On The Orbital Evolution of Jupiter Mass Protoplanet Embedded in A Self-Gravity Disk

We performed a series of hydro-dynamic simulations to investigate the orbital migration of a Jovian planet embedded in a proto-stellar disk. In order to take into account of the effect of the disk's self gravity, we developed and adopted an \textbf{Antares} code which is based on a 2-D Godunov scheme to obtain the exact Reimann solution for isothermal or polytropic gas, with non-reflecting boundary conditions. Our simulations indicate that in the study of the runaway (type III) migration, it is important to carry out a fully self consistent treatment of the gravitational interaction between the disk and the embedded planet. Through a series of convergence tests, we show that adequate numerical resolution, especially within the planet's Roche lobe, critically determines the outcome of the simulations. We consider a variety of initial conditions and show that isolated, non eccentric protoplanet planets do not undergo type III migration. We attribute the difference between our and previous simulations to the contribution of a self consistent representation of the disk's self gravity. Nevertheless, type III migration cannot be completely suppressed and its onset requires finite amplitude perturbations such as that induced by planet-planet interaction. We determine the radial extent of type III migration as a function of the disk's self gravity.Comment: 19 pages, 13 figure

Chemical constituents and acetylcholinesterase inhibitory activity of Piper abbreviatum Opiz

Plants of the genus Piper have long been used as medicinal herbs. The chemistry of Piper species has been widely investigated and phytochemical investigations conducted in all parts of the world have led to the isolation of a number of physiologically active compounds. Thus, this study was carried out to investigate the phytochemicals from Piper abbreviatum and their acetylcholinesterase inhibitory activity, which has not been previously investigated. Fractionation and purification of the aerial parts of P. abbreviatum led to the isolation and identification of five methoxylated flavonoids, namely 5,7-dimethoxyflavone, 4ʹ,5,7-trimethoxyflavone, 3',4',5,7-tetramethoxyflavone, 5-hydroxy-7-methoxyflavone, 5-hydroxy-4ʹ,7-dimethoxyflavone, together with lupeol, lupenone, β-sitosterol, and β-sitostenone. The structures of these compounds were obtained by analysis of their spectroscopic data, as well as the comparison with that of reported data. Acetylcholinesterase inhibitory activity revealed that all isolated flavones were found to inhibit AChE with percentage inhibition values ranged from 24.2 to 58.2%. This is the first report on the isolation of methoxylated flavonoid from P. abbreviatum. The high variants of flavonoid compounds from this species may be used as chemotaxonomic markers for this Piper species.                     KEY WORDS: Piperaceae, Piper, Piper abbreviatum, Flavonoid, Acetylcholinesterase   Bull. Chem. Soc. Ethiop. 2020, 34(3), 625-632. DOI: https://dx.doi.org/10.4314/bcse.v34i3.1

Second Cluster Integral and Excluded Volume Effects for the Pion Gas

The quantum mechanical formula for Mayer's second cluster integral for the gas of relativistic particles with hard-core interaction is derived. The proper pion volume calculated with quantum mechanical formula is found to be an order of magnitude larger than its classical evaluation. The second cluster integral for the pion gas is calculated in quantum mechanical approach with account for both attractive and hard-core repulsive interactions. It is shown that, in the second cluster approximation, the repulsive pion-pion-interactions as well as the finite width of resonances give important but almost canceling contributions. In contrast, an appreciable deviation from the ideal gas of pions and pion resonances is observed beyond the second cluster approximation in the framework of the Van der Waals excluded-volume model.Comment: 29 pages, Latex, 9 PS-figure

Topology Design of Extended Torus and Ring for Low Latency Network-on-Chip Architecture

In essence, Network-on-Chip (NoC) also known as on-chip interconnection network has been proposed as a design solution to System-on-Chip (SoC). The routing algorithm, topology and switching technique are significant because of the most influential effect on the overall performance of Network-on-Chip (NoC). Designing of large scale topology alongside the support of deadlock free, low latency, high throughput and low power consumption is notably challenging in particular with expanding network size. This paper proposed an 8x8 XX-Torus and 64 nodes XX-Ring topology schemes for Network-on-Chip to minimize the latency by decrease the node diameter from the source node to destination node. Correspondingly, we compare in differences on the performance of mesh, full-mesh, torus and ring topologies with XX-Torus and XX-Ring topologies in term of latency. Results show that XX-Ring outperforms the conventional topologies in term of latency. XX-Ring decreases the average latency by 106.28%, 14.80%, 6.7 1%, 1.73%, 442.24% over the mesh, fully-mesh, torus, XX-torus, and Ring topologies

PAPPA: Primordial Anisotropy Polarization Pathfinder Array

The Primordial Anisotropy Polarization Pathfinder Array (PAPPA) is a balloon-based instrument to measure the polarization of the cosmic microwave background and search for the signal from gravity waves excited during an inflationary epoch in the early universe. PAPPA will survey a 20 x 20 deg patch at the North Celestial Pole using 32 pixels in 3 passbands centered at 89, 212, and 302 GHz. Each pixel uses MEMS switches in a superconducting microstrip transmission line to combine the phase modulation techniques used in radio astronomy with the sensitivity of transition-edge superconducting bolometers. Each switched circuit modulates the incident polarization on a single detector, allowing nearly instantaneous characterization of the Stokes I, Q, and U parameters. We describe the instrument design and status.Comment: 12 pages, 9 figures. Proceedings of the Fundamental Physics With CMB workshop, UC Irvine, March 23-25, 2006, to be published in New Astronomy Review

Undetermined states: how to find them and their applications

We investigate the undetermined sets consisting of two-level, multi-partite pure quantum states, whose reduced density matrices give absolutely no information of their original states. Two approached of finding these quantum states are proposed. One is to establish the relation between codewords of the stabilizer quantum error correction codes (SQECCs) and the undetermined states. The other is to study the local complementation rules of the graph states. As an application, the undetermined states can be exploited in the quantum secret sharing scheme. The security is guaranteed by their undetermineness.Comment: 6 pages, no figur

The Harmonic Measure for critical Potts clusters

We present a technique, which we call "etching," which we use to study the harmonic measure of Fortuin-Kasteleyn clusters in the Q-state Potts model for Q=1-4. The harmonic measure is the probability distribution of random walkers diffusing onto the perimeter of a cluster. We use etching to study regions of clusters which are extremely unlikely to be hit by random walkers, having hitting probabilities down to 10^(-4600). We find good agreement between the theoretical predictions of Duplantier and our numerical results for the generalized dimension D(q), including regions of small and negative q.Comment: 20 pages, 10 figure

Phase coherent VLBI using a satellite link

The results from experiments using the Hermes (formerly CTS) communications satellite to provide a local oscillator and data link between two antennas are presented. The techniques used to compensate for the satellite motion and translation oscillator are described. Plans for a series of three station experiments to measure UT and polar motion using the ANIK-B satellite to synchronize the local oscillators are discussed

Magnetoelectric Effect and Spontaneous Polarization in HoFe3_3(BO3_3)4_4 and Ho0.5_{0.5}Nd0.5_{0.5}Fe3_3(BO3_3)4_4

The thermodynamic, magnetic, dielectric, and magnetoelectric properties of HoFe$_3$(BO$_3$)$_4$ and Ho$_{0.5}$Nd$_{0.5}$Fe$_3$(BO$_3$)$_4$ are investigated. Both compounds show a second order Ne\'{e}l transition above 30 K and a first order spin reorientation transition below 10 K. HoFe$_3$(BO$_3$)$_4$ develops a spontaneous electrical polarization below the Ne\'{e}l temperature (T$_N$) which is diminished in external magnetic fields. No magnetoelectric effect could be observed in HoFe$_3$(BO$_3$)$_4$. In contrast, the solid solution Ho$_{0.5}$Nd$_{0.5}$Fe$_3$(BO$_3$)$_4$ exhibits both, a spontaneous polarization below T$_N$ and a magnetoelectric effect at higher fields that extends to high temperatures. The superposition of spontaneous polarization, induced by the internal magnetic field in the ordered state, and the magnetoelectric polarizations due to the external field results in a complex behavior of the total polarization measured as a function of temperature and field.Comment: 12 pages, 15 figure