A Complementary Resistive Switch-based Crossbar Array Adder

Redox-based resistive switching devices (ReRAM) are an emerging class of non-volatile storage elements suited for nanoscale memory applications. In terms of logic operations, ReRAM devices were suggested to be used as programmable interconnects, large-scale look-up tables or for sequential logic operations. However, without additional selector devices these approaches are not suited for use in large scale nanocrossbar memory arrays, which is the preferred architecture for ReRAM devices due to the minimum area consumption. To overcome this issue for the sequential logic approach, we recently introduced a novel concept, which is suited for passive crossbar arrays using complementary resistive switches (CRSs). CRS cells offer two high resistive storage states, and thus, parasitic sneak currents are efficiently avoided. However, until now the CRS-based logic-in-memory approach was only shown to be able to perform basic Boolean logic operations using a single CRS cell. In this paper, we introduce two multi-bit adder schemes using the CRS-based logic-in-memory approach. We proof the concepts by means of SPICE simulations using a dynamical memristive device model of a ReRAM cell. Finally, we show the advantages of our novel adder concept in terms of step count and number of devices in comparison to a recently published adder approach, which applies the conventional ReRAM-based sequential logic concept introduced by Borghetti et al.Comment: 12 pages, accepted for IEEE Journal on Emerging and Selected Topics in Circuits and Systems (JETCAS), issue on Computing in Emerging Technologie

What changes do we want to see at the next OWCs?

The Organic World Congress (OWC) will analyze the situation of the Organic world in 2014, discuss issues and develop strategies. Approaching our visions in a changing environment requires constant adjustments and actions. This applies equally to farmers, the value chain, consumption and the organic support sector. The OWC is an opportunity to reach shared conclusions on what actions and alliances with likeminded organizations (e.g. nature conversation or animal welfare NGOs) are needed so that the Organic World can grow and become more sustainable at the same time

Applicability of Well-Established Memristive Models for Simulations of Resistive Switching Devices

Highly accurate and predictive models of resistive switching devices are needed to enable future memory and logic design. Widely used is the memristive modeling approach considering resistive switches as dynamical systems. Here we introduce three evaluation criteria for memristor models, checking for plausibility of the I-V characteristics, the presence of a sufficiently non-linearity of the switching kinetics, and the feasibility of predicting the behavior of two anti-serially connected devices correctly. We analyzed two classes of models: the first class comprises common linear memristor models and the second class widely used non-linear memristive models. The linear memristor models are based on Strukovs initial memristor model extended by different window functions, while the non-linear models include Picketts physics-based memristor model and models derived thereof. This study reveals lacking predictivity of the first class of models, independent of the applied window function. Only the physics-based model is able to fulfill most of the basic evaluation criteria.Comment: 9 pages; accepted for IEEE TCAS-

Engineering design of the FRX-C experiment

Research on Compact Toroid (CT) configurations has been greatly accelerated in the last few years because of their potential for providing a practical and economical fusion system. Los Alamos research is being concentrated on two types of configurations: (1) magnetized-gun-produced Spheromaks (configurations that contain a mixture of toroidal and poloidal fields); and (2) field-reversed configurations (FRCs) that contain purely poloidal magnetic field. This paper describes the design of FRX-C, a field-reversed theta pinch used to form FRCs

Shallow rainwater lenses in deltaic areas with saline seepage

In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and size. Our findings are based on different types of field measurements and detailed numerical groundwater models applied in the south-western delta of the Netherlands. By combining the applied techniques we could extrapolate measurements at point scale (groundwater sampling, temperature and electrical soil conductivity (TEC)-probe measurements, electrical cone penetration tests (ECPT)) to field scale (continuous vertical electrical soundings (CVES), electromagnetic survey with EM31), and even to regional scale using helicopter-borne electromagnetic measurements (HEM). The measurements show a gradual mixing zone between infiltrating fresh rainwater and upward flowing saline groundwater. The mixing zone is best characterized by the depth of the centre of the mixing zone <i>D</i><sub>mix</sub>, where the salinity is half that of seepage water, and the bottom of the mixing zone <i>B</i><sub>mix</sub>, with a salinity equal to that of the seepage water (Cl-conc. 10 to 16 g l<sup>−1</sup>). <i>D</i><sub>mix</sub> is found at very shallow depth in the confining top layer, on average at 1.7 m below ground level (b.g.l.), while <i>B</i><sub>mix</sub> lies about 2.5 m b.g.l. The model results show that the constantly alternating upward and downward flow at low velocities in the confining layer is the main mechanism of mixing between rainwater and saline seepage and determines the position and extent of the mixing zone (<i>D</i><sub>mix</sub> and <i>B</i><sub>mix</sub>). Recharge, seepage flux, and drainage depth are the controlling factors

Age Trajectories of the Structural Connectome in Child and Adolescent Offspring of Individuals With Bipolar Disorder or Schizophrenia

Background: Offspring of parents with severe mental illness (e.g., bipolar disorder or schizophrenia) are at elevated risk of developing psychiatric illness owing to both genetic predisposition and increased burden of environmental stress. Emerging evidence indicates a disruption of brain network connectivity in young offspring of patients with bipolar disorder and schizophrenia, but the age trajectories of these brain networks in this high-familial-risk population remain to be elucidated. Methods: A total of 271 T1-weighted and diffusion-weighted scans were obtained from 174 offspring of at least 1 parent diagnosed with bipolar disorder (n = 74) or schizophrenia (n = 51) and offspring of parents without severe mental illness (n = 49). The age range was 8 to 23 years; 97 offspring underwent 2 scans. Anatomical brain networks were reconstructed into structural connectivity matrices. Network analysis was performed to investigate anatomical brain connectivity. Results: Offspring of parents with schizophrenia had differential trajectories of connectivity strength and clustering compared with offspring of parents with bipolar disorder and parents without severe mental illness, of global efficiency compared with offspring of parents without severe mental illness, and of local connectivity compared with offspring of parents with bipolar disorder. Conclusions: The findings of this study suggest that familial high risk of schizophrenia is related to deviations in age trajectories of global structural connectome properties and local connectivity strength.</p

The effect of artificial diffusivity on the flute instability

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FRC formation and trapping by counter injection for MTF liner implosions

A new simplified design is being developed for injecting and trapping Field-Reversed Configurations (FRCs) into liners, which is compatible with the energetic liner implosions of interest for Magnetized Target Fusion (MTF). Conical theta pinches that inject from each end of the liner region are proposed. The conical angle can be chosen to make axial translation out of the conical theta pinch into the liner region occur on approximately the same time scale as radial compression. Thus no crowbar switch is needed for the high-voltage fast-rising current pulse. The toroidal field from conical theta-pinch injection and/or Z-pinch preionization should rapidly annihilate upon merging of the two oppositely directed FRCs. Two dc coils in a Helmholtz-like configuration are all that are needed to serve the functions of cusp, translation, and mirror fields for trapping in the liner. The mirror strength required for trapping is not as critical as when using onesided injection because the merging FRCs have no net momentum when they collide. Previously observed damping of axial kinetic energy suggests that viscous damping parallel to B 'is strong for FRCs with mfp comparable to FRC length, and conversion of directed energy to thermal energy should occur on a time scale comparable to the injection time. The electrical/mechanical details will be described, accompanied by numerical simulations of FRC formation using the MACH2 numerical code

SUSCEPTIBILITY OF WINTER TICK LARVAE AND EGGS TO ENTOMOPATHOGENIC FUNGI - BEAUVERIA BASSIANA, BEAUVERIA CALEDONICA, METARHIZIUM ANISOPLIAE, AND SCOPULARIOPSIS BREVICAULIS

An isolate of the soil fungus Scopulariopsis brevicaulis was identified from the surface of female winter ticks (Dermacentor albipictus) collected from recently dead moose (Alces alces) calves in New Hampshire in the northeastern United States. It was the sole isolate, and it matched with 98% nucITS similarity (molecular systematics Blast match) to S. brevicaulis species from soil and other tick species. Inoculation of tick larvae and eggs with 108 spores/mL + 0.05% Tween (aqueous inoculum) resulted in mortality, reduced survival time, and recovery of S. brevicaulis from within tick tissues. Rapid water loss and death from dehydration were the pathogenic consequences of the fungal infection. Three entomopathogenic fungal isolates from laboratory culture (Beauveria bassiana, B. caledonica,and Metarhizium anisopliae) inoculated concurrently at the same dose, were slightly less pathogenic to eggs than larvae of winter ticks. We conclude that S. brevicaulis imposes a limitation on the free-living stages of the winter tick population in specific environmental conditions, but commercial fungal treatments as used in local situations to control ticks, are impractical as a means of controlling winter tick density across moose habitats