Association between the squat lobster Gastroptychus formosus and cold-water corals in the North Atlantic

Although there are no previous descriptions of the habits of chirostylids in the North Atlantic, it is likely that species in the genera Uroptychus, Eumunida and Gastroptychus have close ecological ties with deep-sea corals since they have all been recorded in trawl samples containing corals from ∼200m depth. We analysed in situ distribution of Gastroptychus formosus and potential hosts using a ROV at a range of north-eastern Atlantic sites and found that this species forms a close association with deep-sea corals that resembles the chirostylid-anthozoan associations reported in shallow Indo-Pacific waters. We update the known distribution for G. formosus, confirming that it is an amphiatlantic species that occurs along the Mid-Atlantic Ridge at least as far south as the Azores and along continental margins from the Canary Islands to Scotland at depths of 600-1700m. The adults have very specific habitat preferences, being only found on gorgonian and antipatharian corals with a strong preference for Leiopathes sp. as a host. This highly restricted habitat preference is likely to render chirostylids vulnerable to the impacts of demersal fishing both directly, as by-catch, and indirectly through habitat loss. © 2010 Marine Biological Association of the United Kingdom

Extremal curves in nilpotent Lie groups

We classify extremal curves in free nilpotent Lie groups. The classification is obtained via an explicit integration of the adjoint equation in Pontryagin Maximum Principle. It turns out that abnormal extremals are precisely the horizontal curves contained in algebraic varieties of a specific type. We also extend the results to the nonfree case.Comment: 30 pages, final versio

Observing bulk diamond spin coherence in high-purity nanodiamonds

Nitrogen-vacancy centres (NVs) in diamond are attractive for research straddling quantum information science and nanoscale magnetometry and thermometry. While ultrapure bulk diamond NVs sustain the longest spin coherence times among optically accessible spins, nanodiamond NVs display persistently poor spin coherence. Here we introduce high-purity nanodiamonds accommodating record-long NV coherence times, >60 us, observed via universal dynamical decoupling. We show that the main contribution to decoherence comes from nearby nitrogen impurities rather than surface states. We protect the NV spin free precession, essential to DC magnetometry, by driving solely these impurities into the motional narrowing regime. This extends the NV free induction decay time from 440 ns, longer than that in type Ib bulk diamond, to 1.27 us, which is comparable to that in type IIa (impurity-free) diamond. These properties allow the simultaneous exploitation of both high sensitivity and nanometre resolution in diamond-based emergent quantum technologies.Comment: Additional data and analysis in PDF format is available for download at the publications section of http://www.amop.phy.cam.ac.uk/amop-m

Confirmatory factor analysis of Clinical Outocmes in Routine Evaluation (CORE-OM) used as a measure of emotional distress in people with tinnitus

BACKGROUND: People with troublesome tinnitus often experience emotional distress. Therefore a psychometrically sound instrument which can evaluate levels of distress and change over time is necessary to understand this experience. Clinical Outcomes in Routine Evaluation (CORE-OM) is a measure of emotional distress which has been widely used in mental health research. Although originally designed as a 4-factor questionnaire, factor analyses have not supported this structure and a number of alternative factor structures have been proposed in different samples. The aims of this study were to test the factor structure of the CORE-OM using a large representative tinnitus sample and to use it to investigate levels of emotional distress amongst people with a range of tinnitus experience. METHODS: The CORE-OM was completed by 342 people experiencing tinnitus who self-rated their tinnitus on a 5-point scale from ‘not a problem’ to ‘a very big problem’. Confirmatory factor analysis was used to test all ten factor models which have been previously derived across a range of population samples. Model fit was assessed using fit criterion and theoretical considerations. Mean scores on the full questionnaire and its subscales were compared between tinnitus problem categories using one-way ANOVA. RESULTS: The best fitting model included 33 of the 34 original items and was divided into three factors: negatively worded items, positively worded items and risk. The full questionnaire and each factor were found to have good internal consistency and factor loadings were high. There was a statistically significant difference in total CORE-OM scores across the five tinnitus problem categories. However there was no significant difference between those who rated their tinnitus ‘not a problem’, and ‘a small problem’ or ‘a moderate problem.’ CONCLUSION: This study found a 3-factor structure for the CORE-OM to be a good fit for a tinnitus population. It also found evidence of a relationship between emotional distress as measured by CORE-OM and perception of tinnitus as a problem. Its use in tinnitus clinics is to be recommended, particularly when emotional distress is a target of therapy

QCD Matching Conditions at Thresholds

The use of MS-like renormalization schemes in QCD requires an implementation of nontrivial matching conditions across thresholds, a fact often overlooked in the literature. We shortly review the use of these matching conditions in QCD and check explicitly that the prediction for $\alpha_s(M_Z)$, obtained by running the strong coupling constant from the $M_\tau$ scale, does not substantially depend on the exact value of the matching point chosen in crossing the $b$-quark threshold when the appropriate matching conditions are taken into account.Comment: 9 pages and 2 postscript figures added after the TeX file, LaTeX, CERN-TH.6899/9

T wave alternans in idiopathic long QT syndrome

AbstractObjectives. The study evaluates the association between T wave alternans and the risk of cardiac events (syncope, aborted cardiac arrest or cardiac death) in a large population of patients with idiopathic long QT syndrome.Background. T wave alternans is an infrequently recorded electrocardiographic (ECG) finding in patients with delayed repolarization, and its clinical significance is not clear.Methods. A total of 4,656 ECG recordings in 2,442 patients enrolled in the International Long QT Syndrome Registry were reviewed for episodes of T wave alternans. To determine the risk associated with T wave alternans, independent of corrected QT interval (QTc) duration, patients with T wave alternans were matched for QTc value (every 0.025 s1/2) to patients with long QT syndrome without T wave alternans.Results. T wave alternans was identified in 39 patients (25 of whom had a QTc interval >0.50 s1/2). A strong association between QTc prolongation and T wave alternans was observed (odds ratio 1.23 per 0.01-s1/2unit increase in QTc, p < 0.0001). Conditional logistic regression analyses with adjustment for age, gender, status and QTc value revealed that T wave alternans did not make a significant independent contribution to the risk of cardiac events. The risk of experiencing a major cardiac event was primarily related to length of QTc.Conclusions. T wave alternans, a marker of electrical instability and regional heterogeneity of repolarization, identifies a high risk subset of patients with prolonged repolarization. Patients with T wave alternans have an increased risk of cardiac events, but this risk is primarily related to the magnitude of repolarization delay (QTc prolongation). T wave alternans does not make an independent contribution to the risk of cardiac events after adjustment for QTc length

Curvature Diffusions in General Relativity

We define and study on Lorentz manifolds a family of covariant diffusions in which the quadratic variation is locally determined by the curvature. This allows the interpretation of the diffusion effect on a particle by its interaction with the ambient space-time. We will focus on the case of warped products, especially Robertson-Walker manifolds, and analyse their asymptotic behaviour in the case of Einstein-de Sitter-like manifolds.Comment: 34 page

Flavour in supersymmetric Grand Unification: a democratic approach

We consider the flavour problem in a supersymmetric Grand Unified theory with gauged SU(6) group, where the Higgs doublets are understood as pseudo-Goldstone bosons of a larger \SU(6)\otimes\SU(6) global symmetry of the Higgs superpotential. A key element of this work is that we never appeal to any flavour symmetry. One main interesting feature emerges: only one of the light fermions, an up-type quark, to be identified with the top, can get a Yukawa coupling at renormalizable level. This fact, together with bottom-tau Yukawa unification, also implied in our scheme, gives rise to a characteristic correlation between the top and the Higgs mass. By including a flavour-blind discrete symmetry and requiring that all higher dimensional operators be mediated by the exchange of appropriate heavy multiplets, it is possible to give an approximate description of all masses and mixing angles in term of a hierarchy of grand unified scales. A special ``texture'' arises, implying a relation between the top mass and the third generation mixing angles. Several other possible consequences of this approach are pointed out, concerning the $\mu/s$ mass ratio, the Cabibbo angle and the proton decay.Comment: 14 pages, 4 figures in LaTeX, IFUP -- TH. 7/9

Prenatal sonographic diagnosis of Nager acrofacial dysostosis with unilateral upper limb involvement

No Abstract.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/61218/1/2074_ftp.pd