title: Correlations between MO eigenvectors and enthalpies of formation for simple organic substances

authors: Lee, Matthew Colin John

subjects: enthalpy of formation

abstract: Bondingness, originally used in a qualitative analysis of the barrier to rotation in ethane, has been used to model ΔfH° (g) for simple organic substances. The model is parameterised with a set of 345 molecules including alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, alkenoates, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. The model is compared with a current empirical scheme as well as a comparison of variations of the model using different simple steric potentials. Using bondingness and the most approximate quantum chemical models a model can be formulated that is comparable with empirical group methods but requiring less parameters.

text: Correlations between MO eigenvectors and enthalpies of formation for simple organic substances Bondingness, originally used in a qualitative analysis of the barrier to rotation in ethane, has been used to model ΔfH° (g) for simple organic substances. The model is parameterised with a set of 345 molecules including alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, ketones, carboxylic acids, esters, alkenoates, amines, amides, diazenes, nitriles, nitroalkanes, nitrates, thiols and benzenoids. The model is compared with a current empirical scheme as well as a comparison of variations of the model using different simple steric potentials. Using bondingness and the most approximate quantum chemical models a model can be formulated that is comparable with empirical group methods but requiring less parameters.

year: 2009

title: Investigating the vertical structure of sediment fluxes across an intertidal mudflat

authors: Beisly, Toby

subjects: Oceanography

abstract: Muddy coastal environments consisting of fine grained, cohesive sediment, are important systems for their provision of crucial ecosystem services and unique ecology. Such environments are governed by complex sediment transport patterns connecting the system to the wider coastal environment. To understand sediment transport it is necessary to measure suspended sediment concentrations and current velocities, from which, sediment fluxes can be estimated. Measurements of suspended sediment concentration (SSC) are typically carried out through the use of a variety of instruments, including, optical backscatter sensors or acoustic backscatter sensors; while acoustic doppler velocimeters, electromagnetic current meters and acoustic doppler current profilers are used to provide measurements of flow velocities.  
To reliably estimate sediment flux, accurate vertical profiles of SSC and currents are required. Despite the need for profile information, typically flux calculations are based on observations from a single measurement location and exploited through the water column. However, the sensitivity of flux measurements to the vertical resolution (e.g., number of instruments) or to the method of extrapolation is rarely quantified. 
This study elucidates the significant sensitivity of measurements to the instrument arrangement and technique used to extrapolate the data. Our results, taken in the field under real life conditions, indicate that single, or even double, vertical instrument arrangements are likely to have a large margin of error associated with any resulting flux estimates. However, a more even spread of instruments over the water column appears to give a more accurate estimate of flux. We find that under calm conditions (small waves) the Rouse SSC models provide a good estimate of SSC while the velocity model; law of the wall, contains significant uncertainty in its velocity estimates. These results demonstrate the uncertainty associated with such dynamic environments, and as such, the need for robust measurement techniques and an understanding of the vertical structure of SSC and currents. Such understanding of sediment transport is crucial for making informed decisions around the management of intertidal muddy environments.

text: Investigating the vertical structure of sediment fluxes across an intertidal mudflat Muddy coastal environments consisting of fine grained, cohesive sediment, are important systems for their provision of crucial ecosystem services and unique ecology. Such environments are governed by complex sediment transport patterns connecting the system to the wider coastal environment. To understand sediment transport it is necessary to measure suspended sediment concentrations and current velocities, from which, sediment fluxes can be estimated. Measurements of suspended sediment concentration (SSC) are typically carried out through the use of a variety of instruments, including, optical backscatter sensors or acoustic backscatter sensors; while acoustic doppler velocimeters, electromagnetic current meters and acoustic doppler current profilers are used to provide measurements of flow velocities.  
To reliably estimate sediment flux, accurate vertical profiles of SSC and currents are required. Despite the need for profile information, typically flux calculations are based on observations from a single measurement location and exploited through the water column. However, the sensitivity of flux measurements to the vertical resolution (e.g., number of instruments) or to the method of extrapolation is rarely quantified. 
This study elucidates the significant sensitivity of measurements to the instrument arrangement and technique used to extrapolate the data. Our results, taken in the field under real life conditions, indicate that single, or even double, vertical instrument arrangements are likely to have a large margin of error associated with any resulting flux estimates. However, a more even spread of instruments over the water column appears to give a more accurate estimate of flux. We find that under calm conditions (small waves) the Rouse SSC models provide a good estimate of SSC while the velocity model; law of the wall, contains significant uncertainty in its velocity estimates. These results demonstrate the uncertainty associated with such dynamic environments, and as such, the need for robust measurement techniques and an understanding of the vertical structure of SSC and currents. Such understanding of sediment transport is crucial for making informed decisions around the management of intertidal muddy environments.

year: 2023

title: Addiction Phenomenology In Substance Use  And Non-Substance Use Disorders

authors: McLachlan, Andre David

subjects: Addiction

abstract: There is growing research evidence and public concern over the burgeoning of disorders which share common features with substance addictions. In order to investigate the presence and role of addiction features in disorders outside of substance addictions, symptoms of addiction were explored within three addiction groups: alcohol dependence (AD), an established addiction (n = 24); pathological gambling (PG) a disorder with growing empirical support as an addiction (n = 20); and compulsive shopping (CS), a proposed 'novel' addiction(n = 20).
Participants were recruited from either the general population, or from the Auckland Salvation Army Bridge residential alcohol and drug treatment programme; Salvation Army Oasis Gambling Service; Pacific Peoples Addiction Service Incorporated; or Te Kahui Hauora O Ngati Koata Trust. Participants completed a battery of self-report measures comprising a demographics questionnaire; Addictive Disorder Questionnaire (ADQ); anxiety and depression subscales of the Symptom Checklist 90 Revised (SCL-90R); Barratt Impulsivity Scale II-r; and substance specific adaptations of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).
Three general categories of addiction symptoms: physiological, salience and dyscontrol, were identified as broad aspects of addiction, common across all three groups. Measurable aspects of addiction, including impulsivity, obsessions, anxiety and depression were found to be endorsed similarly across the three addictions, irrespective of the severity of their addiction. Compulsions were found to be higher in the AD group. Higher anxiety was found to be correlated with higher addiction in the behavioural addictions (CS and PG), whereas depression and anxiety were associated with higher addiction severity in the AD group.
The results provide support for broadening addiction diagnostic definitions, to be more encompassing of the psychological and physiological experiences of each symptom; and developing different diagnostic categories for non-substance addictions that reflect the severity of the addiction. Results also provide evidence for developmental phases of addiction, from an early 'hedonistic' impulsive phase, to a compulsive phase, in which increased dyscontrol, mood and anxiety, marks the severity of the addiction.

text: Addiction Phenomenology In Substance Use  And Non-Substance Use Disorders There is growing research evidence and public concern over the burgeoning of disorders which share common features with substance addictions. In order to investigate the presence and role of addiction features in disorders outside of substance addictions, symptoms of addiction were explored within three addiction groups: alcohol dependence (AD), an established addiction (n = 24); pathological gambling (PG) a disorder with growing empirical support as an addiction (n = 20); and compulsive shopping (CS), a proposed 'novel' addiction(n = 20).
Participants were recruited from either the general population, or from the Auckland Salvation Army Bridge residential alcohol and drug treatment programme; Salvation Army Oasis Gambling Service; Pacific Peoples Addiction Service Incorporated; or Te Kahui Hauora O Ngati Koata Trust. Participants completed a battery of self-report measures comprising a demographics questionnaire; Addictive Disorder Questionnaire (ADQ); anxiety and depression subscales of the Symptom Checklist 90 Revised (SCL-90R); Barratt Impulsivity Scale II-r; and substance specific adaptations of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS).
Three general categories of addiction symptoms: physiological, salience and dyscontrol, were identified as broad aspects of addiction, common across all three groups. Measurable aspects of addiction, including impulsivity, obsessions, anxiety and depression were found to be endorsed similarly across the three addictions, irrespective of the severity of their addiction. Compulsions were found to be higher in the AD group. Higher anxiety was found to be correlated with higher addiction in the behavioural addictions (CS and PG), whereas depression and anxiety were associated with higher addiction severity in the AD group.
The results provide support for broadening addiction diagnostic definitions, to be more encompassing of the psychological and physiological experiences of each symptom; and developing different diagnostic categories for non-substance addictions that reflect the severity of the addiction. Results also provide evidence for developmental phases of addiction, from an early 'hedonistic' impulsive phase, to a compulsive phase, in which increased dyscontrol, mood and anxiety, marks the severity of the addiction.

year: 2008