Quantum Chemical Logic, Atomic Ionization Energy, and Atomic Size

There has been a distinct lack of understanding of the relationship between experimental ionization energy of atoms and the theoretical measures of atomic size. This is true not only in the education community, but also in the research community

Data Structure for the Use of Patterns in the Perceptual Ordering of the Game of Chess

It is well known that the way one perceives a problem can influence the difficulty of solving the problem in a profound way. In the case of computer chess playing programs, one finds that most programs perceive the game in much the same way. They are all based on Shannon\u27s original proposal for chess playing programs. His approach was to generate all of the possible combinations of moves up to a certain number of plays and then a subset of all combinations to a deeper level thereafter. Each of these moves would then be evaluated as to its relative worth. This paper lays the foundation for research in an alternate method of approaching the game based on how human experts perceive the board initially. A suitable data structure for this is then proposed and discussed

Seasonal change in the daily timing of behaviour of the common vole, Microtus arvalis

1. Seasonal effects on daily activity patterns in the common vole were established by periodic trapping in the field and continuous year round recording of running wheel and freeding activity in cages exposed to natural meteorological conditions. 2. Trapping revealed decreased nocturnality in winter as compared to summer. This was paralelled by a winter reduction in both nocturnal wheel running and feeding time in cages. 3. Frequent trap checks revealed a 2 h rhythm in daytime catches in winter, not in summer. Cage feeding activity in daytime was always organized in c. 2 h intervals, but day-to-day variations in phase blurred the rhythm in summer in a summation of individual daily records. Thus both seasonal and short-term temporal patterns are consistent between field trappings and cage feeding records. 4. Variables associated with the seasonal change in daily pattern were: reproductive state (sexually active voles more nocturnal), age (juveniles more nocturnal), temperature (cold days: less nocturnal), food (indicated by feeding experiments), habitat structure (more nocturnal in habitat with underground tunnels). 5. Minor discrepancies between field trappings and cage feeding activity can be explained by assuming increased trappability of voles in winter. Cage wheel running is not predictive of field trapping patterns and is thought to reflect behavioral motivations not associated with feeding but with other activities (e.g., exploratory, escape, interactive behaviour) undetected by current methods, including radiotelemetry and passage-counting. 6. Winter decrease in nocturnality appears to involve a reduction in nocturnal non-feeding and feeding behaviour and is interpreted primarily as an adaptation to reduce energy expenditure in adverse but socially stable winter conditions.

Possible side reactions due to water in emulsion polymerization by late transition metal complexes II: Deactivation of the catalyst by a Wacker-type reaction

The transition metal catalyzed ethylene polymerization in water suspensions has been increasingly successful in the last couple of years. Water, however, adversely affects the polymerization process by deactivating the catalyst in a Wacker-type reaction. The cationic Pd(II)-diimine Brookhart catalyst 1 is studied here by a combination of quantum mechanics and molecular mechanics to determine the nature of the decomposition reaction. The study considers the decomposition process to take place in two stages. In the first stage, a coordinated olefin is attacked by a hydroxide group to ultimately produce a β-hydroxy-ethyl complex 2. The second step represents a decomposition to acetaldehyde and Pd(0), the latter in the form of palladium black. For the attack of OH on the coordinated ethylene in 1, both an internal path involving transfer from a palladium-coordinated OH group produced from hydrolysis of a Pd-CH 3 bond and an external path based on attack of H 2O on coordinated ethylene were considered. Both paths are found to be feasible. For the second stage the most promising decomposition mode involves isomerization of 2 to the α-hydroxy-ethyl complex 5 followed by abstraction of a proton from the C-OH link to produce the Pd(0)-η 2-acetaldehyde complex 12. Finally, 12 releases acetaldehyde under the deposition of Pd(0) as palladium black

Translating global recommendations on HIV and infant feeding to the local context: the development of culturally sensitive counselling tools in the Kilimanjaro Region, Tanzania

BACKGROUND: This paper describes the process used to develop an integrated set of culturally sensitive, evidence-based counselling tools (job aids) by using qualitative participatory research. The aim of the intervention was to contribute to improving infant feeding counselling services for HIV positive women in the Kilimanjaro Region of Tanzania. METHODS: Formative research using a combination of qualitative methods preceded the development of the intervention and mapped existing practices, perceptions and attitudes towards HIV and infant feeding (HIV/IF) among mothers, counsellors and community members. Intervention Mapping (IM) protocol guided the development of the overall intervention strategy. Theories of behaviour change, a review of the international HIV/IF guidelines and formative research findings contributed to the definition of performance and learning objectives. Key communication messages and colourful graphic illustrations related to infant feeding in the context of HIV were then developed and/or adapted from existing generic materials. Draft materials were field tested with intended audiences and subjected to stakeholder technical review. RESULTS: An integrated set of infant feeding counselling tools, referred to as 'job aids', was developed and included brochures on feeding methods that were found to be socially and culturally acceptable, a Question and Answer Guide for counsellors, a counselling card on the risk of transmission of HIV, and an infant feeding toolbox for demonstration. Each brochure describes the steps to ensure safer infant feeding using simple language and images based on local ideas and resources. The brochures are meant to serve as both a reference material during infant feeding counselling in the ongoing prevention of mother to child transmission (pMTCT) of HIV programme and as take home material for the mother. CONCLUSION: The study underscores the importance of formative research and a systematic theory based approach to developing an intervention aimed at improving counselling and changing customary feeding practices. The identification of perceived barriers and facilitators for change contributed to developing the key counselling messages and graphics, reflecting the socio-economic reality, cultural beliefs and norms of mothers and their significant others