Developmental and evolutionary origins of the pharyngeal apparatus

The vertebrate pharyngeal apparatus, serving the dual functions of feeding and respiration, has its embryonic origin in a series of bulges found on the lateral surface of the head, the pharyngeal arches. Developmental studies have been able to discern how these structures are constructed and this has opened the way for an analysis of how the pharyngeal apparatus was assembled and modified during evolution. For many years, the role of the neural crest in organizing pharyngeal development was emphasized and, as this was believed to be a uniquely vertebrate cell type, it was suggested that the development of the pharyngeal apparatus of vertebrates was distinct from that of other chordates. However, it has now been established that a key event in vertebrate pharyngeal development is the outpocketing of the endoderm to form the pharyngeal pouches. Significantly, outpocketing of the pharyngeal endoderm is a basal deuterostome character and the regulatory network that mediates this process is conserved. Thus, the framework around which the vertebrate pharyngeal apparatus is built is ancient. The pharyngeal arches of vertebrates are, however, more complex and this can be ascribed to these structures being populated by neural crest cells, which form the skeletal support of the pharynx, and mesoderm, which will give rise to the musculature and the arch arteries. Within the vertebrates, as development progresses beyond the phylotypic stage, the pharyngeal apparatus has also been extensively remodelled and this has seemingly involved radical alterations to the developmental programme. Recent studies, however, have shown that these alterations were not as dramatic as previously believed. Thus, while the evolution of amniotes was believed to have involved the loss of gills and their covering, the operculum, it is now apparent that neither of these structures was completely lost. Rather, the gills were transformed into the parathyroid glands and the operculum still exists as an embryonic entity and is still required for the internalization of the posterior pharyngeal arches. Thus, the key steps in our phylogenetic history are laid out during the development of our pharyngeal apparatus

Negotiating the Delivery of Gypsy & Traveller Sites through Local Planning

The 20 page report “Negotiating the delivery of Gypsy &Traveller sites through local planning” has found no substantive evidence to support the assertions made by some developers that the inclusion of pitches in housing schemes can impact on the viability of the development. This follows efforts to engage with mortgage lenders in the UK. The report has been informed by a survey of Local Authorities and an investigation of how residential property prices may be affected by the proximity of other land uses. The report concludes that ‘certainty increases viability’ and points to how the well-scoped plans can decrease the risk and uncertainty felt by developers and lenders. The Mid Devon Local Plan Review includes site allocation policies for urban extensions which place requirements for the delivery of pitches for Gypsies and Travellers

Should health professionals screen women for domestic violence? : systematic review

Objective To assess the evidence for the acceptability and effectiveness of screening women for domestic violence in healthcare settings. Design Systematic review of published quantitative studies. Search strategy Three electronic databases (Medline, Embase, and CINAHL) were searched for articles published in the English language up to February 2001. Included studies Surveys that elicited the attitudes of women and health professionals on the screening of women in health settings; comparative studies conducted in healthcare settings that measured rates of identification of domestic violence in the presence and absence of screening; studies measuring outcomes of interventions for women identified in health settings who experience abuse from a male partner or ex­partner compared with abused women not receiving an intervention. Results 20 papers met the inclusion criteria. In four surveys, 43­85% of women respondents found screening in healthcare settings acceptable. Two surveys of health professionals' views found that two thirds of physicians and almost half of emergency department nurses were not in favour of screening. In nine studies of screening compared with no screening, most detected a greater proportion of abused women identified by healthcare professionals. Six studies of interventions used weak study designs and gave inconsistent results. Other than increased referral to outside agencies, little evidence exists for changes in important outcomes such as decreased exposure to violence. No studies measured quality of life, mental health outcomes, or potential harm to women from screening programmes. Conclusion Although domestic violence is a common problem with major health consequences for women, implementation of screening programmes in healthcare settings cannot be justified. Evidence of the benefit of specific interventions and lack of harm from screening is needed

Elimination of the chirp of optical pulses through cascaded nonlinearities in periodically poled lithium niobate waveguides

We propose and demonstrate a novel method for the elimination of arbitrary frequency chirp from short optical pulses. The technique is based on the combination of two cascaded second-order nonlinearities in two individual periodically poled lithium niobate waveguides

Why the lack of adequate social housing in the UK is an important issue and how it may be solved

Jo Richardson explores the lack of adequate social housing in the UK, finding that it is partly due to planning and finance processes and insufficient capital funding from government, and partly due to rejection of new developments by local people and an inability to get developers to see that building social homes is ‘viable’. Negotiation with local people in the planning process for new housing, as well as possible learning and adaptation from long-running tax incentive schemes in other countries, could help solve the issue

A sediment trap experiment in the Vema Channel to evaluate the effect of horizontal particle fluxes on measured vertical fluxes

Sediment traps are used to measure fluxes and collect samples for studies in biology, chemistry and geology, yet we have much to learn about factors that influence particle collection rates. Toward this end, we deployed cylindrical sediment traps on five current meter moorings across the Vema Channel to field-test the effect of different horizontal particle fluxes on the collection rate of the traps— instruments intended for the collection of vertically settling particles. The asymmetric flow of Antarctic Bottom Water through the Vema Channel created an excellent natural flume environment in which there were vertical and lateral gradients in the distribution of both horizontal velocity and particle concentration and, therefore, the resulting horizontal flux. Horizontal effects were examined by comparing quantities of collected material (apparent vertical fluxes) with the horizontal fluxes of particles past each trap. We also looked for evidence of hydrodynamic biases by comparing and contrasting the composition of trap material based on particle size and the concentration of Al, Si, Ca, Mg, Mn, Corg and CaCO3. Experimental inverted traps and traps with only side openings were deployed to test a hypothesis of how particles are collected in traps. The vertical flux of surface-water particles should have been relatively uniform over the 45 km region of the mooring locations, so if horizontal transport contributed significantly to collection rates in traps, the calculated trap fluxes should be correlated positively with the horizontal flux. If the horizontal flow caused undertrapping, there should be a negative correlation with velocity or Reynolds number. The gross horizontal flux past different traps varied by a factor of 37, yet the quantity collected by the traps differed by only a factor of 1.4. The calculated horizontal fluxes were 2–4 orders of magnitude larger than the measured apparent vertical fluxes. Mean velocities past the traps ranged from 1–22 cm s−1 (Reynolds numbers of 3,500–43,000 for these traps with a diameter of 30.5 cm and an aspect ratio of ≈3) and showed no statistically significant relationship to the apparent vertical flux. We conclude that at current speeds measured in a very large portion of the world\u27s oceans, vertical fluxes measured with moored, cylindrical traps should exhibit little effect from horizontal currents

Free-Enterprise Farming on Grasslands in Central NSW, Australia

A pathway is described in developing and improving the pastures on family-owned sheep and beef properties at sites near Blayney in central NSW. Initially, the twin approach of sowing perennial grasses, predominantly phalaris (Phalaris aquatica) with subterranean clover (Trifolium subterraneum) plus the recommended addition of superphosphate fertiliser, was closely followed but within a decade ill-thrift in pastures and livestock occurred. Once the core problem of soil acidity was recognised, steps were taken to overcome this constraint with applications of lime. However, an additional modification involving the application of gypsum with lime had to be sorted out and applied. This approach is explained. While recent drought conditions on the Central Tablelands/Slopes have been a factor in reducing the productivity of district pastures, an important part of the problem is a consequence of many landowners not understanding the basic principles of plant and livestock nutrition, an unwillingness of some research/advisory agronomists to recognise the expertise of successful producers, and the implementation of various farmer subsidy and support schemes that appear to reward dependent producers rather than encouraging independence