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In the nanoscale regime, the behavior of both extant and emerging semiconductor devices are often unreliable. Reliability of such devices often trades-off with their energy consumption, speed, and/or chip area. We study the energy-reliability limits for circuits designed using such devices. Using the mutual information propagation in logic circuits technique developed by Pippenger, together with optimization, we obtain lower bounds on the energy consumption for computing n-input boolean functions. Most extant technologies require all gates to have the same electrical operating point and in circuits of such uniform gates, the minimum energy required to achieve any nontrivial reliability scales superlinearly with the number of inputs. On the other hand, in some emerging technologies such as spin electronics, where the gates in a circuit can have different operating points, energy scaling can be linear in the number of inputs. As part of our development we find a simple procedure for energy allocation across gates in a boolean circuit with different operating points.

We study the information-theoretic limit of reliable information processing by a server with queue-length dependent quality of service. We define the capacity for such a system as the number of bits reliably processed per unit time, and characterize it in terms of queuing system parameters. We also characterize the distributions of the arrival and service processes that maximize and minimize the capacity of such systems in a discrete-time setting. For arrival processes with at most one arrival per time slot, we observed a minimum around the memoryless distribution. We also studied the case of multiple arrivals per time slot, and observed that burstiness in arrival has adverse effects on the system. The problem is theoretically motivated by an effort to incorporate the notion of reliability in queueing systems, and is applicable in the contexts of crowdsourcing, multimedia communication, and stream computing. Index Termschannel capacity, quality of service, queuing

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In the framework of the minimal cosmological standard model, the ΛCDM model, the Dark Matter density is now known with an error of a few percent; this error is expected to shrink even further once PLANCK data are analyzed. Matching this precision by theoretical calculations implies that at least leading radiative corrections to the annihilation cross section of the dark matter particles have to be included. Here we compute one kind of large corrections in the context of the minimal supersymmetric extension of the Standard Model: corrections associated with two-point function corrections on chargino and neutralino (collectively denoted bỹ χ) lines. These can be described by effectiveχ-fermion-sfermion andχ-χ-Higgs couplings. We also employ one-loop correctedχ masses, using a recently developed version of the on-shell renormalization scheme. The resulting correction to the predicted Dark Matter density depends strongly on parameter space, but can easily reach 3%.

We study the effect of external infection sources on phase transitions in epidemic processes. In particular, we consider an epidemic spreading on a network via the SIS/SIR dynamics, which in addition is aided by external agents -sources unconstrained by the graph, but possessing a limited infection rate or virulence. Such a model captures many existing models of externally aided epidemics, and finds use in many settings -epidemiology, marketing and advertising, network robustness, etc. We provide a detailed characterization of the impact of external agents on epidemic thresholds. In particular, for the SIS model, we show that any external infection strategy with constant virulence either fails to significantly affect the lifetime of an epidemic, or at best, sustains the epidemic for a lifetime which is polynomial in the number of nodes. On the other hand, a random external-infection strategy, with rate increasing linearly in the number of infected nodes, succeeds under some conditions to sustain an exponential epidemic lifetime. We obtain similar sharp thresholds for the SIR model, and discuss the relevance of our results in a variety of settings.