Synthesis and Biological Evaluation of New Ozonides with Improved Plant Growth Regulatory Activity

The iron oxyallyl carbocation generated from 2,7-dibromocycloheptanone was induced to undergo [4 + 3] cycloaddition reactions with various furans, affording a series of 12-oxatricyclo-[4.4.1.1(2,5)]-dodec-3-en-11-one adducts. Similar methodology was used to prepare two additional cycloadducts using menthofuran and two homologous aliphatic dibromoketones. Dipolar cycloaddition of ozone to the adducts afforded the corresponding secondary ozonides (i.e., 1,2,4-trioxolanes) in variable yields. Ozonides were investigated by quantum mechanics at the B3LYP/6-31+G* level to study structural features including close contacts which may be responsible for enhancing ozonide stability. The effect of these ozonides and their corresponding precursor cycloadducts upon radicle growth of both Sorghum bicolor and Cucumis sativus was evaluated at 5.0 x 10(-4) mol L-1. The most active cycloadducts and ozonides were also evaluated against the weed species Ipomoea grandifolia and Brachiaria decumbens, and the results are discussed. Compared to ozonides previously synthesized in our laboratory, the new ozonides described herein present improved plant growth regulatory activity.

C-H...O hydrogen bonding in 4-phenyl-benzaldehyde: a comprehensive crystallographic, spectroscopic and computational study

The crystal structure of 4-phenyl-benzaldehyde reveals the presence of a dimer linked by the C=O and C( 9)-H groups of adjacent molecules. In the liquid phase, the presence of C-(HO)-O-... bonded forms is revealed by both vibrational and NMR spectroscopy. A Delta H value of - 8.2 +/- 0.5 kJ mol(-1) for the dimerisation equilibrium is established from the temperature-dependent intensities of the bands assigned to the carbonyl-stretching modes. The NMR data suggest the preferential engagement of the C(2,6)-H and C(10/12)/C(11)-H groups as hydrogen bond donors, instead of the C(9)-H group. While ab initio calculations for the isolated dimers are unable to corroborate these NMR results, the radial distribution functions obtained from molecular dynamics simulations show a preference for C(2,6)-H and C(10/12)/C(11)-(HO)-O-... contacts relative to the C(9)-(HO)-O-... ones.

Self-exclusion from health care in women at high risk for postpartum depression

Background A significant proportion of women who are vulnerable to postnatal depression refuse to engage in treatment programmes. Little is known about them, other than some general demographic characteristics. In particular, their access to health care and their own and their infants' health outcomes are uncharted. Methods We conducted a nested cohort case-control study, using data from computerized health systems, and general practitioner (GP) and maternity records, to identify the characteristics, health service contacts, and maternal and infant health outcomes for primiparous antenatal clinic attenders at high risk for postnatal depression who either refused (self-exclusion group) or else agreed (take-up group) to receive additional Health Visiting support in pregnancy and the first 2 months postpartum. Results Women excluding themselves from Health Visitor support were younger and less highly educated than women willing to take up the support. They were less likely to attend midwifery, GP and routine Health Visitor appointments, but were more likely to book in late and to attend accident and emergency department (A&E). Their infants had poorer outcome in terms of gestation, birthweight and breastfeeding. Differences between the groups still obtained when age and education were taken into account for midwifery contacts, A&E attendance and gestation;the difference in the initiation of breast feeding was attenuated, but not wholly explained, by age and education. Conclusion A subgroup of psychologically vulnerable childbearing women are at particular risk for poor access to health care and adverse infant outcome. Barriers to take-up of services need to be understood in order better to deliver care.

Building communities via a learning landscape

The Learning Landscape project described here is known as RedGloo and has several objectives; among others it aims to help students to make friends, contacts and join communities based on interests and competencies. RedGloo provides a space where students can support each other with personal, academic and career development, sharing insights gained from extracurricular activities as well as their degree programmes. It has shown tendencies of becoming a learning community with several communities of practice.

Position paper on the future of social networking

Social networking mediated by web sites is a relatively new phenomenon and as with all technological innovations there continues to be a period of both technical and social adjustment to fit the services in with people’s behaviours, and for people to adjust their practices in the light of the affordances provided by the technology. Social networking benefits strongly from large scale availability. Users gain greater benefit from social networking services when more of their friends are using them.This applies in social terms, but also in eLearning and professional networks. The network effect provides one explanation for the popularity of internet based social networking sites (SNS) because the number of connections between people which can be maintained by using them is greatly increased in comparison to the networks available before the internet. The ability of users to determine how much they trust information available to them from contacts within their social network is important in almost all modes of use. As sources of information on a range of topics from academic to shopping advice, the level of trust which a user can put in other nodes is a key aspect of the utility of the system.

Force distribution in manipulation by a robot hand with equality and inequality constraints

The problem of the appropriate distribution of forces among the fingers of a four-fingered robot hand is addressed. The finger-object interactions are modelled as point frictional contacts, hence the system is indeterminate and an optimal solution is required for controlling forces acting on an object. A fast and efficient method for computing the grasping and manipulation forces is presented, where computation has been based on using the true model of the nonlinear frictional cone of contact. Results are compared with previously employed methods of linearizing the cone constraints and minimizing the internal forces.

Active micromachined integrated terahertz circuits

Schottky barrier diodes have been integrated into on-chip rectangular waveguides. Two novel techniques have been developed to fabricate diodes with posts suitable for integration into waveguides. One technique produces diodes with anode diameters of the order of microns with post heights from 90 to 125 microns and the second technique produces sub-micron anodes with post heights around 20 microns. A method has been developed to incorporate these structures into a rectangular waveguide and provide a top contact onto the anode which could be used as an I.F. output in a mixer circuit. Devices have been fabricated and D.C. characterized.

A solid-state noise source for millimetre wave spectrometry

A novel wide-band noise source for millimetre-wave spectrometry is described. It uses power combined Schottky diodes, reverse biased to avalanche breakdown, mounted in a wide-band tapered slot antenna. Power has been produced from 15 to 200 GHz with an equivalent temperature of 28200 K at 40 GHz.

Negotiating access into firms: obstacles and strategies

Researchers often experience difficulties with the negotiation of access into firms for the purpose of data collection. The question we explore is: What are the main obstacles associated with access negotiation into firms; and what strategies do researchers employ to increase their chances of success? Our research work on the tendering process of contractors took place between 2006 and 2008. We successfully negotiated access into four firms (two each in Ghana and the UK) to observe live examples of tender preparation The techniques we employed in negotiating access were personal contacts, contacting firms through online details and professional institutions, etc. With all of this effort, our average success rate was less than 5 per cent. The main obstacles encountered were firms’ reluctance because of commercial sensitiveness and fear that the data could eventually be divulged to their competitors or end up in the public domain. However, some firms agreed mainly because of the written assurances of confidentiality and anonymity in reporting the study; reputation of the researchers’ academic institution; gatekeepers who spoke to their colleagues on our behalf; academic purpose of the study; and a feedback report which was promised in return for access to the case studies. Although the access through personal contacts is by far the easiest, it is not always possible. Researchers can approach firms as complete strangers, especially in a foreign country, and that could make the firms more likely to assist the research.

Modeling the tetraphenylalanine-PEG hybrid amphiphile: from DFT calculations on the peptide to molecular dynamics simulations on the conjugate

The conformational properties of the hybrid amphiphile formed by the conjugation of a hydrophobic peptide with four phenylalanine (Phe) residues and hydrophilic poly(ethylene glycol), have been investigated using quantum mechanical calculations and atomistic molecular dynamics simulations. The intrinsic conformational preferences of the peptide were examined using the building-up search procedure combined with B3LYP/ 6-31G(d) geometry optimizations, which led to the identification of 78, 78, and 92 minimum energy structures for the peptides containing one, two, and four Phe residues. These peptides tend to adopt regular organizations involving turn-like motifs that define ribbon or helicallike arrangements. Furthermore, calculations indicate that backbone ... side chain interactions involving the N-H of the amide groups and the pi clouds of the aromatic rings play a crucial role in Phe-containing peptides. On the other hand,MD simulations on the complete amphiphile in aqueous solution showed that the polymer fragment rapidly unfolds maximizing the contacts with the polar solvent, even though the hydrophobic peptide reduce the number of waters of hydration with respect to an individual polymer chain of equivalent molecular weight. In spite of the small effect of the peptide in the hydrodynamic properties of the polymer, we conclude that the two counterparts of the amphiphile tend to organize as independent modules.

Social networks and positive and negative affect

We followed 100 university students in the UK for one week, instructing them to record all face-to-face, phone and digital contacts during the day as well as their positive and negative affect. We wanted to see how positive and negative affect spread around a social network while taking into account participants’ socio-demographic data, personality, general health and gratitude scores. We focused on the participants’ connections with those in their class; excluding friends and family outside this group. The data was analysed using actor-based models implemented in SIENA. Results show differences between positive and negative affect dynamics in this environment and an influence of personality traits on the average number and rate of communication.

‘The Pages are Bugged': the politics of listening in the poetry of W.S. Graham

This paper probes the public dimensions of the work of the twentieth-century Scottish poet W. S. Graham. It draws upon the public contacts and contexts that Graham's lyrics structure and reconfigure, in texts that have appeared to critics to demonstrate the poet's textual aloneness, his intellectual and geographical banishment. Repeatedly addressing his St Ives community of artists and writers, lovers and companions, Graham's work sets up strategic routes through a succession of publicly-minded verbal engagements. Refusing to allow one passively to listen in to the poet's isolation, the lyrics invite, rebuff, tease, avoid, dally with, and proposition audiences and interlocutors. Graham's poetry speaks from within and without tradition, location and heritage, subtly attuning readers to the politics of its handling of national allegiance, identity, class and patronage.

The Gift of the Nile: Hellenizing Egypt from Aeschylus to Alexander

The Egyptians mesmerized the ancient Greeks for scores of years. The Greek literature and art of the classical period are especially thick with representations of Egypt and Egyptians. Yet despite numerous firsthand contacts with Egypt, Greek writers constructed their own Egypt, one that differed in significant ways from actual Egyptian history, society, and culture. Informed by recent work on orientalism and colonialism, this book unravels the significance of these misrepresentations of Egypt in the Greek cultural imagination in the fifth and fourth centuries B.C.E. Looking in particular at issues of identity, otherness, and cultural anxiety, Phiroze Vasunia shows how Greek authors constructed an image of Egypt that reflected their own attitudes and prejudices about Greece itself. He focuses his discussion on Aeschylus Suppliants; Book 2 of Herodotus; Euripides' Helen; Plato's Phaedrus, Timaeus, and Critias; and Isocrates' Busiris. Reconstructing the history of the bias that informed these writings, Vasunia shows that Egypt in these works was shaped in relation to Greek institutions, values, and ideas on such subjects as gender and sexuality, death, writing, and political and ethnic identity. This study traces the tendentiousness of Greek representations by introducing comparative Egyptian material, thus interrogating the Greek texts and authors from a cross-cultural perspective. A final chapter also considers the invasion of Egypt by Alexander the Great and shows how he exploited and revised the discursive tradition in his conquest of the country. Firmly and knowledgeably rooted in classical studies and the ancient sources, this study takes a broad look at the issue of cross-cultural exchange in antiquity by framing it within the perspective of contemporary cultural studies. In addition, this provocative and original work shows how Greek writers made possible literary Europe's most persistent and adaptable obsession: the barbarian.