Enteric nervous system development in avian and zebrafish models

AbstractOur current understanding of the developmental biology of the enteric nervous system (ENS) and the genesis of ENS diseases is founded almost entirely on studies using model systems. Although genetic studies in the mouse have been at the forefront of this field over the last 20 years or so, historically it was the easy accessibility of the chick embryo for experimental manipulations that allowed the first descriptions of the neural crest origins of the ENS in the 1950s. More recently, studies in the chick and other non-mammalian model systems, notably zebrafish, have continued to advance our understanding of the basic biology of ENS development, with each animal model providing unique experimental advantages. Here we review the basic biology of ENS development in chick and zebrafish, highlighting conserved and unique features, and emphasising novel contributions to our general understanding of ENS development due to technical or biological features

Coherent imaging of extended objects

When used with coherent light, optical imaging systems, even diffraction-limited, are inherently unable to reproduce both the amplitude and the phase of a two-dimensional field distribution because their impulse response function varies slowly from point to point (a property known as non-isoplanatism). For sufficiently small objects, this usually results in a phase distortion and has no impact on the measured intensity. Here, we show that the intensity distribution can also be dramatically distorted when objects of large extension or of special shapes are imaged. We illustrate the problem using two simple examples: the pinhole camera and the aberration-free thin lens. The effects predicted by our theorical analysis are also confirmed by experimental observations.Comment: 10 pages, 9 figures, submitted to Optics Communication

Manual versus powered toothbrushes for oral health; an update

Background: Plaque removal is a cornerstone in the prevention and treatment of periodontal diseases. Powered toothbrushes have been devised to assist in plaque removal. An earlier Cochrane systematic review found that only powered toothbrushes with a rotation-oscillation action were more effective at removing plaque and reducing gingivitis. That review requires updating to include recent trials. Objective: To compare the effects of manual and powered toothbrushes on plaque removal and gingival health. Method: We searched the Cochrane Oral Health Group Trials Register, CENTRAL; MEDLINE, EMBASE and CINAHL to 9 March 2011. Manufacturers and authors were contacted for additional data. Trials were selected for random allocation of participants to use a manual or powered toothbrush. Participants were members of the public with uncompromised manual dexterity who brushed unsupervised for at least 4 weeks. There was no language restriction. Primary outcomes were plaque and gingivitis scores at the end of the trial. Assessment of methodological quality and data extraction were conducted in duplicate. Potential sources of heterogeneity were examined, along with sensitivity analyses for quality and publication bias. Results: Fifty trials, involving 4326 participants, provided data. Effect sizes, calculated as standardized mean difference (95% confidence intervals) for brushes with a rotation oscillation action were: 1 to 3 months >3 months Plaque -0.53 (-0.74 to -0.31) -0.66 (-1.28 to -0.03) Gingivitis -0.49 (-0.73 to -0.26) -0.34 (-0.56 to -0.11) This represents approximately 27% fewer sites with bleeding on probing in the long term. No other powered designs were consistently superior to manual toothbrushes. There was considerable heterogeneity between trials. Sensitivity analyses revealed the results to be robust when selecting trials of high quality. Conclusion: Rotation-oscillation powered toothbrushes remove plaque and reduce gingivitis more than manual brushes in the short and long term

Evaluation capacity building in response to the agricultural research impact agenda: Emerging insights from Ireland, Catalonia (Spain), New Zealand, and Uruguay

Performance-based funding and calls for public-funded science to demonstrate societal impact are encouraging public research organisations to evaluate impact, the so-called impact agenda. This paper explores evaluation methods of four fully or partially public-funded agricultural research organisations and how they are building evaluative capacity to respond to the impact agenda. Drawing on cross- organisational comparison of the readiness of each organisation to implement evaluation, the implications for improving evaluative capacity building (ECB) are discussed. This study extends the current literature on ECB, as very little has focussed on research organisations in general, and particularly agricultural research.Postprint (author's final draft

The Impact of Agricultural Knowledge Transfer Resources on Farm Level Profitability during the Economic Recession – A Quantitative Study

Purpose: The outcomes from agricultural knowledge transfer (KT) are dependent on the access to and the quality of services available, coupled with the motivation of prospective clients to implement new skills. Within this context, the allocation of resources particularly in terms of the location of KT offices and number of agricultural advisers are important considerations for understanding KT impact. This quantitative study evaluates the impact of the rationalisation of KT resources on farm profitability for KT clients in Ireland during the recessionary period 2008-2014. Design/Methodology: Teagasc, the public KT service provider in Ireland, experienced significant office closures (43%) and staff reduction (38%) during the economic crisis, yet client numbers declined only slightly (4.5%). Administrative data is merged with a panel data set on farm level performance to test the impact of KT through Random Effects estimation. Findings: The results show that annual contract holders gained a 12.3% benefit to their market gross margin per hectare over the period. However, there was a negative effect of 0.2% for each additional client assigned to the adviser which averaged at 9.6% per adviser. Practical Implications: The quantitative findings provide a measure of impact that represents the value for money for the KT service. The key implication is that the client ratio for advisers should be considered when allocating resources and lower ratios would positively impact client margins. Theoretical Implications: This article outlines the value of quantitative studies to estimate impact in a clear translatable manner which can aid the policy discussion around resource deployment particularly in a recessionary period. The employment of a Random Effects estimator on a panel data set provides a solid base for the analysis. Originality/Value: This study evaluates the impact of KT on farm level profitability during a recessionary period when resources were constrained, and uses spatial variables and client densities to examine the regional effects

Stable ultrahigh-density magneto-optical recordings using introduced linear defects

The stability of data bits in magnetic recording media at ultrahigh densities is compromised by thermal `flips' -- magnetic spin reversals -- of nano-sized spin domains, which erase the stored information. Media that are magnetized perpendicular to the plane of the film, such as ultrathin cobalt films or multilayered structures, are more stable against thermal self-erasure than conventional memory devices. In this context, magneto-optical memories seem particularly promising for ultrahigh-density recording on portable disks, and bit densities of $\sim$100 Gbit inch$^{-2}$ have been demonstrated using recent advances in the bit writing and reading techniques. But the roughness and mobility of the magnetic domain walls prevents closer packing of the magnetic bits, and therefore presents a challenge to reaching even higher bit densities. Here we report that the strain imposed by a linear defect in a magnetic thin film can smooth rough domain walls over regions hundreds of micrometers in size, and halt their motion. A scaling analysis of this process, based on the generic physics of disorder-controlled elastic lines, points to a simple way by which magnetic media might be prepared that can store data at densities in excess of 1 Tbit inch$^{-2}$.Comment: 5 pages, 4 figures, see also an article in TRN News at http://www.trnmag.com/Stories/041801/Defects_boost_disc_capacity_041801.htm

Quantum Holographic Encoding in a Two-dimensional Electron Gas

The advent of bottom-up atomic manipulation heralded a new horizon for attainable information density, as it allowed a bit of information to be represented by a single atom. The discrete spacing between atoms in condensed matter has thus set a rigid limit on the maximum possible information density. While modern technologies are still far from this scale, all theoretical downscaling of devices terminates at this spatial limit. Here, however, we break this barrier with electronic quantum encoding scaled to subatomic densities. We use atomic manipulation to first construct open nanostructures--"molecular holograms"--which in turn concentrate information into a medium free of lattice constraints: the quantum states of a two-dimensional degenerate Fermi gas of electrons. The information embedded in the holograms is transcoded at even smaller length scales into an atomically uniform area of a copper surface, where it is densely projected into both two spatial degrees of freedom and a third holographic dimension mapped to energy. In analogy to optical volume holography, this requires precise amplitude and phase engineering of electron wavefunctions to assemble pages of information volumetrically. This data is read out by mapping the energy-resolved electron density of states with a scanning tunnelling microscope. As the projection and readout are both extremely near-field, and because we use native quantum states rather than an external beam, we are not limited by lensing or collimation and can create electronically projected objects with features as small as ~0.3 nm. These techniques reach unprecedented densities exceeding 20 bits/nm2 and place tens of bits into a single fermionic state.Comment: Published online 25 January 2009 in Nature Nanotechnology; 12 page manuscript (including 4 figures) + 2 page supplement (including 1 figure); supplementary movie available at http://mota.stanford.ed

Enteric Neurospheres Are Not Specific to Neural Crest Cultures: Implications for Neural Stem Cell Therapies

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited

Expression of Distal-less, dachshund, and optomotor blind in Neanthes arenaceodentata (Annelida, Nereididae) does not support homology of appendage-forming mechanisms across the Bilateria

The similarity in the genetic regulation of arthropod and vertebrate appendage formation has been interpreted as the product of a plesiomorphic gene network that was primitively involved in bilaterian appendage development and co-opted to build appendages (in modern phyla) that are not historically related as structures. Data from lophotrochozoans are needed to clarify the pervasiveness of plesiomorphic appendage forming mechanisms. We assayed the expression of three arthropod and vertebrate limb gene orthologs, Distal-less (Dll), dachshund (dac), and optomotor blind (omb), in direct-developing juveniles of the polychaete Neanthes arenaceodentata. Parapodial Dll expression marks premorphogenetic notopodia and neuropodia, becoming restricted to the bases of notopodial cirri and to ventral portions of neuropodia. In outgrowing cephalic appendages, Dll activity is primarily restricted to proximal domains. Dll expression is also prominent in the brain. dac expression occurs in the brain, nerve cord ganglia, a pair of pharyngeal ganglia, presumed interneurons linking a pair of segmental nerves, and in newly differentiating mesoderm. Domains of omb expression include the brain, nerve cord ganglia, one pair of anterior cirri, presumed precursors of dorsal musculature, and the same pharyngeal ganglia and presumed interneurons that express dac. Contrary to their roles in outgrowing arthropod and vertebrate appendages, Dll, dac, and omb lack comparable expression in Neanthes appendages, implying independent evolution of annelid appendage development. We infer that parapodia and arthropodia are not structurally or mechanistically homologous (but their primordia might be), that Dll’s ancestral bilaterian function was in sensory and central nervous system differentiation, and that locomotory appendages possibly evolved from sensory outgrowths