Construction of the generalized Cech complex

In this paper, we introduce an algorithm which constructs the generalized Cech complex. The generalized Cech complex represents the topology of a wireless network whose cells are different in size. This complex is often used in many application to locate the boundary holes or to save energy consumption in wireless networks. The complexity of a construction of the Cech complex to analyze the coverage structure is found to be a polynomial time

Surplus Angle and Sign-flipped Coulomb Force in Projectable Horava-Lifshitz Gravity

We obtain the static spherically symmetric vacuum solutions of Horava-Lifshitz gravity theory, imposing the detailed balance condition only in the UV limit. We find the solutions in two different coordinate systems, the Painlev\'e-Gullstrand coordinates and the Poincare coordinates, to examine the consequences of imposing the projectability condition. The solutions in two coordinate systems are distinct due to the non-relativistic nature of the HL gravity. In the Painleve-Gullstrand coordinates complying with the projectability condition, the solution involves an additional integration constant which yields surplus angle and implies attractive Coulomb force between same charges.Comment: 13 page

Towards energy resolution at the statistical limit from a negative ion time projection chamber

We make a proof-of-principle demonstration that improved energy resolution can be obtained in a negative-ion time projection chamber, by individually counting each electron produced by ionizing radiation.Comment: Submitted to Nucl. Instr. Meth.

Magnetic effects on the low-T/|W| instability in differentially rotating neutron stars

Dynamical instabilities in protoneutron stars may produce gravitational waves whose observation could shed light on the physics of core-collapse supernovae. When born with sufficient differential rotation, these stars are susceptible to a shear instability (the "low-T/|W| instability"), but such rotation can also amplify magnetic fields to strengths where they have a considerable impact on the dynamics of the stellar matter. Using a new magnetohydrodynamics module for the Spectral Einstein Code, we have simulated a differentially-rotating neutron star in full 3D to study the effects of magnetic fields on this instability. Though strong toroidal fields were predicted to suppress the low-T/|W| instability, we find that they do so only in a small range of field strengths. Below 4e13 G, poloidal seed fields do not wind up fast enough to have an effect before the instability saturates, while above 5e14 G, magnetic instabilities can actually amplify a global quadrupole mode (this threshold may be even lower in reality, as small-scale magnetic instabilities remain difficult to resolve numerically). Thus, the prospects for observing gravitational waves from such systems are not in fact diminished over most of the magnetic parameter space. Additionally, we report that the detailed development of the low-T/|W| instability, including its growth rate, depends strongly on the particular numerical methods used. The high-order methods we employ suggest that growth might be considerably slower than found in some previous simulations.Comment: REVTeX 4.1, 21 pages, 18 figures, submitting to Physical Review

Enhancing Received Signal Strength-Based Localization through Coverage Hole Detection and Recovery

In wireless sensor networks (WSNs), Radio Signal Strength Indicator (RSSI)-based localization techniques have been widely used in various applications, such as intrusion detection, battlefield surveillance, and animal monitoring. One fundamental performance measure in those applications is the sensing coverage of WSNs. Insufficient coverage will significantly reduce the effectiveness of the applications. However, most existing studies on coverage assume that the sensing range of a sensor node is a disk, and the disk coverage model is too simplistic for many localization techniques. Moreover, there are some localization techniques of WSNs whose coverage model is non-disk, such as RSSI-based localization techniques. In this paper, we focus on detecting and recovering coverage holes of WSNs to enhance RSSI-based localization techniques whose coverage model is an ellipse. We propose an algorithm inspired by Voronoi tessellation and Delaunay triangulation to detect and recover coverage holes. Simulation results show that our algorithm can recover all holes and can reach any set coverage rate, up to 100% coverage

A One-Hole Cu\u3csub\u3e4\u3c/sub\u3eS Cluster with N\u3csub\u3e2\u3c/sub\u3eO Reductase Activity: A Structural and Functional Model for Cu\u3csub\u3eZ\u3c/sub\u3e

During bacterial denitrification, two-electron reduction of N2O occurs at a [Cu4(μ4-S)] catalytic site (CuZ*) embedded within the nitrous oxide reductase (N2OR) enzyme. In this Communication, an amidinate-supported [Cu4(μ4-S)] model cluster in its one-hole (S = 1/2) redox state is thoroughly characterized. Along with its two-hole redox partner and fully reduced clusters reported previously, the new species completes the two-electron redox series of [Cu4(μ4-S)] model complexes with catalytically relevant oxidation states for the first time. More importantly, N2O is reduced by the one-hole cluster to produce N2 and the two-hole cluster, thereby completing a closed cycle for N2O reduction. Not only is the title complex thus the best structural model for CuZ* to date, but it also serves as a functional CuZ* mimic