Anisotropic Transport of Quantum Hall Meron-Pair Excitations

Double-layer quantum Hall systems at total filling factor $\nu_T=1$ can exhibit a commensurate-incommensurate phase transition driven by a magnetic field $B_{\parallel}$ oriented parallel to the layers. Within the commensurate phase, the lowest charge excitations are believed to be linearly-confined Meron pairs, which are energetically favored to align with $B_{\parallel}$. In order to investigate this interesting object, we propose a gated double-layer Hall bar experiment in which $B_{\parallel}$ can be rotated with respect to the direction of a constriction. We demonstrate the strong angle-dependent transport due to the anisotropic nature of linearly-confined Meron pairs and discuss how it would be manifested in experiment.Comment: 4 pages, RevTex, 3 postscript figure

Back Extensor Strengthening Exercise and Backpack Wearing Treatment for Camptocormia in Parkinson's Disease: A Retrospective Pilot Study

Objective To investigate the effect of a conservative treatment regime in Parkinson's disease patients with camptocormia. Methods Nine patients with Parkinson's disease were included in a retrospective pilot study of the value of back extensor strengthening exercise. Six inpatients received a 30-minute treatment, twice daily for 5 weeks, being treated on average for 34 days; while three outpatients visited the clinic and were educated for home exercise and backpack wearing treatment. Outpatients should be scheduled to visit the outpatient department to check physical status every 2–4 weeks for an average of 3 months. Results All patients except one showed statistically significant improvements in activities of daily living (ADL) and motor symptoms, as measured by flexion angle at standing posture, Unified Parkinson's Disease Rating Scale (UPDRS) II and III, and modified Hoehn-Yahr staging. Conclusion Conservative treatment is effective in postural correction of camptocormia in Parkinson's disease, as well as improvement in ADL and motor symptoms

The Correlation Between Electrodiagnostic Results and Ultrasonographic Findings in the Severity of Carpal Tunnel Syndrome in Females

Objective: To determine which ultrasonographic measurement can be used as an indicator reflecting the severity of carpal tunnel syndrome (CTS), by comparing electrodiagnostic results with ultrasonographic measurements in females. Many previous studies have tried to reveal that the ultrasonography (US) can possibility be used for diagnosis and severity of CTS. However, the criteria are different by gender. Thus far, there have been many efforts towards providing patients with a CTS diagnosis and severity prediction using US, but studies’ results are still unclear due to lack of data on gender differences. Methods: We collected data from 54 female patients. We classified the severity of CTS according to electrodiagnostic results. Ultrasonographic measurements included proximal and distal cross-sectional areas of the median nerve and carpal tunnel. Results: The severity by electrodiagnostic results statistically correlated to the proximal cross-sectional area (CSA) of the median nerve and carpal tunnel. However, there was no relationship between the proximal and distal nerve/tunnel indexes and the severity by electrodiagnostic results. Conclusion: In female patients with CTS, the proximal CSAs of the median nerve and carpal tunnel increase. They correlate with the severity by electrodiagnostic findings. The CSA of the proximal median nerve could be particularly used as a predictor of the severity of CTS in female patients. However, the nerve/tunnel index is constant, irrespective of the severity of CTS

Simulation Study on Miscibility Effect of CO 2

The minimum miscibility pressure (MMP) determines the main mechanism of CO2 flooding, which is either an immiscible or miscible process. This paper examines the recovery improvements of CO2 flooding in terms of both the injection temperature and solvent composition. The results show that a lower temperature injection and LPG (liquefied petroleum gas) mixture can considerably improve oil recovery due to the reduced MMP in the swept area caused by the injected solvent. For the pure CO2 injection at the reservoir temperature, oil recovery is 59% after 1.0 PV CO2 injection. The oil recoveries by CO2-LPG mixtures are improved to 73% with 0.1 mole fractions of LPG and 81% with 0.2 mole fractions of LPG. The recovery factor from low-temperature CO2 injection is 78%, which is 32% higher compared to the isothermal case. The recoveries obtained by low-temperature CO2-LPG injection increase up to 87% of the initial oil. Heat transfer between the reservoir and the formation of over/underburden should be considered in order to describe the process more accurately. Additionally, the recovery factors from the heat transfer models are decreased by 4–12% in comparison with the original nonisothermal models

Many skyrmion wave functions and skyrmion statistics in quantum Hall ferromagnets

We determine the charge and statistical angle of skyrmions in quantum Hall ferromagnets by performing Berry phase calculations based on the microscopic variational wave functions for many-skyrmion states. We find, in contradiction to a recent claim by Dziarmaga, that both the charge and the statistical angle of a skyrmion are independent of its spin (size), and are identical to those of Laughlin quasiparticles at the same filling factor. We discuss some subtleties in the use of these variational wave functions.Comment: 11 pages, RevTex, no figure. Accepted in Phys. Rev. B, Rapid Communication

Discovery of "isolated" comoving T Tauri stars in Cepheus

During the course of a large spectroscopic survey of X-ray active late-type stars in the solar neighbourhood, we discovered four lithium-rich stars packed within just a few degrees on the sky. These very young stars are projected several degrees away from the Cepheus-Cassiopea clouds, in front of an area void of interstellar matter. As such, they are very good "isolated" T Tauri star candidates. We acquired high-resolution optical spectra as well as photometric data allowing us to investigate in detail their nature and physical parameters with the aim of testing the "runaway" and "in-situ" formation scenarios. We derive accurate radial and rotational velocities and perform an automatic spectral classification. The spectral subtraction technique is used to infer chromospheric activity level in the H-alpha line core and clean the spectra of photospheric lines before measuring the equivalent width of the lithium absorption line. Both physical (lithium content, magnetic activity) and kinematical indicators show that all stars are very young (ages in the range 10-30 Myr). In particular, the spectral energy distribution of TYC4496-780-1 displays a strong near- and far-infrared excess, typical of T Tauri stars still surrounded by an accretion disc. They also share the same Galactic motion, proving that they form a homogeneous moving group of stars with the same origin. The most plausible explanation of how these "isolated" T Tauri stars formed is the "in-situ" model, although accurate distances are needed to clarify their connection with the Cepheus-Cassiopeia complex

Spin mapping, phase diagram, and collective modes in double layer quantum Hall systems at ν=2\nu=2

An exact spin mapping is identified to simplify the recently proposed hard-core boson description (Demler and Das Sarma, Phys. Rev. Lett., to be published) of the bilayer quantum Hall system at filling factor 2. The effective spin model describes an easy-plane ferromagnet subject to an external Zeeman field. The phase diagram of this effective model is determined exactly and found to agree with the approximate calculation of Demler and Das Sarma, while the Goldstone-mode spectrum, order parameter stiffness and Kosterlitz-Thouless temperature in the canted antiferromagnetic phase are computed approximately.Comment: 4 pages with 2 figures include

Persistent Currents and Dissipation in Narrow Bilayer Quantum Hall Bars

Bilayer quantum Hall states support a flow of nearly dissipationless staggered current which can only decay through collective channels. We study the dominant finite-temperature dissipation mechanism which in narrow bars is driven by thermal nucleation of pseudospin solitons. We find the finite-temperature resistivity, predict the resulting staggered current-voltage characteristics, and calculate the associated zero-temperature critical staggered current and gate voltage.Comment: 4 pgs. REVTeX, 3 eps figure