Low-temperature behavior of two-dimensional Gaussian Ising spin glasses

We perform Monte Carlo simulations of large two-dimensional Gaussian Ising spin glasses down to very low temperatures $\beta=1/T=50$. Equilibration is ensured by using a cluster algorithm including Monte Carlo moves consisting of flipping fundamental excitations. We study the thermodynamic behavior using the Binder cumulant, the spin-glass susceptibility, the distribution of overlaps, the overlap with the ground state and the specific heat. We confirm that $T_c=0$. All results are compatible with an algebraic divergence of the correlation length with an exponent $\nu$. We find $-1/\nu=-0.295(30)$, which is compatible with the value for the domain-wall and droplet exponent $\theta\approx-0.29$ found previously in ground-state studies. Hence the thermodynamic behavior of this model seems to be governed by one single exponent.Comment: 7 pages, 11 figure

Nodular Sarcoidosis Masquerading as Cancer.

Nodular lung disease is a rare pulmonary manifestation of sarcoidosis and resembles metastatic neoplasm disease. Nodular sarcoidosis is rare, varying from 1.6% to 4% of patients with sarcoidosis. Radiographic nodules measure from 1 to 5 cm in diameter that typically consist of coalescent granulomas. There is limited data on this form of sarcoidosis and its presentation can mimic primary or metastatic pulmonary neoplasms. Nodular sarcoidosis has a favorable prognosis, and resolution can be seen with oral corticosteroids. Herein, we present such a case of nodular pulmonary sarcoidosis with a lung nodule measured up to 6 cm

Positive effective Q12 electrostrictive coefficient in perovskites

It is demonstrated that for classical perovskites such as BaTiO3, SrTiO3 and PbTiO3 electrostrictive strain induced by an electric field may not obey traditionally considered "extension along the field, contraction perpendicular to it" behavior if a sample is cut obliquely to the cubic crystallographic directions

Voyager observations of Jovian millisecond radio bursts

Voyager Planetary Radio Astronomy data collected over 30-day intervals centered on the two close encounters with Jupiter were utilized to study the characteristics of millisecond-duration radio bursts (s-bursts) at frequencies between 5 and 15 MHz. In this frequency range, s-bursts are found to occur almost independently of Central Meridian Longitude and to depend entirely on the phase of Io with respect to the observer's planetocentric line of sight. Individual bursts typically cover a total frequency range of about 1.5 to 3 MHz, and they are usually strongly circularly polarized. Most bursts in a particular s-burst storm will exhibit the same polarization sense (either right-hand or left-hand), and there is some evidence for a systematic pattern in which one polarizations sense is preferred over the other as a function of Io phase and Central Meridian Longitude. These data are all suggestive of a radio source that is located along the instantaneous Io flux tube and that extends over a linear dimension of 5000 km along the field lines in both the northern and southern Hemispheres

Results of long-term synoptic monitoring of Jupiter's decametric radiation

Results of the analysis of the large, homogeneous set of measurements of Jupiter's emission at 16.7 and 22.2 MHz for the apparitions during the period 1966-1974 were presented. An update of the radio rotation period determination which includes provision for beaming effects due to variations in the Jovicentric declination of the earth was presented. Some estimates of the magnitude of possible long-term variations in the rotation period were also discussed. The data clearly shows the Io-independent emission features associated with the System III central meridian longitudes of all three major Io-related source regions. There is also some evidence for heretofore unrecognized Io-related emission features which are apparently independent of the central meridian longitude. The possibility of three kinds of emission are suggested: (1) Io-stimulated, sharply beamed emission, (2) Io-independent, sharply beamed emission, and (3) Io-stimulated, broadly beamed emission

Quiver Gauge Theory of Nonabelian Vortices and Noncommutative Instantons in Higher Dimensions

We construct explicit BPS and non-BPS solutions of the Yang-Mills equations on the noncommutative space R^{2n}_\theta x S^2 which have manifest spherical symmetry. Using SU(2)-equivariant dimensional reduction techniques, we show that the solutions imply an equivalence between instantons on R^{2n}_\theta x S^2 and nonabelian vortices on R^{2n}_\theta, which can be interpreted as a blowing-up of a chain of D0-branes on R^{2n}_\theta into a chain of spherical D2-branes on R^{2n} x S^2. The low-energy dynamics of these configurations is described by a quiver gauge theory which can be formulated in terms of new geometrical objects generalizing superconnections. This formalism enables the explicit assignment of D0-brane charges in equivariant K-theory to the instanton solutions.Comment: 45 pages, 4 figures; v2: minor correction

Scalable quantum computation with fast gates in two-dimensional microtrap arrays of trapped ions

We theoretically investigate the use of fast pulsed two-qubit gates for trapped ion quantum computing in a two-dimensional microtrap architecture. In one dimension, such fast gates are optimal when employed between nearest neighbours, and we examine the generalisation to a two-dimensional geometry. We demonstrate that fast pulsed gates are capable of implementing high-fidelity entangling operations between ions in neighbouring traps faster than the trapping period, with experimentally demonstrated laser repetition rates. Notably, we find that without increasing the gate duration, high-fidelity gates are achievable even in large arrays with hundreds of ions. To demonstrate the usefulness of this proposal, we investigate the application of these gates to the digital simulation of a 40-mode Fermi-Hubbard model. This also demonstrates why shorter chains of gates required to connect arbitrary pairs of ions makes this geometry well suited for large-scale computation

Relationship between auroral substorms and the occurrence of terrestrial kilometric radiation

The correlation between magnetospheric substorms as inferred from the AE(11) index and the occurrence of terrestrial kilometric radiation (TKR) is examined. It is found that AE and TKR are well correlated when observations are made from above the 15-03 hr local time zone and are rather poorly correlated over the 03-15 hr zone. High-resolution dynamic spectra obtained during periods of isolated substorms indicate that low-intensity, high-frequency TKR commences at about the same time as the substorm phase. The substorm expansion phase corresponds to a rapid intensification and bandwidth increase of TKR. When combined with previous results, these new observations imply that many TKR events begin at low altitudes and high frequencies (about 400-500 kHz) and spread to higher altitudes and lower frequencies as the substorm expands

Terrestrial kilometric radiation: 3-average spectral properties

A study is presented of the average spectral properties of terrestrial kilometric radiation (TKR) derived from observations made by radio astronomy experiments onboard the IMP-6 and RAE-2 spacecraft. As viewed from near the equatorial plane, TKR is most intense and most often observed in the 21-24 hr local time zone and is rarely seen in the 09-12 hr zone. The peak flux density usually occurs near 240 kHz, but there is evidence that the peak occurs at a somewhat lower frequency on the dayside. The frequency of the peak in the average flux spectrum varies inversely with increasing substorm activity as inferred from the auroral electrojet index (AE) from a maximum near 300 kHz during very quiet times to a minimum below 200 kHz during very disturbed times. The absolute flux levels in the 100-600 kHz TKR band increase significantly with increasing AE. The average power associated with a particular source region seems to decrease rapidly with increasing source altitude