Electron-stimulated desorption of D (H) from condensed D2O (H2O) films

The electron-stimulated desorption (ESD) of D⁻ and H⁻ ions from condensed D₂O and H₂O films is investigated. Three low-energy peaks are observed in the ESD anion yield, which are identified as arising from excitation of ²B₁, ²A₁ and ²B₂ dissociative electron attachment (DEA) resonances. Additional structure is observed between 18 and 32 eV, which may be due to ion pair formation or to DEA resonances involving the 2a₁ orbital. The ion yield resulting from excitation of the ²B₁ resonance increases as the film is heated. We attribute the increase in the ion yield to thermally induced hydrogen bond breaking near the surface, which enhances the lifetimes of the excited states that lead to desorption.     

The relationship between physical observables and the potential energy surface in the He-HF system

This paper examines the effect of infinitesimal functional variations in a rigid rotor He-HF potential surface on several different types of observables: inelastic cross sections, rate constants, and rotational energy level populations. The dynamics and kinetic observables studied were found to be sensitive to a large number of Legendre components of the potential with the region of highest sensitivity dependent upon the energy or temperature as well as the states related by the individual observable. Sensitivity to the entire surface tends to show a large degree of structure due to competition among sensitivities to the individual potential components. Significant information loss has been observed in the transition from microscopic to macroscopic observables.     

How Focusing Phenomena in the Instructional Environment Support Individual Students' Generalizations

This article sets forth a way of connecting the classroom instructional environment with individual students' generalizations. To do so, we advance the notion of focusing phenomena, that is, regularities in the ways in which teachers, students, artifacts, and curricular materials act together to direct attention toward certain mathematical properties over others. The construct of focusing phenomena emerged from an empirical study conducted during a 5-week unit on slope and linear functions in a high school classroom using a reform curriculum. Qualitative evidence from interviews with 7 students revealed that students interpreted the m value in y = b + mx as a difference rather than a ratio as a result of counterproductive generalization afforded by focusing phenomena. Classroom analysis revealed 4 focusing phenomena, which regularly directed students' attention to various sets of differences rather than to the coordination of quantities.     

Sensitivity of hypersaline Arabian Gulf to seawater desalination plants

Due to the hot, arid nature of its bordering lands, seawater in the Arabian Gulf can have significant evaporation rates leading to hypersaline conditions. If additional desalination plants were to operate along its coast, then the extraction of desalinated water and returned brine waste stream into the Gulf would increase the salinity. This paper uses a tidally and cross-sectionally averaged mathematical model that reveals multiplicative dependence of the salinity on factors associated with river flow, evaporation rates and each of the desalination plants. Present-day desalinated water production rates are in the linear regime, but hypersalinity has exponential sensitivity to the position and volumetric rate of desalinated water extraction.     

Territories,corridors, and networks: A biological model for the premodern state

When depicted on maps as homogenous territorial wholes, ancient states are visually summarized as static entities in a way that conceals the highly fluid dynamics of polity formation, maintenance, and growth. Models derived from studies of animal behavior show that “territory” does not consist of an undifferentiated use of the landscape. Instead, the concept of territory can be parsed into a series of resource‐rich nodes linked by corridors of access, surrounded by unutilized regions and boundaries marked at points of competition. Ancient human groups also can be analyzed as having perceived and occupied landscapes through strategies of flexible networks in which nodes and corridors were surrounded by unutilized spaces around which boundaries were selectively identified and defended. This strategy is identifiable in human social groups at different levels of complexity ranging from hunter‐gatherers through ancient chiefdoms and states. © 2007 Wiley Periodicals, Inc. Complexity 12: 28–35, 2007     

A six-step synthesis of (S)-5-ethenyl-3-(1-methyl-2-pyrrolidinyl)pyridine (SIB-1508Y) from (S)-nicotine

The anti-Parkinson’s agent SIB-1508Y was prepared in six steps from (S)-nicotine in 20% overall yield. The strategy involves a regioselective formylation at C-5 of a 1,4-dihydronicotine intermediate.     

Discontinuity in decision-making when objectives conflict: a military command decision case study

In previous work, we considered the representation of human decision-making processes in closed-form simulation models of conflict. An important element of this representation is the rapid planning process that embodies the processing of information for situation assessment to support a course of action decision (eg in a military headquarters). The application of this work is in support of operational analysis models for defence procurement and balance of investment. This paper describes the application of non-linear multi-attribute utility theory in conflict scenarios in order to extend the representation of the rapid planning process to account for a wider set of subjective attributes of the decision-maker. The results show, through examination of experimental data, that decision-making can be modelled through a particular class of utility functions. These utilities embody a geometry which allows us to classify the types of decision being made when there are conflicting objectives and when decision-makers adopt very different and subjective appraisals of constraints and beliefs in outcome. The experimental results help to demonstrate that the subjective nature of the situation assessment, and the personality, training, experience and history of the decision-maker are central to the functional representations. This paper presents a way to capture this deeper representation of human decision-making in a way that is potentially useful for quantitative modelling using the rapid planning process as a basis.     

Towards a fully optimised organic LED device: Analysis of surface synthesis using coupling reactions by ToF-SIMS

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) and polarisation-modulation reflection-absorption infrared spectroscopy (PM-RAIRS) have been used to monitor the surface synthesis of self-assembled aromatic π-conjugated molecular wires on gold substrates as a step towards a novel structure for organic electroluminescent devices (OLEDs). The wires have been synthesised using a series of Schiff's base coupling reactions in solution on a self-assembled monolayer of an aromatic thiolate anchor. ToF-SIMS and PM-RAIRS measurements have demonstrated that: (i) the anchor molecules self-assemble at the gold surface, (ii) the anchor molecules selectively react through imino coupling reactions with additional wire units with high efficiency and (iii) the wire-like structure is predominantly orientated normal to the surface.