title: The molecular basis of the effect of temperature on enzyme activity

authors: Daniel, Roy M.

subjects: adaptation

abstract: Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the twostate (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme’s catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

text: The molecular basis of the effect of temperature on enzyme activity Experimental data show that the effect of temperature on enzymes cannot be adequately explained in terms of a two-state model based on increases in activity and denaturation. The Equilibrium Model provides a quantitative explanation of enzyme thermal behaviour under reaction conditions by introducing an inactive (but not denatured) intermediate in rapid equilibrium with the active form. The temperature midpoint (Teq) of the rapid equilibration between the two forms is related to the growth temperature of the organism, and the enthalpy of the equilibrium (ΔHeq) to its ability to function over various temperature ranges. In the present study, we show that the difference between the active and inactive forms is at the enzyme active site. The results reveal an apparently universal mechanism, independent of enzyme reaction or structure, based at or near the active site, by which enzymes lose activity as temperature rises, as opposed to denaturation which is global. Results show that activity losses below Teq may lead to significant errors in the determination of ΔG*cat made on the basis of the twostate (‘Classical’) model, and the measured kcat will then not be a true indication of an enzyme’s catalytic power. Overall, the results provide a molecular rationale for observations that the active site tends to be more flexible than the enzyme as a whole, and that activity losses precede denaturation, and provide a general explanation in molecular terms for the effect of temperature on enzyme activity.

year: 2010

title: Investigating Strategies to Support Reverse-Engineering of Interactive Systems

authors: Alsharif, Aman

subjects: Reverse-Engineering

abstract: Most software applications today provide a graphical user interface (GUI), which facilitates the use of the software by offering graphical and visual elements to the users. The correctness of the user interface is fundamental to the correct implementation of the overall software. Using reverse engineering tools and methods is one of the most efficient ways to understand a system, and to assess its functionality and usability. However, traditional reverse engineering methods are not well suited to interactive elements of a system. This research examines and analyzes reverse engineering techniques of interactive systems written in the Java programming language, with the aim of creating a set of models of the entire system namely, Presentation Models (PModels) and Presentation Interaction Models (PIMs), which are very effective in describing structural and functional behavioral features of the interactive system. This study will also highlight some of the problems that exist in this domain and investigate several possibilities for improving the process.

text: Investigating Strategies to Support Reverse-Engineering of Interactive Systems Most software applications today provide a graphical user interface (GUI), which facilitates the use of the software by offering graphical and visual elements to the users. The correctness of the user interface is fundamental to the correct implementation of the overall software. Using reverse engineering tools and methods is one of the most efficient ways to understand a system, and to assess its functionality and usability. However, traditional reverse engineering methods are not well suited to interactive elements of a system. This research examines and analyzes reverse engineering techniques of interactive systems written in the Java programming language, with the aim of creating a set of models of the entire system namely, Presentation Models (PModels) and Presentation Interaction Models (PIMs), which are very effective in describing structural and functional behavioral features of the interactive system. This study will also highlight some of the problems that exist in this domain and investigate several possibilities for improving the process.

year: 2013

title: Looking Past the Mess: Māori Homelessness and Mental Health Care

authors: Johnson, Diana

subjects: Homelessness

abstract: Homelessness is a pressing social and health concern that affects Māori disproportionately. This research explores the provision of mental health services to Māori who are homeless. The thesis has two primary aims. First, to document the experiences of Māori homeless people who live with mental health concerns and their relationships with mental health professionals. Second, to document the experiences of mental health professionals and how they interact with, provide care for, and build relationships with Māori Homeless. The skills of, and the difficulties faced by these professionals in provisions of quality of care are also considered. Three male and three female homeless participants were recruited from the Waikato and Auckland regions. All participants had received care from Non Governmental Organisations (NGOs) and/or District Health Board services (DHB). Participating mental health professionals included one female and five males. Mental health professionals included counsellors, therapists, psychologists, social workers, crisis team coordinator, and a cultural advisor. All participants took part in individual semi-structured interviews conducted in an open and conversational manner.  Key themes for homeless participants included their general life histories of mental illness, mental health service use, relationship with professionals, cultural issues, and concerns that Māori homeless wanted to discuss. Key themes for mental health professionals included their approaches when working with homeless people, relationship building, barriers to working with this group and possible solutions, linking with other professionals or organisations, and issues mental health professionals wanted to discuss. Findings highlight the importance of strong therapeutic relationships between homeless clients and mental health professionals, the need for more joined up (multi-level agency) approach to service delivery, and the importance of Māori ideology in restoring wellbeing and dignity. Findings suggest that the effectiveness of mental health service delivery relies in part on information provided by stakeholders. Information provided by homeless people and mental health professionals informs both service delivery and the ways in which practitioners can best support the needs of homeless people.

text: Looking Past the Mess: Māori Homelessness and Mental Health Care Homelessness is a pressing social and health concern that affects Māori disproportionately. This research explores the provision of mental health services to Māori who are homeless. The thesis has two primary aims. First, to document the experiences of Māori homeless people who live with mental health concerns and their relationships with mental health professionals. Second, to document the experiences of mental health professionals and how they interact with, provide care for, and build relationships with Māori Homeless. The skills of, and the difficulties faced by these professionals in provisions of quality of care are also considered. Three male and three female homeless participants were recruited from the Waikato and Auckland regions. All participants had received care from Non Governmental Organisations (NGOs) and/or District Health Board services (DHB). Participating mental health professionals included one female and five males. Mental health professionals included counsellors, therapists, psychologists, social workers, crisis team coordinator, and a cultural advisor. All participants took part in individual semi-structured interviews conducted in an open and conversational manner.  Key themes for homeless participants included their general life histories of mental illness, mental health service use, relationship with professionals, cultural issues, and concerns that Māori homeless wanted to discuss. Key themes for mental health professionals included their approaches when working with homeless people, relationship building, barriers to working with this group and possible solutions, linking with other professionals or organisations, and issues mental health professionals wanted to discuss. Findings highlight the importance of strong therapeutic relationships between homeless clients and mental health professionals, the need for more joined up (multi-level agency) approach to service delivery, and the importance of Māori ideology in restoring wellbeing and dignity. Findings suggest that the effectiveness of mental health service delivery relies in part on information provided by stakeholders. Information provided by homeless people and mental health professionals informs both service delivery and the ways in which practitioners can best support the needs of homeless people.

year: 2009