San Francisco State University

About: San Francisco State University is a education organization based out in San Francisco, California, United States. It is known for research contribution in the topics: Population & Planet. The organization has 5669 authors who have published 11433 publications receiving 408075 citations. The organization is also known as: San Francisco State & San Francisco State Normal School.

RENO: a high-efficient reconfigurable neuromorphic computing accelerator design

Abstract: Neuromorphic computing is recently gaining significant attention as a promising candidate to conquer the well-known von Neumann bottleneck. In this work, we propose RENO -- a efficient reconfigurable neuromorphic computing accelerator. RENO leverages the extremely efficient mixed-signal computation capability of memristor-based crossbar (MBC) arrays to speedup the executions of artificial neural networks (ANNs). The hierarchically arranged MBC arrays can be configured to a variety of ANN topologies through a mixed-signal interconnection network (M-Net). Simulation results on seven ANN applications show that compared to the baseline general-purpose processor, RENO can achieve on average 178.4x (27.06x) performance speedup and 184.2x (25.23x) energy savings in high-efficient multilayer perception (high-accurate auto-associative memory) implementation. Moreover, in the comparison to a pure digital neural processing unit (D-NPU) and a design with MBC arrays co-operating through a digital interconnection network, RENO still achieves the fastest execution time and the lowest energy consumption with similar computation accuracy.

Response of bed surface patchiness to reductions in sediment supply

Abstract: [1] River beds are often arranged into patches of similar grain size and sorting. Patches can be distinguished into “free patches,” which are zones of sorted material that move freely, such as bed load sheets; “forced patches,” which are areas of sorting forced by topographic controls; and “fixed patches” of bed material rendered immobile through localized coarsening that remain fairly persistent through time. Two sets of flume experiments (one using bimodal, sand-rich sediment and the other using unimodal, sand-free sediment) are used to explore how fixed and free patches respond to stepwise reductions in sediment supply. At high sediment supply, migrating bed load sheets formed even in unimodal, sand-free sediment, yet grain interactions visibly played a central role in their formation. In both sets of experiments, reductions in supply led to the development of fixed coarse patches, which expanded at the expense of finer, more mobile patches, narrowing the zone of active bed load transport and leading to the eventual disappearance of migrating bed load sheets. Reductions in sediment supply decreased the migration rate of bed load sheets and increased the spacing between successive sheets. One-dimensional morphodynamic models of river channel beds generally are not designed to capture the observed variability, but should be capable of capturing the time-averaged character of the channel. When applied to our experiments, a 1-D morphodynamic model (RTe-bookAgDegNormGravMixPW.xls) predicted the bed load flux well, but overpredicted slope changes and was unable to predict the substantial variability in bed load flux (and load grain size) because of the migration of mobile patches. Our results suggest that (1) the distribution of free and fixed patches is primarily a function of sediment supply, (2) the dynamics of bed load sheets are primarily scaled by sediment supply, (3) channels with reduced sediment supply may inherently be unable to transport sediment uniformly across their width, and (4) cross-stream variability in shear stress and grain size can produce potentially large errors in width-averaged sediment flux calculations.

Policy Diffusion Dynamics in America

Abstract: Policy Diffusion Dynamics in America integrates research from agenda setting and epidemiology to model factors that shape the speed and scope of public policy diffusion. Drawing on a data set of more than 130 policy innovations, the research demonstrates that the 'laboratories of democracy' metaphor for incremental policy evaluation and emulation is insufficient to capture the dynamic process of policy diffusion in America. A significant subset of innovations trigger outbreaks - the extremely rapid adoption of innovation across states. The book demonstrates how variation in the characteristics of policies, the political and institutional traits of states, and differences among interest group carriers interact to produce distinct patterns of policy diffusion.

Photophysiology in two major Southern Ocean phytoplankton taxa: Photoprotection in Phaeocystis antarctica and Fragilariopsis cylindrus

Abstract: Phytoplankton communities in the Ross Sea, Antarctica, are characterized by the haptophyte Phaeocystis antarctica Karsten, which dominates deep mixed layers, and diatoms, including Fragilariopsis cylindrus Grunow, that thrive in shallower mixed layers. To investigate whether differences in photoprotective strategies explain these distributions, photosynthetic parameters, pigments, and fluorescence properties were measured in cultures grown under several irradiance regimes and during acclimation to increased irradiance. In P. antarctica, cellular concentrations of all pigments declined with increasing growth irradiance under continuous light, but xanthophyll cycle pigment concentrations increased with increasing irradiance under dynamic conditions without changes in chlorophyll. In contrast, F. cylindrus exhibited declines in chlorophyll cell−1 with increasing irradiance under both continuous and dynamic conditions, but xanthophyll cycle cell21 pigments increased under continuous irradiance and declined under dynamic irradiance. P. antarctica did not exhibit non-photochemical quenching (NPQ) unless exposed to irradiance in excess of the mean growth irradiance. F. cylindrus exhibited NPQ in response to lower irradiances but displayed less photoinhibitory quenching than P. antarctica after exposure to very high irradiance. Inhibitor experiments suggest that both taxa rely upon xanthophyll cycle photoprotection to maintain photosynthetic performance but only P. antarctica relies heavily upon protein synthesis, presumably for D1 protein repair. F. cylindrus can thrive in shallow mixed layers because its high capacity for heat dissipation minimizes photoinhibition. P. antarctica utilizes xanthophyll cycle photoprotection to a lesser degree, but is able to dominate deeper mixed layers by effectively repairing the photodamage incurred when it is mixed to the surface.

Observation of two-dimensional surface solitons.

Abstract: We report the first experimental observation of two-dimensional surface solitons at the boundaries (edges or corners) of a finite optically induced photonic lattice. Both in-phase and gap nonlinear surface self-trapped states were observed under single-site excitation conditions. Our experimental results are in good agreement with theoretical predictions.