1-Naphthyl- and mesityltellurium(IV,II) derivatives of small bite chelating organic ligands: effect of steric bulk and intramolecular secondary bonding interaction on molecular geometry and supramolecular association

The synthesis and characterization of unsymmetric diorganotellurium compounds containing a sterically demanding I-naphthyl or
mesitylligand and a small bite chelating organic ligand capable of 1,4-Te···N(O) intramolecular interaction is described. The reaction
of ArTeCl₃ (Ar = I-C_lOH₇, Np; 2,4,6-Me₃C₆H_2' Mes) with (SB)HgCI [SB = the Schiff base, 2-(4,4'-N0₂C₆H₄CH=NC₆H₃-Me)] or a methyl ketone (RCOCH₃) afforded the corresponding dichlorides (SB)ArTeCI₂ (Ar = Np, 1Aa; Mes, 1Ba) or (RCOCH₂)ArTeCl₂ (Ar = Np; R = Ph (2Aa), Me (3Aa), Np (4Aa); Ar = Mes, R = Ph (2Ba)). Reduction of 1Aa and 1Ba by Na₂S₂0₅ readily gave the tellurides (SB)ArTe (Ar = Np (1A), Mes, (1B) but that of dichlorides derived from methylketones was complicated due to partial decomposition to tellurium powder and diarylditelluride (Ar₂Te₂), resulting in poor yields of the corresponding tellurides 2A, 2B and 3A. Oxidation of the isolated tellurides with S0₂Cl₂, Br₂ and I₂ yielded the corresponding dihalides. All the synthesized compounds have been characterized with the help of IR, ¹H, ^l3C, and ¹²⁵Te NMR and in the case of 2Aa, and 2Ba by X-ray crystallography. Appearance of only one ¹²⁵Te signal indicated that the unsymmetric derivatives were stable to disproportionation to symmetric species. Intramolecular 1,4-Te· . ·0 secondary bonding interactions (SBIs) are exhibited in the crystal structures of both the tellurium(IV) dichlorides, 2Aa, and 2Ba. Steric repulsion of the mesityl group in the latter dominates over lone pair-bond pair repulsion, resulting in significant widening of the equatorial C-Te-C angle. This appears to be responsible for the lack of Te· . ·CI involved supramolecular associations in the crystal structure of 2Ba.

Novel organotin and organotellurium complexes : building blocks for new materials?

The research produced a series of novel oranotin and organotellurium compounds that are potential building blocks for new materials. In particular, one carbonate cluster has practical applications in the fixation and recovery of carbon dioxide gas from the atmosphere.

Enabling electronic medicine at Kiwicare : the case of video conferencing adoption for psychiatry in New Zealand

Telemedicine emerges as a viable solution to New Zealand health providers in reaching out to rural patients, in offering medical services and conducting administrative meetings and training. No research exists about adoption of telemedicine in New Zealand. The purpose of this case study was to explain factors influencing adoption of telemedicine utilizing video conferencing technology (TMVC) within a New Zealand hospital known as KiwiCare. Since TMVC is part of IT, tackling it from within technological innovation literature may assist in providing an insight into its adoption within KiwiCare and into the literature. Findings indicate weak presence of critical assessment into technological innovation factors prior to the adoption decision, thereby leading to its weak utilization. Factors like complexity, compatibility and trialability were not assessed extensively by KiwiCare and would have hindered TMVC adoption. TMVC was mainly assessed according to its relative advantage and to its cost effectiveness along with other facilitating and accelerating factors. This is essential but should be alongside technological and other influencing factors highlighted in the literature.

Machine learning for user modeling

At first blush, user modeling appears to be a prime candidate for straightforward application of standard machine learning techniques. Observations of the user's behavior can provide training examples that a machine learning system can use to form a model designed to predict future actions. However, user modeling poses a number of challenges for machine learning that have hindered its application in user modeling, including: the need for large data sets; the need for labeled data; concept drift; and computational complexity. This paper examines each of these issues and reviews approaches to resolving them.

The implementation of OECD corporate governance principles in post-crisis Asia

The recent OECD Principles on Corporate Governance provide a framework for the convergence of global corporate governance practice. This paper considers the implementation of these global ‘best-practice’ standards of governance as part of the continuing post-economic-crisis reform throughout Asia. These initiatives have explicitly acknowledged that no single model of governance can exist, and instead have focused on those elements apparently common and, therefore, applicable to all countries. Notwithstanding the existence of these elements, this paper investigates the difficulties involved when attempting to implement general rules across countries at different stages of economic and legal development. While implementation will be hindered by obvious cultural disparities, long-term change in practice requires a cultural shift in the philosophical and financial bases of the firm.

The quest for single-enantiomer outcomes in free-radical chemistry

A significant challenge facing free-radical chemists is in the area of stereocontrol, specifically the ability to control the direction of reagent attack at a prochiral radical. While significant inroads have been made in the area of diastereoselective radical chemistry, less successful have been attempts to provide truly enantioselective processes. This article highlights recent efforts in the area of enantioselective free-radical reduction chemistry and describes how single-enantiomer outcomes are possible when simple enantiopure stannanes are used in conjunction with large, sterically-demanding Lewis acids. Selectivities in excess of 90% are now possible, with one example in excess of 99.5% ee provided.

Extending distannoxane double ladders using rigid spacers: a double ladder with eight chiral tin atoms-and a twist!

The new bulky silicon-containing ditin precursor p-(RCl₂SnCH₂SiMe₂)₂C₆H₄ (R = CH₂SiMe₃ (4)) has been synthesized and further reacted to form a unique double ladder {[p-(R(Cl)SnCH₂SiMe₂)₂C₆H₄]O}₄ (6). The two layers within 6 are twisted with respect to one another, resulting in a helical motif and a total absence of molecular symmetry so that there are eight chiral tin atoms within the system. The structure is compared to the double ladder {[m-(R(Cl)SnCH₂CH₂)₂C₆H₄]O}₄ (11), which was prepared from the less sterically demanding ditin precursor m-(RCl₂SnCH₂CH₂)₂C₆H₄ (10). The two layers within 11 are parallel, and the molecule contains only two kinds of tin atom.

Lack of genetic divergence found with microsatellite DNA markers in the tarakihi Nemadactylus macropterus

Three classes of molecular markers are commonly employed during population genetic studies of marine taxa: allozymes, mitochondrial DNA (mtDNA), and microsatellite DNA. These markers differ in their levels of polymorphism, and the ease and cost of their application. Nemadactylus macropterus is a commercially important marine fish from New Zealand and southern Australia that has been the subject of genetic (allozyme, mtDNA) and non-genetic (otolith microchemistry, larval advection) studies of stock structure. We collected microsatellite DNA data from this species to compare the utility of these molecular markers with those genetic methods previously applied to N. macropterus. Microsatellites did not indicate significant divergence among Australian samples, or between Australian and New Zealand samples. The latter is incongruent with the allozyme and mtDNA studies, and it is suggested that allelic homoplasy has hindered the resolution of population structure when using microsatellites.

Agency theory, national culture and management Control Systems

Management control system of an organization is the structured facet of management, the formal vehicle by which the management process is executed. In most organizations, systems exist for planning, organizing, directing, controlling and motivating. Depending on the level of appropriateness and quality of the management control systems, the task of management is either facilitated or hindered. The end goal of a management control system is achieving organizational objectives. Because employees (agents) do not always give their best efforts for achieving organizational objectives, management control systems need to strive for aligning goals of agents (e.g., employees, subordinates) with that of principals (e.g., senior management, owners). Agency theory and its extension, principal agent model, provide insights to the problem of goal congruence and suggest remedies, at least in the Western cultural context. Whether the agency theory presumptions, predictions and prescriptions are universally applicable is an important issue in management. Their validity in different cultural contexts is largely unknown. The available literature to date indicates the possibility that agency theory may not be valid in non-western cultures. However, further empirical research is needed in non-western cultures to shed more light to this issue.

Methodological and conceptual issues in the search for a relationship between animal body-size distributions and benthic habitat architecture

Benthic ecologists have studied the distribution of animal body sizes because it is a form of ‘taxon-free’ classification that may be a useful metric for describing variation within and between ecological communities. In particular, the idea that the allometry of physiological and life-history traits may control species composition and relative abundances implies a functional link between body-size distributions and communities. The physical structure of aquatic habitats has often been cited as the mechanism by which habitat may determine body-size distributions in communities. However, further progress is hindered by a lack of theoretical clarity regarding the mechanisms that connect body size to the characteristics of ecological communities, leading to methods that may obscure interesting trends in body-size data. This review examines the methodological and conceptual issues hindering progress in the search for a relationship between animal body size and habitat architecture and suggests ways to resolve these issues. Problems are identified with current methods for the measurement of animal body size, the data and measures used to quantify body-size distributions and the methods used to identify patterns therein. Fundamentally, renewed emphasis on the mechanisms by which animal body sizes are influenced by habitat architecture is required to refine methodology and synthesise results from pattern-seeking and mechanistic studies.

Small-scale temporal variation in propagule supply of an intertidal red alga

Information on the variability in supply of algal propagules is scarce, hindered by the difficulty in identifying propagules, but this variability may affect the distribution and abundance of algal assemblages. This study examined the small-scale (½ hourly to hourly) temporal variation in propagule supply of Chondrus verrucosus (Gigartinaceae, Rhodophyta) over a dense, isolated bed in south-eastern Japan in summer and winter of 1999. Either 0.5 litre scoop samples or 5 litre pump samples were collected ½ hourly to hourly over 13, 22.5, and 30 h on three occasions in summer (June & July) and 32 h on one occasion in winter (December). Sampling was conducted around either the new moon (two occasions in summer) or full moon (one occasion in both summer and winter) and incorporated full tidal sequences including daytime (summer) and nighttime (winter) low-low (LL) tides. Chondrus verrucosus was the only red alga with spores within the size range of 15–20 μm that was fertile in the study area and surrounds at the time of sampling facilitating identification of spores. Spores in scoop samples were settled onto Petri dishes and identified on the basis of cell shape, colour and size. Pump samples were filtered onto transparent membrane filters and identified using epifluorescence microscopy: C. verrucosus spores fluoresced bright yellow and were easily distinguished from other micro-organisms of similar size, which fluoresced red or green. Results showed that while propagules could be found in the water column at most times, propagule supply of C. verrucosus was greatest during the 1–2 h period following LL tides. Variability in propagule supply was less than in previous studies examining surface or offshore waters. Spore release is thought to be stimulated by either desiccation or salinity changes associated with periods of emersion at low tide followed by re-immersion on incoming tides.

Teledermatology : the case of telemedicine adoption and success in New Zealand

Using a theoretical framework extracted from thetechnological innovation theories, this research attempts to explain factors influencing the adoption and diffusion of telemedicine utilising the video conferencing technology (TMVC) for dermatology within health Waikato (HW) in New Zealand. Findings indicate weak presence of critical assessment into technological innovation factors prior to TMVC adoption. Factors such as complexity, compatibility, and trialability were not assessed extensively by HW and could have hindered its adoption. TMVC was mainly assessed according to its relative advantage and cost effectiveness. This is essential but should consider other important factors explained in this research. The successful diffusion of TMVC in the case study relied on its economical benefit and on its effectiveness as a diagnostic tool. This research highlights the importance of the product champion factor on the successful adoption and diffusion of TMVC.