Zigzag transitions and nonequilibrium pattern formation in colloidal chains

Paramagnetic colloidal particles that are optically trapped in a linear array can form a zigzag pattern when an external magnetic field induces repulsive interparticle interactions. When the traps are abruptly turned off, the particles form a nonequilibrium expanding pattern with a zigzag symmetry, even when the strength of the magnetic interaction is weaker than that required to break the linear symmetry of the equilibrium state. We show that the transition to the equilibrium zigzag state is always potentially possible for purely harmonic traps. For anharmonic traps that have a finite height, the equilibrium zigzag state becomes unstable above a critical anharmonicity. A normal mode analysis of the equilibrium line configuration demonstrates that increasing the magnetic field leads to a hardening and softening of the spring constants in the longitudinal and transverse directions, respectively. The mode that first becomes unstable is the mode with the zigzag symmetry, which explains the symmetry of nonequilibrium patterns. Our analytically tractable models help to give further insight into the way that the interplay of such factors as the length of the chain, hydrodynamic interactions, thermal fluctuations affect the formation and evolution of the experimentally observed nonequilibrium patterns.Comment: 16 pages, 8 figures; to appear in the Journal of Chemical Physic

Stochastic dynamics of resistive switching: fluctuations lead to optimal particle number

Resistive switching (RS) is one of the foremost candidates for building novel types of non-volatile random access memories. Any practical implementation of such a memory cell calls for a strong miniaturization, at which point fluctuations start playing a role that cannot be neglected. A detailed understanding of switching mechanisms and reliability is essential. For this reason, we formulate a particle model based on the stochastic motion of oxygen vacancies. It allows us to investigate fluctuations in the resistance states of a switch with two active zones. The vacancies' dynamics are governed by a master equation. Upon the application of a voltage pulse, the vacancies travel collectively through the switch. By deriving a generalized Burgers equation we can interpret this collective motion as nonlinear traveling waves, and numerically verify this result. Further, we define binary logical states by means of the underlying vacancy distributions, and establish a framework of writing and reading such memory element with voltage pulses. Considerations about the discriminability of these operations under fluctuations together with the markedness of the RS effect itself lead to the conclusion, that an intermediate vacancy number is optimal for performance

Reference climate dataset for the Indus, Ganges, and Brahmaputra river basins

This work was carried out by the Himalayan Adaptation, Water and Resilience (HI-AWARE) consortium under the Collaborative Adaptation Research Initiative in Africa and Asia (CARIAA) with financial support from the UK Government’s Department for International Development and the International Development Research Centre, Ottawa, Canada.High-altitude climates are particularly uncertain, and commonly used climate datasets are grossly inaccurate at high altitudes. Therefore, a novel reference climate dataset covering the Indus, Ganges, and Brahmaputra (IGB) river basins has been constructed with a particular focus on improved representation of high-altitude precipitation. This document describes the construction of a historical climate dataset for the IGB river basins, which has been constructed for widespread use in the HI-AWARE project. The dataset covers the period from 1 January 1981 to 31 December 2010 with a daily time step and covers the IGB river basins at 10x10 km spatial resolution. Additionally, the upstream parts of the basins are covered at 5x5 km spatial resolution in a separate dataset to account for the larger variability in mountainous terrain. The methods used to generate the dataset have been discussed and the contents of the dataset have been illustrated in this document

Faculty String Quartet: Won-Mo Kim, Violin; Arthur Lewis, Viola; Kathryn Gray, Violin; Lutz Rath, Cello; April 21, 1974

Centennial East Recital HallSunday EveningApril 21, 19748:15 p.m

Distribution of mineral constituents in Yedoma permafrost: implications for Yedoma formation

Ice-rich permafrost deposits such as Yedoma are highly sensitive to thaw and given that they contain up to one third of the organic carbon content of the Northern circumpolar permafrost region, their degradation is considered to be a potential climate tipping point on Earth. Accurately predicting the impact of climate warming on the fate of organic carbon in Yedoma requires better constraints on the mineral element reserve in these deposits. This study provides evidence for the homogeneity of chemical composition and mineralogy of Yedoma deposits with depth. This suggests that upon deep thaw through thermokarst or thermo-erosion a high reserve in mineral nutrients is likely to be exposed also from deeper deposits

Ensemble Concerts: Faculty Chamber Concert, December 12, 1973

Centennial East Recital HallWednesday EveningDecember 12, 19738:15 p.m

Faculty Artist Recital: Tim Hurtz, Oboe; Christine Snyder, Soprano; Won-Mo Kim, Violin; Arthur Lewis, Viola; Lutz Rath, Cello; March 20, 1974

Centennial East Recital HallWednesday EveningMarch 20, 19748:15 p.m

Ультразвуковое исследование при дегенеративно-дистрофических и воспалительных заболеваниях коленного сустава

Рассмотрены актуальные вопросы диагностики заболеваний коленного сустава − деформирующего остеоартроза, ревматоидного и псориатического артритов. Предложены критерии дифференциальной диагностики этих заболеваний.Urgent issues of diagnosis of knee joint diseases (osteoarthrosis deformans, rheumatoid and psoriatic arthritis) are discussed. The criteria of differential diagnosis are suggested