Linear Correlations

2017 ◽  
pp. 75-91 ◽  
Author(s):  
Amir Momeni ◽  
Matthew Pincus ◽  
Jenny Libien
Keyword(s):  
Linear Correlations

Short Communication: A Note of Caution to Users of ECOSAR

1999 ◽  
Vol 34 (1) ◽  
pp. 179-182 ◽  
Author(s):  
Klaus L.E. Kaiser ◽  
John C. Dearden ◽  
Werner Klein ◽  
T. Wayne Schultz
Keyword(s):  
Environmental Protection Agency ◽  
Partition Coefficients ◽  
Short Communication ◽  
Computer Software ◽  
Aquatic Organisms ◽  
Protection Agency ◽  
Personal Computer Software ◽  
Linear Correlations ◽  
Class Representative ◽  
Chemical Class

Abstract ECOSAR (1998), a personal computer software program available from the U.S. Environmental Protection Agency (EPA) and affiliated vendors, is used to estimate the toxicity of chemicals to aquatic organisms, particularly fish, daphnid and algae species. It relies on approximately 150 equations, each for a chemical class of substances (Clements et al. 1996), which are linear correlations (SARs) of measured toxicity values of class-representative compounds with their octanol/water partition coefficients, with the latter taken from a database or computed by a companion program.

scholarly journals Comprehensive Thermal Characteristics of Different Cultivars of Flaxseed Oil (Linum usittatissimum L.)

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 1958
Author(s):  
Jolanta Tomaszewska-Gras ◽  
Mahbuba Islam ◽  
Liliana Grzeca ◽  
Anna Kaczmarek ◽  
Emilia Fornal
Keyword(s):  
Differential Scanning Calorimetry ◽  
Heating Rate ◽  
Fatty Acid Content ◽  
Thermal Characteristics ◽  
Principal Component ◽  
Flaxseed Oil ◽  
Scanning Calorimetry ◽  
Total Oxidation ◽  
Increasing Temperature ◽  
Linear Correlations

The aim of this study was to describe the thermal properties of selected cultivars of flaxseed oil by the use of the differential scanning calorimetry (DSC) technique. The crystallization and melting profiles were analyzed depending on different scanning rates (1, 2, 5 °C/min) as well as oxidative induction time (OIT) isothermally at 120 °C and 140 °C, and oxidation onset temperatures (Ton) at 2 and 5 °C/min were measured. The crystallization was manifested as a single peak, differing for a cooling rate of 1 and 2 °C/min. The melting curves were more complex with differences among the cultivars for a heating rate of 1 and 2 °C/min, while for 5 °C/min, the profiles did not differ, which could be utilized in analytics for profiling in order to assess the authenticity of the flaxseed oil. Moreover, it was observed that flaxseed oil was highly susceptible to thermal oxidation, and its stability decreased with increasing temperature and decreasing heating rate. Significant negative linear correlations were found between unsaturated fatty acid content (C18:2, C18:3 n-3) and DSC parameters (OIT, Ton). Principal component analysis (PCA) also established a strong correlation between total oxidation value (TOTOX), peroxide value (PV) and all DSC parameters of thermo-oxidative stability.

scholarly journals A statistical analysis of the nulling pulsar population

2021 ◽  
Vol 502 (4) ◽  
pp. 4669-4679
Author(s):  
Sofia Z Sheikh ◽  
Mariah G MacDonald
Keyword(s):  
Statistical Analysis ◽  
Pulse Width ◽  
Local Minimum ◽  
Broad Band ◽  
Selection Effects ◽  
Clustering Methods ◽  
Pulsar Emission ◽  
Spin Period ◽  
Null State ◽  
Linear Correlations

ABSTRACT Approximately 8 per cent of the ∼2800 known pulsars exhibit ‘nulling,’ a temporary broad-band cessation of normal pulsar emission. Nulling behaviour can be coarsely quantified by the nulling fraction, which describes the percentage of time a given pulsar will be found in a null state. In this paper, we perform the most thorough statistical analysis thus far of the properties of 141 known nulling pulsars. We find weak, non-linear correlations between nulling fraction and pulse width, as well as nulling fraction and spin period which could be attributed to selection effects. We also further investigate a recently hypothesized gap at 40 per cent nulling fraction. While a local minimum does exist in the distribution, we cannot confirm a consistent and unique break in the distribution when we investigate with univariate and multivariate clustering methods, nor can we prove the existence of two statistically distinct populations about this minimum. Using the same methods, we find that nulling pulsars are a statistically different population from normal, radio, non-nulling pulsars, which has never been quantitatively verified. In addition, we summarize the findings of the prior nulling pulsar statistics literature, which are notoriously contradictory. This study, in context, furthers the idea that nulling fraction alone does not contain enough information to describe the behaviour of a nulling pulsar and that other parameters such as null lengths and null randomness, in addition to a better understanding of selection effects, are required to fully understand this phenomenon.

Non-metamict uranoan pyrochlore and uranpyrochlore from tuff near Ndale, Fort Portal area, Uganda

1989 ◽  
Vol 53 (370) ◽  
pp. 257-262 ◽  
Author(s):  
D. D. Hogarth ◽  
J. E. T. Horne
Keyword(s):  
Cell Size ◽  
Linear Correlation ◽  
Metamorphic Rocks ◽  
Portal Area ◽  
Geological Age ◽  
Unit Cells ◽  
Positive Linear Correlation ◽  
Crystalline Nature ◽  
Linear Correlations

AbstractA thin (100 m) cover of flat-lying, Recent, calcite-rich tuff at Ndale near Fort Portal, Uganda, unconformably overlies steeply dipping Precambrian metamorphic rocks. It is locally radioactive owing to uranium-rich pyrochlore minerals and lesser amounts of zircon, monazite, titanite, and an unidentified thorium phosphate. In one concentrate, four grains of uranpyrochlore and one grain of uranoan pyrochlore showed a positive linear correlation of Ti with U, and negative linear correlations of Ti with Na, F and Sr. Ta remained high and relatively constant [11 anal., ave. 14.5 (0.6)% Ta2O5]. In the same concentrate the composition of a separate grain of uranoan pyrochlore did not plot on these lines and Ta was comparatively low [2 anal., ave. 4.5 (0.3)% Ta2O5]. The data suggest two separate paths of differentiation. However, zoned grains were not observed. Unit cells were cubic with a = 10.351 ± 0.002 Å for a grain with 12.9% UO2tot and 10.333 ± 0.002 Å for a grain with 26.6% UO2tot. On heating in air the cell size decreased, possibly due to oxidation of U4+. The crystalline nature of these minerals can be attributed to a very young (4000–5000 yr) geological age.

ChemInform Abstract: CARBENE SINGLET-TRIPLET GAPS. LINEAR CORRELATIONS WITH SUBSTITUENT Π-DONATION

1981 ◽  
Vol 12 (49) ◽  
Author(s):  
P. H. MUELLER ◽  
N. G. RONDAN ◽  
K. N. HOUK ◽  
J. F. HARRISON ◽  
D. HOOPER ◽  
...  
Keyword(s):  
Linear Correlations

Evaluation of fluorescence excitation–emission and LC-OCD as methods of detecting removal of NOM and DBP precursors by enhanced coagulation

2011 ◽  
Vol 11 (5) ◽  
pp. 621-630 ◽  
Author(s):  
J. K. Wassink ◽  
R. C. Andrews ◽  
R. H. Peiris ◽  
R. L. Legge
Keyword(s):  
Natural Organic Matter ◽  
Principal Component ◽  
Close Correlation ◽  
Quantitative Detection ◽  
Aluminium Sulphate ◽  
Fluorescence Excitation ◽  
Enhanced Coagulation ◽  
Carbon Detection ◽  
Linear Correlations ◽  
By Products

Bench-scale tests were conducted to evaluate enhanced coagulation as a method for removing natural organic matter (NOM) from a surface water to reduce the formation of disinfection by-products (DBPs). Aluminium sulphate (alum) and two polyaluminium chloride (PACl) coagulants were used, as well as alum with pH depression. Using a PACl coagulant alone or alum with pH depression was shown to attain 35% removal of TOC at lower dosages (31 and 29 mg/L, respectively) when compared to the use of alum alone (43 mg/L). In addition to TOC and UV254, a fluorescence excitation–emission matrix (FEEM) approach and liquid chromatography–organic carbon detection (LC-OCD) were used to further characterize the removal of NOM in both untreated and filtered waters. Principal component analysis of FEEM was able to identify the presence of humic-like substances (HS), protein-like substances (PS), and colloidal/particulate matter (CPM); HS were found to have a close correlation with TOC and UV254. LC-OCD enabled the quantitative detection of hydrophobic and hydrophilic DOC; the latter was further separated into five components, the largest of which was HS. Strong linear correlations were calculated between TOC, UV254, HS, and hydrophilic DOC (r2 > 0.96); these parameters were also found to be closely correlated with the formation of trihalomethanes (THMs, r2 > 0.78) and haloacetic acids (HAAs, r2 > 0.92). Linear correlations with THMs and HAAs indicated that FEEM and LC-OCD provide good measures of DBP precursors when compared with TOC and UV254.

Critical Speed as a Measure of Aerobic Fitness for Male Rugby Union Players

2019 ◽  
Vol 14 (4) ◽  
pp. 518-524 ◽  
Author(s):  
Mark Kramer ◽  
Mark Watson ◽  
Rosa Du Randt ◽  
Robert W. Pettitt
Keyword(s):  
Exercise Test ◽  
Critical Speed ◽  
Time Trial ◽  
Rugby Union ◽  
Graded Exercise Test ◽  
Graded Exercise ◽  
Level 1 ◽  
Rugby Players ◽  
Linear Correlations ◽  
Test Level

Purpose:To compare critical speed (CS) derived from all-out testing (AOT) for linear and shuttle running with metrics from a graded exercise test, the Yo-Yo Intermittent Recovery Test  Level 1 (YYIR1), and estimation of an 800-m-shuttle time trial.Methods:Twelve male rugby players completed a graded exercise test, the YYIR1, a linear AOT, shuttle AOTs of 25 and 50 m, and an 800-m-shuttle time trial consisting of 32 × 25-m shuttles.Results:Strong linear correlations were observed between maximum oxygen uptake () and CS (m·s−1) derived from the linear AOT (3.68 [0.62],r = .90,P < .01) and 50-m-shuttle AOT (3.19 [0.26],r = .83,P < .01). Conversely,showed lower correlations with speeds evoking CS from 25-m AOT (2.86 [0.18],r = .42,P = .18) and YYIR1 (4.36 [0.11],r = .55,P = .07). The 800-m time trial (213.58 [15.84] s) was best predicted using parameters from the 25-m AOT (r = .93, SEE = 6.60 s,P < .001).Conclusions:The AOT is a valuable method of assessing performance-specific fitness, with CS from linear and 50-m-shuttle AOTs being strong predictors of, rivaling metrics from the graded exercise test. The YYIR1 offered limited utility compared with the AOT method.

Comparison of the tussive effects of histamine and methacholine in humans

1983 ◽  
Vol 55 (2) ◽  
pp. 541-546 ◽  
Author(s):  
A. M. Chausow ◽  
A. S. Banner
Keyword(s):  
Chronic Cough ◽  
Volume Ratio ◽  
Forced Expiratory Volume ◽  
Additional Mechanism ◽  
Cough Response ◽  
Inhalation Challenge ◽  
The Relationship ◽  
Linear Correlations

The tussive and bronchoconstrictive effects of histamine inhalation in 7 normals, 7 asthmatics, and 24 patients with chronic cough (PCC) were measured by counting coughs during a standard histamine inhalation challenge. All PCC had a tussive response. Fifteen PCC exhibited significant linear correlations between cough count and either the change in forced expiratory volume at 1.0 (delta FEV1) or conductance-volume ratio (sGaw) (delta sGaw). Normals and asthmatics had little or no cough. Metaproterenol pretreatment in seven PCC reduced both the FEV1 and cough response to histamine without changing the relationship between cough and delta FEV1. The tussive and bronchoconstrictive effects of methacholine inhalation were also measured in 7 asthmatics and 16 PCC. One asthmatic coughed. Fifteen PCC coughed. There were significant linear correlations between cough count and delta FEV1 or delta sGaw in 10 PCC. At comparable delta FEV1 and delta sGaw, histamine produced more cough than methacholine. These data indicate that during inhalation of histamine or methacholine by PCC cough is related to, and may be caused by, bronchoconstriction. Histamine also causes cough by an additional mechanism not related to bronchoconstriction.

scholarly journals Relationship between the indexes of insulin resistance and metabolic status in dairy cows during early lactation

2017 ◽  
Vol 67 (1) ◽  
pp. 57-70 ◽  
Author(s):  
Marko Cincović ◽  
Danijela Kirovski ◽  
Ivan Vujanac ◽  
Branislava Belić ◽  
Radojica Djoković
Keyword(s):  
Insulin Resistance ◽  
Insulin Sensitivity ◽  
Body Condition ◽  
Negative Correlation ◽  
Body Condition Score ◽  
Metabolic Status ◽  
Early Lactation ◽  
Igf I ◽  
Condition Score ◽  
Linear Correlations

AbstractInsulin resistance is a phenomenon which accompanies the ongoing metabolic adaptation in cows during early lactation. The aim of our study was to determine the linear correlations of HOMA (Homeostatic Model Assessment), QUICKI (Quantitative Insulin Sensitivity Check Index) and RQUICKI (Revised Quantitative Insulin Sensitivity Check Index) indexes of insulin resistance with the metabolic status of cows (concentration of hormones, metabolites and body condition score). The experiment included 40 Holstein-Frisian cows in the first week after calving. Indexes of insulin resistance valued: 18.68±5.43 (HOMA), 0.39±0.06 (QUICKI) and 0.45±0.06 (RQUICKI). Linear correlations were examined by testing the coefficient of correlation (r), determination (r2,%) and regression parameter beta (b) in linear equation. A negative correlation was found between HOMA and IGF-I (insulin growth factor I) (r=−0.51, r2=25.0, b=−1.1257, p<0.01). HOMA showed a positive correlation with BHB (betahidroxybutyrate) (r=0.48, r2=23.2, b=0.0234, p<0.01). A positive correlation was found between QUICKI and IGF-I (r=0.30, r2=10.0 b=46.7900, p<0.05) and cholesterol (r=0.44, r2=18.3, b=1.9021, p<0.01). In contrast, QUICKI and BHB (r=0.51, r2=27.1, b=−1.7241, p<0.01), just like QUICKI and BCS (r=0.46, r2=20.9, b=−2.424, p<0.01), showed a negative correlation. RQUICKI showed positive correlations with IGF-I (r=0.48, r2=22.8, b=28.1230, p<0.01), T4 (r=0.47, r2=22.1, b=87.142, p<0.01) and triglycerides (r=0.36, r2=13, b=0.0407, p<0.05) but negative correlations with cortisol (r=−0.36, r2=13.0, b=−9.0332, p<0.05), STH (somatotropic hormone) (r=−0.42, r2=17.3, b=−5.4976, p<0.01), BHB (r=−0.62, r2=38.3, b=−1.1872, p<0.01), total bilirubin (r=−0.58, r2=33.7, b=−7.131, p<0.01) and BCS (body condition score) (r=−0.6, r2=36.4, b=−1.8347, p<0.01). In conclusion, indexes of insulin resistance may be used to evaluate the metabolic status of cows in early lactation. RQUICKI might be the most appropriate predictor of metabolic status due to its linear relationship with most of the parameters included in homeorhetic process.

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