title: Can we avoid high coupling?

authors: Taube-Schock, Craig

subjects: coupling

abstract: It is considered good software design practice to organize source code into modules and to favour within-module connections (cohesion) over between-module connections (coupling), leading to the oft-repeated maxim "low coupling/high cohesion". Prior research into network theory and its application to software systems has found evidence that many important properties in real software systems exhibit approximately scale-free structure, including coupling; researchers have claimed that such scale-free structures are ubiquitous. This implies that high coupling must be unavoidable, statistically speaking, apparently contradicting standard ideas about software structure. We present a model that leads to the simple predictions that approximately scale-free structures ought to arise both for between-module connectivity and overall connectivity, and not as the result of poor design or optimization shortcuts. These predictions are borne out by our large-scale empirical study. Hence we conclude that high coupling is not avoidable--and that this is in fact quite reasonable.

text: Can we avoid high coupling? It is considered good software design practice to organize source code into modules and to favour within-module connections (cohesion) over between-module connections (coupling), leading to the oft-repeated maxim "low coupling/high cohesion". Prior research into network theory and its application to software systems has found evidence that many important properties in real software systems exhibit approximately scale-free structure, including coupling; researchers have claimed that such scale-free structures are ubiquitous. This implies that high coupling must be unavoidable, statistically speaking, apparently contradicting standard ideas about software structure. We present a model that leads to the simple predictions that approximately scale-free structures ought to arise both for between-module connectivity and overall connectivity, and not as the result of poor design or optimization shortcuts. These predictions are borne out by our large-scale empirical study. Hence we conclude that high coupling is not avoidable--and that this is in fact quite reasonable.

year: 2011

title: Regioisomeric preferences in the orthomanganation of meta-substituted acetophenones and isopropyl benzoates, and application of iodo-demanganation with iodine chloride to the synthesis of 2-iodo-3-O-substituted and other ortho-iodo arylcarbonyl compounds

authors: Cooney, Janine M.

subjects: Manganese

abstract: Synthesis is reported of regioisomeric ortho-[Mn(CO)4] derivatives of aryl ketones (2-chlorothioxanthen-9-one and 3′,4′-methylenedioxyacetophenone) and esters (isopropyl 3-methoxy- and 3-acetoxy-benzoate), as well as of the single ortho-[Mn(CO)4] products from methyl 4-methoxy- and 3,5-dimethoxy-benzoate. Factors influencing the preference for manganation at the crowded positions ortho to the C=O in meta-substituted aryl ketones and esters are considered. The frequency of the lowest energy metal carbonyl stretching mode is useful in the structural assignment of the regioisomers. Isopropyl 2-iodo-3-methoxy- and 2-iodo-3-acetoxy-benzoates are obtained by reaction of iodine chloride to replace the Mn(CO)4 group at the crowded 2-position of the corresponding orthomanganated 3-O-substituted benzoate esters. ortho-Iodoacetophenones were prepared likewise, without α-iodination, some with iodine in crowded positions (2′-iodo-3′-methoxy-, -3′,4′-methylenedioxy- and -3′,4′,5′-trimethoxy-acetophenone), others with O-protected 2′-hydroxy groups (2′-benzyloxy- and 2′-t-butyldimethylsilyloxy-3′,4′-dimethoxy-6′-iodobenzene and 2′-t-butyldimethylsiloxy-6′-iodobenzene). Potential general synthetic routes to derivatives of 2-iodo-3-hydroxy-, 2-iodo-3,4-dihydroxy-, and 2-iodo-6-hydroxy-aryl carbonyl compounds are indicated. The corresponding routes to 3-iodo-4-acetyl-2,5-dimethylthiophene and 3-iodo-2-acetylthiophene are also reported.

text: Regioisomeric preferences in the orthomanganation of meta-substituted acetophenones and isopropyl benzoates, and application of iodo-demanganation with iodine chloride to the synthesis of 2-iodo-3-O-substituted and other ortho-iodo arylcarbonyl compounds Synthesis is reported of regioisomeric ortho-[Mn(CO)4] derivatives of aryl ketones (2-chlorothioxanthen-9-one and 3′,4′-methylenedioxyacetophenone) and esters (isopropyl 3-methoxy- and 3-acetoxy-benzoate), as well as of the single ortho-[Mn(CO)4] products from methyl 4-methoxy- and 3,5-dimethoxy-benzoate. Factors influencing the preference for manganation at the crowded positions ortho to the C=O in meta-substituted aryl ketones and esters are considered. The frequency of the lowest energy metal carbonyl stretching mode is useful in the structural assignment of the regioisomers. Isopropyl 2-iodo-3-methoxy- and 2-iodo-3-acetoxy-benzoates are obtained by reaction of iodine chloride to replace the Mn(CO)4 group at the crowded 2-position of the corresponding orthomanganated 3-O-substituted benzoate esters. ortho-Iodoacetophenones were prepared likewise, without α-iodination, some with iodine in crowded positions (2′-iodo-3′-methoxy-, -3′,4′-methylenedioxy- and -3′,4′,5′-trimethoxy-acetophenone), others with O-protected 2′-hydroxy groups (2′-benzyloxy- and 2′-t-butyldimethylsilyloxy-3′,4′-dimethoxy-6′-iodobenzene and 2′-t-butyldimethylsiloxy-6′-iodobenzene). Potential general synthetic routes to derivatives of 2-iodo-3-hydroxy-, 2-iodo-3,4-dihydroxy-, and 2-iodo-6-hydroxy-aryl carbonyl compounds are indicated. The corresponding routes to 3-iodo-4-acetyl-2,5-dimethylthiophene and 3-iodo-2-acetylthiophene are also reported.

year: 2001-09-01

title: Māori & Psychology Research Unit Annual Report 2012

authors: Waitoki, Waikaremoana

abstract: Annual report of the Māori and Psychology Research Unit (MPRU) 2012. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

text: Māori & Psychology Research Unit Annual Report 2012 Annual report of the Māori and Psychology Research Unit (MPRU) 2012. The unit was established in August of 1997. The unit is designed to provide a catalyst and support network for enhancing research concerning the psychological needs, aspirations, and priorities of Maori people. The MPRU is well situated to draw together skilled and experienced interdisciplinary research groups by networking and establishing working relationships with staff and students within the Faculty of Arts and Social Sciences, the University, and the wider community.

year: 2012