894 research outputs found

    Scaling and non-Abelian signature in fractional quantum Hall quasiparticle tunneling amplitude

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    We study the scaling behavior in the tunneling amplitude when quasiparticles tunnel along a straight path between the two edges of a fractional quantum Hall annulus. Such scaling behavior originates from the propagation and tunneling of charged quasielectrons and quasiholes in an effective field analysis. In the limit when the annulus deforms continuously into a quasi-one-dimensional ring, we conjecture the exact functional form of the tunneling amplitude for several cases, which reproduces the numerical results in finite systems exactly. The results for Abelian quasiparticle tunneling is consistent with the scaling anaysis; this allows for the extraction of the conformal dimensions of the quasiparticles. We analyze the scaling behavior of both Abelian and non-Abelian quasiparticles in the Read-Rezayi Z_k-parafermion states. Interestingly, the non-Abelian quasiparticle tunneling amplitudes exhibit nontrivial k-dependent corrections to the scaling exponent.Comment: 16 pages, 4 figure

    Two new species of centipedes, Tygarrup daliensis sp. nov. (Mecistocephalidae) and Australobius cangshanensis sp. nov. (Lithobiidae), from Southwestern China

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    Two new species of Chilopoda from Yunnan Province, China, are described as new: Tygarrup daliensis sp. nov. (Geophilomorpha, Mecistocephalidae) and Australobius cangshanensis sp. nov. (Lithobiomorpha, Lithobiidae). Tygarrup daliensis sp. nov. differs from other Tygarrup species by its each side of clypeal plagula with up to 15 se-tae, arranged in three irregular rows; labral posterior ala rough, with about 10 longitudinal slanting stripes near to mid-piece tooth; mandible with 9 pectinate dentate lamellae, 1st mandibular pectinate lamella bearing 6 teeth; each coxopleuron of last leg-bearing segments with about 50 pores of various size. Australobius cangshanensis sp. nov. is distinguished from congeners by a row of about 60 short setae transversely on each posterior part of 6th and 7th sternites; forcipular coxosternite with 7–10 coxosternal teeth, and porodonts between 5th and 6th or between 4th and 5th innermost teeth

    An Algorithm for Preferential Selection of Spectroscopic Targets in LEGUE

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    We describe a general target selection algorithm that is applicable to any survey in which the number of available candidates is much larger than the number of objects to be observed. This routine aims to achieve a balance between a smoothly-varying, well-understood selection function and the desire to preferentially select certain types of targets. Some target-selection examples are shown that illustrate different possibilities of emphasis functions. Although it is generally applicable, the algorithm was developed specifically for the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) survey that will be carried out using the Chinese Guo Shou Jing Telescope. In particular, this algorithm was designed for the portion of LEGUE targeting the Galactic halo, in which we attempt to balance a variety of science goals that require stars at fainter magnitudes than can be completely sampled by LAMOST. This algorithm has been implemented for the halo portion of the LAMOST pilot survey, which began in October 2011.Comment: 17 pages, 7 figures, accepted for publication in RA

    Generation of heralded optical `Schroedinger cat' states by photon-addition

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    Optical "Schr\"odinger cat" states, the non-classical superposition of two quasi-classical coherent states, serve as a basis for gedanken experiments testing quantum physics on mesoscopic scales and are increasingly recognized as a resource for quantum information processing. Here, we report the first experimental realization of optical "Schr\"odinger cats" by adding a photon to a squeezed vacuum state, so far only photon-subtraction protocols have been realized. Photon-addition gives us the advantage of using heralded signal photons as experimental triggers, and we can generate "Schr\"odinger cats" at rates exceeding 8.5×1048.5 \times 10^4 counts per second; at least one order of magnitude higher than all previously reported realizations. Wigner distributions with pronounced negative parts are demonstrated at down to -8.89 dB squeezing, even when the initial squeezed vacuum input state has low purity. Benchmarking against such a degraded squeezed input state we report a maximum fidelity of more than 80% with a maximum cat amplitude of α1.66|\alpha| \approx 1.66. Our experiment uses photon-addition from pairs, one of those photons is used for monitoring, giving us enhanced control; moreover the pair production rates are high and should allow for repeated application of photon-addition via repeat-stages.Comment: 5 pages, 2 figures, 1 tabl

    Manipulation Therapy Relieved Pain More Rapidly Than Acupuncture among Lateral Epicondylalgia (Tennis Elbow) Patients: A Randomized Controlled Trial with 8-Week Follow-Up

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    Radial bone adjustment manipulation treatment may be effective to reduce pain rapidly in lateral epicondylalgia patients and the pathological tension in the biceps brachii muscle is highly concerned. To prove this hypothesis, we conducted a randomized controlled trial and included 35 patients with lateral epicondylalgia for more than 2 months. Either manipulation treatment (n=16) or acupuncture (n=19) was given to these patients for 2 weeks and all patients’ symptoms were followed up for 8 weeks after treatment. Both groups demonstrated changes in pain VAS score, grip strength, and DASH questionnaire. Lateral epicondylalgia patients who received manipulation treatment felt pain relief sooner than those who had acupuncture treatments during the first few treatments. However, both acupuncture and manipulation are effective, while the difference has no significance at the 8-week follow-up. The trial was registered with Current Controlled Trials ISRCTN81308551 on 5 February 2016

    Scintillation Arc from FRB 20220912A

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    We present the interstellar scintillation analysis of fast radio burst (FRB) 20220912A during its extremely active episode in 2022 using data from the Five-hundred-meter Aperture Spherical Radio Telescope (FAST). We detect a scintillation arc in the FRB's secondary spectrum, which describes the power in terms of the scattered FRB signals' time delay and Doppler shift. The arc indicates that the scintillation is caused by a highly localized region of the ionized interstellar medium (IISM). Our analysis favors a Milky Way origin for the localized scattering medium but cannot rule out a host galaxy origin. We present our method for detecting the scintillation arc, which can be applied generally to sources with irregularly spaced bursts or pulses. These methods could help shed light on the complex interstellar environment surrounding the FRBs and in our Galaxy.Comment: SCIENCE CHINA Physics, Mechanics & Astronomy , Volume 67, Issue 1: 219512 (2024

    LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) The survey science plan

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    We describe the current plans for a spectroscopic survey of millions of stars in the Milky Way galaxy using the Guo Shou Jing Telescope (GSJT, formerly the Large Area Multi-Object Spectroscopic Telescope - LAMOST). The survey will obtain spectra for 2.5 million stars brighter than r<19r<19 during dark/grey time, and 5 million stars brighter than r<17r<17 or J<16J<16 on nights that are moonlit or have low transparency. The survey will begin in fall of 2012, and will run for at least four years. The telescope design constrains the optimal declination range for observations to 10<δ<5010^\circ<\delta<50^\circ, and site conditions lead to an emphasis on stars in the direction of the Galactic anticenter. The survey is divided into three parts with different target selection strategies: disk, anticenter, and spheroid. The resulting dataset will be used to study the merger history of the Milky Way, the substructure and evolution of the disks, the nature of the first generation of stars through identification of the lowest metallicity stars, and star formation through study of open clusters and the OB associations. Detailed design of the LEGUE survey will be completed after a review of the results of the pilot survey in summer 2012.Comment: 19 pages, 1 figure, accepted for publication in RA

    FAST observations of an extremely active episode of FRB 20201124A: IV. Spin Period Search

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    We report the properties of more than 800 bursts detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio telescope (FAST) during an extremely active episode on UTC September 25th-28th, 2021 in a series of four papers. In this fourth paper of the series, we present a systematic search of the spin period and linear acceleration of the source object from both 996 individual pulse peaks and the dedispersed time series. No credible spin period was found from this data set. We rule out the presence of significant periodicity in the range between 1 ms to 100 s with a pulse duty cycle <0.49±0.08< 0.49\pm0.08 (when the profile is defined by a von-Mises function, not a boxcar function) and linear acceleration up to 300300 m s2^{-2} in each of the four one-hour observing sessions, and up to 0.60.6 m s2^{-2} in all 4 days. These searches contest theoretical scenarios involving a 1 ms to 100 s isolated magnetar/pulsar with surface magnetic field <1015<10^{15} G and a small duty cycle (such as in a polar-cap emission mode) or a pulsar with a companion star or black hole up to 100 M_{\rm \odot} and Pb>10P_b>10 hours. We also perform a periodicity search of the fine structures and identify 53 unrelated millisecond-timescale "periods" in multi-components with the highest significance of 3.9 σ\sigma. The "periods" recovered from the fine structures are neither consistent nor harmonically related. Thus they are not likely to come from a spin period. We caution against claiming spin periodicity with significance below \sim 4 σ\sigma with multi-components from one-off FRBs. We discuss the implications of our results and the possible connections between FRB multi-components and pulsar micro-structures.Comment: Accepted by Research in Astronomy and Astrophysics (RAA

    FAST observations of an extremely active episode of FRB 20201124A: III. Polarimetry

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    As the third paper in the multiple-part series, we report the statistical properties of radio bursts detected from the repeating fast radio burst (FRB) source FRB 20201124A with the Five-hundred-meter Aperture Spherical radio telescope (FAST) during an extremely active episode between the 25th and the 28th of September 2021 (UT). We focus on the polarisation properties of 536 bright bursts with S/N>50\mathrm{S/N}>50. We found that the Faraday rotation measures (RMs) monotonically dropped from 579 rad m2-579 \ {\rm rad \ m^{-2}} to 605 rad m2-605 \ {\rm rad \ m^{-2}} in the 4-day window. The RM values were compatible with the values (300-300 to 900 rad m2-900\ {\rm rad \ m^{-2}} ) reported 4 month ago (Xu et al. 2022). However, the RM evolution rate in the current observation window was at least an order of magnitude smaller than the one ($\sim 500\ {\rm rad \ m^{-2}\, day^{-1}})previouslyreportedduringtherapidRMvariationphase,butisstillhigherthantheone() previously reported during the rapid RM-variation phase, but is still higher than the one (\le 1\ {\rm rad \ m^{-2} day^{-1}})duringthelaterRMnoevolutionphase.TheburstsofFRB20201124Awerehighlypolarisedwiththetotaldegreeofpolarisation(circularpluslinear)greaterthan90polarisationpositionangles(PAs),degreeoflinearpolarisation( ) during the later RM no-evolution phase. The bursts of FRB 20201124A were highly polarised with the total degree of polarisation (circular plus linear) greater than 90% for more than 90\% of all bursts. The distribution of linear polarisation position angles (PAs), degree of linear polarisation (L/I),anddegreeofcircularpolarisation(), and degree of circular polarisation (V/I)canbecharacterisedwithunimodaldistributionfunctions.Duringtheobservationwindow,thedistributionsbecamewiderwithtime,i.e.withlargerscatter,butthecentroidsofthedistributionfunctionsremainednearlyconstant.Forindividualbursts,significantPAvariations(confidencelevel5) can be characterised with unimodal distribution functions. During the observation window, the distributions became wider with time, i.e. with larger scatter, but the centroids of the distribution functions remained nearly constant. For individual bursts, significant PA variations (confidence level 5-\sigma$) were observed in 33% of all bursts. The polarisation of single pulses seems to follow certain complex trajectories on the Poincar\'e sphere, which may shed light on the radiation mechanism at the source or the plasma properties along the path of FRB propagation.Comment: 25 pages, 16 figures. Accepted by Research in Astronomy and Astrophysics (RAA
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