Algorithms for Rapidly Dispersing Robot Swarms in Unknown Environments

We develop and analyze algorithms for dispersing a swarm of primitive robots in an unknown environment, R. The primary objective is to minimize the makespan, that is, the time to fill the entire region. An environment is composed of pixels that form a connected subset of the integer grid. There is at most one robot per pixel and robots move horizontally or vertically at unit speed. Robots enter R by means of k>=1 door pixels Robots are primitive finite automata, only having local communication, local sensors, and a constant-sized memory. We first give algorithms for the single-door case (i.e., k=1), analyzing the algorithms both theoretically and experimentally. We prove that our algorithms have optimal makespan 2A-1, where A is the area of R. We next give an algorithm for the multi-door case (k>1), based on a wall-following version of the leader-follower strategy. We prove that our strategy is O(log(k+1))-competitive, and that this bound is tight for our strategy and other related strategies.Comment: 17 pages, 4 figures, Latex, to appear in Workshop on Algorithmic Foundations of Robotics, 200

Transport properties in Simplified Double Exchange model

Transport properties of the manganites by the double-exchange mechanism are considered. The system is modeled by a simplified double-exchange model, i.e. the Hund coupling of the itinerant electron spins and local spins is simplified to the Ising-type one. The transport properties such as the electronic resistivity, the thermal conductivity, and the thermal power are calculated by using Dynamical mean-field theory. The transport quantities obtained qualitatively reproduce the ones observed in the manganites. The results suggest that the Simplified double exchange model underlies the key properties of the manganites.Comment: 5 pages, 5 eps figure

Experimental Determination of Elastic Anisotropy of Berea Sandstone, Chicopee Shale and Chelmsford Granite

We use the ultrasonic transmission method to measure P-, SH-, and SV-wave velocities for Chelmsford Granite, Chicopee Shale, and Berea Sandstone in different directions up to 1000 bars confining pressure. The velocity measurements indicate that these three rocks are elastically anisotropic. The stiffness constants, dynamic Young's moduli, dynamic Poisson's ratios, and dynamic bulk moduli of these three rocks were also calculated. These elastic constants, together with velocity measurements, suggest that: (1) Elastic anisotropy is due to the combined effects of pores/cracks and mineral grain orientation. (2) Elastic anisotropy decreases with increasing confining pressure. The residual anisotropy at higher confining pressure is due to mineral grain orientation

Eksperimentasi Model Pembelajaran Kooperatif Tipe Numbered Heads Together Dan Pairs Check Dengan Pendekatan Saintifik Pada Materi Fungsi Ditinjau Dari Adversity Quotient Siswa Kelas VIII SMP Negeri Se-kabupaten Sukoharjo Tahun Pelajaran 2014/2015

The purpose of this study was to determine the effect of learning models on the knowledge and skill aspect viewed from adversity quotient (AQ). The learning models compared were learning model of the Numbered Heads Together (NHT) with scientific approach, Pairs Check (PC) with scientific approach, and classical with scientific approach. This research was a quasi-experimental research. The population of the research was all of the eighth grade students of the State Junior High School in Sukoharjo. The instruments used to collect data were mathematics knowledge aspect test, mathematics skill aspect test and adversity quotient questionnaire. Technique of analyzing data that used was unbalanced two ways multivariat analysis of variance. From the research, it can be concluded that: (1) learning by using cooperative learning model of NHT with scientific approach gave the same knowledge and skill aspect with learning by using cooperative learning model of PC with scientific approach, learning by using cooperative learning model of NHT with scientific approach gave the same knowledge and skill aspect with learning by using classical learning with scientific approach, learning by using cooperative learning model of PC with scientific approach gave better knowledge and skill aspect than learning by using classical learning with scientific approach, (2) students who have adversity quotient of Climber gave better knowledge and skill aspect than students who have adversity quotient of Camper and Quitter, students who have adversity quotient of Camper gave the same knowledge and skill aspect with the students who have adversity quotient of Quitter, (3) on each learning model, students who have adversity quotient of Climber gave better knowledge and skill aspect than students who have adversity quotient of Camper and Quitter, students who have adversity quotient of Camper gave the same knowledge and skill aspect with the students who have adversity quotient of Quitter, (4) on each adversity quotient, learning by using cooperative learning model of NHT with scientific approach gave the same knowledge and skill aspect with learning by using cooperative learning model of PC with scientific approach, learning by using cooperative learning model of NHT with scientific approach gave the same knowledge and skill aspect with learning by using classical learning with scientific approach, learning by using cooperative learning model of PC with scientific approach gave better knowledge and skill aspect than learning by using classical learning with scientific approach

Application of the level-set method to the implicit solvation of nonpolar molecules

A level-set method is developed for numerically capturing the equilibrium solute-solvent interface that is defined by the recently proposed variational implicit solvent model (Dzubiella, Swanson, and McCammon, Phys. Rev. Lett. {\bf 104}, 527 (2006) and J. Chem.\Phys. {\bf 124}, 084905 (2006)). In the level-set method, a possible solute-solvent interface is represented by the zero level-set (i.e., the zero level surface) of a level-set function and is eventually evolved into the equilibrium solute-solvent interface. The evolution law is determined by minimization of a solvation free energy {\it functional} that couples both the interfacial energy and the van der Waals type solute-solvent interaction energy. The surface evolution is thus an energy minimizing process, and the equilibrium solute-solvent interface is an output of this process. The method is implemented and applied to the solvation of nonpolar molecules such as two xenon atoms, two parallel paraffin plates, helical alkane chains, and a single fullerene $C_{60}$. The level-set solutions show good agreement for the solvation energies when compared to available molecular dynamics simulations. In particular, the method captures solvent dewetting (nanobubble formation) and quantitatively describes the interaction in the strongly hydrophobic plate system

Hook3 is a scaffold for the opposite-polarity microtubule-based motors cytoplasmic dynein-1 and KIF1C.

The unidirectional and opposite-polarity microtubule-based motors, dynein and kinesin, drive long-distance intracellular cargo transport. Cellular observations suggest that opposite-polarity motors may be coupled. We recently identified an interaction between the cytoplasmic dynein-1 activating adaptor Hook3 and the kinesin-3 KIF1C. Here, using in vitro reconstitutions with purified components, we show that KIF1C and dynein/dynactin can exist in a complex scaffolded by Hook3. Full-length Hook3 binds to and activates dynein/dynactin motility. Hook3 also binds to a short region in the "tail" of KIF1C, but unlike dynein/dynactin, this interaction does not activate KIF1C. Hook3 scaffolding allows dynein to transport KIF1C toward the microtubule minus end, and KIF1C to transport dynein toward the microtubule plus end. In cells, KIF1C can recruit Hook3 to the cell periphery, although the cellular role of the complex containing both motors remains unknown. We propose that Hook3's ability to scaffold dynein/dynactin and KIF1C may regulate bidirectional motility, promote motor recycling, or sequester the pool of available dynein/dynactin activating adaptors

Gradient Clogging in Depth Filtration

We investigate clogging in depth filtration, in which a dirty fluid is ``cleaned'' by the trapping of dirt particles within the pore space during flow through a porous medium. This leads to a gradient percolation process which exhibits a power law distribution for the density of trapped particles at downstream distance x from the input. To achieve a non-pathological clogging (percolation) threshold, the system length L should scale no faster than a power of ln w, where w is the width. Non-trivial behavior for the permeability arises only in this extreme anisotropic geometry.Comment: 4 pages, 3 figures, RevTe

Transport and Boundary Scattering in Confined Geometries: Analytical Results

We utilize a geometric argument to determine the effects of boundary scattering on the carrier mean-free path in samples of various cross sections. Analytic expressions for samples with rectangular and circular cross sections are obtained. We also outline a method for incorporating these results into calculations of the thermal conductivity.Comment: 35 pages, Late

Resonant Photon-Assisted Tunneling Through a Double Quantum Dot: An Electron Pump From Spatial Rabi Oscillations

The time average of the fully nonlinear current through a double quantum dot, subject to an arbitrary combination of ac and dc voltages, is calculated exactly using the Keldysh nonequilibrium Green function technique. When driven on resonance, the system functions as an efficient electron pump due to Rabi oscillation between the dots. The pumping current is maximum when the coupling to the leads equals the Rabi frequency.Comment: 6 pages, REVTEX 3.0, 3 postscript figure