Summer Isles geophysical survey, BGS Project 05/04 RV Calanus operations report

This report describes the operation of BGS Project 05/04, a swath bathymetry and surface tow boomer survey in the Summer Isles Region, carried out from 4th to 24th July 2005. The vessel used was the RV Calanus chartered from the Scottish Association Of Marine Science (SAMS), based in Oban. Because of the inshore nature of the work operations were carried out on a 12 hour daily basis but with personnel living on the vessel. Calanus proved well suited to the work and a very detailed swath coverage of the Summer Islands region together with Loch Broom and Little Loch Broom was achieved in the first two weeks of the survey. The last four days of operations were devoted to a surface tow boomer survey. The survey was a part of the BGS Offshore Mapping and Modelling Project E2027S73, North Atlantic Correlation

Audio-visual speech perception: a developmental ERP investigation

Being able to see a talking face confers a considerable advantage for speech perception in adulthood. However, behavioural data currently suggest that children fail to make full use of these available visual speech cues until age 8 or 9. This is particularly surprising given the potential utility of multiple informational cues during language learning. We therefore explored this at the neural level. The event-related potential (ERP) technique has been used to assess the mechanisms of audio-visual speech perception in adults, with visual cues reliably modulating auditory ERP responses to speech. Previous work has shown congruence-dependent shortening of auditory N1/P2 latency and congruence-independent attenuation of amplitude in the presence of auditory and visual speech signals, compared to auditory alone. The aim of this study was to chart the development of these well-established modulatory effects over mid-to-late childhood. Experiment 1 employed an adult sample to validate a child-friendly stimulus set and paradigm by replicating previously observed effects of N1/P2 amplitude and latency modulation by visual speech cues; it also revealed greater attenuation of component amplitude given incongruent audio-visual stimuli, pointing to a new interpretation of the amplitude modulation effect. Experiment 2 used the same paradigm to map cross-sectional developmental change in these ERP responses between 6 and 11 years of age. The effect of amplitude modulation by visual cues emerged over development, while the effect of latency modulation was stable over the child sample. These data suggest that auditory ERP modulation by visual speech represents separable underlying cognitive processes, some of which show earlier maturation than others over the course of development

Kinetic and thermodynamic analysis of leech-derived tryptase inhibitor interaction with bovine tryptase and bovine trypsin

The interaction of leech-derived tryptase inhibitor (LDTI) with bovine liver capsule tryptase (BLCT) and bovine trypsin has been studied using both thermodynamic and kinetic approaches. Several differences were detected: (i) the equilibrium affinity of LDTI for BLCT (K-a = 8.9 x 10(5) M-1) is about 600-fold lower than that for bovine trypsin (K-a = 5.1 x 10(8) M-1); (ii) LDTI behaves as a purely non-competitive inhibitor of BLCT, while it is a purely competitive inhibitor of bovine trypsin. These functional data are compared with those previously reported for the LDTI binding to human tryptase, where tight inhibition occurs at two of the four active sites of the tetramer (K-a = 7.1 x 10(8) M-1). Amino acid sequence alignment of BLCT, human beta II-tryptase and bovine trypsin allows us to infer some possible structural basis for the observed functional differences

Conformational Mobility of the Pyrrolidine Ring of Proline in Peptides and Peptide Hormones as Manifest in Carbon 13 Spin-Lattice Relaxation Times

Abstract The spin-lattice relaxation times (T1) of carbon 13 in natural abundance were determined for proline, N-acetyl-prolineamide, glycylproline, cyclo(triprolyl), and a series of proline-containing peptide hormones. The data are interpreted in terms of rapid interconversion of proline between various ring-puckered forms. The nature of the puckering depends upon the type of group attached to proline. In proline, the β, γ, and δ carbon atoms are appreciably more mobile than the α carbon atom, suggesting rapid interconversion between a number of ring-puckered forms. In melanocyte-stimulating hormone release-inhibiting hormone (Pro-Leu-Gly-NH2) and its dimethylamido analog, the γ carbon atom has the greatest mobility, suggesting a rapid endo-exo interconversion at this position. In Gly-Pro and in acetyl-Pro-NH2, the cis and trans conformers of proline have very similar T1 values, indicating very little dependence of the dynamic proline ring conformation on the conformation at the peptide bond; in both isomers, the proline ring interconverts rapidly between half-chair conformers puckered at Cβ and Cγ. In thyrotropin-releasing hormone (lGlu-His-Pro-NH2), the proline ring conformation is similar to that in Gly-Pro, and independent of the state of ionization of the histidine residue. Oxytocin [see PDF for equation] , lysine-vasopressin [see PDF for equation] , [Ile5]angiotensin II (Asp-Arg-Val-Tyr-Ile-His-Pro-Phe), and luteinizing hormone-releasing hormone ( lGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2) all have proline in the trans conformation about the peptide bond, and the δ carbon atom has a mobility comparable to that of the α carbon atom. The latter reflects severe steric constraints at Cδ due to the neighboring residues. In oxytocin and angiotensin II, the β carbon atom is considerably more mobile than Cα or Cδ. In luteinizing hormonereleasing hormone, the proline ring apparently undergoes rapid interconversion between half-chair forms puckered at Cβ and Cγ, whereas in lysine-vasopressin, the mobility of Cγ is greatest

Simplified methods of assessing the impact of grid frequency dynamics upon generating plants

The frequency of the national electricity grid is affected by fluctuations in supply and demand, and so continually "judders" in an essentially unpredictable fashion around 50 Hz. At present such perturbations do not seemingly affect Nuclear Electric as most of their plant is run at more or less constant load, but they would like to be able to offer the national grid a mode of operation in which they "followed" the grid frequency: i.e., as the frequency rose above or fell below 50 Hz, the plant's output would be adjusted so as to tend to restore the frequency to 50 Hz. The aim is to maintain grid frequency within 0.2 Hz of its notional value. Such a mode of operation, however, would cause a certain amount of damage to plant components owing to the consequent continual changes in temperature and pressure within them. Nuclear Electric currently have complex computational models of how plants will behave under these conditions, which allows them to compute plant data (e.g., reactor temperatures) from given grid frequency data. One approach to damage assessment would require several years'-worth of real grid data to be fed into this model and the corresponding damage computed (via "cycle distributions" created by their damage experts). The results of this analysis would demonstrate one of three possibilities: the damage may be acceptable under all reasonable operating conditions; or it may be acceptable except in the case of an exceptional abrupt change in grid frequency (caused by power transmission line failure, or another power station suddenly going off-line, for instance), in which case some kind of backup supply (e.g., gas boilers) would be required; or it may simply be unacceptable. However, their current model runs in approximately real time, making it inappropriate for such a large amount of data: our problem was to suggest alternative approaches. Specifically, we were asked the following questions: - Can component damage be reliably estimated directly from cycle distributions of grid frequency? i.e., are there maps from frequency cycle distributions to plant parameter cycle distributions? - Can a simple model of plant dynamics be used to assess the potential for such maps? - What methods can be used to select representative samples of grid frequency behaviour? - What weightings should be applied to the selections? - Is it possible to construct a "cycle transform" (Fourier transform) which will capture the essential features of grid frequency and which can then be inverted to generate simulated frequency transients? We did not consider this last question, other than to say "probably not". We were supplied with data of the actual grid frequency measurements for the evening of 29/7/95, and the corresponding plant responses (obtained using Nuclear Electric's current computational model). A simplified nonlinear mathematical model of the plant was also provided. Two main approaches were considered: statistical prediction and analytical modelling via a reduction of the simplified plant model

D-Brane Dynamics and NS5 Rings

We consider the classical motion of a probe D-brane moving in the background geometry of a ring of NS5 branes, assuming that the latter are non-dynamical. We analyse the solutions to the Dirac-Born-Infield (DBI) action governing the approximate dynamics of the system. In the near horizon (throat) approximation we find several exact solutions for the probe brane motion. These are compared to numerical solutions obtained in more general cases. One solution of particular interest is when the probe undergoes oscillatory motion through the centre of the ring (and perpendicular to it). By taking the ring radius sufficiently large, this solution should remain stable to any stringy corrections coming from open-strings stretching between the probe and the NS5-branes along the ring.Comment: 17 pages, Latex, 8 figures; References adde

C9orf72 plays a central role in Rab GTPase-dependent regulation of autophagy

A GGGGCC hexanucleotide repeat expansion in the first intron of the C9orf72 gene is the most common genetic defect associated with amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) (C9ALS/FTD). Haploinsufficiency and a resulting loss of C9orf72 protein function has been suggested as a possible pathogenic mechanism in C9ALS/FTD. C9ALS/FTD patients exhibit specific ubiquitin and p62/sequestosome-1 positive but TDP-43 negative inclusions in the cerebellum and hippocampus, indicating possible autophagy deficits in these patients. In a recent study, we investigated this possibility by reducing expression of C9orf72 in cell lines and primary neurons and found that C9orf72 regulates the initiation of autophagy. C9orf72 interacts with Rab1a, preferentially in its GTP-bound state, as well as the ULK1 autophagy initiation complex. As an effector of Rab1a, C9orf72 controls the Rab1a-dependent trafficking of the ULK1 initiation complex prior to autophagosome formation. In line with this function, C9orf72 depletion in cell lines and primary neurons caused the accumulation of p62/sequestosome-1-positive inclusions. In support of a role in disease pathogenesis, C9ALS/FTD patient-derived iNeurons showed markedly reduced levels of autophagy. In this Commentary we summarise recent findings supporting the key role of C9orf72 in Rab GTPase-dependent regulation of autophagy and discuss autophagy dysregulation as a pathogenic mechanism in ALS/FTD

Homeless population

The aim was to derive and analyze a model for numbers of homeless and non-homeless people in a borough, in particular to see how these figures might be affected by different policies regarding housing various categories of people. Most attention was focused on steady populations although the stability of these and possible timescales of dynamic problems were also discussed. The main outcome of this brief study is the identification of the key role played by the constant k_1 - the constant which fixes the speed at which the homeless are rehoused in permanent council property. Reducing this constant, i.e. making the system "fairer" with less priority to accommodating homeless families, appears to have little effect on the sizes of other categories on the waiting list but there is a marked increase in the number of households in temporary accommodation. The model, indicated by the size of its longest time-scale, should be modified to allow for births etc. It could be varied by allowing people to remove themselves from the register or by allowing the rates at which registered and unregistered people become homeless to differ, but these modifications are unlikely to substantially change the main result. The inclusion of movement from the homeless to the general population would have the effect of limiting the numbers in temporary accommodation. However, it is thought this effect is very small so a great reduction in k_1 would be needed for this flow to become significant

Determination of the Structure and Conformation of Bacterial Polysaccharides by Carbon 13 Nuclear Magnetic Resonance STUDIES ON THE GROUP-SPECIFIC ANTIGENS OF NEISSERIA MENINGITIDIS SEROGROUPS A AND X

Abstract The application of carbon 13 nuclear magnetic resonance to analysis of some phosphorylated acetamidohexose-containing meningococcal polysaccharides is described. A complete assignment of the spectra of both the serogroup A and X polysaccharides has been made. In addition the spectrum of a structurally related 1 →6-α-linked 2-acetamido-2-deoxy-d-glucose phosphate polysaccharide from Staphylococcus lactis NCTC 2102 has also been completely assigned. This has resulted in the structural elucidation of the serogroup X polysaccharide as a homopolymer of 2-acetamido-2-deoxy-d-glucopyranose, linked by 1→4-α-phosphodiester bonds. In addition, the O-acetyl substituents of the serogroup A polysaccharide have been located at C-3 of approximately 70% of the repeating units (1→6-α-linked 2-acetamido-2-deoxy-d-mannopyranose phosphate) of the homopolymer. Preliminary conformational information was also obtained from the large three-bond couplings between 31P and 13C (3J3131p-1313c), indicative of highly extended backbone formations