Establishing neuronal identity in vertebrate neurogenic placodes

The trigeminal and epibranchial placodes of vertebrate embryos form different types of sensory neurons. The trigeminal placodes form cutaneous sensory neurons that innervate the face and jaws, while the epibranchial placodes (geniculate, petrosal and nodose) form visceral sensory neurons that innervate taste buds and visceral organs. In the chick embryo, the ophthalmic trigeminal (opV) placode expresses the paired homeodomain transcription factor Pax3 from very early stages, while the epibranchial placodes express Pax2. Here, we show that Pax3 expression in explanted opV placode ectoderm correlates at the single cell level with neuronal specification and with commitment to an opV fate. When opV (trigeminal) ectoderm is grafted in place of the nodose (epibranchial) placode, Pax3-expressing cells form Pax3-positive neurons on the same schedule as in the opV placode. In contrast, Pax3-negative cells in the grafted ectoderm are induced to express the epibranchial placode marker Pax2 and form neurons in the nodose ganglion that express the epibranchial neuron marker Phox2a on the same schedule as host nodose neurons. They also project neurites along central and peripheral nodose neurite pathways and survive until well after the main period of cell death in the nodose ganglion. The older the opV ectoderm is at the time of grafting, the more Pax3-positive cells it contains and the more committed it is to an opV fate. Our results suggest that, within the neurogenic placodes, there does not appear to be a two-step induction of 'generic' neurons followed by specification of the neuron to a particular fate. Instead, there seems to be a one-step induction in which neuronal subtype identity is coupled to neuronal differentiation

The role of expected protein levels in determining the impact of protein premiums and discounts: a note

Fraser (1997) considered the impact of protein premiums and discounts on a grower’s income stream and willingness‐to‐pay for a forward contract where the protein premium and discount system is centred on a grower’s existing expected protein level. This article extends these results to consider the impact of a protein premium and discount system which is not centred on a grower’s existing expected protein level. The article suggests that the grower’s existing expected protein level plays a crucial role in determining the impact of the system.Crop Production/Industries,

Respiratory Syncytial Virus

RSV infection has an estimated global incidence of 33 million cases in children <5 years of age, with 10% requiring hospital admission and up to 199 000 dying of the disease. There is growing evidence that severe infantile RSV bronchiolitis, a condition characterised by an inflammatory reaction to the virus, is associated with later childhood wheeze in some vulnerable children; however, a direct causal relationship with asthma has not yet been established. RSV infection is also increasingly recognised as a cause of morbidity and mortality in those with underlying airway disease, the immunocompromised and frail elderly persons. Novel molecular-based diagnostic tools are becoming established, but treatment remains largely supportive, with palivizumab the only licensed agent currently available for passive prophylaxis of selected pre-term infants. While effective treatments remain elusive, there is optimism about the testing of novel antiviral drugs and the development of vaccines that may induce long-lasting immunity without the risk of disease augmentation

Water system virus detection

The performance of a waste water reclamation system is monitored by introducing a non-pathogenic marker virus, bacteriophage F2, into the waste-water prior to treatment and, thereafter, testing the reclaimed water for the presence of the marker virus. A test sample is first concentrated by absorbing any marker virus onto a cellulose acetate filter in the presence of a trivalent cation at low pH and then flushing the filter with a limited quantity of a glycine buffer solution to desorb any marker virus present on the filter. Photo-optical detection of indirect passive immune agglutination by polystyrene beads indicates the performance of the water reclamation system in removing the marker virus. A closed system provides for concentrating any marker virus, initiating and monitoring the passive immune agglutination reaction, and then flushing the system to prepare for another sample

Real-time digital modelling in design education and practice

Real-time modelling represents the first thoroughgoing application of the digital realm to architecture and urban design, and as such marks a clear advance on the partial applications that were previously the norm. The authors have pooled their combined expertise in architecture and computer games to adapt the principles and techniques of real-time environments from computer games to designing buildings. The outcome is proprietary software called Cadai, which allows architectural and urban design proposals to be modelled in realistic detail, both externally and internally, and then be "walked" around in their entirety by viewers. This paper argues that real-time modelling offers three advances on previous forms of 3D digital modelling: it enables digital modelling to be used from the earliest sketch stages of a design project; it allows collective online meetings of the project team inside the evolving design scheme, wherever the participants are in the world; and it enables greater user-participation in decisions about planning schemes, given that anyone familiar with computer game environments can now properly understand and experience architectural and urban design proposals. The paper explains the properties of Cadai and showcases some real-time models built by students at Oxford Brookes University and the University of Westminster, along with the first major commercial real-time model produced in Cadai for a brownfield development proposal in Northern England. Our contention is that real-time modelling will soon become the dominant way that computers operate in architectural and urban design, and will remain so for the foreseeable future

A comparison of the use of vacuum metal deposition versus cyanoacrylate fuming for visualisation of fingermarks and grab impressions on fabrics

Both vacuum metal deposition (VMD) and cyanoacrylate fuming (CAF) are techniques used to visualise latent fingermarks on smooth non-porous surfaces such as plastic and glass. VMD was initially investigated in the 1970s as to its effectiveness for visualising prints on fabrics, but was abandoned when radioactive sulphur dioxide was found to be more effective. However, interest in VMD was resurrected in the 1990s when CAF was also used routinely. We now report on studies to determine whether VMD or CAF is the more effective technique for the detection of marks on fabrics. Four different fabrics, nylon, polyester, polycotton and cotton, were utilised during this study, along with 15 donors who ranged in their age and ability to leave fingermarks, from good to medium to poor, thus reflecting the general population. Once samples were collected they were kept for a determined time (1, 2, 3, 4, 5, 6, 7, 14, 21 or 28 days) and then treated using either the gold and zinc metal VMD process or standard cyanoacrylate fuming.The smoother fabrics, such as nylon, consistently produced greater ridge detail whereas duller fabrics, like cotton tended only to show empty prints and impressions of where the fabric had been touched, rather than any ridge details. The majority of fabrics did however allow the development of touch marks that could be targeted for DNA taping which potentially could lead to a DNA profile. Of the two techniques VMD was around 5 times more effective than CAF, producing a greater amount of ridge detail, palmar flexion creases and target areas on more samples and fabrics

Robust filtering for gene expression time series data with variance constraints

This is the post print version of the article. The official published version can be obtained from the link below - Copyright 2007 Taylor & Francis Ltd.In this paper, an uncertain discrete-time stochastic system is employed to represent a model for gene regulatory networks from time series data. A robust variance-constrained filtering problem is investigated for a gene expression model with stochastic disturbances and norm-bounded parameter uncertainties, where the stochastic perturbation is in the form of a scalar Gaussian white noise with constant variance and the parameter uncertainties enter both the system matrix and the output matrix. The purpose of the addressed robust filtering problem is to design a linear filter such that, for the admissible bounded uncertainties, the filtering error system is Schur stable and the individual error variance is less than a prespecified upper bound. By using the linear matrix inequality (LMI) technique, sufficient conditions are first derived for ensuring the desired filtering performance for the gene expression model. Then the filter gain is characterized in terms of the solution to a set of LMIs, which can easily be solved by using available software packages. A simulation example is exploited for a gene expression model in order to demonstrate the effectiveness of the proposed design procedures.This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) of the UK under Grants GR/S27658/01 and EP/C524586/1, the Biotechnology and Biological Sciences Research Council (BBSRC) of the UK under Grants BB/C506264/1 and 100/EGM17735, the Nuffield Foundation of the UK under Grant NAL/00630/G, and the Alexander von Humboldt Foundation of Germany

Collisions of small ice particles under microgravity conditions (II): Does the chemical composition of the ice change the collisional properties?

Context: Understanding the collisional properties of ice is important for understanding both the early stages of planet formation and the evolution of planetary ring systems. Simple chemicals such as methanol and formic acid are known to be present in cold protostellar regions alongside the dominant water ice; they are also likely to be incorporated into planets which form in protoplanetary disks, and planetary ring systems. However, the effect of the chemical composition of the ice on its collisional properties has not yet been studied. Aims: Collisions of 1.5 cm ice spheres composed of pure crystalline water ice, water with 5% methanol, and water with 5% formic acid were investigated to determine the effect of the ice composition on the collisional outcomes. Methods: The collisions were conducted in a dedicated experimental instrument, operated under microgravity conditions, at relative particle impact velocities between 0.01 and 0.19 m s^-1, temperatures between 131 and 160 K and a pressure of around 10^-5 mbar. Results: A range of coefficients of restitution were found, with no correlation between this and the chemical composition, relative impact velocity, or temperature. Conclusions: We conclude that the chemical composition of the ice (at the level of 95% water ice and 5% methanol or formic acid) does not affect the collisional properties at these temperatures and pressures due to the inability of surface wetting to take place. At a level of 5% methanol or formic acid, the structure is likely to be dominated by crystalline water ice, leading to no change in collisional properties. The surface roughness of the particles is the dominant factor in explaining the range of coefficients of restitution