Pdf's of Derivatives and Increments for Decaying Burgers Turbulence

A Lagrangian method is used to show that the power-law with a -7/2 exponent in the negative tail of the pdf of the velocity gradient and of velocity increments, predicted by E, Khanin, Mazel and Sinai (1997 Phys. Rev. Lett. 78, 1904) for forced Burgers turbulence, is also present in the unforced case. The theory is extended to the second-order space derivative whose pdf has power-law tails with exponent -2 at both large positive and negative values and to the time derivatives. Pdf's of space and time derivatives have the same (asymptotic) functional forms. This is interpreted in terms of a "random Taylor hypothesis".Comment: LATEX 8 pages, 3 figures, to appear in Phys. Rev.

Investigating the Influence of High-Speed Gantry Rotation in Cardiac CT on Motion Artifacts in Aortic Stenosis Patients Not Premedicated with β-Blockers: The FAST-CCT Randomized Trial Protocol.

Coronary CT angiography (CCTA) is increasingly used as a non-invasive tool to assess coronary artery disease (CAD). However, CCTA is subject to motion artifacts, potentially limiting its clinical utility. Despite faster (0.35 and 0.28 s/rot) gantry rotation times, low (60-65 bpm) heartbeat is recommended, and the use of β-blockers is often needed. Technological advancements have resulted in the development of faster rotation speeds (0.23 s/rot). However, their added value in patients not premedicated with β-blockers remains unclear. This prospective single-center, two-arm, randomized, controlled trial aims to assess the influence of fast rotation on coronary motion artifacts, diagnostic accuracy of CCTA for CAD, and patient safety. We will randomize a total of 142 patients aged ≥ 50 scheduled for an aortic stenosis work-up to receive CCTA with either a fast (0.23) or standard (0.28 s/rot) gantry speed. rate of CCTAs with coronary motion artifacts hindering interpretation. assessable coronary segments rate, diagnostic accuracy against invasive coronary angiography (ICA), motion artifact magnitude per segment, contrast-to-noise ratio (CNR), and patient ionizing radiation dose. The local ethics committee has approved the protocol. Potential significance: FAST-CCT may improve motion artifact reduction and diagnosis quality, thus eliminating the need for rate control and β-blocker administration. gov identifier: NCT05709652

Prevalence and risk factors for therapy escalation in ulcerative colitis in the Swiss IBD Cohort Study

BACKGROUND: Physicians traditionally treat ulcerative colitis (UC) using a step-up approach. Given the paucity of data, we aimed to assess the cumulative probability of UC-related need for step-up therapy and to identify escalation-associated risk factors. METHODS: Patients with UC enrolled into the Swiss IBD Cohort Study were analyzed. The following steps from the bottom to the top of the therapeutic pyramid were examined: (1) 5-aminosalicylic acid and/or rectal corticosteroids, (2) systemic corticosteroids, (3) immunomodulators (IM) (azathioprine, 6-mercaptopurine, methotrexate), (4) TNF antagonists, (5) calcineurin inhibitors, and (6) colectomy. RESULTS: Data on 996 patients with UC with a median disease duration of 9 years were examined. The point estimates of cumulative use of different treatments at years 1, 5, 10, and 20 after UC diagnosis were 91%, 96%, 96%, and 97%, respectively, for 5-ASA and/or rectal corticosteroids, 63%, 69%, 72%, and 79%, respectively, for systemic corticosteroids, 43%, 57%, 59%, and 64%, respectively, for IM, 15%, 28%, and 35% (up to year 10 only), respectively, for TNF antagonists, 5%, 9%, 11%, and 12%, respectively, for calcineurin inhibitors, 1%, 5%, 9%, and 18%, respectively, for colectomy. The presence of extraintestinal manifestations and extended disease location (at least left-sided colitis) were identified as risk factors for step-up in therapy with systemic corticosteroids, IM, TNF antagonists, calcineurin inhibitors, and surgery. Cigarette smoking at diagnosis was protective against surgery. CONCLUSIONS: The presence of extraintestinal manifestations, left-sided colitis, and extensive colitis/pancolitis at the time of diagnosis were associated with use of systemic corticosteroids, IM, TNF antagonists, calcineurin inhibitors, and colectomy during the disease course

Anomalous scaling of a passive scalar in the presence of strong anisotropy

Field theoretic renormalization group and the operator product expansion are applied to a model of a passive scalar field, advected by the Gaussian strongly anisotropic velocity field. Inertial-range anomalous scaling behavior is established, and explicit asymptotic expressions for the n-th order structure functions of scalar field are obtained; they are represented by superpositions of power laws with nonuniversal (dependent on the anisotropy parameters) anomalous exponents. In the limit of vanishing anisotropy, the exponents are associated with tensor composite operators built of the scalar gradients, and exhibit a kind of hierarchy related to the degree of anisotropy: the less is the rank, the less is the dimension and, consequently, the more important is the contribution to the inertial-range behavior. The leading terms of the even (odd) structure functions are given by the scalar (vector) operators. For the finite anisotropy, the exponents cannot be associated with individual operators (which are essentially ``mixed'' in renormalization), but the aforementioned hierarchy survives for all the cases studied. The second-order structure function is studied in more detail using the renormalization group and zero-mode techniques.Comment: REVTEX file with EPS figure

Electronic correlation in the infrared optical properties of the quasi two dimensional κ\kappa-type BEDT-TTF dimer system

The polarized optical reflectance spectra of the quasi two dimensional organic correlated electron system $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]$Y$, $Y =$ Br and Cl are measured in the infrared region. The former shows the superconductivity at $T_{\rm c} \simeq$ 11.6 K and the latter does the antiferromagnetic insulator transition at $T_{\rm N} \simeq$ 28 K. Both the specific molecular vibration mode $\nu_{3}(a_{g})$ of the BEDT-TTF molecule and the optical conductivity hump in the mid-infrared region change correlatively at $T^{*} \simeq$ 38 K of $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Br, although no indication of $T^{*}$ but the insulating behaviour below $T_{\rm ins} \simeq$ 50-60 K are found in $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl. The results suggest that the electron-molecular vibration coupling on the $\nu_{3}(a_{g})$ mode becomes weak due to the enhancement of the itinerant nature of the carriers on the dimer of the BEDT-TTF molecules below $T^{*}$, while it does strong below $T_{\rm ins}$ because of the localized carriers on the dimer. These changes are in agreement with the reduction and the enhancement of the mid-infrared conductivity hump below $T^{*}$ and $T_{\rm ins}$, respectively, which originates from the transitions between the upper and lower Mott-Hubbard bands. The present observations demonstrate that two different metallic states of $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Br are regarded as {\it a correlated good metal} below $T^{*}$ including the superconducting state and {\it a half filling bad metal} above $T^{*}$. In contrast the insulating state of $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl below $T_{\rm ins}$ is the Mott insulator.Comment: 8 pages, 7 figure

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Search for direct production of charginos and neutralinos in events with three leptons and missing transverse momentum in √s = 7 TeV pp collisions with the ATLAS detector

A search for the direct production of charginos and neutralinos in final states with three electrons or muons and missing transverse momentum is presented. The analysis is based on 4.7 fb−1 of proton–proton collision data delivered by the Large Hadron Collider and recorded with the ATLAS detector. Observations are consistent with Standard Model expectations in three signal regions that are either depleted or enriched in Z-boson decays. Upper limits at 95% confidence level are set in R-parity conserving phenomenological minimal supersymmetric models and in simplified models, significantly extending previous results

Measurement of the inclusive isolated prompt photon cross-section in pp collisions at sqrt(s)= 7 TeV using 35 pb-1 of ATLAS data

A measurement of the differential cross-section for the inclusive production of isolated prompt photons in pp collisions at a center-of-mass energy sqrt(s) = 7 TeV is presented. The measurement covers the pseudorapidity ranges |eta|<1.37 and 1.52<=|eta|<2.37 in the transverse energy range 45<=E_T<400GeV. The results are based on an integrated luminosity of 35 pb-1, collected with the ATLAS detector at the LHC. The yields of the signal photons are measured using a data-driven technique, based on the observed distribution of the hadronic energy in a narrow cone around the photon candidate and the photon selection criteria. The results are compared with next-to-leading order perturbative QCD calculations and found to be in good agreement over four orders of magnitude in cross-section.Comment: 7 pages plus author list (18 pages total), 2 figures, 4 tables, final version published in Physics Letters