measurement underwent elective total arch replacement. These patients were classified into the sarcopenia (Group S, n  = 81) and non-sarcopenia (Group N, n  = 185) groups. The mean age was 76.2 ± 5.6 years in Group S and 75.7 ± 5.7 years in Group N ( P  = 0.553). Hospital mortality was 3.7% (3/81) in Group S and 2.2% (4/185) in Group N ( P  = 0.483). Mean follow-up was 48.3 ± 38.7 months. Five-year survival was significantly worse in Group S (S: 63.2 ± 6.6% vs N: 88.7 ± 2.6%, P  < 0.001). A multivariable Cox proportional hazard analysis showed that sarcopenia significantly predicted poor survival (hazard ratio 2.59; 95% confidence interval 1.27-5.29; P  = 0.011). Sarcopenia did not predict hospital death following total arch replacement, but it was negatively associated with overall survival. Sarcopenia can be an additional risk factor to estimate the outcomes of thoracic aortic surgery. © The Author 2017. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Three-dimensional and thermal surface imaging produces reliable measures of joint shape and temperature: a potential tool for quantifying arthritis

PubMed Central

Spalding, Steven J; Kwoh, C Kent; Boudreau, Robert; Enama, Joseph; Lunich, Julie; Huber, Daniel; Denes, Louis; Hirsch, Raphael

2008-01-01

Introduction The assessment of joints with active arthritis is a core component of widely used outcome measures. However, substantial variability exists within and across examiners in assessment of these active joint counts. Swelling and temperature changes, two qualities estimated during active joint counts, are amenable to quantification using noncontact digital imaging technologies. We sought to explore the ability of three dimensional (3D) and thermal imaging to reliably measure joint shape and temperature. Methods A Minolta 910 Vivid non-contact 3D laser scanner and a Meditherm med2000 Pro Infrared camera were used to create digital representations of wrist and metacarpalphalangeal (MCP) joints. Specialized software generated 3 quantitative measures for each joint region: 1) Volume; 2) Surface Distribution Index (SDI), a marker of joint shape representing the standard deviation of vertical distances from points on the skin surface to a fixed reference plane; 3) Heat Distribution Index (HDI), representing the standard error of temperatures. Seven wrists and 6 MCP regions from 5 subjects with arthritis were used to develop and validate 3D image acquisition and processing techniques. HDI values from 18 wrist and 9 MCP regions were obtained from 17 patients with active arthritis and compared to data from 10 wrist and MCP regions from 5 controls. Standard deviation (SD), coefficient of variation (CV), and intraclass correlation coefficients (ICC) were calculated for each quantitative measure to establish their reliability. CVs for volume and SDI were <1.3% and ICCs were greater than 0.99. Results Thermal measures were less reliable than 3D measures. However, significant differences were observed between control and arthritis HDI values. Two case studies of arthritic joints demonstrated quantifiable changes in swelling and temperature corresponding with changes in symptoms and physical exam findings. Conclusion 3D and thermal imaging provide reliable measures of joint volume, shape, and thermal patterns. Further refinement may lead to the use of these technologies to improve the assessment of disease activity in arthritis. PMID:18215307

Effect of surface crystallographic orientation on the oxidation behavior of Ni-based alloy

NASA Astrophysics Data System (ADS)

Wang, Xu; Szpunar, J. A.; Zhang, Lina

2015-02-01

Dependence of initial oxidation behavior on crystalline orientation of Haynes 230 at 900 °C was investigated by a novel method. Analysis of oxidation rate reveals that the oxide thicknesses are different for grains having different orientations. Orientation mapping was performed on oxidized specimen and grains having near {1 1 1} were easily indexed by electron backscattered diffraction. We determined that planes with deviation angle lower than 20° were all well indexed after oxidation. Results demonstrate that substrate orientation plays an important role on oxidation rate during the initial stage.

Temperature effect on refractive index sensing performance of a U-shape tapered plastic optical fiber

NASA Astrophysics Data System (ADS)

Teng, Chuanxin; Yu, Fangda; Jing, Ning; Zheng, Jie

2016-11-01

The temperature dependence of a refractive index (RI) sensing probe based on a U-shape tapered plastic optical fiber (POF) was investigated experimentally. The changes in light propagation loss in the probe induced by temperature are of the same order of magnitude as those induced by measured RI changes. The temperature dependence loss and temperature dependence RI deviation of the sensing probe were measured (at the wavelength of 635 nm) in temperature of 10-60 °C. By extracting pure temperature dependence of the sensing probe alone, the influence of temperature to the sensor was characterized.

Retention Indices for Frequently Reported Compounds of Plant Essential Oils

NASA Astrophysics Data System (ADS)

Babushok, V. I.; Linstrom, P. J.; Zenkevich, I. G.

2011-12-01

Gas chromatographic retention indices were evaluated for 505 frequently reported plant essential oil components using a large retention index database. Retention data are presented for three types of commonly used stationary phases: dimethyl silicone (nonpolar), dimethyl silicone with 5% phenyl groups (slightly polar), and polyethylene glycol (polar) stationary phases. The evaluations are based on the treatment of multiple measurements with the number of data records ranging from about 5 to 800 per compound. Data analysis was limited to temperature programmed conditions. The data reported include the average and median values of retention index with standard deviations and confidence intervals.

Seismic velocity deviation log: An effective method for evaluating spatial distribution of reservoir pore types

NASA Astrophysics Data System (ADS)

Shirmohamadi, Mohamad; Kadkhodaie, Ali; Rahimpour-Bonab, Hossain; Faraji, Mohammad Ali

2017-04-01

Velocity deviation log (VDL) is a synthetic log used to determine pore types in reservoir rocks based on a combination of the sonic log with neutron-density logs. The current study proposes a two step approach to create a map of porosity and pore types by integrating the results of petrographic studies, well logs and seismic data. In the first step, velocity deviation log was created from the combination of the sonic log with the neutron-density log. The results allowed identifying negative, zero and positive deviations based on the created synthetic velocity log. Negative velocity deviations (below - 500 m/s) indicate connected or interconnected pores and fractures, while positive deviations (above + 500 m/s) are related to isolated pores. Zero deviations in the range of [- 500 m/s, + 500 m/s] are in good agreement with intercrystalline and microporosities. The results of petrographic studies were used to validate the main pore type derived from velocity deviation log. In the next step, velocity deviation log was estimated from seismic data by using a probabilistic neural network model. For this purpose, the inverted acoustic impedance along with the amplitude based seismic attributes were formulated to VDL. The methodology is illustrated by performing a case study from the Hendijan oilfield, northwestern Persian Gulf. The results of this study show that integration of petrographic, well logs and seismic attributes is an instrumental way for understanding the spatial distribution of main reservoir pore types.

Theoretical and experimental investigations of sensor location for optimal aeroelastic system state estimation

NASA Technical Reports Server (NTRS)

Liu, G.

1985-01-01

One of the major concerns in the design of an active control system is obtaining the information needed for effective feedback. This involves the combination of sensing and estimation. A sensor location index is defined as the weighted sum of the mean square estimation errors in which the sensor locations can be regarded as estimator design parameters. The design goal is to choose these locations to minimize the sensor location index. The choice of the number of sensors is a tradeoff between the estimation quality based upon the same performance index and the total costs of installing and maintaining extra sensors. An experimental study for choosing the sensor location was conducted on an aeroelastic system. The system modeling which includes the unsteady aerodynamics model developed by Stephen Rock was improved. Experimental results verify the trend of the theoretical predictions of the sensor location index for different sensor locations at various wind speeds.

Density estimation in wildlife surveys

USGS Publications Warehouse

Bart, Jonathan; Droege, Sam; Geissler, Paul E.; Peterjohn, Bruce G.; Ralph, C. John

2004-01-01

Several authors have recently discussed the problems with using index methods to estimate trends in population size. Some have expressed the view that index methods should virtually never be used. Others have responded by defending index methods and questioning whether better alternatives exist. We suggest that index methods are often a cost-effective component of valid wildlife monitoring but that double-sampling or another procedure that corrects for bias or establishes bounds on bias is essential. The common assertion that index methods require constant detection rates for trend estimation is mathematically incorrect; the requirement is no long-term trend in detection "ratios" (index result/parameter of interest), a requirement that is probably approximately met by many well-designed index surveys. We urge that more attention be given to defining bird density rigorously and in ways useful to managers. Once this is done, 4 sources of bias in density estimates may be distinguished: coverage, closure, surplus birds, and detection rates. Distance, double-observer, and removal methods do not reduce bias due to coverage, closure, or surplus birds. These methods may yield unbiased estimates of the number of birds present at the time of the survey, but only if their required assumptions are met, which we doubt occurs very often in practice. Double-sampling, in contrast, produces unbiased density estimates if the plots are randomly selected and estimates on the intensive surveys are unbiased. More work is needed, however, to determine the feasibility of double-sampling in different populations and habitats. We believe the tension that has developed over appropriate survey methods can best be resolved through increased appreciation of the mathematical aspects of indices, especially the effects of bias, and through studies in which candidate methods are evaluated against known numbers determined through intensive surveys.

Simulation and Analysis of Topographic Effect on Land Surface Albedo over Mountainous Areas

NASA Astrophysics Data System (ADS)

Hao, D.; Wen, J.; Xiao, Q.

2017-12-01

Land surface albedo is one of the significant geophysical variables affecting the Earth's climate and controlling the surface radiation budget. Topography leads to the formation of shadows and the redistribution of incident radiation, which complicates the modeling and estimation of the land surface albedo. Some studies show that neglecting the topography effect may lead to significant bias in estimating the land surface albedo for the sloping terrain. However, for the composite sloping terrain, the topographic effects on the albedo remain unclear. Accurately estimating the sub-topographic effect on the land surface albedo over the composite sloping terrain presents a challenge for remote sensing modeling and applications. In our study, we focus on the development of a simplified estimation method for land surface albedo including black-sky albedo (BSA) and white-sky albedo (WSA) of the composite sloping terrain at a kilometer scale based on the fine scale DEM (30m) and quantitatively investigate and understand the topographic effects on the albedo. The albedo is affected by various factors such as solar zenith angle (SZA), solar azimuth angle (SAA), shadows, terrain occlusion, and slope and aspect distribution of the micro-slopes. When SZA is 30°, the absolute and relative deviations between the BSA of flat terrain and that of rugged terrain reaches 0.12 and 50%, respectively. When the mean slope of the terrain is 30.63° and SZA=30°, the absolute deviation of BSA caused by SAA can reach 0.04. The maximal relative and relative deviation between the WSA of flat terrain and that of rugged terrain reaches 0.08 and 50%. These results demonstrate that the topographic effect has to be taken into account in the albedo estimation.

Phased-array vector velocity estimation using transverse oscillations.

PubMed

Pihl, Michael J; Marcher, Jonne; Jensen, Jorgen A

2012-12-01

A method for estimating the 2-D vector velocity of blood using a phased-array transducer is presented. The approach is based on the transverse oscillation (TO) method. The purposes of this work are to expand the TO method to a phased-array geometry and to broaden the potential clinical applicability of the method. A phased-array transducer has a smaller footprint and a larger field of view than a linear array, and is therefore more suited for, e.g., cardiac imaging. The method relies on suitable TO fields, and a beamforming strategy employing diverging TO beams is proposed. The implementation of the TO method using a phased-array transducer for vector velocity estimation is evaluated through simulation and flow-rig measurements are acquired using an experimental scanner. The vast number of calculations needed to perform flow simulations makes the optimization of the TO fields a cumbersome process. Therefore, three performance metrics are proposed. They are calculated based on the complex TO spectrum of the combined TO fields. It is hypothesized that the performance metrics are related to the performance of the velocity estimates. The simulations show that the squared correlation values range from 0.79 to 0.92, indicating a correlation between the performance metrics of the TO spectrum and the velocity estimates. Because these performance metrics are much more readily computed, the TO fields can be optimized faster for improved velocity estimation of both simulations and measurements. For simulations of a parabolic flow at a depth of 10 cm, a relative (to the peak velocity) bias and standard deviation of 4% and 8%, respectively, are obtained. Overall, the simulations show that the TO method implemented on a phased-array transducer is robust with relative standard deviations around 10% in most cases. The flow-rig measurements show similar results. At a depth of 9.5 cm using 32 emissions per estimate, the relative standard deviation is 9% and the relative bias is -9%. At the center of the vessel, the velocity magnitude is estimated to be 0.25 ± 0.023 m/s, compared with an expected peak velocity magnitude of 0.25 m/s, and the beam-to-flow angle is calculated to be 89.3° ± 0.77°, compared with an expected angle value between 89° and 90°. For steering angles up to ±20° degrees, the relative standard deviation is less than 20%. The results also show that a 64-element transducer implementation is feasible, but with a poorer performance compared with a 128-element transducer. The simulation and experimental results demonstrate that the TO method is suitable for use in conjunction with a phased-array transducer, and that 2-D vector velocity estimation is possible down to a depth of 15 cm.

Estimation of surface temperature in remote pollution measurement experiments

NASA Technical Reports Server (NTRS)

Gupta, S. K.; Tiwari, S. N.

1978-01-01

A simple algorithm has been developed for estimating the actual surface temperature by applying corrections to the effective brightness temperature measured by radiometers mounted on remote sensing platforms. Corrections to effective brightness temperature are computed using an accurate radiative transfer model for the 'basic atmosphere' and several modifications of this caused by deviations of the various atmospheric and surface parameters from their base model values. Model calculations are employed to establish simple analytical relations between the deviations of these parameters and the additional temperature corrections required to compensate for them. Effects of simultaneous variation of two parameters are also examined. Use of these analytical relations instead of detailed radiative transfer calculations for routine data analysis results in a severalfold reduction in computation costs.

What to use to express the variability of data: Standard deviation or standard error of mean?

PubMed

Barde, Mohini P; Barde, Prajakt J

2012-07-01

Statistics plays a vital role in biomedical research. It helps present data precisely and draws the meaningful conclusions. While presenting data, one should be aware of using adequate statistical measures. In biomedical journals, Standard Error of Mean (SEM) and Standard Deviation (SD) are used interchangeably to express the variability; though they measure different parameters. SEM quantifies uncertainty in estimate of the mean whereas SD indicates dispersion of the data from mean. As readers are generally interested in knowing the variability within sample, descriptive data should be precisely summarized with SD. Use of SEM should be limited to compute CI which measures the precision of population estimate. Journals can avoid such errors by requiring authors to adhere to their guidelines.

System statistical reliability model and analysis

NASA Technical Reports Server (NTRS)

Lekach, V. S.; Rood, H.

1973-01-01

A digital computer code was developed to simulate the time-dependent behavior of the 5-kwe reactor thermoelectric system. The code was used to determine lifetime sensitivity coefficients for a number of system design parameters, such as thermoelectric module efficiency and degradation rate, radiator absorptivity and emissivity, fuel element barrier defect constant, beginning-of-life reactivity, etc. A probability distribution (mean and standard deviation) was estimated for each of these design parameters. Then, error analysis was used to obtain a probability distribution for the system lifetime (mean = 7.7 years, standard deviation = 1.1 years). From this, the probability that the system will achieve the design goal of 5 years lifetime is 0.993. This value represents an estimate of the degradation reliability of the system.

[Measurement and analysis on complex refraction indices of pear pollen in infrared band].

PubMed

Li, Le; Hu, Yi-hua; Gu, You-lin; Chen, Wei; Zhao, Yi-zheng; Chen, Shan-jing

2015-01-01

Pollen is an important part of bioaerosols, and its complex refractive index is a crucial parameter for study on optical characteristics and detection, identification of bioaerosols. The reflection spectra of pear pollen within the 2. 5 - 15µm waveband were measured by squash method. Based on the measured data, the complex refractive index of pear pollen within the wave-band of 2. 5 to 15 µm was calculated by using Kramers-Kroning (K-K) relation, and calculation deviation about incident angle and different reflectivities at high and low frequencies.were analyzed. The results indicate that 18 degrees angle of incidence and different reflectivities at high and low frequencies have little effect on the results, and it is practicable to calculate the complex refractive index of pollen based on its reflection spectral data. The data of complex refractive index of pollen have some reference value for optical characteristics of pollen, detection and identification of bioaerosols.

Index of refraction measurements and window corrections for PMMA under shock compression

NASA Astrophysics Data System (ADS)

Chapman, David James; Eakins, Daniel E.; Williamson, David Martin; Proud, William

2012-03-01

Symmetric plate impact experiments were performed to investigate the change in the refractive index of Polymethylmethacrylate (PMMA) under shock loading. Flyer and target geometries allowed the measurement of shock velocity, particle velocity, and refractive index in the shocked state, using a Het-V system (1550 nm). The change in refractive index of PMMA as a function of density is generally considered to be well described by the Gladstone-Dale relationship, meaning that the "apparent" velocity measured by a laser velocity interferometer is the "true" velocity, and hence there is no window correction. The results presented here demonstrate that the behaviour of PMMA deviates from an ideal Gladstone-Dale description, requiring a small velocity correction of order 1% at peak stresses up to 1.9 GPa. These results are consistent with literature values measured using a wavelength of 632.8 nm by [1].

Joint Entropy for Space and Spatial Frequency Domains Estimated from Psychometric Functions of Achromatic Discrimination

PubMed Central

Silveira, Vladímir de Aquino; Souza, Givago da Silva; Gomes, Bruno Duarte; Rodrigues, Anderson Raiol; Silveira, Luiz Carlos de Lima

2014-01-01

We used psychometric functions to estimate the joint entropy for space discrimination and spatial frequency discrimination. Space discrimination was taken as discrimination of spatial extent. Seven subjects were tested. Gábor functions comprising unidimensionalsinusoidal gratings (0.4, 2, and 10 cpd) and bidimensionalGaussian envelopes (1°) were used as reference stimuli. The experiment comprised the comparison between reference and test stimulithat differed in grating's spatial frequency or envelope's standard deviation. We tested 21 different envelope's standard deviations around the reference standard deviation to study spatial extent discrimination and 19 different grating's spatial frequencies around the reference spatial frequency to study spatial frequency discrimination. Two series of psychometric functions were obtained for 2%, 5%, 10%, and 100% stimulus contrast. The psychometric function data points for spatial extent discrimination or spatial frequency discrimination were fitted with Gaussian functions using the least square method, and the spatial extent and spatial frequency entropies were estimated from the standard deviation of these Gaussian functions. Then, joint entropy was obtained by multiplying the square root of space extent entropy times the spatial frequency entropy. We compared our results to the theoretical minimum for unidimensional Gábor functions, 1/4π or 0.0796. At low and intermediate spatial frequencies and high contrasts, joint entropy reached levels below the theoretical minimum, suggesting non-linear interactions between two or more visual mechanisms. We concluded that non-linear interactions of visual pathways, such as the M and P pathways, could explain joint entropy values below the theoretical minimum at low and intermediate spatial frequencies and high contrasts. These non-linear interactions might be at work at intermediate and high contrasts at all spatial frequencies once there was a substantial decrease in joint entropy for these stimulus conditions when contrast was raised. PMID:24466158

Joint entropy for space and spatial frequency domains estimated from psychometric functions of achromatic discrimination.

PubMed

Silveira, Vladímir de Aquino; Souza, Givago da Silva; Gomes, Bruno Duarte; Rodrigues, Anderson Raiol; Silveira, Luiz Carlos de Lima

2014-01-01

We used psychometric functions to estimate the joint entropy for space discrimination and spatial frequency discrimination. Space discrimination was taken as discrimination of spatial extent. Seven subjects were tested. Gábor functions comprising unidimensionalsinusoidal gratings (0.4, 2, and 10 cpd) and bidimensionalGaussian envelopes (1°) were used as reference stimuli. The experiment comprised the comparison between reference and test stimulithat differed in grating's spatial frequency or envelope's standard deviation. We tested 21 different envelope's standard deviations around the reference standard deviation to study spatial extent discrimination and 19 different grating's spatial frequencies around the reference spatial frequency to study spatial frequency discrimination. Two series of psychometric functions were obtained for 2%, 5%, 10%, and 100% stimulus contrast. The psychometric function data points for spatial extent discrimination or spatial frequency discrimination were fitted with Gaussian functions using the least square method, and the spatial extent and spatial frequency entropies were estimated from the standard deviation of these Gaussian functions. Then, joint entropy was obtained by multiplying the square root of space extent entropy times the spatial frequency entropy. We compared our results to the theoretical minimum for unidimensional Gábor functions, 1/4π or 0.0796. At low and intermediate spatial frequencies and high contrasts, joint entropy reached levels below the theoretical minimum, suggesting non-linear interactions between two or more visual mechanisms. We concluded that non-linear interactions of visual pathways, such as the M and P pathways, could explain joint entropy values below the theoretical minimum at low and intermediate spatial frequencies and high contrasts. These non-linear interactions might be at work at intermediate and high contrasts at all spatial frequencies once there was a substantial decrease in joint entropy for these stimulus conditions when contrast was raised.

Absolute distance measurement with correction of air refractive index by using two-color dispersive interferometry.

PubMed

Wu, Hanzhong; Zhang, Fumin; Liu, Tingyang; Li, Jianshuang; Qu, Xinghua

2016-10-17

Two-color interferometry is powerful for the correction of the air refractive index especially in the turbulent air over long distance, since the empirical equations could introduce considerable measurement uncertainty if the environmental parameters cannot be measured with sufficient precision. In this paper, we demonstrate a method for absolute distance measurement with high-accuracy correction of air refractive index using two-color dispersive interferometry. The distances corresponding to the two wavelengths can be measured via the spectrograms captured by a CCD camera pair in real time. In the long-term experiment of the correction of air refractive index, the experimental results show a standard deviation of 3.3 × 10^-8 for 12-h continuous measurement without the precise knowledge of the environmental conditions, while the variation of the air refractive index is about 2 × 10^-6. In the case of absolute distance measurement, the comparison with the fringe counting interferometer shows an agreement within 2.5 μm in 12 m range.

Longitudinal and cross-sectional analyses of visual field progression in participants of the Ocular Hypertension Treatment Study.

PubMed

Artes, Paul H; Chauhan, Balwantray C; Keltner, John L; Cello, Kim E; Johnson, Chris A; Anderson, Douglas R; Gordon, Mae O; Kass, Michael A

2010-12-01

To assess agreement between longitudinal and cross-sectional analyses for determining visual field progression in data from the Ocular Hypertension Treatment Study. Visual field data from 3088 eyes of 1570 participants (median follow-up, 7 years) were analyzed. Longitudinal analyses were performed using change probability with total and pattern deviation, and cross-sectional analyses were performed using the glaucoma hemifield test, corrected pattern standard deviation, and mean deviation. The rates of mean deviation and general height change were compared to estimate the degree of diffuse loss in emerging glaucoma. Agreement on progression in longitudinal and cross-sectional analyses ranged from 50% to 61% and remained nearly constant across a wide range of criteria. In contrast, agreement on absence of progression ranged from 97.0% to 99.7%, being highest for the stricter criteria. Analyses of pattern deviation were more conservative than analyses of total deviation, with a 3 to 5 times lesser incidence of progression. Most participants developing field loss had both diffuse and focal changes. Despite considerable overall agreement, 40% to 50% of eyes identified as having progressed with either longitudinal or cross-sectional analyses were identified with only one of the analyses. Because diffuse change is part of early glaucomatous damage, pattern deviation analyses may underestimate progression in patients with ocular hypertension.

Analysis of measurement deviations for the patient-specific quality assurance using intensity-modulated spot-scanning particle beams

NASA Astrophysics Data System (ADS)

Li, Yongqiang; Hsi, Wen C.

2017-04-01

To analyze measurement deviations of patient-specific quality assurance (QA) using intensity-modulated spot-scanning particle beams, a commercial radiation dosimeter using 24 pinpoint ionization chambers was utilized. Before the clinical trial, validations of the radiation dosimeter and treatment planning system were conducted. During the clinical trial 165 measurements were performed on 36 enrolled patients. Two or three fields of particle beam were used for each patient. Measurements were typically performed with the dosimeter placed at special regions of dose distribution along depth and lateral profiles. In order to investigate the dosimeter accuracy, repeated measurements with uniform dose irradiations were also carried out. A two-step approach was proposed to analyze 24 sampling points over a 3D treatment volume. The mean value and the standard deviation of each measurement did not exceed 5% for all measurements performed on patients with various diseases. According to the defined intervention thresholds of mean deviation and the distance-to-agreement concept with a Gamma index analysis using criteria of 3.0% and 2 mm, a decision could be made regarding whether the dose distribution was acceptable for the patient. Based measurement results, deviation analysis was carried out. In this study, the dosimeter was used for dose verification and provided a safety guard to assure precise dose delivery of highly modulated particle therapy. Patient-specific QA will be investigated in future clinical operations.

Comparison of relationships between four common anthropometric measures and incident diabetes.

PubMed

Lee, Crystal Man Ying; Woodward, Mark; Pandeya, Nirmala; Adams, Robert; Barrett-Connor, Elizabeth; Boyko, Edward J; Eliasson, Mats; Franco, Laercio J; Fujimoto, Wilfred Y; Gonzalez, Clicerio; Howard, Barbara V; Jacobs, David R; Keinanen-Kiukaanniemi, Sirkka; Magliano, Dianna; Schreiner, Pamela; Shaw, Jonathan E; Stevens, June; Taylor, Anne; Tuomilehto, Jaakko; Wagenknecht, Lynne; Huxley, Rachel R

2017-10-01

First, to conduct a detailed exploration of the prospective relations between four commonly used anthropometric measures with incident diabetes and to examine their consistency across different population subgroups. Second, to compare the ability of each of the measures to predict five-year risk of diabetes. We conducted a meta-analysis of individual participant data on body mass index (BMI), waist circumference (WC), waist-hip and waist-height ratio (WHtR) from the Obesity, Diabetes and Cardiovascular Disease Collaboration. Cox proportional hazard models were used to estimate the association between a one standard deviation increment in each anthropometric measure and incident diabetes. Harrell's concordance statistic was used to test the predictive accuracy of each measure for diabetes risk at five years. Twenty-one studies with 154,998 participants and 9342 cases of incident diabetes were available. Each of the measures had a positive association with incident diabetes. A one standard deviation increment in each of the measures was associated with 64-80% higher diabetes risk. WC and WHtR more strongly associated with risk than BMI (ratio of hazard ratios: 0.95 [0.92,0.99] - 0.97 [0.95,0.98]) but there was no appreciable difference between the four measures in the predictive accuracy for diabetes at five years. Despite suggestions that abdominal measures of obesity have stronger associations with incident diabetes and better predictive accuracy than BMI, we found no overall advantage in any one measure at discriminating the risk of developing diabetes. Any of these measures would suffice to assist in primary diabetes prevention efforts. Copyright © 2017 Elsevier B.V. All rights reserved.

Elevated serum ferritin concentration is associated with incident type 2 diabetes mellitus in a Chinese population: A prospective cohort study.

PubMed

Chen, Ling; Li, Yufeng; Zhang, Fang; Zhang, Simin; Zhou, Xianghai; Ji, Linong

2018-05-01

We aimed to evaluate the association between serum ferritin levels and incident type 2 diabetes mellitus risk in a Chinese population. This cohort study assessed 2225 Chinese individuals aged 25-75 years. Diabetes mellitus was diagnosed using the 1999 World Health Organization definition with a median follow-up period of 20 months. Cox proportional hazard models were used to estimate adjusted hazard ratios and 95% confidence intervals (CI) for incident diabetes when serum ferritin concentrations increased by one standard deviation. During the follow-up period, 112 cases (62 men and 50 women) of type 2 diabetes mellitus were identified. Baseline serum ferritin levels were higher in the diabetes than the non-diabetes group. After adjusting for age, body mass index, waist circumference, mean arterial pressure, fasting plasma glucose, fasting insulin, hemoglobin A1c, total cholesterol, high-density lipoprotein cholesterol, alanine transaminase and triglyceride levels, family history of diabetes mellitus, pork meat consumption, neutrophil/lymphocyte ratio, education, and annual household income, the hazard ratios for incident diabetes corresponding to one standard deviation increase in serum ferritin levels were 1.17 (95% CI 1.03, 1.34), 1.20 (95% CI 1.003, 1.43), and 1.03 (95% CI 0.82, 1.31) for the total population, men, and women, respectively. High serum ferritin levels were associated with a higher risk of incident type 2 diabetes mellitus independent of traditional risk factors in the total population and men. Copyright © 2018 Elsevier B.V. All rights reserved.

Ambulatory blood pressure profiles in familial dysautonomia.

PubMed

Goldberg, Lior; Bar-Aluma, Bat-El; Krauthammer, Alex; Efrati, Ori; Sharabi, Yehonatan

2018-02-12

Familial dysautonomia (FD) is a rare genetic disease that involves extreme blood pressure fluctuations secondary to afferent baroreflex failure. The diurnal blood pressure profile, including the average, variability, and day-night difference, may have implications for long-term end organ damage. The purpose of this study was to describe the circadian pattern of blood pressure in the FD population and relationships with renal and pulmonary function, use of medications, and overall disability. We analyzed 24-h ambulatory blood pressure monitoring recordings in 22 patients with FD. Information about medications, disease severity, renal function (estimated glomerular filtration, eGFR), pulmonary function (forced expiratory volume in 1 s, FEV1) and an index of blood pressure variability (standard deviation of systolic pressure) were analyzed. The mean (± SEM) 24-h blood pressure was 115 ± 5.6/72 ± 2.0 mmHg. The diurnal blood pressure variability was high (daytime systolic pressure standard deviation 22.4 ± 1.5 mmHg, nighttime 17.2 ± 1.6), with a high frequency of a non-dipping pattern (16 patients, 73%). eGFR, use of medications, FEV1, and disability scores were unrelated to the degree of blood pressure variability or to dipping status. This FD cohort had normal average 24-h blood pressure, fluctuating blood pressure, and a high frequency of non-dippers. Although there was evidence of renal dysfunction based on eGFR and proteinuria, the ABPM profile was unrelated to the measures of end organ dysfunction or to reported disability.

Estimating Douglas-fir site quality from aerial photographs.

Treesearch

Grover A. Choate

1961-01-01

This study investigated the feasibility of developing a technique for estimating site index of Douglas-fir in the Pacific Northwest, using aerial photos and topographic maps. Physiographic features were used as indicators of site index. Analysis showed that although most of the features were highly significant as criteria for predicting site index, they explained less...

Association between direct measurement of active serum calcium and risk of type 2 diabetes mellitus: A prospective study.

PubMed

Zaccardi, F; Webb, D R; Carter, P; Pitocco, D; Khunti, K; Davies, M J; Kurl, S; Laukkanen, J A

2015-06-01

Previous prospective studies showing a positive association between serum calcium and incidence of type 2 diabetes mellitus (T2DM) have relied on total calcium or an indirect estimate of active, ionized calcium (iCa). We aimed to assess this relationship using a direct measurement of iCa. iCa and cardiometabolic risk factors were measured in a population-based sample of 2350 men without a known history of T2DM at baseline. Associations between iCa levels and incident cases of T2DM (self-reported, ascertained with a glucose tolerance test, or determined by record linkage to national registers) were estimated using Cox regression analyses adjusted for potential confounders. At baseline, mean (standard deviation) age was 53 (5) years and mean iCa 1.18 (0.05) mmol/L. During a median follow-up of 23.1 years, 140 new cases of T2DM were recorded. In a multivariable analysis adjusted for age, body mass index, systolic blood pressure, serum HDL-cholesterol, and family history of T2DM, there was no association comparing second (hazard ratio 0.84; 95% confidence interval 0.59-1.18), third (0.77; 0.52-1.14), or fourth (0.98; 0.69-1.39) vs first quartile of iCa (p for trend 0.538); further adjustment for C-reactive protein, physical activity level, and triglycerides did not change the estimates (p for trend 0.389). In this study, we did not find evidence of an association between direct measurement of active calcium and risk of T2DM. Further studies are needed to confirm our findings and define the relationship between factors influencing indirect calcium estimation and incident T2DM. Copyright © 2015 Elsevier B.V. All rights reserved.

Passive activity observation (PAO) method to estimate outdoor thermal adaptation in public space: case studies in Australian cities.

PubMed

Sharifi, Ehsan; Boland, John

2018-06-18

Outdoor thermal comfort is influenced by people's climate expectations, perceptions and adaptation capacity. Varied individual response to comfortable or stressful thermal environments results in a deviation between actual outdoor thermal activity choices and those predicted by thermal comfort indices. This paper presents a passive activity observation (PAO) method for estimating contextual limits of outdoor thermal adaptation. The PAO method determines which thermal environment result in statistically meaningful changes may occur in outdoor activity patterns, and it estimates thresholds of outdoor thermal neutrality and limits of thermal adaptation in public space based on activity observation and microclimate field measurement. Applications of the PAO method have been demonstrated in Adelaide, Melbourne and Sydney, where outdoor activities were analysed against outdoor thermal comfort indices between 2013 and 2014. Adjusted apparent temperature (aAT), adaptive predicted mean vote (aPMV), outdoor standard effective temperature (OUT_SET), physiological equivalent temperature (PET) and universal thermal comfort index (UTCI) are calculated from the PAO data. Using the PAO method, the high threshold of outdoor thermal neutrality was observed between 24 °C for optional activities and 34 °C for necessary activities (UTCI scale). Meanwhile, the ultimate limit of thermal adaptation in uncontrolled public spaces is estimated to be between 28 °C for social activities and 48 °C for necessary activities. Normalised results indicate that city-wide high thresholds for outdoor thermal neutrality vary from 25 °C in Melbourne to 26 °C in Sydney and 30 °C in Adelaide. The PAO method is a relatively fast and localised method for measuring limits of outdoor thermal adaptation and effectively informs urban design and policy making in the context of climate change.

Nonrapid Eye Movement-Predominant Obstructive Sleep Apnea: Detection and Mechanism.

PubMed

Yamauchi, Motoo; Fujita, Yukio; Kumamoto, Makiko; Yoshikawa, Masanori; Ohnishi, Yoshinobu; Nakano, Hiroshi; Strohl, Kingman P; Kimura, Hiroshi

2015-09-15

Obstructive sleep apnea (OSA) can be severe and present in higher numbers during rapid eye movement (REM) than nonrapid eye movement (NREM) sleep; however, OSA occurs in NREM sleep and can be predominant. In general, ventilation decreases an average 10% to 15% during transition from wakefulness to sleep, and there is variability in just how much ventilation decreases. As dynamic changes in ventilation contribute to irregular breathing and breathing during NREM sleep is mainly under chemical control, our hypothesis is that patients with a more pronounced reduction in ventilation during the transition from wakefulness to NREM sleep will have NREM- predominant rather than REM-predominant OSA. A retrospective analysis of 451 consecutive patients (apnea-hypopnea index [AHI] > 5) undergoing diagnostic polysomnography was performed, and breath-to-breath analysis of the respiratory cycle duration, tidal volume, and estimated minute ventilation before and after sleep onset were examined. Values were calculated using respiratory inductance plethysmography. The correlation between the percent change in estimated minute ventilation during wake-sleep transitions and the percentage of apnea-hypopneas in NREM sleep (%AHI in NREM; defined as (AHI-NREM) / [(AHI-NREM) + (AHI-REM)] × 100) was the primary outcome. The decrease in estimated minute ventilation during wake-sleep transitions was 15.0 ± 16.6% (mean ± standard deviation), due to a decrease in relative tidal volume. This decrease in estimated minute ventilation was significantly correlated with %AHI in NREM (r = -0.222, p < 0.01). A greater dynamic reduction in ventilation back and forth from wakefulness to sleep contributes to the NREM predominant OSA phenotype via induced ventilatory instability. © 2015 American Academy of Sleep Medicine.

Analysis of DGPS/INS and MLS/INS final approach navigation errors and control performance data

NASA Technical Reports Server (NTRS)

Hueschen, Richard M.; Spitzer, Cary R.

1992-01-01

Flight tests were conducted jointly by NASA Langley Research Center and Honeywell, Inc., on a B-737 research aircraft to record a data base for evaluating the performance of a differential DGPS/inertial navigation system (INS) which used GPS Course/Acquisition code receivers. Estimates from the DGPS/INS and a Microwave Landing System (MLS)/INS, and various aircraft parameter data were recorded in real time aboard the aircraft while flying along the final approach path to landing. This paper presents the mean and standard deviation of the DGPS/INS and MLS/INS navigation position errors computed relative to the laser tracker system and of the difference between the DGPS/INS and MLS/INS velocity estimates. RMS errors are presented for DGPS/INS and MLS/INS guidance errors (localizer and glideslope). The mean navigation position errors and standard deviation of the x position coordinate of the DGPS/INS and MLS/INS systems were found to be of similar magnitude while the standard deviation of the y and z position coordinate errors were significantly larger for DGPS/INS compared to MLS/INS.

Investigation of Deviations from Ideality in the Two Liquid Phase Region of Systems of Medium Molecular Weight Hydrocarbon Mixtures and Water.

DTIC Science & Technology

1986-02-01

determined by refractometry using a Bausch and Lomb Refractometer (Abbe 3-L). Refractive index calibrations for the binary mixtures examined are given in...mixture sample was taken and analyzed by refractometry . b. Results The results of the vapor pressure experiments and the Redlich- Kister coefficients

Underweight, Obesity and Exercise among Adults with Intellectual Disabilities in Supported Accommodation in Northern England

ERIC Educational Resources Information Center

Emerson, E.

2005-01-01

Significant deviation from normal weight (obesity and underweight) and lack of physical exercise have been identified as three of the most significant global behavioural risks to health. Body mass index (BMI) and levels of physical activity were measured in a sample of 1542 adults with intellectual disabilities (ID) receiving supported…

Growth and Puberty in a 2-Year Open-Label Study of Lisdexamfetamine Dimesylate in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder.

PubMed

Banaschewski, Tobias; Johnson, Mats; Nagy, Peter; Otero, Isabel Hernández; Soutullo, César A; Yan, Brian; Zuddas, Alessandro; Coghill, David R

2018-05-01

Stimulant medications for the treatment of attention-deficit/hyperactivity disorder have a history of safe and effective use; however, concerns exist that they may adversely affect growth trajectories in children and adolescents. The objective of this study was to evaluate the longer-term effects of lisdexamfetamine dimesylate on weight, height, body mass index and pubertal development in children and adolescents with attention-deficit/hyperactivity disorder. Children and adolescents aged 6-17 years with attention-deficit/hyperactivity disorder took open-label lisdexamfetamine dimesylate (30, 50 or 70 mg/day) in this open-label 2-year safety and efficacy study. Safety evaluations included treatment-emergent adverse events, measurement of weight, height and body mass index, and self-reported pubertal status using Tanner staging. The safety analysis population comprised all enrolled participants (N = 314) and 191 (60.8%) completed the study. Weight decrease was reported as a treatment-emergent adverse event in 63 participants (20.1%) and two participants (0.6%) discontinued the study as a result of treatment-emergent adverse events of weight decrease. Growth retardation of moderate intensity was reported as a treatment-emergent adverse event for two participants. From baseline to the last on-treatment assessment, there were increases in mean weight of 2.1 kg (standard deviation 5.83) and height of 6.1 cm (standard deviation 4.90), and a body mass index decrease of 0.5 kg/m 2 (standard deviation 1.72). Mean weight, height and body mass index z-scores decreased over the first 36 weeks of the study and then stabilised. Changes from baseline to the last on-treatment assessment in mean z-scores for weight, height and body mass index were significantly less than zero (- 0.51, - 0.24 and - 0.59, respectively; nominal p < 0.0001). The proportion of participants with a z-score of < - 1 ranged from 5.1% (baseline) to 22.1% (week 84) for weight, 8.2% (baseline) to 12.6% (week 96) for height, and 8.3% (baseline) to 28.8% (week 96) for body mass index. Thirteen participants (4.1%) shifted to a weight below the fifth percentile at the last on-treatment assessment from a higher weight category at baseline. At the last on-treatment assessment, most participants remained at their baseline Tanner stage or had shifted higher. Findings from this comprehensive examination of growth outcomes associated with lisdexamfetamine dimesylate treatment over 2 years were consistent with previous studies of stimulant medications. Whilst mean weight and height increased over the course of the study, there was a small but transient reduction in mean weight, height and body mass index z-scores. A small increase in the proportion of participants in the lowest weight and body mass index categories highlights the importance of the regular monitoring of weight and height. There was no evidence of delayed onset of puberty. CLINICALTRIALS. NCT01328756.

Coastal Vertical Land motion in the German Bight

NASA Astrophysics Data System (ADS)

Becker, Matthias; Fenoglio, Luciana; Reckeweg, Florian

2017-04-01

In the framework of the ESA Sea Level Climate Change Initiative (CCI) we analyse a set of GNSS equipped tide gauges at the German Bight. Main goals are the determination of tropospheric zenith delay corrections for altimetric observations, precise coordinates in ITRF2008 and vertical land motion (VLM) rates of the tide gauge stations. These are to be used for georeferencing the tide gauges and the correction of tide gauge observations for VLM. The set of stations includes 38 GNSS stations. 19 stations are in the German Bight, where 15 of them belong to the Bundesanstalt für Gewässerkunde, 3 to EUREF and 1 to GREF. These stations are collocated with tide gauges (TGs). The other 19 GNSS stations in the network belong to EUREF, IGS and GREF. We analyse data in the time span from 2008 till the end of 2016 with the Bernese PPP processing approach. Data are partly rather noisy and disturbed by offsets and data gaps at the coastal TG sites. Special effort is therefore put into a proper estimation of the VLM. We use FODITS (Ostini2012), HECTOR (Bos et al, 2013), CATS (Williams, 2003) and the MIDAS approach of Blewitt (2016) to robustly derive rates and realistic error estimates. The results are compared to those published by the European Permanent Network (EPN), ITRF and the Système d'Observation du Niveau des Eaux Littorales (SONEL) for common stations. Vertical motion is small in general, at the -1 to -2 mm/yr level for most coastal stations. A comparison of the standard deviations of the velocity differences to EPN with the mean values of the estimated velocity standard deviations for our solution shows a very good agreement of the estimated velocities and their standard deviations with the reference solution from EPN. In the comparison with results by SONEL the standard deviation of the differences is slightly higher. The discrepancies may arise from differences in the time span analyzed and gaps, offsets and data preprocessing. The combined estimation of functional and stochastic parameters is rather sensitive to the characteristics of the time series and thus the estimated velocity also depends on the applied stochastic model and on the selected parameters. The GPS vertical land motion rates are finally compared to the difference between sea level rates measured by co-located altimetry and by tide gauge station data, which gives another estimation of VLM.

Novel index for micromixing characterization and comparative analysis

PubMed Central

Jain, Mranal; Nandakumar, K.

2010-01-01

The most basic micromixer is a T- or Y-mixer, where two confluent streams mix due to transverse diffusion. To enhance micromixing, various modifications of T-mixers are reported such as heterogeneously charged walls, grooves on the channel base, geometric variations by introducing physical constrictions, etc. The performance of these reported designs is evaluated against the T-mixer in terms of the deviation from perfectly mixed state and mixing length (device length required to achieve perfect mixing). Although many studies have noticed the reduced flow rates for improved mixer designs, the residence time is not taken into consideration for micromixing performance evaluation. In this work, we propose a novel index, based on residence time, for micromixing characterization and comparative analysis. For any given mixer, the proposed index identifies the nondiffusive mixing enhancement with respect to the T-mixer. Various micromixers are evaluated using the proposed index to demonstrate the usefulness of the index. It is also shown that physical constriction mixer types are equivalent to T-mixers. The proposed index is found to be insightful and could be used as a benchmark for comparing different mixing strategies. PMID:20689773

Refractive Index of Sodium Iodide

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

Jellison Jr, Gerald Earle; Boatner, Lynn A; Ramey, Joanne Oxendine

2012-01-01

The refractive index of sodium iodide, an important scintillator material that is widely used for radiation detection, is based on a single measurement made by Spangenberg at one wavelength using the index-matching liquid immersion method (Z. Kristallogr., 57, 494-534 (1923)). In the present paper, we present new results for the refractive index of sodium iodide as measured by the minimum deviation technique at six wavelengths between 436 nm (n=1.839 0.002) and 633 nm (n=1.786 0.002). These 6 measurements can be fit to a Sellmeier model, resulting in a 2 of 1.02, indicating a good fit to the data. In addition,more » we report on ellipsometry measurements, which suggest that the near-surface region of the air sensitive NaI crystal seriously degrades, even in a moisture-free environment, resulting in a significantly lower value of the refractive index near the surface. First-principles theoretical calculations of the NaI refractive index that agree with the measured values within 0.025-0.045 are also presented and discussed.« less

Standard and reduced radiation dose liver CT images: adaptive statistical iterative reconstruction versus model-based iterative reconstruction-comparison of findings and image quality.

PubMed

Shuman, William P; Chan, Keith T; Busey, Janet M; Mitsumori, Lee M; Choi, Eunice; Koprowicz, Kent M; Kanal, Kalpana M

2014-12-01

To investigate whether reduced radiation dose liver computed tomography (CT) images reconstructed with model-based iterative reconstruction ( MBIR model-based iterative reconstruction ) might compromise depiction of clinically relevant findings or might have decreased image quality when compared with clinical standard radiation dose CT images reconstructed with adaptive statistical iterative reconstruction ( ASIR adaptive statistical iterative reconstruction ). With institutional review board approval, informed consent, and HIPAA compliance, 50 patients (39 men, 11 women) were prospectively included who underwent liver CT. After a portal venous pass with ASIR adaptive statistical iterative reconstruction images, a 60% reduced radiation dose pass was added with MBIR model-based iterative reconstruction images. One reviewer scored ASIR adaptive statistical iterative reconstruction image quality and marked findings. Two additional independent reviewers noted whether marked findings were present on MBIR model-based iterative reconstruction images and assigned scores for relative conspicuity, spatial resolution, image noise, and image quality. Liver and aorta Hounsfield units and image noise were measured. Volume CT dose index and size-specific dose estimate ( SSDE size-specific dose estimate ) were recorded. Qualitative reviewer scores were summarized. Formal statistical inference for signal-to-noise ratio ( SNR signal-to-noise ratio ), contrast-to-noise ratio ( CNR contrast-to-noise ratio ), volume CT dose index, and SSDE size-specific dose estimate was made (paired t tests), with Bonferroni adjustment. Two independent reviewers identified all 136 ASIR adaptive statistical iterative reconstruction image findings (n = 272) on MBIR model-based iterative reconstruction images, scoring them as equal or better for conspicuity, spatial resolution, and image noise in 94.1% (256 of 272), 96.7% (263 of 272), and 99.3% (270 of 272), respectively. In 50 image sets, two reviewers (n = 100) scored overall image quality as sufficient or good with MBIR model-based iterative reconstruction in 99% (99 of 100). Liver SNR signal-to-noise ratio was significantly greater for MBIR model-based iterative reconstruction (10.8 ± 2.5 [standard deviation] vs 7.7 ± 1.4, P < .001); there was no difference for CNR contrast-to-noise ratio (2.5 ± 1.4 vs 2.4 ± 1.4, P = .45). For ASIR adaptive statistical iterative reconstruction and MBIR model-based iterative reconstruction , respectively, volume CT dose index was 15.2 mGy ± 7.6 versus 6.2 mGy ± 3.6; SSDE size-specific dose estimate was 16.4 mGy ± 6.6 versus 6.7 mGy ± 3.1 (P < .001). Liver CT images reconstructed with MBIR model-based iterative reconstruction may allow up to 59% radiation dose reduction compared with the dose with ASIR adaptive statistical iterative reconstruction , without compromising depiction of findings or image quality. © RSNA, 2014.

Red, Straight, no bends: primordial power spectrum reconstruction from CMB and large-scale structure

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

Ravenni, Andrea; Verde, Licia; Cuesta, Antonio J., E-mail: andrea.ravenni@pd.infn.it, E-mail: liciaverde@icc.ub.edu, E-mail: ajcuesta@icc.ub.edu

2016-08-01

We present a minimally parametric, model independent reconstruction of the shape of the primordial power spectrum. Our smoothing spline technique is well-suited to search for smooth features such as deviations from scale invariance, and deviations from a power law such as running of the spectral index or small-scale power suppression. We use a comprehensive set of the state-of the art cosmological data: Planck observations of the temperature and polarisation anisotropies of the cosmic microwave background, WiggleZ and Sloan Digital Sky Survey Data Release 7 galaxy power spectra and the Canada-France-Hawaii Lensing Survey correlation function. This reconstruction strongly supports the evidencemore » for a power law primordial power spectrum with a red tilt and disfavours deviations from a power law power spectrum including small-scale power suppression such as that induced by significantly massive neutrinos. This offers a powerful confirmation of the inflationary paradigm, justifying the adoption of the inflationary prior in cosmological analyses.« less

Red, Straight, no bends: primordial power spectrum reconstruction from CMB and large-scale structure

NASA Astrophysics Data System (ADS)

Ravenni, Andrea; Verde, Licia; Cuesta, Antonio J.

2016-08-01

We present a minimally parametric, model independent reconstruction of the shape of the primordial power spectrum. Our smoothing spline technique is well-suited to search for smooth features such as deviations from scale invariance, and deviations from a power law such as running of the spectral index or small-scale power suppression. We use a comprehensive set of the state-of the art cosmological data: Planck observations of the temperature and polarisation anisotropies of the cosmic microwave background, WiggleZ and Sloan Digital Sky Survey Data Release 7 galaxy power spectra and the Canada-France-Hawaii Lensing Survey correlation function. This reconstruction strongly supports the evidence for a power law primordial power spectrum with a red tilt and disfavours deviations from a power law power spectrum including small-scale power suppression such as that induced by significantly massive neutrinos. This offers a powerful confirmation of the inflationary paradigm, justifying the adoption of the inflationary prior in cosmological analyses.

Relative trace-element concern indexes for eastern Kentucky coals

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

Collins, S.L.

Coal trace elements that could affect environmental quality were studied in 372 samples (collected and analyzed by the Kentucky Geological Survey and the United States Geological Survey) from 36 coal beds in eastern Kentucky. Relative trace-element concern indexes are defined as the weighted sum of standarized (substract mean; divide by standard deviation) concentrations. Index R is calculated from uranium and thorium, index 1 from elements of minor concern (antimony, barium, bromine, chloride, cobalt, lithium, manganese, sodium, and strontium), index 2 from elements of moderate concern (chromium, copper, fluorine, nickel, vanadium, and zinc), and index 4 from elements of greatest concernmore » (arsenic, boron, cadmium, lead, mercury, molybdenum, and selenium). Numericals indicate weights, except that index R is weighted by 1, and index 124 is the unweighted sum of indexes 1, 2, and 4. Contour mapping indexes is valid because all indexes have nonnugget effect variograms. Index 124 is low west of Lee and Bell counties, and in Pike County. Index 124 is high in the area bounded by Boyd, Menifee, Knott, and Martin counties and in Owsley, Clay, and Leslie counties. Coal from some areas of eastern Kentucky is less likely to cause environmental problems than that from other areas. Positive correlations of all indexes with the centered log ratios of ash, and negative correlations with centered log ratios of carbon, hydrogen, nitrogen, oxygen, and sulfur indicate that trace elements of concern are predominantly associated with ash. Beneficiation probably would reduce indexes significantly.« less

Estimating Achievement Gaps from Test Scores Reported in Ordinal "Proficiency" Categories

ERIC Educational Resources Information Center

Ho, Andrew D.; Reardon, Sean F.

2012-01-01

Test scores are commonly reported in a small number of ordered categories. Examples of such reporting include state accountability testing, Advanced Placement tests, and English proficiency tests. This paper introduces and evaluates methods for estimating achievement gaps on a familiar standard-deviation-unit metric using data from these ordered…

The Treatment Effect of Grade Repetitions

ERIC Educational Resources Information Center

Mahjoub, Mohamed-Badrane

2017-01-01

This paper estimates the treatment effect of grade repetitions in French junior high schools, using a value-added test score as outcome and quarter of birth as instrument. With linear two-stage least squares, local average treatment effect is estimated at around 1.6 times the standard deviation of the achievement gain. With non-linear…

Estimating the probability that the sample mean is within a desired fraction of the standard deviation of the true mean.

PubMed

Schillaci, Michael A; Schillaci, Mario E

2009-02-01

The use of small sample sizes in human and primate evolutionary research is commonplace. Estimating how well small samples represent the underlying population, however, is not commonplace. Because the accuracy of determinations of taxonomy, phylogeny, and evolutionary process are dependant upon how well the study sample represents the population of interest, characterizing the uncertainty, or potential error, associated with analyses of small sample sizes is essential. We present a method for estimating the probability that the sample mean is within a desired fraction of the standard deviation of the true mean using small (n<10) or very small (n < or = 5) sample sizes. This method can be used by researchers to determine post hoc the probability that their sample is a meaningful approximation of the population parameter. We tested the method using a large craniometric data set commonly used by researchers in the field. Given our results, we suggest that sample estimates of the population mean can be reasonable and meaningful even when based on small, and perhaps even very small, sample sizes.

Estimating occupant satisfaction of HVAC system noise using quality assessment index.

PubMed

Forouharmajd, Farhad; Nassiri, Parvin; Monazzam, Mohammad R; Yazdchi, Mohammadreza

2012-01-01

Noise may be defined as any unwanted sound. Sound becomes noise when it is too loud, unexpected, uncontrolled, happens at the wrong time, contains unwanted pure tones or unpleasant. In addition to being annoying, loud noise can cause hearing loss, and, depending on other factors, can affect stress level, sleep patterns and heart rate. The primary object for determining subjective estimations of loudness is to present sounds to a sample of listeners under controlled conditions. In heating, ventilation and air conditioning (HVAC) systems only the ventilation fan industry (e.g., bathroom exhaust and sidewall propeller fans) uses loudness ratings. In order to find satisfaction, percent of exposure to noise is the valuable issue for the personnel who are working in these areas. The room criterion (RC) method has been defined by ANSI standard S12.2, which is based on measured levels of in HVAC systems noise in spaces and is used primarily as a diagnostic tool. The RC method consists of a family of criteria curves and a rating procedure. RC measures background noise in the building over the frequency range of 16-4000 Hz. This rating system requires determination of the mid-frequency average level and determining the perceived balance between high-frequency (HF) sound and low-frequency (LF) sound. The arithmetic average of the sound levels in the 500, 1000 and 2000 Hz octave bands is 44.6 dB; therefore, the RC 45 curve is selected as the reference for spectrum quality evaluation. The spectral deviation factors in the LF, medium-frequency sound and HF regions are 2.9, 7.5 and -2.3, respectively, giving a Quality Assessment Index (QAI) of 9.8. This concludes the QAI is useful in estimating an occupant's probable reaction when the system design does not produce optimum sound quality. Thus, a QAI between 5 and 10 dB represents a marginal situation in which acceptance by an occupant is questionable. However, when sound pressure levels in the 16 or 31.5 Hz octave bands exceed 65 dB, vibration in lightweight office construction is possible.

Tests for qualitative treatment-by-centre interaction using a 'pushback' procedure.

PubMed

Ciminera, J L; Heyse, J F; Nguyen, H H; Tukey, J W

1993-06-15

In multicentre clinical trials using a common protocol, the centres are usually regarded as being a fixed factor, thus allowing any treatment-by-centre interaction to be omitted from the error term for the effect of treatment. However, we feel it necessary to use the treatment-by-centre interaction as the error term if there is substantial evidence that the interaction with centres is qualitative instead of quantitative. To make allowance for the estimated uncertainties of the centre means, we propose choosing a reference value (for example, the median of the ordered array of centre means) and converting the individual centre results into standardized deviations from the reference value. The deviations are then reordered, and the results 'pushed back' by amounts appropriate for the corresponding order statistics in a sample from the relevant distribution. The pushed-back standardized deviations are then restored to the original scale. The appearance of opposite signs among the destandardized values for the various centres is then taken as 'substantial evidence' of qualitative interaction. Procedures are presented using, in any combination: (i) Gaussian, or Student's t-distribution; (ii) order-statistic medians or outward 90 per cent points of the corresponding order statistic distributions; (iii) pooling or grouping and pooling the internally estimated standard deviations of the centre means. The use of the least conservative combination--Student's t, outward 90 per cent points, grouping and pooling--is recommended.

SIMMAX: A modern analog technique to deduce Atlantic sea surface temperatures from planktonic foraminifera in deep-sea sediments

NASA Astrophysics Data System (ADS)

Pflaumann, Uwe; Duprat, Josette; Pujol, Claude; Labeyrie, Laurent D.

1996-02-01

We present a data set of 738 planktonic foraminiferal species counts from sediment surface samples of the eastern North Atlantic and the South Atlantic between 87°N and 40°S, 35°E and 60°W including published Climate: Long-Range Investigation, Mapping, and Prediction (CLIMAP) data. These species counts are linked to Levitus's [1982] modern water temperature data for the four caloric seasons, four depth ranges (0, 30, 50, and 75 m), and the combined means of those depth ranges. The relation between planktonic foraminiferal assemblages and sea surface temperature (SST) data is estimated using the newly developed SIMMAX technique, which is an acronym for a modern analog technique (MAT) with a similarity index, based on (1) the scalar product of the normalized faunal percentages and (2) a weighting procedure of the modern analog's SSTs according to the inverse geographical distances of the most similar samples. Compared to the classical CLIMAP transfer technique and conventional MAT techniques, SIMMAX provides a more confident reconstruction of paleo-SSTs (correlation coefficient is 0.994 for the caloric winter and 0.993 for caloric summer). The standard deviation of the residuals is 0.90°C for caloric winter and 0.96°C for caloric summer at 0-m water depth. The SST estimates reach optimum stability (standard deviation of the residuals is 0.88°C) at the average 0- to 75-m water depth. Our extensive database provides SST estimates over a range of -1.4 to 27.2°C for caloric winter and 0.4 to 28.6°C for caloric summer, allowing SST estimates which are especially valuable for the high-latitude Atlantic during glacial times. An electronic supplement of this material may be obtained on adiskette or Anonymous FTP from KOSMOS.AGU.ORG. (LOGIN toAGU's FTP account using ANONYMOUS as the username and GUESTas the password. Go to the right directory by typing CD APPEND. TypeLS to see what files are available. Type GET and the name of the file toget it. Finally type EXIT to leave the system.) (Paper 95PA01743,SIMMAX: A modern analog technique to deduce Atlantic sea surfacetemperatures from planktonic foraminifera in deep-sea sediments, UwePflaumann, Josette Duprat, Claude Pujol, and Laurent D. Labeyrie).Diskette may be ordered from American Geophysical Union, 2000Florida Avenue, N.W., Washington, DC 20009; Payment mustaccompany order.

Evaluation of the MV (CAPON) Coherent Doppler Lidar Velocity Estimator

NASA Technical Reports Server (NTRS)

Lottman, B.; Frehlich, R.

1997-01-01

The performance of the CAPON velocity estimator for coherent Doppler lidar is determined for typical space-based and ground-based parameter regimes. Optimal input parameters for the algorithm were determined for each regime. For weak signals, performance is described by the standard deviation of the good estimates and the fraction of outliers. For strong signals, the fraction of outliers is zero. Numerical effort was also determined.

Automatic estimation of voice onset time for word-initial stops by applying random forest to onset detection.

PubMed

Lin, Chi-Yueh; Wang, Hsiao-Chuan

2011-07-01

The voice onset time (VOT) of a stop consonant is the interval between its burst onset and voicing onset. Among a variety of research topics on VOT, one that has been studied for years is how VOTs are efficiently measured. Manual annotation is a feasible way, but it becomes a time-consuming task when the corpus size is large. This paper proposes an automatic VOT estimation method based on an onset detection algorithm. At first, a forced alignment is applied to identify the locations of stop consonants. Then a random forest based onset detector searches each stop segment for its burst and voicing onsets to estimate a VOT. The proposed onset detection can detect the onsets in an efficient and accurate manner with only a small amount of training data. The evaluation data extracted from the TIMIT corpus were 2344 words with a word-initial stop. The experimental results showed that 83.4% of the estimations deviate less than 10 ms from their manually labeled values, and 96.5% of the estimations deviate by less than 20 ms. Some factors that influence the proposed estimation method, such as place of articulation, voicing of a stop consonant, and quality of succeeding vowel, were also investigated. © 2011 Acoustical Society of America

Weather radar equation and a receiver calibration based on a slice approach

NASA Astrophysics Data System (ADS)

Yurchak, B. S.

2012-12-01

Two circumstances are essential when exploiting radar measurement of precipitation. The first circumstance is a correct physical-mathematical model linking parameters of a rainfall microstructure with a magnitude of a return signal (the weather radar equation (WRE)). The second is a precise measurement of received power that is fitted by a calibration of radar receiver. WRE for the spatially extended geophysical target (SEGT), such as cloud or rain, has been derived based on "slice" approach [1]. In this approach, the particles located close to the wavefront of the radar illumination are assumed to produce backscatter that is mainly coherent. This approach allows the contribution of the microphysical parameters of the scattering media to the radar cross section to be more comprehensive than the model based on the incoherent approach (e.g., Probert-Jones equation (PJE)). In the particular case, when the particle number fluctuations within slices pertain the Poisson law, the WRE derived is transformed to PJE. When Poisson index (standard deviation / mean number of particles) of a slice deviates from 1, the deviation of return power estimated by PJE from the actual value varies from +8 dB to - 12 dB. In general, the backscatter depends on mean, variance and third moment of the particle size distribution function (PSDF). The incoherent approach assumes only dependence on the sixth moment of PSDF (radar reflectivity Z). Additional difference from the classical estimate can be caused by a correlation between slice field reflectivity [2]. Overall, the deviation in particle statistics of a slice from the Poisson law is one of main physical factors that contribute to errors in radar precipitation measurements based on Z-conception. One of the components of calibration error is caused by difference between processing by weather radar receiver of the calibration pulse, and actual return signal from SEGT. A receiver with non uniform amplitude-frequency response (AFR) processes these signals with the same input power but with different radio-frequency spectrums (RFS). This causes different output magnitude due to different distortion experienced while RFS passing through a receiver filter. To assess the calibration error, RFS of signals from SEGT has been studied including theoretical, experimental and simulation stages [3]. It is shown that the return signal carrier wave is phase modulated due to overlapping of replicas of RF-probing pulse reflected from SEGT's slices. The RFSs depends on the phase statistics of the carrier wave and on RFS of the probing pulse. The bandwidth of SEGT's RFS is not greater than that of the probing pulse. Typical phase correlation interval was found to be around the same as that of the probing pulse duration. Application of a long calibration signal (proportional to SEGT extension) causes the error up to -1 dB for conventional radar with matched filter. To eliminate the calibration error, a power estimate of individual return waveform should be corrected with the transformation loss coefficient calculated based on RFS and AFR parameters. To embrace with calibration the high and low frequency parts of a receiver, the calibration should be performed with a long pulse. That long pulse is composed from adjoining replicas of a probe pulse with random initial phases and having the same magnitude governed by the power of probe pulse.

Assessing Causality in the Association between Child Adiposity and Physical Activity Levels: A Mendelian Randomization Analysis

PubMed Central

Richmond, Rebecca C.; Davey Smith, George; Ness, Andy R.; den Hoed, Marcel; McMahon, George; Timpson, Nicholas J.

2014-01-01

Background Cross-sectional studies have shown that objectively measured physical activity is associated with childhood adiposity, and a strong inverse dose–response association with body mass index (BMI) has been found. However, few studies have explored the extent to which this association reflects reverse causation. We aimed to determine whether childhood adiposity causally influences levels of physical activity using genetic variants reliably associated with adiposity to estimate causal effects. Methods and Findings The Avon Longitudinal Study of Parents and Children collected data on objectively assessed activity levels of 4,296 children at age 11 y with recorded BMI and genotypic data. We used 32 established genetic correlates of BMI combined in a weighted allelic score as an instrumental variable for adiposity to estimate the causal effect of adiposity on activity. In observational analysis, a 3.3 kg/m2 (one standard deviation) higher BMI was associated with 22.3 (95% CI, 17.0, 27.6) movement counts/min less total physical activity (p = 1.6×10−16), 2.6 (2.1, 3.1) min/d less moderate-to-vigorous-intensity activity (p = 3.7×10−29), and 3.5 (1.5, 5.5) min/d more sedentary time (p = 5.0×10−4). In Mendelian randomization analyses, the same difference in BMI was associated with 32.4 (0.9, 63.9) movement counts/min less total physical activity (p = 0.04) (∼5.3% of the mean counts/minute), 2.8 (0.1, 5.5) min/d less moderate-to-vigorous-intensity activity (p = 0.04), and 13.2 (1.3, 25.2) min/d more sedentary time (p = 0.03). There was no strong evidence for a difference between variable estimates from observational estimates. Similar results were obtained using fat mass index. Low power and poor instrumentation of activity limited causal analysis of the influence of physical activity on BMI. Conclusions Our results suggest that increased adiposity causes a reduction in physical activity in children and support research into the targeting of BMI in efforts to increase childhood activity levels. Importantly, this does not exclude lower physical activity also leading to increased adiposity, i.e., bidirectional causation. Please see later in the article for the Editors' Summary PMID:24642734

Worldwide Historical Estimates of Leaf Area Index, 1932-2000

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

Scurlock, JMO

2002-02-06

Approximately 1000 published estimates of leaf area index (LAI) from nearly 400 unique field sites, covering the period 1932-2000, have been compiled into a single data set. LA1 is a key parameter for global and regional models of biosphere/atmosphere exchange of carbon dioxide, water vapor, and other materials. It also plays an integral role in determining the energy balance of the land surface. This data set provides a benchmark of typical values and ranges of LA1 for a variety of biomes and land cover types, in support of model development and validation of satellite-derived remote sensing estimates of LA1 andmore » other vegetation parameters. The LA1 data are linked to a bibliography of over 300 original source references. These historic LA1 data are mostly from natural and seminatural (managed) ecosystems, although some agricultural estimates are also included. Although methodologies for determining LA1 have changed over the decades, it is useful to represent the inconsistencies (e.g., in maximum value reported for a particular biome) that are actually found in the scientific literature. Needleleaf (coniferous) forests are by far the most commonly measured biome/land cover types in this compilation, with 22% of the measurements from temperate evergreen needleleaf forests, and boreal evergreen needleleaf forests and crops the next most common (about 9% each). About 40% of the records in the data set were published in the past 10 years (1991-2000), with a further 20% collected between 1981 and 1990. Mean LAI ({+-} standard deviation), distributed between 15 biome/land cover classes, ranged from 1.31 {+-} 0.85 for deserts to 8.72 {+-} 4.32 for tree plantations, with evergreen forests (needleleaf and broadleaf) displaying the highest LA1 among the natural terrestrial vegetation classes. We have identified statistical outliers in this data set, both globally and according to the different biome/land cover classes, but despite some decreases in mean LA1 values reported, our overall conclusions remained the same. This report documents the development of this data set, its contents, and its availability on the Internet from the Oak Ridge National Laboratory Distributed Active Archive Center for Biogeochemical Dynamics. Caution is advised in using these data, which were collected using a wide range of methodologies and assumptions that may not allow comparisons among sites.« less

Quadriceps femoris spasticity in children with cerebral palsy: measurement with the pendulum test and relationship with gait abnormalities.

PubMed

Szopa, Andrzej; Domagalska-Szopa, Małgorzata; Kidoń, Zenon; Syczewska, Małgorzata

2014-12-16

Development of a reliable and objective test of spasticity is important for assessment and treatment of children with cerebral palsy. The pendulum test has been reported to yield reliable measurements of spasticity and to be sensitive to variations in spasticity in these children. However, the relationship between the pendulum test scores and other objective measures of spasticity has not been studied. The present study aimed to assess the effectiveness of an accelerometer-based pendulum test as a measurement of spasticity in CP, and to explore the correlation between the measurements of this test and the global index of deviation from normal gait in in children with cerebral palsy. We studied thirty-six children with cerebral palsy, including 18 with spastic hemiplegia and 18 with spastic diplegia, and a group of 18 typically-developing children. Knee extensor spasticity was assessed bilaterally using the accelerometer-based pendulum test and three-dimensional gait analysis. The Gillette Gait Index was calculated from the results of the gait analysis. The data from the accelerometer-based pendulum test could be used to distinguish between able-bodied children and children with cerebral palsy. Additionally, two of the measurements, first swing excursion and relaxation index, could be used to differentiate the degree of knee extensor spasticity in the children with cerebral palsy. Only a few moderate correlations were found between the Gillette Gait Index and the pendulum test data. This study demonstrates that the pendulum test can be used to discriminate between typically developing children and children with CP, as well as between various degrees of spasticity, such as spastic hemiplegia and spastic diplegia, in the knee extensor muscle of children with CP. Deviations from normal gait in children with CP were not correlated with the results of the pendulum test.

Diagnostic capability of scanning laser polarimetry with variable cornea compensator in Indian patients with early primary open-angle glaucoma.

PubMed

Parikh, Rajul S; Parikh, Shefali R; Kumar, Rajesh S; Prabakaran, S; Babu, J Gansesh; Thomas, Ravi

2008-07-01

To evaluate the diagnostic ability of scanning laser polarimetry (GDx variable corneal compensator [VCC]) for early glaucoma in Asian Indian eyes. Cross-sectional observational study. Two groups of patients (early glaucoma and normal) who satisfied the inclusion and exclusion criteria were included. Early glaucoma was diagnosed in presence of open angles, characteristic glaucomatous optic disc changes correlating with the visual field (VF) on automated perimetry (VF defect fulfilling at least 2 of 3 Anderson and Patella's criteria with mean deviation >or= -6 decibels). Normal subjects had visual acuity >or= 20/30 and intraocular pressure < 22 mmHg, with a normal optic disc and fields and no ocular abnormality. All patients underwent complete ophthalmic evaluation, including VF examination (24-2/30-2 Swedish interactive threshold algorithm standard program) and imaging with GDx VCC. Sensitivity, specificity, positive predictive value and negative predictive value, area under the receiving operating characteristic curve, and likelihood ratios (LRs) were calculated for various GDx VCC parameters. Seventy-four eyes (74 patients) with early glaucoma and 104 eyes (104 normal subjects) were enrolled. TSNIT Std Dev (temporal-superior-nasal-inferior-temporal standard deviation) had the best combination of sensitivity and specificity-61.3 and 95.2, respectively-followed by nerve fiber index score > 50 (sensitivity, 52.7%; specificity, 99%). Nerve fiber index score > 50 had positive and negative predictive values of 74.3% and 97.6%, respectively, for an assumed glaucoma prevalence of 5%. Nerve fiber index score > 50 had a positive LR (+LR) of 54.8 for early glaucoma. GDx VCC has moderate sensitivity, with high specificity, in the diagnosis of early glaucoma. The high +LR for the nerve fiber index score can provide valuable diagnostic information for individual patients.

Severity of Illness Scores May Misclassify Critically Ill Obese Patients.

PubMed

Deliberato, Rodrigo Octávio; Ko, Stephanie; Komorowski, Matthieu; Armengol de La Hoz, M A; Frushicheva, Maria P; Raffa, Jesse D; Johnson, Alistair E W; Celi, Leo Anthony; Stone, David J

2018-03-01

Severity of illness scores rest on the assumption that patients have normal physiologic values at baseline and that patients with similar severity of illness scores have the same degree of deviation from their usual state. Prior studies have reported differences in baseline physiology, including laboratory markers, between obese and normal weight individuals, but these differences have not been analyzed in the ICU. We compared deviation from baseline of pertinent ICU laboratory test results between obese and normal weight patients, adjusted for the severity of illness. Retrospective cohort study in a large ICU database. Tertiary teaching hospital. Obese and normal weight patients who had laboratory results documented between 3 days and 1 year prior to hospital admission. None. Seven hundred sixty-nine normal weight patients were compared with 1,258 obese patients. After adjusting for the severity of illness score, age, comorbidity index, baseline laboratory result, and ICU type, the following deviations were found to be statistically significant: WBC 0.80 (95% CI, 0.27-1.33) × 10/L; p = 0.003; log (blood urea nitrogen) 0.01 (95% CI, 0.00-0.02); p = 0.014; log (creatinine) 0.03 (95% CI, 0.02-0.05), p < 0.001; with all deviations higher in obese patients. A logistic regression analysis suggested that after adjusting for age and severity of illness at least one of these deviations had a statistically significant effect on hospital mortality (p = 0.009). Among patients with the same severity of illness score, we detected clinically small but significant deviations in WBC, creatinine, and blood urea nitrogen from baseline in obese compared with normal weight patients. These small deviations are likely to be increasingly important as bigger data are analyzed in increasingly precise ways. Recognition of the extent to which all critically ill patients may deviate from their own baseline may improve the objectivity, precision, and generalizability of ICU mortality prediction and severity adjustment models.

[Functional indices of the participants of the satellite experiments of the "Mars-500" project in the north of Russia in different seasons of a year].

PubMed

Solonin, Iu G; Markov, A L; Boĭko, E R; Potolitsyna, N N; Parshukova, O I

2014-01-01

17 male northerners participating in the satellite experiments of the '"Mars-500" project passed through the morphological, physiometric, psychological and biochemical studies. The prenosological health indices in different seasons were calculated using the hardware-software complex "Ecosan-2007". Seasonal sinusoidal fluctuations were detected for the thermoregulation (body and skin temperature), lipids metabolism (cholesterol, HDL and LDL levels in the blood), circulation regulation under physical exercise (the increase of "double product" and its recovery time). In the majority of the participants the unfavorable deviations of body mass index, "power" and "life" indices, simple visual-motor reaction time, Kerdo vegetative index, physical health levels and regulatory systems activity index (in comparison with the mid-latitude standards) were found.

[Quantitative relationships between hyper-spectral vegetation indices and leaf area index of rice].

PubMed

Tian, Yong-Chao; Yang, Jie; Yao, Xia; Zhu, Yan; Cao, Wei-Xing

2009-07-01

Based on field experiments with different rice varieties under different nitrogen application levels, the quantitative relationships of rice leaf area index (LAI) with canopy hyper-spectral parameters at different growth stages were analyzed. Rice LAI had good relationships with several hyper-spectral vegetation indices, the correlation coefficient being the highest with DI (difference index), followed by with RI (ratio index), and NI (normalized index), based on the spectral reflectance or the first derivative spectra. The two best spectral indices for estimating LAI were the difference index DI (854, 760) (based on two spectral bands of 850 nm and 760 nm) and the difference index DI (D676, D778) (based on two first derivative bands of 676 nm and 778 nm). In general, the hyper-spectral vegetation indices based on spectral reflectance performed better than the spectral indices based on the first derivative spectra. The tests with independent dataset suggested that the rice LAI monitoring models with difference index DI (854,760) as the variable could give an accurate LAI estimation, being available for estimation of rice LAI.