Significant Linear Regression Equations Research Articles

Development of a Fuel Model for Cistus spp. and Testing Its Fire Behavior Prediction Performance

This paper presents the development of a fuel model that can describe fuel situations in areas dominated by Cistus spp. (rockrose) in Greece. In order to obtain the necessary fuel data, thirty (30) 1 m2 plots were destructively sampled in phryganic areas dominated by Cistus creticus, Cistus parviflorus, and Cistus salvifolius in western Greece. To develop the fuel model for Cistus spp., field measurements were supplemented with published parameter values for Cistus salvifolius. The resulting fuel model (with a height of 9.44 cm) is suitable for describing Cistus spp.-dominated phryganic areas of relatively low vegetation height in southeastern Europe. Once developed, the fuel model was inputted into the BehavePlus system to produce surface fire rate of spread predictions (ROSpred, m·min−1), which were then compared to 21 surface fire ROS field observations (ROSobs) obtained from wildfires or prescribed burns in areas covered by Cistus spp. It was found that the ROS for the Cistus spp. fuel model significantly underpredicted the actual ROS. A statistically significant linear regression equation was developed to mathematically describe the relationship between the predicted and observed ROS. This equation can be used to adjust BehavePlus predictions to more accurately reflect the real-world fire behavior for this fuel type.

HUBUNGAN PELATIHAN DENGAN KINERJA KARYAWAN

The purpose of this study was to examine the significance of the relationship and establish and test the linearity and significance of the simple linear regression equation between training and employee performance. The research was conducted at the Directorate of Transportation, National Development Planning Agency, Jakarta. The research population is all employees of the Directorate of Transportation, National Development Planning Agency, Jakarta. From this population, a sample of 42 employees was taken using a simple random sampling technique. This study uses a causal survey method. The research data was collected through a research instrument in the form of a questionnaire with a Likert scale, then processed and analyzed using simple linear correlation and regression analysis techniques using the SPSS program. The results of this study indicate that: (1) There is a significant positive relationship between training and employee performance, with a correlation coefficient of 0.695; and (2) the simple linear regression equation Y = 14.552 + 0.412X is a significant linear regression equation to express a linear relationship between training (X) and employee performance (Y) at the Directorate of Transportation, National Development Planning Agency, Jakarta.

Investigation of the relationship between the levels of public trust and corruption: A topological model and statistical methods

The article analyzes the concepts of "trust" and "corruption of society" and explores the interdependence between them using the international indexes Edelman Trust Barometer (ETB) and Corruption Perceptions Index (CPI). The research methods are: 1) the topological model proposed by the authors, based on the averaged values of these indices; 2) correlation and regression analysis; 3) interval method (studying the dependence on the selected intervals of the averaged values of ETB and CPI). The topological model uses data on the values of these indices for 28 countries and was developed in two versions for the time periods (2011–2021) and (2013–2019). In both cases, the model gives a similar picture of the points placement on the coordinate plane, which indicates the stability of the results. A comparison of empirical data over the time periods revealed countries with a relatively stable ratio of ETB and CPI indices (Germany, Indonesia, Canada, Colombia, France) and countries where this ratio is noticeably changing (Australia, Argentina, Brazil, Hong Kong, Italy, the Netherlands). The analysis of the topological model was carried out and zones of low, medium and high levels of corruption were identified. Zones are characterized by a specific type of relationship between ETB and CPI indices. The general type of dependence of the level of trust on corruption in the form of a horizontal S-shaped curve is approximately determined. Regression analysis using time series data for 28 countries was performed. Statistically significant linear regression equations (reflecting the relationship between the considered economic categories) were obtained for some countries (the Netherland, Sweden and Japan). The conclusion about the significant nonlinearity of the studied relationship is made. This is evidenced by both the visual analysis of the topological model and the results of regression analysis conducted for the selected intervals of change values of the ETB and CPI indexes.

ВЗАИМОСВЯЗЬ УРОВНЕЙ ДОВЕРИЯ И КОРРУМПИРОВАННОСТИ ОБЩЕСТВА: МЕЖДУНАРОДНАЯ АНАЛИТИКА

The article discusses the concepts of trust and corruption in society and explores the interdependence between them using the international Edelman Trust Barometer (ETB) Corruption Perceptions Index (CPI). The analysis of the topological model was carried out, on the basis of which the zones of low, medium and high levels of corruption were identified, with a characteristic specific type of relationship between the ETB and CPI indices; the general view of the dependence of the level of trust on corruption in the form of a horizontal S-shaped curve is approximately defined. Statistically significant linear regression equations were obtained, reflecting the relationship of the considered indices for three countries (Germany, Colombia, France).

Optic Nerve Sheath Measurements by Computed Tomography to Predict Intracranial Pressure and Guide Surgery in Patients with Traumatic Brain Injury

Research has shown that the optic nerve sheath diameter (ONSD) is a good predictor of intracranial pressure (ICP) and may predict the need for surgery in patients with head injury. The objective was to test the value of ONSD in predicting the requirement for surgery in patients with traumatic brain injury (TBI). In this retrospective cohort study, we first verified the correlation between ICP and ONSD using data from 62 patients with TBI who had undergone ICP monitoring. Second, we analyzed head computed tomography images from patients with TBI who were admitted to the emergency department where patients had been divided into surgery or conservative treatment groups, dependent on the assessment of a neurosurgeon. The correlation between ICP and ONSD was measured using linear regression analysis. Biologistic and receiver operating characteristic curve analyses were used to test the diagnostic value of ONSD to predict surgery. ONSD was significantly correlated with ICP (r= 0.606; P < 0.01), and there was a significant linear regression equation (ŷ= 0.071× ICP+ 3.533; P < 0.01), with ONSD predicting the requirement for surgery in patients with TBI (area under the curve, 0.920; P < 0.01; 95% confidence interval, 0.877-0.962). ONSD measured via head computed tomography correlates with ICP and can predict the requirement for surgery in patients with TBI following admission to the emergency department.

Determination and prediction of the apparent and standardized ileal amino acid digestibility in cottonseed meals fed to growing pigs.

This experiment was conducted to evaluate the chemical composition and apparent ileal digestibility (AID) and standardized ileal digestibility (SID) of amino acids (AA) in cottonseed meals (CSM) and to develop prediction equations for estimating AA digestibility for growing pigs based on the chemical composition and AA content of CSM. 10 CSM were collected from 10 provinces in China. 11 barrows (initial body weight: 34.4±1.9kg), fitted with an ileal T-cannula, were allotted to 6×11 Youden square with 6 periods and 11 diets. The diets included one N-free diet and 10 CSM test diets containing 40% CSM as the sole source of AA. The nitrogen-free diet was used to measure the basal endogenous losses of CP and AA. The AID and SID for crude protein (CP), Lys, Met, Trp, and Thr among the 10 CSM differed (p<0.05). With R2 values exceeding 0.30, significant linear regression equations for CP, Lys, and Thr were obtained. The best fit equations for predicting the AID and SID of Lys were: AID of Lys=82.94-0.65 neutral detergent fiber, with R2 =0.44, residual standard deviation (RSD)=4.03 and p=0.04; and SID of Lys=135.34-1.01 neutral detergent fiber+34.27 Thr - 58.06 Trp - 84.93 Met, with R2 =0.90, RSD = 1.42 and p=0.01. In conclusion, the results of AID, SID and prediction equations could be used to evaluate the digestibility of CSM in growing pigs.

Is the Laser Diffraction Method Reliable for Soil Particle Size Distribution Analysis?

Core Ideas LDM was evaluated by SPM and SEM for soil PSD determination. LDM significantly overestimated sand and silt but underestimated clay contents compared to SPM. LDM resulted in soil texture class shifts in nearly half of the soil samples in contrast to SPM. Linear conversions were significant for sand and silt but not for clay contents from LDM to SPM. LDM held statistically similar median particle sizes with SEM for PSDs within the clay fraction. The laser diffraction method (LDM) has been increasingly applied for quantifying soil particle size distribution (PSD), owing to its advantages of rapid analysis, high reproducibility, and continuous PSD measurement for a wide range of size fractions. However, some ambiguities exist regarding the comparability of results with those obtained using other classical methods. The objective of the current study was to evaluate LDM‐derived PSDs via comparisons with PSDs obtained with the standard sieve–pipette method (SPM) and from the absolute method of microscopy. A total of 277 soil samples were collected at different soil depths in a typical cropland in the northeast mountainous region of Beijing and analyzed with both SPM and LDM. Due to time and labor constraints, scanning electron microscopy (SEM) was performed on 100 samples randomly selected for the PSDs within the clay fraction withdrawn by SPM. The results manifested on the average 18.9% underestimation of clay content and 25.3% overestimation of silt content by LDM compared to SPM. These disagreements directly caused the shifts of soil texture class in 44.8% of the soil samples. Significant linear regression equations were generated to convert LDM–derived sand and silt contents to SPM–derived ones (p &lt; 0.01). The linear conversions for the clay content were only significant for the calibration samples, but possessed negative coefficients of determination for the validation set. According to SEM, silt‐sized particles were wrongly included in the clay fraction identified by SPM. Eliminating such particles, the clay contents corrected by SEM were significantly lower when assuming the shape of clay particles &lt; 2 µm as plates or discs with constant thickness–diameter ratio of 1/10, and higher when considering the clay particles as spheres for volume calculation, in contrast to those measured by LDM (P &lt; 0.01). Detailed volume‐based PSDs within the clay fraction were further compared between SEM and LDM, revealing dissimilar PSD patterns but statistically similar median particle diameters. These findings suggest the effectiveness of LDM in soil PSD determination. Future work is needed to systematically quantify the impact of other possible factors such as clay mineralogy and refractive index on LDM‐derived PSDs.

Reducing apartment vacancy duration: lessons from affordable housing

PurposeThe purpose of this paper is to determine how much variance in vacancy duration can be explained by the architectural attributes of apartments and to illuminate strategies to reduce vacancy duration utilized by non-profit housing providers.Design/methodology/approachThis is a sequential mixed methods research study with a qualitative variable-gathering phase followed by a quantitative variable-testing phase. Vacancy duration in days was the dependent variable and the attributes of the apartments were the independent variables. Each building functioned as a separate case, with its own results, and the cases were compared to draw conclusions about the strongest predictors for vacancy duration.FindingsEach case study project has a significant linear regression equation with multiple variables contributing to the variance in tenancy duration. The R2 statistic varied for the case study projects from a low of 10.2 percent to a high of 36.9 percent. Factors that resulted in longer vacancies for two or more of the projects include: unit mix, floor level, road proximity and length of tenancy for the tenant moving out. Factors resulting in shorter vacancies include: corner position in the building and relatively larger size of the apartment.Research limitations/implicationsThe geography of the study is limited to Washington State in the USA. However, the case study projects represent three metropolitan statistical areas, with distinct climates and economic conditions. There are limitations to the stepwise analysis method because the degrees of freedom limit the complexity of models that can be estimated.Practical implicationsThis paper highlights influences on vacancy duration and proposes conceptual models for measuring the periods of vacancy duration.Social implicationsThrough this study, architectural contributions to vacancy were uncovered and tested so that subsidized housing, a public good, can be distributed more efficiently.Originality/valueThis research is the first known study to compare vacancy durations on a unit-by-unit basis.

Apparent and standardized ileal digestibility of amino acids in diverse barley cultivars fed to growing pigs.

The objectives of this study were to determine the chemical composition, ileal amino acid (AA) digestibility of barley varieties and to develop equations to predict the AA digestibility based on the chemical characteristics of individual barley. A wide selection of nine barley varieties in the main growing regions of China was used in the experiment. Ten crossbred pigs (30.9±1.8kg) were allotted to a 6×10 Youden Square. The treatments included a nitrogen-free diet and nine barley test diets. Considerable variation was observed in the content of neutral detergent fiber, acid detergent fiber, crude protein (CP) and all AAs among the barley samples. The standardized ileal digestibility (SID) of indispensable AAs with the exception of arginine, phenylalanine and threonine were different (P<0.05) among the nine barley sources tested. With R2 values exceeding 0.50, significant linear regression equations for CP and threonine were obtained. In conclusion, significant differences existed in the ileal digestibility of CP and AAs among barley varieties. It is difficult to predict the SID of most of the amino acids in barely based upon chemical characteristics.

Use of faecal components as markers to estimate intake and digestibility of grazing sheep

This research was carried out to evaluate the use of faecal components as markers to estimate intake and digestibility of Italian Ryegrass (Lolium multiflorum Lam.) of grazing sheep. The research had two phases. In Phase 1 seven indoor experiments were carried out using individual metabolic cages with 16 lambs in each experiment (four treatments with four animals each). Three phenological stages of the pasture (vegetative, pre-flowering and flowering) were evaluated and four different allowances of Italian Ryegrass, collected by grab sampling daily, of 1.5, 2.0, 2.5kg of dry matter/100kg of live weight and ad libitum. The indoor experimental design was completely randomized and the experiments were grouped according to the phenological stages. Organic matter intake (OMI, g/day), total daily production of faeces, faecal crude protein amount (fCP, g/day), faecal crude protein concentration (fCPc, g/kg of organic matter), faecal acid detergent fibre amount (fADF, g/day), faecal acid detergent concentration (fADFc, g/kg of organic matter) and organic matter digestibility (OMD) were assessed in the indoor experiment. In Phase 2, male sheep were used in two grazing experiments to graze Italian Ryegrass under different management conditions, which were herbage allowance, pasture phenological stage and rotational or continuous system. This phase was designed to validate the equations previously obtained. The stocking rate was controlled according the treatment defined, and the herbage mass, sward height, herbage and faecal chemical composition, OMI and OMD were measured. In Phase 1 significant linear regression equations were found between OMI and fCP in each phenological stage (P<0.05). The intake equations were compared by contrasts analysis and found to be different (P<0.001) between phenological stages, confirming the need to use the data separately by maturity stage. Two equations (simple and multiple hyperbolic) were tested for the relationship between OMD and fCPc, and the multiple hyperbolic, which includes fCPc and fADFc showed best accuracy. In Phase 2 the regression between the actual and estimated had a correlation coefficient of 0.94 and relative prediction error of 9.28%, showing the feasibility of using the generated equations.

Органолептическая оценка качества виноградных вин с использованием методов статистического моделирования

Discussed the evaluation of the integral characteristics of the wines produced in the course of establishing their quality, given the strengths and weaknesses of the existing procedures. The methods of instrumental evaluation of wine quality, which often result in ambiguous results. The possibility of a more simple solutions using mathematical modeling methods for certain parameters tasting. Analyzed and set parameters that shape the quality of wine, using a mathematical model which is able to give an assessment of wine tasting, which allows to solve operational problems and significantly reduce the duration of the study. Methods of mathematical statistics established the presence of the relationship between ratings and tasting the volatiles, built adequate statistically significant linear regression equation, using which it is possible to predict the ratings for tasting wines of high, medium and low quality. For the purpose of testing the proposed model predicted tasting evaluation of some wines. Keywords : wine, correlation, statistics, model, a component, regression (Russian) DOI: http://dx.doi.org/10.15826/analitika.2014.18.4.003 1 Yu F.Yakuba , 2 Z. А .Temerdashev, 2 A.A.Khalaphyan 1 North Caucasian Regional Research Institute of Horticulture and Viticulture of the Russian Academy of Agricultural Sciences, Krasnodar, Russian Federation 2 Kuban State University, Krasnodar, Russian Federation REFERENCES 1. Valuiko G.G., Shol‘ts-Kulikov E.P. Teoriia i praktika degustatsii vina [Theory and practice of degustation of wine]. Simferopol‘, Tavrida, 2005. 232 p. (in Russian). 2. Rodopulo A.K. Osnovy biokhimii vinodeliia [Fundamentals of Biochemistry winemaking]. Moscow, Legkaia i pishchevaia promyshlennost‘ Publ., 1983. 240 p. (in Russian). 3. Shol‘ts E.P., Ponomarev S.V. Tekhnologiia pererabotki vinograda [Technology conversion of grapes]. Moscow, Agropromizdat, 1990. 447 p. (in Russian). 4. Yakuba Yu.F. [Direct determination of phenylalanine, tryptophan and tyrosine residues in wines]. Zavodskaia laboratoriia. Diagnostika materialov [Industrial Laboratory. Diagnostics of materials], 2008, vol. 74, no. 2, pp.15-18 (in Russian). 5. Men‘shov V.A., Gagarin M.A., Iakovlev P.V. [Problem of control of quality and identification of winemaking products by methods of mathematical statistics]. Vinograd i vino Rossii [Grape and wine of Russia], 1997, no. 2, pp. 14-20 (in Russian). 6. Ribereau-Gayon P., Dubourdieu D., Doneche B., Lonvaud A. Handbook of Enology. Vol. 2. Chichester, West Susses, England, John Wiley &amp; Sons Lt., 2006, 438 p. 7. Khalapjan A.A. STATISTICA 6. Matematicheskaia statistika s elementami teorii veroiatnostei [STATISTICA 6. Mathematical statistics with elements of theory of probability]. Moscow, Binom, 2010. 491 p. (in Russian). 8. Jackson R.S. Wine science. Principles and application. A.P., 2008. 789 p. 9. Iashin Ia.I., Iashin E.Ia., Iashin A.Ia. Gazovaia khromatografiia [Gas chromatography]. Мoscow, Translit, 2009. 528 p. (in Russian).

A structure-activity relationship study on the mechanisms of methacrylate-induced toxicity using NMR chemical shift of .BETA.-carbon, RP-HPLC log P and semiempirical molecular descriptor

To clarify the mechanism of methacrylate-induced toxicity, a total of 24 acrylates, methacrylates, and dimethacrylates were chosen for a structure-activity relationship (SAR) study in terms of NMR chemical shifts, semiempirical molecular descriptors, and reverse phase (RP)-HPLC log P. Molecular descriptors as well as bulk, electronic, and energy descriptors were calculated using the PM3/CONFLEX method. A significant multiple linear regression equation for methacrylates in mice was denoted as log 1/LD50 (which was function [-(E(HOMO)+E(LUMO))/2, log P]). Besides, significant linear regression equations for methacrylates were denoted as log 1/ED50 in HeLa S3 and in HGF cells as function [E(HOMO) and/or log P]. Results showed that the 13C NMR chemical shift of beta-carbon for methacrylates was correlated with their E(HOMO). Findings of this study thus suggested that it might be possible to predict methacrylate-induced toxicity using physicochemical properties.

Seasonal variations of live moisture content and ignitability in shrubs of the Mediterranean Basin

The objectives of the present study were (i) to describe the seasonal pattern of ignition delay (ID time) and moisture content of live fine fuel (LFMC) for eight common shrub species of the Western Mediterranean Basin, and (ii) to evaluate the relationships between LFMC and ignitability. The experiment was carried out in a shrubland area located in Sardinia, Italy. LFMC and time to ignition or ID time values were determined monthly or twice a month throughout the year. Ignitability was determined by laboratory tests. Meteorological data were also collected from a weather station located in the study area. Significant linear regression equations of ID time v. LFMC were found for most of the species, with R2 values ranging from 67 to 94%. In general, very low values of ID time were observed when LFMC ranged from 70 to 100%. In addition, two groups of species were identified, depending on seasonal changes of both LFMC and ID time (or ignitability): (i) species with LFMC not greater than 100% and high ignitability values all throughout the year, and (ii) species with large seasonal variability of LFMC and ignitability values that were low in winter and high in summer. Significant differences in ignitability among species were also observed.

Development of the fragment constant method for estimating the partition coefficients of nonionic organic mixtures.

The fragment constant model for estimating partition coefficient of nonionic organic mixtures is developed based on group contribution theory. For 60 mixtures randomly composed of eight substituted benzenes, the C(18)-Empore disks/water partition coefficients (K(MD)) are determined. Establishment of a model between these K(MD) and the mole fraction of the fragments (Cl, Br, I, NO(2), CH(3)) acquires the fragments constants for K(MD). The significant linear regression equation, between these fragment constants and that of Hansch, provides an approach for calculating K(MD) of untested nonionic organic mixtures by using the fragment constants of Hansch.

Combined Effect of Sublethal Exposure to Cotton Expressing the Endotoxin Protein of Bacillus thuringiensis and Natural Enemies on Survival of Bollworm (Lepidoptera: Noctuidae) Larvae

The interactions of natural enemies and transgenic cotton expressing the endotoxin of Bacillus thuringiensis Berliner variety kurstaki (BTK cotton) on bollworm, Helicoverpa zea (Boddie), survival were studied. Survival of bollworm larvae was measured on cotton not expressing endotoxin (non-BTK cotton) in field plots with 4 different densities of natural enemies. Larvae were conditioned on BTK or non-BTK cotton for 1, 2, or 4 d before infestation of the non-BTK cotton in the field plots. Environments with varying densities of natural enemies was a significant factor affecting bollworm survival at all postinfestations periods. Larval mortality increased with increased density of natural enemies. Tissue genotype on which bollworm larvae were predisposed significantly affected larval survival in environments with low, medium, and high density of natural enemies at 24, 96, and 48 h postinfestation, respectively. Larvae that were conditioned on BTK cotton tended to survive at lower rates than larvae conditioned on non-BTK cotton. Length of exposure was a significant factor affecting larval survival at all postinfestation time intervals in a cage environment with no natural enemies. In the absence of natural enemies, larval survival was correlated positively with length of exposure. Larvae that were conditioned for 4-d before field infestation survived at significantly higher rates than larvae that were conditioned for 1 and 2 d. Significant interactions between the effects of tissue genotype and length of exposure on larval survival were detected by analysis of variance in the environment with low densities of natural enemies at 48 and 96 h postinfestation. Significant linear regression equations that described larval survival as a function of densities of natural enemies were detected for larvae conditioned on BTK cotton for 1 d at 96 h and 4 d at 48 h postinfestation. Similar equations were found to be significant for larvae conditioned on non-BTK cotton for 2 d at 48 and 96 h postinfestation and for larvae conditioned for 4 d at all postinfestation periods.

Hydrophobic coefficients of s-triazine and phenylurea herbicides

Hydrophobic parameters ( K′, K OW and K OC) were evaluated for 25 s-triazlne and phenylures herbicides. Octanol-water partitioning coefficients (K OW) were measured for 13 s-triazine and 9 phenylurea herbicides by a UV spectrophotometric method. Soil sorption isotherms were determined for chlorotoluron, chloroxuron, cyanazine, and metoxuron in four types of soil. Relationships between K OW, K OC, and the retention capacity factor ( k′) measured in a reversed-phase HPLC system, were analyzed for these two classes of herbicides. Very significant linear regression equations, showing predictive value for stucturally related compounds, were found between logK OW, logK OC and log k′.

Correlation between acute toxicity of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) and total body fat content in mammals

Single oral 30-day LD 50s of 2,3,7,8-tetrachlorobibenzo- p-dioxin (TCDD) were correlated with total body fat (TBF) content in various species and strains of laboratory mammals. LD 50 values and TBF contents were either obtained from the leterature or determined by experiments. A log (LD 50) vs. log (TBF) plot yielded a highly significant linear regression equation ( r 2 = 0.834, P < 0.001, n = 20). It is suggested that this correlation exists for at least two reasons: (1) increasing TBF content in organisms represents an enhanced capacity to remove TCDD from the systemic circulation and (2) different TBF content reflects a differential role and regulation of fat metabolism for various organisms. Extrapolation of this correlation to man suggests that adult humans are among the less sensitive species to the acute toxicity of TCDD.