title: Correlations between MO Eigenvectors and the Thermochemistry of Simple Organic Molecules, Related to Empirical Bond Additivity Schemes

authors: Lee, Matthew Colin John

subjects: MOs

abstract: A bondingness term is further developed to aid in heat of formation (ΔfHº) calculations for C, N, O and S containing molecules. Bondingness originated from qualitative investigations into the antibonding effect in the occupied MOs of ethane. Previous work used a single parameter for bondingness to calculate ΔfHº in an alkane homologous series using an additivity scheme. This work modifies the bondingness algorithm and uses the term to parameterise a test group of 345 molecules consisting of 17 subgroups that include alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. Comparing experimental with calculated ΔfHº values, a standard deviation for the residuals of 6.3 kJ mol 1 can be achieved using bondingness with a simple steric repulsion term (SSR) in a bond additivity scheme, and a standard deviation of 5.2 kJ mol 1 can be achieved using a Lennard-Jones potential. The method is compared with the group method of Pedley, which for a slightly smaller set of 338 molecules, a subset of the test set of 345 molecules, gives a standard deviation of 7.0 kJ mol 1.

Bondingness, along with SSR or a Lennard-Jones potential, is parameterised in the lowest level of ab initio (HF-SCF) or semiempirical quantum chemical calculations. It therefore may be useful in determining the ΔfHº values for the largest molecules that are amenable to quantum chemical calculation.

As part of our analysis we calculated the difference between the lowest energy conformer and the average energy of a mixture populated with higher energy conformers. This is the difference between the experimental ΔfHº value and the ΔfHº calculated for a single conformer. Example calculations which we have followed are given by Dale and Eliel et al.. Dale calculates the energy difference for molecules as large as hexane using relative energies based on the number of 1,4 gauche interactions. We have updated these values with constant increments ascertained by Klauda et al. as well as ab initio MP2 cc-pVDZ relative energies and have included calculations for heptane and octane.

text: Correlations between MO Eigenvectors and the Thermochemistry of Simple Organic Molecules, Related to Empirical Bond Additivity Schemes A bondingness term is further developed to aid in heat of formation (ΔfHº) calculations for C, N, O and S containing molecules. Bondingness originated from qualitative investigations into the antibonding effect in the occupied MOs of ethane. Previous work used a single parameter for bondingness to calculate ΔfHº in an alkane homologous series using an additivity scheme. This work modifies the bondingness algorithm and uses the term to parameterise a test group of 345 molecules consisting of 17 subgroups that include alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. Comparing experimental with calculated ΔfHº values, a standard deviation for the residuals of 6.3 kJ mol 1 can be achieved using bondingness with a simple steric repulsion term (SSR) in a bond additivity scheme, and a standard deviation of 5.2 kJ mol 1 can be achieved using a Lennard-Jones potential. The method is compared with the group method of Pedley, which for a slightly smaller set of 338 molecules, a subset of the test set of 345 molecules, gives a standard deviation of 7.0 kJ mol 1.

Bondingness, along with SSR or a Lennard-Jones potential, is parameterised in the lowest level of ab initio (HF-SCF) or semiempirical quantum chemical calculations. It therefore may be useful in determining the ΔfHº values for the largest molecules that are amenable to quantum chemical calculation.

As part of our analysis we calculated the difference between the lowest energy conformer and the average energy of a mixture populated with higher energy conformers. This is the difference between the experimental ΔfHº value and the ΔfHº calculated for a single conformer. Example calculations which we have followed are given by Dale and Eliel et al.. Dale calculates the energy difference for molecules as large as hexane using relative energies based on the number of 1,4 gauche interactions. We have updated these values with constant increments ascertained by Klauda et al. as well as ab initio MP2 cc-pVDZ relative energies and have included calculations for heptane and octane.

year: 2008

title: How do runners select their shoes? An in-store experience

authors: Fife, Andrew

abstract: We aimed to identify factors that influence running shoe selection and how salespeople and runners experience the in-store selection process. In a cross-sectional design, we surveyed 101 runners (buyers and non-buyers) and 38 salespeople in specialty running stores. Surveys contained questions about demographics, factors influencing shoe choice, sources of footwear advice/education, conscious behaviour, and perceived influence of salespeople on selection. There were no significant differences between buyers and non-buyers regarding how much runners thought about their purchases (i.e., level of consciousness). Salespeople were significantly younger than runners and believed a greater number of factors and sources of advice influenced shoe selection. Runners most frequently identified fit, comfort, and gait analysis or injury prevention as most influential in selecting shoes, in that order. Salespeople believed comfort was the most important for runners. Buyers and non-buyers prioritised advice on running shoes from salespeople, friends, and family, while salespeople primarily got their information from peers. Buyers and non-buyers visiting speciality running stores largely reflect the same population. Salespeople advising runners significantly differed from their target clientele in several regards and overestimated their influence on runners’ selection. We caution runners to carefully consider the advice from salespeople as many employees make recommendations that are not evidence-based and may have limited experience.

text: How do runners select their shoes? An in-store experience We aimed to identify factors that influence running shoe selection and how salespeople and runners experience the in-store selection process. In a cross-sectional design, we surveyed 101 runners (buyers and non-buyers) and 38 salespeople in specialty running stores. Surveys contained questions about demographics, factors influencing shoe choice, sources of footwear advice/education, conscious behaviour, and perceived influence of salespeople on selection. There were no significant differences between buyers and non-buyers regarding how much runners thought about their purchases (i.e., level of consciousness). Salespeople were significantly younger than runners and believed a greater number of factors and sources of advice influenced shoe selection. Runners most frequently identified fit, comfort, and gait analysis or injury prevention as most influential in selecting shoes, in that order. Salespeople believed comfort was the most important for runners. Buyers and non-buyers prioritised advice on running shoes from salespeople, friends, and family, while salespeople primarily got their information from peers. Buyers and non-buyers visiting speciality running stores largely reflect the same population. Salespeople advising runners significantly differed from their target clientele in several regards and overestimated their influence on runners’ selection. We caution runners to carefully consider the advice from salespeople as many employees make recommendations that are not evidence-based and may have limited experience.

year: 2024-06-04

title: Issues in testing the proficiency of learners of indigenous languages: an example relating to young learners of Maori

authors: Crombie, Winifred

subjects: te reo Māori

abstract: In 1999 the New Zealand Ministry of Education commissioned the authors to develop and trial a Māori language proficiency test.  The test was to be appropriate for students in Year 5 of schooling (aged 9/10) who were being educated wholly, or in part, through the medium of Māori language.  In this paper, we discuss the development and trialling of that proficiency test, focusing on the problems we experienced as well as on the test itself and on the ways in which it can be further developed. We also consider the implications of this project for the development of proficiency tests for other indigenous languages.

text: Issues in testing the proficiency of learners of indigenous languages: an example relating to young learners of Maori In 1999 the New Zealand Ministry of Education commissioned the authors to develop and trial a Māori language proficiency test.  The test was to be appropriate for students in Year 5 of schooling (aged 9/10) who were being educated wholly, or in part, through the medium of Māori language.  In this paper, we discuss the development and trialling of that proficiency test, focusing on the problems we experienced as well as on the test itself and on the ways in which it can be further developed. We also consider the implications of this project for the development of proficiency tests for other indigenous languages.

year: 2000-10