A 16-Mb MRAM featuring bootstrapped write drivers

A 16-Mb magnetic random access memory (MRAM) is demonstrated in 0.18-/spl mu/m three-Cu-level CMOS with a three-level MRAM process adder. The chip, the highest density MRAM reported to date, utilizes a 1.42/spl mu/m/sup 2/ 1-transistor 1-magnetic tunnel junction (1T1MTJ) cell, measures 79 mm/sup 2/ and features a /spl times/16 asynchronous SRAM-like interface. The paper describes the cell, architecture, and circuit techniques unique to multi-Mb MRAM design, including a novel bootstrapped write driver circuit. Hardware results are presented.     

The effects of expressive writing following first myocardial infarction: A randomized controlled trial.

Objective: To assess the effects of expressive writing on health care utilization, clinical variables and subjective quality of life following first myocardial infarction (MI). Methods: One-hundred and seventy-nine first MI patients were randomized to Intervention (N = 88) or Control (N = 91) groups. The intervention group wrote about their thoughts and feelings in relation to having had an MI. Controls wrote in a neutral way about daily activities. The main outcome measures were health care utilization, physical status and subjective quality of life (QOL), assessed after one, two, and five months. Results: One-hundred and fifty-six (87%) completed the study. Five months post-intervention, the intervention group had significantly fewer recorded medical appointments compared to controls. The number of prescribed medicines decreased over time within the intervention group but increased within the control group. The intervention group attended significantly more rehabilitation sessions, reported fewer cardiac related symptoms and had lower diastolic blood pressure five months post-intervention. There was no significant group by time interaction on reported physical health. The group by time interaction on reported mental health approached significance, those in the intervention group reporting greater improvement. Conclusion: Expressive writing may be a beneficial strategy which could be incorporated into rehabilitation interventions to help individuals adjust after first MI. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Book Review

Colloidal silver iodide prepared in several different ways has been examined by electron microscopy. It was found that the particles exhibited well-defined shapes and varied in size from 10-5,000 A according to the method of preparation. Electron microscope observations were supported by the examination of single particles using the microdiffraction technique; this revealed that such particles were normally single crystals. Under the electron optical conditions of the Siemens Elmiskop, two types of phenomenon were observed, namely, highly mobile changes of contrast within the particle and the formation of filaments. The filaments also showed changes of contrast during growth and after formation often exhibited a banded structure. The preparation of thin flat particles of silver iodide enabled some preliminary electron microscope observation of internal structure to be carried out directly. Possible mechanisms for the phenonema observed are discussed.     

Deploying intelligent systems on a global scale

Intelligent systems are rarely deployed in isolation. Furthermore, with the advent of the global Internet, corporate intranets, and the Web, the potential for interactions between intelligent systems has never been greater. However, new technologies such as Web services, the semantic Web, grid computing, and peer-to-peer networks have made it easier than ever to create intelligent applications that span not only multiple machines but also multiple sites and organizations. So, one great challenge in intelligent systems research is to harness these technologies to verify and apply longstanding theories from distributed AI, agent systems, and other areas of networked intelligent systems research. Although we can generate knowledge from models, simulations, and small-scale trials, gaining a thorough understanding of intelligent systems requires increasingly large-scale deployments in challenging environments. Unfortunately, such experimentation is time consuming and costly-often requiring significant infrastructure development, maintenance, and low-level implementation before we can tackle more challenging and innovative elements. As the environments in which we employ intelligent systems continue to grow, so do the costs of deploying, testing, and verifying such systems.     

Quantitative sizing of nano/microparticles with a tunable elastomeric pore sensor

The use of a "size-tunable" polyurethane resistive pulse sensor for quantitative sizing of nano- and microparticles is presented. A linear relationship, as first suggested by Maxwell, between particle volume and change in electric resistance across the pore was observed. Particle sizes were quantified for a given size-tunable membrane, by first creating a linear calibration curve to a series of monodisperse carboxylated polystyrene particles of various diameters and then applying this curve to calculate the size of "unknown" nanoparticles. The diameters of a selection of synthetic and biological particles, being PMMA and nonfunctionalized polystyrene particles, along with biological nanoparticles (adenovirus) were calculated using this methodology. Calculated particle diameters and coefficients of variation were shown to be in good agreement with both transmission electron microscopy and dynamic light scattering results.     

The shock Hugoniot of Tuffisitic Kimberlite Breccia

The Hugoniot of a material represents the response to high-rate loading at pressures associated with those produced by blasting charges. The shock Hugoniot curve of a kimberlite, Tuffisitic Kimberlite Breccia (TKB), has been determined between 0.3 and 8.4 GPa using plate impact experiments. The dynamic shear response of TKB is reported for impact stresses between 1.1 and 3.2 GPa. Longitudinal and lateral stress measurements were made using embedded manganin gauges and VISAR in material shocked to a state of uniaxial strain. The shock response of TKB reveals a relatively weak material with no clear Hugoniot Elastic Limit (HEL) in the longitudinal stress measurements. The lateral stress measurements suggest an HEL between 0.6 and 0.9 GPa. Inelastic deformation is observed at all stresses due to a combination of volume compaction and brittle failure. The current data have been compared with similar reports in the literature and theory in order to accurately describe the response of this inhomogeneous geological material.     

A variable pressure method for characterizing nanoparticle surface charge using pore sensors

A novel method using resistive pulse sensors for electrokinetic surface charge measurements of nanoparticles is presented. This method involves recording the particle blockade rate while the pressure applied across a pore sensor is varied. This applied pressure acts in a direction which opposes transport due to the combination of electro-osmosis, electrophoresis, and inherent pressure. The blockade rate reaches a minimum when the velocity of nanoparticles in the vicinity of the pore approaches zero, and the forces on typical nanoparticles are in equilibrium. The pressure applied at this minimum rate can be used to calculate the zeta potential of the nanoparticles. The efficacy of this variable pressure method was demonstrated for a range of carboxylated 200 nm polystyrene nanoparticles with different surface charge densities. Results were of the same order as phase analysis light scattering (PALS) measurements. Unlike PALS results, the sequence of increasing zeta potential for different particle types agreed with conductometric titration.     

Fast piezoelectric actuation of an elastomeric micropore

A viscoelastic membrane unit fabricated from thermoplastic polyurethane, with a formed single micropore, was interfaced to a piezoelectric actuator to demonstrate rapid actuation of the pore. Changes in through-pore conductance were measured as a function of the voltage applied to the actuator. The pore was opened and closed either in a stepwise fashion, or else made to oscillate between more and less open positions at up to 200 Hz. The step-driven response exhibited both a fast (<100 ms) majority component and a slow (∼1 s) minority component. The oscillatory method indicated that the majority component reached 95% of the low frequency (5 Hz) conductance amplitude in ∼5 ms, fast enough for a pore to close upon a particle driven by a 50 Pa pressure head. This advance in the rapid control of very small pores was achieved by reducing the amount of viscoelastic material between the pore and the source of actuation. This technique has potential for measurement and manipulation of micro- and nano-particles.