From dragons to goblins, kings and princesses, there is a never-ending source of inspiration to be tapped into. While some of these aspects of fantasy may never change throughout time, other more unassuming aspects of these books have the capacity to reflect changes in society, thinking, and the idea of childhood. One such aspect is the use of light.
Since EE varies with body mass, comparisons between lean and obese mice are confounded unless EE is normalized to account for body mass differences. Accordingly, when animals experience a sustained increase of energy intake e.
However, the ability to quantify adaptive changes of EE is confounded in that larger animals tend to have a higher metabolic rate than smaller ones. Therefore, to reliably detect changes in EE that are not due simply to differences in body size per se, EE must be normalized to body mass using a method that eliminates this confounding effect.
To date, most rodent studies of obesity use ratio-based normalization methods whereby EE is divided by either total body mass TBM or lean body mass LBM 3 — 6.
However, these two methods can give widely divergent results when applied to the same data 3467. A recent Diabetes Perspectives article 7 cogently reviewed the confounding effect of normalizing EE via division by TBM in mice, particularly when groups being compared differ in fat mass FM.
Despite its intuitive appeal, dividing EE by LBM is theoretically problematic as a means to remove the influence of body size variation from group comparisons. One approach that has been forwarded to obviate this mathematical bias is to use allometric scaling 15 wherein a TBM scaling exponent b and scaling coefficient a must be identified based on the data 1516 such that EE divided by TBMb assumes the constant expected value a.
This approach, however, is limited by interpretational and other difficulties 17and the notion that a predetermined fixed TBM scaling exponent can be applied universally has been challenged 16 Normalizing EE in human studies is now accomplished using multiple regression methods that adjust group comparisons of EE for differences in body mass so as to eliminate the influence of body size variation per se from evaluations of key independent variables such as ethnicity, sex, genotype, or nutritional status 919 — Although multiple regression has been used in animal studies 1129 — 35the relative importance of FM and LBM as determinants of metabolic rate in mice remains an open question.
Indeed, both human and animal investigations suggest that the energy cost of FM in vivo is greater than expected on the basis of its intrinsic metabolic rate 202831 This possibility is consistent with evidence that changes in FM can influence metabolic rate at least in part through homeostatic adjustments of EE that promote body weight stability 237 — Testing this hypothesis, however, requires the application of valid strategies for normalizing EE to body size.
In the current work, we demonstrate in a large sample of mice that ratio-based normalization of EE is problematic, even when LBM is used in lieu of TBM.
Moreover, multiple regression analysis indicates that variation in FM makes a surprisingly large contribution to EE. These findings lead us to support recommendations for the broad use of regression-based approaches to normalizing EE in mice that take both FM and LBM into account 9 — 121943 Our results confirm each of these predictions and therefore implicate circulating leptin in the mechanism whereby FM variation affects EE.
The mouse sample used in the regression analysis to identify the independent roles of LBM and FM as determinants of EE the main regression analysis was aggregated from four separate projects involving separate mouse cohorts evaluated over the 2-year period from to at the Mouse Metabolic Phenotyping Center MMPC, funded by the National Institutes of Health located at the University of Washington.
Per the policies of this program, the nature of the specific mutations affecting mice used in portions of this analysis a total of four mutations affecting a subset of 71 mice cannot be disclosed until the investigators who generated these mice have independently published their findings.
Each of the four mouse cohorts was arbitrarily assigned a project number. The total sample size was All metabolic and body composition evaluations were conducted by the same investigator K.
Mice with monogenic obesity e. Regression modeling and statistical analysis. Regression modeling was performed using R www.
Correlations are reported as Pearson r values. The h average and minimum light cycle EE values, measures of average and resting metabolic rate, respectively, were the dependent variables in the main regression analysis.
Minimum light cycle EE was the lowest EE recorded in association with no activity, and all values were compared to the 5th percentile value of EE to preclude the use of erroneous outlier values in the analysis.
The latter enabled us to estimate the unique influence on EE due to the genotype WT versus mutant within each of the four projects see the supplemental online appendix at http: Age was also examined but proved inconsequential after adjustment for the other factors.
We also conducted two sub-analyses restricted to each of the two largest projects: Accordingly, we used nonlinear regression KaleidaGraph; Synergy Software, Reading, PA to fit a rational function of this form to ratio-normalized EE outcomes to assess the validity of ratio-based normalization methods.
Considerations relating to the use of allometric scaling to normalize EE data are addressed in the online appendix. Respiratory gas exchange analysis and EE quantification. The second light and dark cycles were selected as the h period of metabolic data analysis.
Ambient temperature during testing was Measurements of respiratory gas exchange were made at min intervals, as were external air reference values to permit baselining EE data are expressed in terms of calories per minute using the Lusk equation Calibration standards were as follows: LBM and FM were quantified based on the averages of triplicate measures in each of the tests performed.
The coefficients of variation for the triplicate measures were 1.
The dependent variable in the leptin replacement studies was the h average EE encompassing one complete light and dark cycle.Analysis of Light as a Determinant of Innate Purity Essay An Analysis of the Role of Light as a Determinant of Inner Purity Children’s fairytales have always been one of the best places for a writer to let his or her imagination run wild - Analysis of Light as a Determinant of Innate Purity Essay introduction.
Discriminant analysis is described by the number of categories that is possessed by the dependent variable. As in statistics, everything is assumed up until infinity, so in this case, when the dependent variable has two categories, then the type used is two-group discriminant analysis.
It can be used to know whether heavy, medium and light. The determinant is useful for solving linear equations, capturing how linear transformation change area or volume, and changing variables in integrals.
The determinant can be viewed as a function whose input is a square matrix and whose output is a number. In algebra, a determinant is a function depending on n that associates a scalar, det(A), to analysis (Electrical and Electronic engineering).
5. For handling large amount of data in computers, which is widely useful at present. 6.
It is widely used in other fields like Statistics, Psychology, Operation Research. ABSTRACT - Results from twelve studies provided the opportunity to identify determinant attributes in retail store selection. Generalizations of the findings appeared possible in light of the variation among the studies in terms of retail environment, market differentiation, and national boundaries.
Background: Light and/or intermittent smokers have been the fastest growing segment of cigarette smokers in the United States over the past two decades. Defining their behavioral characteristics is a critical public health priority. Methods: Our sample included 78, U.S.
adults from three pooled contemporary population-based surveys: the NHIS, NSDUH, and – NHANES.