To determine the accuracy of a new actigraphy system for the measurement of periodic leg movements (PLMs). Continuous measurements of leg movements, made overnight, are essential to diagnose and ...monitor treatment for PLMs. We have developed the Actiwatch with Cambridge Neuro-Technology Ltd (Cambridge, UK) to detect leg movements consistent with PLMs, to record these movements from both feet over three consecutive nights and to report standard indices of PLMs. We describe three studies designed to validate this device.
The Actiwatch was assessed on a bench model across a range of movement amplitudes. The level of agreement on individual movements between the Actiwatch and bilateral anterior tibialis electromyography (BATEMG) measures was assessed in 199 epochs from five patients with known PLMs. The ability of the Actiwatch to correctly identify patients with PLMs was assessed in a comparison with polysomnography (PSG) in 50 consecutive patients investigated in the sleep laboratory.
The Actiwatch detected all mechanically generated movements (100% sensitivity and 100% specificity) on the bench test. On individual movements BATEMG measurement and the Actiwatch agreed on 94% of epochs. The sensitivity and specificity of the Actiwatch to detect leg movements in severe PLMs as defined by BATEMG (PLMI≥25) are high (100% sensitive and 97% specific). Our bilateral system gave better agreement with BATEMG than previous systems but the two measures are still not interchangeable.
EMG is only a surrogate measure of limb movement and indices measured in this way correlate poorly with symptoms. We have demonstrated that the Actiwatch faithfully records movement, which offers the potential to reassess the relationships between limb movement indices and symptoms. This which offers a convenient and economical alternative to PSG in the study of large populations to increase our understanding of the epidemiology and clinical significance of PLMs.
A recent study showed that a critically endangered migratory predator species, the Balearic shearwater Puffinus mauretanicus, rapidly expanded northwards in northeast Atlantic waters after the ...mid-1990s. As a significant positive correlation was found between the long-term changes in the abundance of this seabird and sea temperature around the British Isles, it was hypothesized that the link between the biogeographic shift and temperature occurred through the food web. Here, we test this conjecture and reveal concomitant changes in a regional index of sea temperature, plankton (total calanoid copepod), fish prey (anchovy and sardine) and the Balearic shearwater for the period 1980–2003. All three trophic levels exhibit a significant shift detected between 1994 and 1996. Our findings therefore support the assertion of both a direct and an indirect effect of climate change on the spatial distribution of post-breeding Balearic shearwater through a trophic cascade.
We report the observation of the X(3872) in the J/psipi(+)pi(-) channel, with J/psi decaying to mu(+)mu(-), in p (p) over bar collisions at roots=1.96 TeV. Using approximately 230 pb(-1) of data ...collected with the Run II D0 detector, we observe 522+/-100 X(3872) candidates. The mass difference between the X(3872) state and the J/psi is measured to be 774.9+/-3.1(stat)+/-3.0(syst) MeV/c(2). We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the psi(2S) state.
We present various properties of the production of the X(3872) and ψ(2S) states based on 10.4 fb−1 collected by the D0 experiment in Tevatron pp collisions at √s = 1.96 TeV. For both states, we ...measure the nonprompt fraction fNP of the inclusive production rate due to decays of b-flavored hadrons. We find the fNP values systematically below those obtained at the LHC. The fNP fraction for ψ(2S) increases with transverse momentum, whereas for the X(3872) it is constant within large uncertainties, in agreement with the LHC results. The ratio of prompt to nonprompt ψ(2S) production, (1 − fNP)=fNP, decreases only slightly going from the Tevatron to the LHC, but for the X(3872), this ratio decreases by a factor of about 3. We test the soft-pion signature of the X(3872) modeled as a weakly bound charm-meson pair by studying the production of the X(3872) as a function of the kinetic energy of the X(3872) and the pion in the X(3872)π center-of-mass frame. For a subsample consistent with prompt production, the results are incompatible with a strong enhancement in the production of the X(3872) at the small kinetic energy of the X(3872) and the π in the X(3872)π center-of-mass frame expected for the X þ soft-pion production mechanism. For events consistent with being due to decays of b hadrons, there is no significant evidence for the soft-pion effect, but its presence at the level expected for the binding energy of 0.17 MeV and the momentum scale Λ ¼ M(π) is not ruled out.
The standard model of particle physics contains parameters-such as particle masses-whose origins are still unknown and which cannot be predicted, but whose values are constrained through their ...interactions. In particular, the masses of the top quark (Mt) and W boson (MW) constrain the mass of the long-hypothesized, but thus far not observed, Higgs boson. A precise measurement of Mt can therefore indicate where to look for the Higgs, and indeed whether the hypothesis of a standard model Higgs is consistent with experimental data. As top quarks are produced in pairs and decay in only about 10-24 s into various final states, reconstructing their masses from their decay products is very challenging. Here we report a technique that extracts more information from each top-quark event and yields a greatly improved precision (of ± 5.3 GeV/c2) when compared to previous measurements. When our new result is combined with our published measurement in a complementary decay mode and with the only other measurements available, the new world average for Mt becomes 178.0 ± 4.3 GeV/c2. As a result, the most likely Higgs mass increases from the experimentally excluded value of 96 to 117 GeV/c2, which is beyond current experimental sensitivity. The upper limit on the Higgs mass at the 95% confidence level is raised from 219 to 251 GeV/c2.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We present a measurement of the ratio of events with correlated t and {bar t} spins to the total number of t{bar t} events. This ratio f is evaluated using a matrix-element-based approach in 729 ...t{bar t} candidate events with a single lepton {ell} (electron or muon) and at least four jets. The analyzed p{bar p} collisions data correspond to an integrated luminosity of 5.3 fb{sup -1} and were collected with the D0 detector at the Fermilab Tevatron collider operating at a center-of-mass energy {radical}s = 1.96 TeV. Combining this result with a recent measurement of f in dileptonic final states, we find f in agreement with the standard model. In addition, the combination provides evidence for the presence of spin correlation in t{bar t} events with a significance of more than 3 standard deviations.
The inclusive e+psingle and double differential cross sections for neutral and charged current processes are measured with the H1 detector at HERA. The data were taken in 1999 and 2000 at a ...centre-of-mass energy of \(\sqrt{s} = 319{\rm GeV}\) and correspond to an integrated luminosity of 65.2 pb-1. The cross sections are measured in the range of four-momentum transfer squared Q2 between 100 and \(30 000{\rm GeV}^2\) and Bjorken x between 0.0013 and 0.65. The neutral current analysis for the new e+p data and the earlier e-p data taken in 1998 and 1999 is extended to small energies of the scattered electron and therefore to higher values of inelasticity y, allowing a determination of the longitudinal structure function FL at high Q2 (\(110-700{\rm GeV}^2\)). A new measurement of the structure function \(x\tilde{F}_3\) is obtained using the new e+p and previously published \(e^\pm p\) neutral current cross section data at high Q2. These data together with H1 low Q2 precision data are further used to perform new next-to-leading order QCD analyses in the framework of the Standard Model to extract flavour separated parton distributions in the proton.
Correlations in the azimuthal angle between the two largest transverse momentum jets have been measured using the D0 detector in p (p) over bar collisions at a center-of-mass energy root s=1.96 TeV. ...The analysis is based on an inclusive dijet event sample in the central rapidity region corresponding to an integrated luminosity of 150 pb(-1). Azimuthal correlations are stronger at larger transverse momenta. These are well described in perturbative QCD at next-to-leading order in the strong coupling constant, except at large azimuthal differences where contributions with low transverse momentum are significant.
We present a measurement of the W boson pair-production cross section in p(p) over bar collisions at a center-of-mass energy of root s=1.96 TeV. The data, collected with the Run II D0 detector at ...Fermilab, correspond to an integrated luminosity of 224-252 pb(-1) depending on the final state (ee, e mu, or mu mu). We observe 25 candidates with a background expectation of 8.1 +/- 0.6(stat)+/- 0.6(syst)+/- 0.5(lum) events. The probability for an upward fluctuation of the background to produce the observed signal is 2.3x10(-7), equivalent to 5.2 standard deviations. The measurement yields a cross section of 13.8(-3.8)(+4.3)(stat)(-0.9)(+1.2)(syst)+/- 0.9(lum) pb, in agreement with predictions from the standard model.
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