title: Feature selection for discrete and numeric class machine learning

authors: Hall, Mark A.

subjects: computer science

abstract: Algorithms for feature selection fall into two broad categories: wrappers use the learning algorithm itself to evaluate the usefulness of features, while filters evaluate features according to heuristics based on general characteristics of the data. For application to large databases, filters have proven to be more practical than wrappers because they are much faster. However, most existing filter algorithms only work with discrete classification problems. 
This paper describes a fast, correlation-based filter algorithm that can be applied to continuous and discrete problems. Experiments using the new method as a preprocessing step for naïve Bayes, instance-based learning, decision trees, locally weighted regression, and model trees show it to be an effective feature selector - it reduces the data in dimensionality by more than sixty percent in most cases without negatively affecting accuracy. Also, decision and model trees built from the pre-processed data are often significantly smaller.

text: Feature selection for discrete and numeric class machine learning Algorithms for feature selection fall into two broad categories: wrappers use the learning algorithm itself to evaluate the usefulness of features, while filters evaluate features according to heuristics based on general characteristics of the data. For application to large databases, filters have proven to be more practical than wrappers because they are much faster. However, most existing filter algorithms only work with discrete classification problems. 
This paper describes a fast, correlation-based filter algorithm that can be applied to continuous and discrete problems. Experiments using the new method as a preprocessing step for naïve Bayes, instance-based learning, decision trees, locally weighted regression, and model trees show it to be an effective feature selector - it reduces the data in dimensionality by more than sixty percent in most cases without negatively affecting accuracy. Also, decision and model trees built from the pre-processed data are often significantly smaller.

year: 1999-04

title: In vitro Effects of Selenium on DNA Damage in BRCA1 Cell Lines

authors: Mayall, Kirsty Rose

subjects: Selenium

abstract: Cancer of the breast is the most common cancer affecting women, with a 1 in 9 lifetime risk of developing breast cancer. Carriers of mutations in the breast cancer susceptibility gene, BRCA1, present with an increased lifetime risk of 80-95% of developing breast cancer. BRCA1 is a tumour-suppressor gene that is involved in DNA repair of double-strand breaks and transcriptional regulation.

Studies have shown that oral supplementation with Selenium (Se) could potentially be an effective preventive agent against BRCA1-mutation carriers. Se is an essential trace mineral that plays critical roles in maintaining health in humans. Se functions by protecting lipid membranes, proteins and DNA from free radical damage and is involved in redox regulation in the cell. These functions are mediated through specific Se-dependent proteins termed selenoproteins, in which Se is incorporated.

Se supplementation may exert its benefits by enhancing the DNA damage repair response. The effects also appear to be dependent on selenoprotein genotypes and concentration of Se in the body/diet. It is possible that Se supplementation may be effective in reducing the risk of breast cancer in BRCA1 carriers, but the use of organic Se compounds is likely to be preferable, but the dose-response needs to be determined.

The objectives of this research thesis are to evaluate the dose-response of sodium selenite and methylseleninic acid (MSA) in two BRCA1-mutated cancer cell lines in vitro. The MTT assay was used to monitor cell activity, along with the comet assay to evaluate the DNA damage level using a dose-response curve of the two Se compounds on control and bleomycin-induced DNA damaged cells. In addition, DNA from each cell line was sequenced to confirm the presence of the published BRCA1 mutation.

The data presented within this thesis demonstrates that a commonly-used inorganic form of Se, sodium selenite, is more genotoxic than the organic Se compound, MSA, in malignant BRCA1-mutated cells. Sodium selenite also has more direct cytotoxicity in BRCA1-mutated cells than MSA, as demonstrated by the MTT assay. However the enhanced repair capacity from Se on DNA damage in cells demonstrated by others has not been reproduced. Preliminary data showed potential at much lower doses (2 μM) of Se. Interestingly, the volatile metabolites produced from MSA appear to reduce DNA damage, supportive of this hypothesis. In order to understand if the effects observed are linked specifically to the BRCA1 mutation or breast cancer in general, future research should include the investigation of the effects of Se on breast cancer using alternative breast cancer cell lines, as well as non-malignant cells.

text: In vitro Effects of Selenium on DNA Damage in BRCA1 Cell Lines Cancer of the breast is the most common cancer affecting women, with a 1 in 9 lifetime risk of developing breast cancer. Carriers of mutations in the breast cancer susceptibility gene, BRCA1, present with an increased lifetime risk of 80-95% of developing breast cancer. BRCA1 is a tumour-suppressor gene that is involved in DNA repair of double-strand breaks and transcriptional regulation.

Studies have shown that oral supplementation with Selenium (Se) could potentially be an effective preventive agent against BRCA1-mutation carriers. Se is an essential trace mineral that plays critical roles in maintaining health in humans. Se functions by protecting lipid membranes, proteins and DNA from free radical damage and is involved in redox regulation in the cell. These functions are mediated through specific Se-dependent proteins termed selenoproteins, in which Se is incorporated.

Se supplementation may exert its benefits by enhancing the DNA damage repair response. The effects also appear to be dependent on selenoprotein genotypes and concentration of Se in the body/diet. It is possible that Se supplementation may be effective in reducing the risk of breast cancer in BRCA1 carriers, but the use of organic Se compounds is likely to be preferable, but the dose-response needs to be determined.

The objectives of this research thesis are to evaluate the dose-response of sodium selenite and methylseleninic acid (MSA) in two BRCA1-mutated cancer cell lines in vitro. The MTT assay was used to monitor cell activity, along with the comet assay to evaluate the DNA damage level using a dose-response curve of the two Se compounds on control and bleomycin-induced DNA damaged cells. In addition, DNA from each cell line was sequenced to confirm the presence of the published BRCA1 mutation.

The data presented within this thesis demonstrates that a commonly-used inorganic form of Se, sodium selenite, is more genotoxic than the organic Se compound, MSA, in malignant BRCA1-mutated cells. Sodium selenite also has more direct cytotoxicity in BRCA1-mutated cells than MSA, as demonstrated by the MTT assay. However the enhanced repair capacity from Se on DNA damage in cells demonstrated by others has not been reproduced. Preliminary data showed potential at much lower doses (2 μM) of Se. Interestingly, the volatile metabolites produced from MSA appear to reduce DNA damage, supportive of this hypothesis. In order to understand if the effects observed are linked specifically to the BRCA1 mutation or breast cancer in general, future research should include the investigation of the effects of Se on breast cancer using alternative breast cancer cell lines, as well as non-malignant cells.

year: 2015

title: Ngā kanohi hou – identifying and exploring the issues: Experiences of an intern

authors: Masters-Awatere, Bridgette

subjects: Maori

abstract: The current paper reflects upon the discovery of an intern from the post graduate diploma in community psychology programme (PGDipPsych (Com). The PGDipPsych (Com) is currently facilitated through the University of Waikato School of Arts and Social Sciences, Psychology Department. This journey of discovery is presented from the perspective of a Māori student who is employed in a mainstream public health organisation. The perspective of a person who is new to the workforce, and the “real world,” who views the surrounding environment with a pair of fresh eyes.

This paper highlights the importance of the internship period as it supports the student who moves from a structured environment with a strong emphasis on theory, towards a competitive, semi structured environment that is driven by deadlines, budgets and contracts.

Factors identified are the demands of Māori communities on Māori health researchers, supportive versus competitive environments, the benefits and drawbacks of being based in a mainstream health organisation, and the future direction of Māori health research. It is hoped that the current paper will encourage further discussion about the future direction of a diploma programme such as the PGDipPsychCom for Māori graduates of a New Zealand tertiary institution.

text: Ngā kanohi hou – identifying and exploring the issues: Experiences of an intern The current paper reflects upon the discovery of an intern from the post graduate diploma in community psychology programme (PGDipPsych (Com). The PGDipPsych (Com) is currently facilitated through the University of Waikato School of Arts and Social Sciences, Psychology Department. This journey of discovery is presented from the perspective of a Māori student who is employed in a mainstream public health organisation. The perspective of a person who is new to the workforce, and the “real world,” who views the surrounding environment with a pair of fresh eyes.

This paper highlights the importance of the internship period as it supports the student who moves from a structured environment with a strong emphasis on theory, towards a competitive, semi structured environment that is driven by deadlines, budgets and contracts.

Factors identified are the demands of Māori communities on Māori health researchers, supportive versus competitive environments, the benefits and drawbacks of being based in a mainstream health organisation, and the future direction of Māori health research. It is hoped that the current paper will encourage further discussion about the future direction of a diploma programme such as the PGDipPsychCom for Māori graduates of a New Zealand tertiary institution.

year: 1999