541 research outputs found
Spectrum of the Schr\"odinger operator in a perturbed periodically twisted tube
We study Dirichlet Laplacian in a screw-shaped region, i.e. a straight
twisted tube of a non-circular cross section. It is shown that a local
perturbation which consists of "slowing down" the twisting in the mean gives
rise to a non-empty discrete spectrum.Comment: LaTeX2e, 10 page
Curvature induced toroidal bound states
Curvature induced bound state (E < 0) eigenvalues and eigenfunctions for a
particle constrained to move on the surface of a torus are calculated. A limit
on the number of bound states a torus with minor radius a and major radius R
can support is obtained. A condition for mapping constrained particle wave
functions on the torus into free particle wave functions is established.Comment: 6 pages, no figures, Late
Kinetics of plasma cell‐free DNA and creatine kinase in a canine model of tissue injury
Background:
Cell‐free DNA (cfDNA) comprises short, double‐stranded circulating DNA sequences released from damaged cells. In people, cfDNA concentrations correlate well with disease severity and tissue damage. No reports are available regarding cfDNA kinetics in dogs.
Objectives/Hypothesis:
Cell‐free DNA will have a short biological half‐life and would be able to stratify mild, moderate, and severe tissue injury. Our study aims were to determine the kinetics and biological half‐life of cfDNA and to contrast them with those of creatine kinase (CK).
Animals:
Three groups of 10 dogs undergoing open ovariohysterectomy, surgery for cranial cruciate ligament rupture (CCLR), or hemilaminectomy.
Methods:
Plasma for cfDNA and CK analysis was collected at admission, at induction of anesthesia, postsurgery (time 0) and at 6, 12, 24, 36, 48, 60, and 72 hours after surgery.
Results:
The biological half‐life of plasma cfDNA and CK were 5.64 hours (95% confidence interval [CI 95], 4.36–7.98 hours) and 28.7 hours (CI95, 25.3–33.3 hours), respectively. In the hemilaminectomy group, cfDNA concentrations differed significantly from admission at 6–12 hours after surgery. Creatine kinase activity differed among the surgical groups and reached a peak 6 hours after surgery. In the ovariohysterectomy and CCLR groups, plasma CK activity 72 hours after surgery did not differ from admission activity of the ovariohysterectomy group. In contrast, in the hemilaminectomy group, plasma CK activity after 72 hours did not return to the ovariohysterectomy group admission activity.
Conclusions and Clinical Importance:
Plasma CK activity has a longer biological half‐life than previously thought. In contrast to plasma CK activity, cfDNA has a short half‐life and could be a useful marker for peracute severe tissue injury
Dark matter search results from the complete exposure of the PICO-60 C3F8 bubble chamber
[EN] Final results are reported from operation of the PICO-60 C3F8 dark matter detector, a bubble chamber filled with 52 kg of C3F8 located in the SNOLAB underground laboratory. The chamber was operated at thermodynamic thresholds as low as 1.2 keV without loss of stability. A new blind 1404-kg-day exposure at 2.45 keV threshold was acquired with approximately the same expected total background rate as the previous 1167-kg-day exposure at 3.3 keV. This increased exposure is enabled in part by a new optical tracking analysis to better identify events near detector walls, permitting a larger fiducial volume. These results set the most stringent direct-detection constraint to date on the weakly interacting massive particle (WIMP)-proton spin-dependent cross section at 3.2 x 10(-41) cm(2) for a 25 GeV WIMP, improving on previous PICO results for 3-5 GeV WIMPs by an order of magnitude.The PICO Collaboration wishes to thank SNOLAB and its staff for support through underground space, logistical and technical services. SNOLAB operations are supported by the Canada Foundation for Innovation and the Province of Ontario Ministry of Research and Innovation, with underground access provided by Vale at the Creighton mine site. We are grateful to Genevieve Belanger and Alexander Pukhov of the Universit e de Savoie for their useful correspondence regarding the interpretation of PICO results. We wish to acknowledge the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Foundation for Innovation (CFI) for funding. We acknowledge the support from the National Science Foundation (NSF) (Grants No. 0919526, No. 1506337, No. 1242637, No. 1205987, and No. 1806722). We acknowledge that this work is supported by the U.S. Department of Energy (DOE) Office of Science, Office of High Energy Physics (under Award No. DE-SC-0012161), by the DOE Office of Science Graduate Student Research (SCGSR) award, by DGAPA-UNAM (PAPIIT No. IA100118) and Consejo Nacional de Ciencia y Tecnologia (CONACyT, Mexico, Grants No. 252167 and No. A1-S-8960), by the Department of Atomic Energy (DAE), Government of India, under the Centre for AstroParticle Physics II project (CAPP-II) at the Saha Institute of Nuclear Physics (SINP), European Regional Development FundProject "Engineering applications of microworld physics" (No. CZ. 02.1.01/0.0/0.0/16_019/0000766), and the Spanish (Ministry of Science, Innovation and Universities) Ministerio de Ciencia, Innovacion y Universidades (Red Consolider MultiDark, FPA2017-90566-REDC). This work is partially supported by the Kavli Institute for Cosmological Physics at the University of Chicago through NSF Grant No. 1125897, and an endowment from the Kavli Foundation and its founder Fred Kavli. We also wish to acknowledge the support from Fermi National Accelerator Laboratory under Contract No. DE-AC02-07CH11359, and from Pacific Northwest National Laboratory, which is operated by Battelle for the U.S. Department of Energy under Contract No. DE-AC05-76RL01830. We also thank Compute Canada (www.computecanada.ca) and the Centre for Advanced Computing, ACENET, Calcul Quebec, Compute Ontario and WestGrid for computational support.Amole, C.; Ardid Ramírez, M.; Arnquist, I.; Asner, DM.; Baxter, D.; Behnke, E.; Bressler, M.... (2019). Dark matter search results from the complete exposure of the PICO-60 C3F8 bubble chamber. Physical Review D: covering particles, fields, gravitation, and cosmology. 100(2):1-9. https://doi.org/10.1103/PhysRevD.100.022001191002Olive, K. A. (2014). Review of Particle Physics. Chinese Physics C, 38(9), 090001. doi:10.1088/1674-1137/38/9/090001Komatsu, E., Dunkley, J., Nolta, M. R., Bennett, C. L., Gold, B., Hinshaw, G., … Wright, E. L. (2009). FIVE-YEAR
WILKINSON MICROWAVE ANISOTROPY PROBE
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Hot Spots and Transition from d-Wave to Another Pairing Symmetry in the Electron-Doped Cuprate Superconductors
We present a simple theoretical explanation for a transition from d-wave to
another superconducting pairing observed in the electron-doped cuprates. The
d_{x^2-y^2} pairing potential Delta, which has the maximal magnitude and
opposite signs at the hot spots on the Fermi surface, becomes suppressed with
the increase of electron doping, because the hot spots approach the Brillouin
zone diagonals, where Delta vanishes. Then, the d_{x^2-y^2} pairing is replaced
by either singlet s-wave or triplet p-wave pairing. We argue in favor of the
latter and discuss experiments to uncover it.Comment: 6 pages, 4 figures, RevTeX 4. V.2: Extra figure and many references
added. V.3: Minor update of references for the proof
The 3D Structure of N132D in the LMC: A Late-Stage Young Supernova Remnant
We have used the Wide Field Spectrograph (WiFeS) on the 2.3m telescope at
Siding Spring Observatory to map the [O III] 5007{\AA} dynamics of the young
oxygen-rich supernova remnant N132D in the Large Magellanic Cloud. From the
resultant data cube, we have been able to reconstruct the full 3D structure of
the system of [O III] filaments. The majority of the ejecta form a ring of
~12pc in diameter inclined at an angle of 25 degrees to the line of sight. We
conclude that SNR N132D is approaching the end of the reverse shock phase
before entering the fully thermalized Sedov phase of evolution. We speculate
that the ring of oxygen-rich material comes from ejecta in the equatorial plane
of a bipolar explosion, and that the overall shape of the SNR is strongly
influenced by the pre-supernova mass loss from the progenitor star. We find
tantalizing evidence of a polar jet associated with a very fast oxygen-rich
knot, and clear evidence that the central star has interacted with one or more
dense clouds in the surrounding ISM.Comment: Accepted for Publication in Astrophysics & Space Science, 18pp, 8
figure
Jupiter's X-ray Emission During Solar Minimum
The 2007–2009 solar minimum was the longest of the space age. We present the first of two companion papers on Chandra and XMM‐Newton X‐ray campaigns of Jupiter through February–March 2007. We find that low solar X‐ray flux during solar minimum causes Jupiter's equatorial regions to be exceptionally X‐ray dim (0.21 GW at minimum; 0.76 GW at maximum). While the Jovian equatorial emission varies with solar cycle, the aurorae have comparably bright intervals at solar minimum and maximum. We apply atomic charge exchange models to auroral spectra and find that iogenic plasma of sulphur and oxygen ions provides excellent fits for XMM‐Newton observations. The fitted spectral S:O ratios of 0.4–1.3 are in good agreement with in situ magnetospheric S:O measurements of 0.3–1.5, suggesting that the ions that produce Jupiter's X‐ray aurora predominantly originate inside the magnetosphere. The aurorae were particularly bright on 24–25 February and 8–9 March, but these two observations exhibit very different spatial, spectral, and temporal behavior; 24–25 February was the only observation in this campaign with significant hard X‐ray bremsstrahlung from precipitating electrons, suggesting this may be rare. For 8–9 March, a bremsstrahlung component was absent, but bright oxygen O6+ lines and best‐fit models containing carbon, point to contributions from solar wind ions. This contribution is absent in the other observations. Comparing simultaneous Chandra ACIS and XMM‐Newton EPIC spectra showed that ACIS systematically underreported 0.45‐ to 0.6‐keV Jovian emission, suggesting quenching may be less important for Jupiter's atmosphere than previously thought. We therefore recommend XMM‐Newton for spectral analyses and quantifying opacity/quenching effects
Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events
The - oscillation frequency has been measured with a sample of
23 million \B\bar B pairs collected with the BABAR detector at the PEP-II
asymmetric B Factory at SLAC. In this sample, we select events in which both B
mesons decay semileptonically and use the charge of the leptons to identify the
flavor of each B meson. A simultaneous fit to the decay time difference
distributions for opposite- and same-sign dilepton events gives ps.Comment: 7 pages, 1 figure, submitted to Physical Review Letter
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
Jet size dependence of single jet suppression in lead-lead collisions at sqrt(s(NN)) = 2.76 TeV with the ATLAS detector at the LHC
Measurements of inclusive jet suppression in heavy ion collisions at the LHC
provide direct sensitivity to the physics of jet quenching. In a sample of
lead-lead collisions at sqrt(s) = 2.76 TeV corresponding to an integrated
luminosity of approximately 7 inverse microbarns, ATLAS has measured jets with
a calorimeter over the pseudorapidity interval |eta| < 2.1 and over the
transverse momentum range 38 < pT < 210 GeV. Jets were reconstructed using the
anti-kt algorithm with values for the distance parameter that determines the
nominal jet radius of R = 0.2, 0.3, 0.4 and 0.5. The centrality dependence of
the jet yield is characterized by the jet "central-to-peripheral ratio," Rcp.
Jet production is found to be suppressed by approximately a factor of two in
the 10% most central collisions relative to peripheral collisions. Rcp varies
smoothly with centrality as characterized by the number of participating
nucleons. The observed suppression is only weakly dependent on jet radius and
transverse momentum. These results provide the first direct measurement of
inclusive jet suppression in heavy ion collisions and complement previous
measurements of dijet transverse energy imbalance at the LHC.Comment: 15 pages plus author list (30 pages total), 8 figures, 2 tables,
submitted to Physics Letters B. All figures including auxiliary figures are
available at
http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HION-2011-02
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