Performance Analysis of Dense Small Cell Networks with Practical Antenna Heights under Rician Fading

In this paper, we examine the combined impacts of distance-dependent Rician fading channel model and the absolute difference between the heights of base station (BS) and user equipment (UE) antennas on the coverage probability and the area spectral efficiency in an interference-limited ultra-dense (UD) small cell network (SCN). Exploiting distance dependent models for both path loss and multi-path fading, we show that in interference-limited UD-SCNs, Rician fading with variant Rician K factor aggravates the performance loss caused by the difference between the heights of the BS and UE antennas in comparison to Rayleigh fading. In particular, we demonstrate that due to presence of the specular LOS component in the Rician fading, both the coverage probability and the area spectral efficiency experience a more steep decline towards zero as the BS density increases. Our performance analysis has a prominent impact on the deployment of UD-SCNs in the 5th-generation of mobile networks, as it indicates that the right modelling of multi-path fading makes a significant difference when assessing the performance of UD-SCNs with non-identical UE-BS antenna heights

Exact solutions of noncommutative vacuum Einstein field equations and plane-fronted gravitational waves

We construct a class of exact solutions of the noncommutative vacuum Einstein field equations, which are noncommutative analogues of the plane-fronted gravitational waves in classical gravity.Comment: 10 pages, comments adde

cDNA Cloning of Biologically Active Chicken Interleukin-18

By searching a chicken EST database, we identified a cDNA clone that appeared to contain the entire open reading frame (ORF) of chicken interleukin-18 (ChIL-18). The encoded protein consists of 198 amino acids and exhibits approximately 30% sequence identity to IL-18 of humans and various others mammals. Sequence comparisons reveals a putative caspase-1 cleavage site at aspartic acid 29 of the primary translation product, indicating that mature ChIL-18 might consist of 169 amino acids. Bacterially expressed ChIL-18 in which the N-terminal 29 amino acids of the putative precursor molecule were replaced by a histidine tag induced the synthesis of interferon-γ (IFN-γ) in cultured primary chicken spleen cells, indicating that the recombinant protein is biologically active

The Influence of Solar Flares on the Lower Solar Atmosphere: Evidence from the Na D Absorption Line Measured by GOLF/SOHO

Solar flares presumably have an impact on the deepest layers of the solar atmosphere and yet the observational evidence for such an impact is scarce. Using ten years of measurements of the Na D$_{1}$ and Na D$_2$ Fraunhofer lines, measured by GOLF onboard SOHO, we show that this photospheric line is indeed affected by flares. The effect of individual flares is hidden by solar oscillations, but a statistical analysis based on conditional averaging reveals a clear signature. Although GOLF can only probe one single wavelength at a time, we show that both wings of the Na line can nevertheless be compared. The varying line asymmetry can be interpreted as an upward plasma motion from the lower solar atmosphere during the peak of the flare, followed by a downward motion.Comment: 13 pages, 7 figure

Suppression of static stripe formation by next-neighbor hopping

We show from real-space Hartree-Fock calculations within the extended Hubbard model that next-nearest neighbor (t') hopping processes act to suppress the formation of static charge stripes. This result is confirmed by investigating the evolution of charge-inhomogeneous corral and stripe phases with increasing t' of both signs. We propose that large t' values in YBCO prevent static stripe formation, while anomalously small t' in LSCO provides an additional reason for the appearance of static stripes only in these systems.Comment: 4 pages, 5 figure

Upper critical field for underdoped high-T_c superconductors. Pseudogap and stripe--phase

We investigate the upper critical field in a stripe--phase and in the presence of a phenomenological pseudogap. Our results indicate that the formation of stripes affects the Landau orbits and results in an enhancement of $H_{c2}$. On the other hand, phenomenologically introduced pseudogap leads to a reduction of the upper critical field. This effect is of particular importance when the magnitude of the gap is of the order of the superconducting transition temperature. We have found that a suppression of the upper critical field takes place also for the gap that originates from the charge--density waves.Comment: 7 pages, 5 figure

Gravitational collapse of spherically symmetric stars in noncommutative general relativity

Gravitational collapse of a class of spherically symmetric stars is investigated. We quantise the geometries describing the gravitational collapse by a deformation quantisation procedure. This gives rise to oncommutative spacetimes with gravitational collapse

Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature and density sensitive line ratios, Doppler shifted emission lines and nonthermal broadening, abundance measurements, differential emission measure profiles, and continuum temperatures and energetics, among others. In this paper I shall review some of the advances made in recent years using these techniques, focusing primarily on studies that have utilized data from Hinode/EIS and SDO/EVE, while also providing some historical background and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the Topical Issue on Solar and Stellar Flare