Cellular Nonlinear/Neural Network (CNN) technology is both a revolutionary concept and an experimentally proven new computing paradigm. Analogic cellular computers based on CNNs are set to change the way analog signals are processed and are paving the way to an entire new analog computing industry. This unique undergraduate-level textbook includes many examples and exercises, including CNN simulator and development software accessible via the Internet. It is an ideal introduction to CNNs and analogic cellular computing for students, researchers and engineers from a wide range of disciplines. Leon Chua, co-inventor of the CNN, and Tams Roska are both highly respected pioneers in the field.
Catalytic hydroarylation of alkenes is a desirable process because it can occur under neutral conditions with regioselectivity complementary to that of acid-catalyzed reactions and stereoselectivity derived from the catalyst. We report an intermolecular asymmetric addition of the C-H bonds of indoles, thiophenes, pyrroles, and furans to bicycloalkenes in high yield with high enantiomeric excess. These heteroarene alkylations occur ortho to the heteroatom. This selectivity is observed even with unprotected indoles, which typically undergo alkylation at the C3 position. Initial mechanistic studies revealed that oxidative addition of a heteroarene C-H bond to a neutral Ir(I) species occurs within minutes at room temperature and occurs in the catalytic cycle prior to the turnover-limiting step. Products from syn addition of the C-H bond across the olefin were observed.
Imagine visiting your favorite place, taking a few pictures, and then turning those pictures into a photorealisic three-dimensional computer model. The work presented in this thesis combines techniques from computer vision and computer graphics to make this possible. The applications range from architectural planning and archaeological reconstructions to virtual environments and cinematic special effects. This thesis presents an
This article explores the physical and emotional health status of 71 African-American grandmothers raising their grandchildren as a result of the crack cocaine involvement of the children's parents. A comparison of self-assessed health ratings with qualitative responses revealed a tendency for respondents to downplay their own health problems and symptoms.
Advisor Perspectives welcomes guest contributions. The views presented here do not necessarily represent those of Advisor Perspectives. This is an update of the authors ' 6 April 2009 column comparing today's global crisis to the Great Depression. World industrial production, trade, and stock markets are diving faster now than during 1929-30. Fortunately, the policy response to date is much better. The update shows that trade and stock markets have shown some improvement without reversing the overall conclusion-- today's crisis is at least as bad as the Great Depression. Editor’s note: The 6 April 2009 Vox column by Barry Eichengreen and Kevin O’Rourke shattered all Vox readership records, with 30,000 views in less than 48 hours and over 100,000 within the week. The authors will update the charts as new data emerges; this updated column is the first, presenting monthly data up to April 2009. (The updates and
This paper introduces an analytic method to determine the sensitivity to random parameter variations of analog VLSI neural network architectures for linear image filtering. The authors compare the robustness of several different circuit architectures for low pass filtering. This method can also determine which components within a particular architecture should specified the most precisely.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>
An important component of the drive towards intelligent vehicles is the ability to maintain a fixed distance from a lead vehicle using feedback provided by range sensors. We are investigating the possibility of using stereo vision to provide the range information, in conjunction with a scanning laser radar sensor. The vision algorithms build on fixation and reconstruction algorithms designed for active vision systems, and combine stereo and motion cues. We shall present preliminary results comparing the quality of range measurements provided by a vision system with the laser radar system, using data obtained off-line. Later we will implement the tracker in real time on a network of C40 DSPs, and combine the laser and vision sensing in a cooperative manner.
We used variation in algal d 13 C between river habitats to study the spatial scale of energy flow through river food webs. We found a strong negative relationship between herbivore d 13 C (which reflects algal d 13 C) and water velocity in three productive Northern California rivers but not in unproductive streams. The contrast among habitats suggests that water velocity affects algal d 13 C most strongly when CO2 availability is low relative to photosynthetic rates. Our results help explain the wide variation in published river biota d 13 C and show that past studies using carbon isotope analyses may have significantly underestimated the importance of algal‐derived carbon to river food webs. While flow‐related variation in d 13 C complicates this common application of carbon isotope analysis, we show that it provides a natural tracer of the flux of algal production derived from different habitats within rivers to higher trophic levels. Measurements of consumer d 13 C showed that most invertebrate and vertebrate consumers relied on local production, except for filter‐feeding insects and steelhead trout, which relied on production derived from multiple sources. Stable carbon isotopes may thus be used to spatially delineate the habitats that support river food webs, providing previously unavailable information for understanding and managing river ecosystems.
Abstract Cells of the cyanobacterium Synechococcus 6301 were grown under illumination whose spectral composition favoured absorption either by the phycobilisome (PBS) light-harvesting antenna of photosystem II (PS II) or by the chlorophyll (Chi) a light-harvesting antenna of photosystem I (PS I). Cells grown under PS I-light developed relatively high PS II/PS I and PBS/Chl ratios. Cells grown under PS II-light developed relatively low PS II/PS I and PBS/Chl ratios. Thus, the primary difference between cells in the two acclimation states appeared to be the relative concentration of PBS-PS II and PS I complexes in the thylakoid membrane. Measurements of the quantum yield of oxygen evolution suggested a higher efficiency of cellular photosynthesis upon the adjustment of photosystem stoichiometry to a specific light condition. The quantum yield of oxygen evolution was nevertheless lower under PBS than Chi excitation, suggesting quenching of excitation energy in the photochemical apparatus of PS II in Synechococcus 6301. This phenomenon was more pronounced in the PS II-light than in the PS I-light grown cells. Room temperature and 77 K fluorescence emission spectroscopy indicated that excess excitation energy in the PBS was not transferred to PS I, suggesting the operation of a non-radiative and non-photochemical decay of excitation energy at the PBS-PS II complex. This non-photochemical quenching was specific to conditions where excitation of PS II occurred in excess of its capacity for useful photochemistry.
This work quantifies the performance of gas-diffusion electrodes using multiphysics modeling and provides design guidance.
In this tutorial we continue our program of clarifying chaos by examining the relationship between chaotic and stochastic processes. To do this, we construct chaotic analogs of stochastic processes, stochastic differential equations, and discuss estimation and prediction models. The conclusion of this section is that from the composition of simple nonlinear periodic dynamical systems arise chaotic dynamical systems, and from the time-series of chaotic solutions of finite-difference and differential equations are formed chaotic processes, the analogs of stochastic processes. Chaotic processes are formed from chaotic dynamical systems in at least two ways. One is by the superposition of a large class of chaotic time-series. The second is through the compression of the time-scale of a chaotic time-series. As stochastic processes that arise from uniform random variables are not constructable, and chaotic processes are constructable, we conclude that chaotic processes are primary and that stochastic processes are idealizations of chaotic processes. Also, we begin to explore the relationship between the prime numbers and the possible role they may play in the formation of chaos.
