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The ability to differentiate between ions is a property of ion channels that is crucial for their biological functions. However, the fundamental structural features that define anion selectivity and distinguish anion-permeable from cation-permeable channels are poorly understood. Voltage-gated chloride (Cl-) channels belonging to the ClC family are(More)
Autosomal dominant myotonia congenita is an inherited disorder of skeletal muscle caused by mutations in a voltage-gated Cl- channel gene (CLCN1, 7q35). Here, we report that a mutation predicting the substitution of Gly 230 by glutamic acid (G230E) between segments D3 and D4 dramatically alters the pore properties of a recombinant human muscle Cl- channel(More)
— A necessary and sufficient condition is given for the exact reduction of systems modeled by linear fractional transformations (LFT's) on structured operator sets. This condition is based on the existence of a rank-deficient solution to either of a pair of linear matrix inequalities which generalize Lyapunov equations; the notion of Gramians is thus also(More)
—Error-bounds are developed for balanced truncation of linear time-varying systems, leading to an extension of the " twice the sum of the tail " formulas, well known in the time-invariant case. The approach relies on an operator-theoretic framework for analysis of linear time-varying systems. This provides a multivariable notion of frequency for such(More)
Traditionally, it had been assumed that the efficiency requirements of TCP dictate that the buffer size at the router must be of the order of the bandwidth-delay (<i>C</i> &#215; RTT) product. Recently, this assumption was questioned in a number of papers, and the rule was shown to be conservative for certain traffic models. In particular, by appealing to(More)
New techniques are presented for the model reduction of linear time-varying and linear periodically-varying systems, including the formulation and proof of guaranteed upper bounds for the error. The commonly used method of balanced truncation for linear time-invariant systems is generalized to the time-varying case with explicit error bounds that are(More)
— This paper introduces a new method for reducing large directed graphs to simpler graphs with fewer nodes. The reduction is carried out through node and edge aggregation, where the simpler graph is representative of the original large graph. Representativeness is measured using a metric defined herein, which is motivated by thermodynamic free energy and(More)