title: Thai Grade 11 students' alternative conceptions for acid-base chemistry

authors: Artdej, Romklao

subjects: acid-base chemistry

abstract: This study involved the development of a two-tier diagnostic instrument to assess Thai high school students' understanding of acid-base chemistry. The acid-base diagnostic test (ABDT) comprising 18 items was administered to 55 Grade 11 students in a science and mathematics programme during the second semester of the 2008 academic year. Analysis of students' responses from this study followed the methodology outlined by Calik and Ayas. The research findings suggest that the ABDT, the multiple choice diagnostic instrument, enables researchers and teachers to classify students' understanding at different levels. Most students exhibited alternative conceptions for several concepts: acid-base theory, dissociation of strong acids or bases, and dissociation of weak acids/bases. Interestingly, one of the concepts that students appeared to find most difficult, and for which they exhibited the most alternative conceptions, was acid-base theory. Some alternative conceptions revealed in this study differ from earlier reports, such as the concept of electrolyte and non-electrolyte solutions as well as the concentration changes of H3O⁺and OH⁻ in water. These research findings present valuable information for facilitating better understanding of acid-base chemistry by providing insight into the preventable and correctable alternative conceptions exhibited by students.

text: Thai Grade 11 students' alternative conceptions for acid-base chemistry This study involved the development of a two-tier diagnostic instrument to assess Thai high school students' understanding of acid-base chemistry. The acid-base diagnostic test (ABDT) comprising 18 items was administered to 55 Grade 11 students in a science and mathematics programme during the second semester of the 2008 academic year. Analysis of students' responses from this study followed the methodology outlined by Calik and Ayas. The research findings suggest that the ABDT, the multiple choice diagnostic instrument, enables researchers and teachers to classify students' understanding at different levels. Most students exhibited alternative conceptions for several concepts: acid-base theory, dissociation of strong acids or bases, and dissociation of weak acids/bases. Interestingly, one of the concepts that students appeared to find most difficult, and for which they exhibited the most alternative conceptions, was acid-base theory. Some alternative conceptions revealed in this study differ from earlier reports, such as the concept of electrolyte and non-electrolyte solutions as well as the concentration changes of H3O⁺and OH⁻ in water. These research findings present valuable information for facilitating better understanding of acid-base chemistry by providing insight into the preventable and correctable alternative conceptions exhibited by students.

year: 2010

title: The nature and causes of coastal landsliding on the Maungatapu Peninsula, Tauranga, New Zealand

authors: Bird, Gerard Anthony

abstract: Lengths of cliffed coastline in Quaternary sediments around Tauranga Harbour, and particularly on the Maungatapu Peninsula, have been subjected to major landsliding episodes during and after rainstorms in recent years. This study is intended to broaden the database concerning coastal landsliding by documenting a descriptive and analytical study of the landslides, and to provide information useful for those attempting to control the effects of the landslides. 

A field mapping project was undertaken, associating patterns of landslide scars, marine erosion and groundwater seepage from cliff faces. More intensive studies at three sample sites included surveying, soil strength and physical index testing, hydraulic conductivity determinations and groundwater table observations. A number of working hypotheses, concerning the nature and causes of the landslide events, are erected and tested using the results of these descriptive studies. The hypotheses are further evaluated in factor sensitivity studies, using a simplified Janbu slope stability analysis program, which was written as part of the study. 

It has been found that the landslide events occur as parts of one of two cliff evolutionary sequences observed on the Maungatapu Peninsula. Where the rate of basal erosion by tidal currents and wind driven waves exceeds the rate of cliff crest retreat due to various cliff face modifying processes, the cliff segment gradually steepens. Failures in the material above an impermeable clay bed in the Pahoia Tuffs are triggered by high pore water pressures. Critical pore water pressures occur when long wet periods, culminating in medium to long return period storms, produce high seepage flows through the sandy material above the impermeable clay bed. The failures initially occur in a rotational manner, apparently causing the liquefaction of a bed of low bulk density silty sand lenses within a denser sandy mud matrix. Subsequent movements are therefore rapid and translatory, producing elongate annular debris lobes extending from the cliff base. 

The results of the study are then applied in formulating coastal management strategies, and in suggesting appropriate site stabilisation techniques.

text: The nature and causes of coastal landsliding on the Maungatapu Peninsula, Tauranga, New Zealand Lengths of cliffed coastline in Quaternary sediments around Tauranga Harbour, and particularly on the Maungatapu Peninsula, have been subjected to major landsliding episodes during and after rainstorms in recent years. This study is intended to broaden the database concerning coastal landsliding by documenting a descriptive and analytical study of the landslides, and to provide information useful for those attempting to control the effects of the landslides. 

A field mapping project was undertaken, associating patterns of landslide scars, marine erosion and groundwater seepage from cliff faces. More intensive studies at three sample sites included surveying, soil strength and physical index testing, hydraulic conductivity determinations and groundwater table observations. A number of working hypotheses, concerning the nature and causes of the landslide events, are erected and tested using the results of these descriptive studies. The hypotheses are further evaluated in factor sensitivity studies, using a simplified Janbu slope stability analysis program, which was written as part of the study. 

It has been found that the landslide events occur as parts of one of two cliff evolutionary sequences observed on the Maungatapu Peninsula. Where the rate of basal erosion by tidal currents and wind driven waves exceeds the rate of cliff crest retreat due to various cliff face modifying processes, the cliff segment gradually steepens. Failures in the material above an impermeable clay bed in the Pahoia Tuffs are triggered by high pore water pressures. Critical pore water pressures occur when long wet periods, culminating in medium to long return period storms, produce high seepage flows through the sandy material above the impermeable clay bed. The failures initially occur in a rotational manner, apparently causing the liquefaction of a bed of low bulk density silty sand lenses within a denser sandy mud matrix. Subsequent movements are therefore rapid and translatory, producing elongate annular debris lobes extending from the cliff base. 

The results of the study are then applied in formulating coastal management strategies, and in suggesting appropriate site stabilisation techniques.

year: 1981

title: A humanistic approach to addressing the needs of Maori homeless people with mental health concerns

authors: Johnson, Diana

subjects: Maori

abstract: Homelessness is a human tragedy that is often associated with mental illness. Maori people are overrepresented in the homeless population and among people experiencing mental illness in New Zealand. Little is known about the mental health experiences of Maori homeless people or the efforts of practitioners who render assistance. The authors explore the experiences of six Maori homeless people and six mental health professionals. Findings highlight the importance of a humanistic and culturally informed approach to addressing the needs of homeless people and restoring their wellness and dignity.

text: A humanistic approach to addressing the needs of Maori homeless people with mental health concerns Homelessness is a human tragedy that is often associated with mental illness. Maori people are overrepresented in the homeless population and among people experiencing mental illness in New Zealand. Little is known about the mental health experiences of Maori homeless people or the efforts of practitioners who render assistance. The authors explore the experiences of six Maori homeless people and six mental health professionals. Findings highlight the importance of a humanistic and culturally informed approach to addressing the needs of homeless people and restoring their wellness and dignity.

year: 2013