Cholesterol crystals rupture biological membranes and human plaques during acute cardiovascular events--a novel insight into plaque rupture by scanning electron microscopy

Plaque rupture and/or erosion are considered the leading cause of cardiovascular events. To elucidate this process, we demonstrated that during cholesterol crystallization the occupied volume increases rapidly and sharp-tipped crystals cut through thin biological membranes in their path. The amount of cholesterol correlated directly with both peak level and rate of crystal growth (r = 0.98; r = 0.99; p < 0.01, respectively). These observations suggest that crystallization of cholesterol in atherosclerotic plaques can induce cap rupture and/or erosion. Observations by scanning electron microscopy confirmed similar findings of cholesterol crystals perforating the lumen surface in human coronary artery segments with ruptured plaque.     

A network management and control scenario for multimedia applications

Emergence of multimedia applications requires that appropriate management and control activities be provided and organized in a somewhat integrated framework. Such issues as coordination of operations on the shared information, provision of the user requirements in terms of quality of service and efficient handling of the available network resources result in more critical problems when they regard multimedia objects. Mainly this is due to the time-constrained requirements that arise from the need of synchronization among multiple streams of information which are different in their nature and granularity. This paper discusses the impact of the above issues on network management and control and proposes an architectural model for the management and control of broadband applications that require handling of multimedia information.     

Domain decomposition preconditioners for the spectral collocation method

We propose and analyze several block iteration preconditioners for the solution of elliptic problems by spectral collocation methods in a region partitioned into several rectangles. It is shown that convergence is achieved with a rate that does not depend on the polynomial degree of the spectral solution. The iterative methods here presented can be effectively implemented on multiprocessor systems due to their high degree of parallelism.     

The Effect of Climatic Parameters on the Heat Transfer Mechanisms in a Solar Distillation Still

This paper deals with a simple and inexpensive solar desalination configuration. The performance of a simple solar still operating under Maltese climatic conditions is analyzed both theoretically and experimentally. The internal and external heat transfer modes of the distillation unit are examined. This paper concludes that the distillation rate in a simple solar distiller increases with ambient temperature and solar radiation, even though the condensation capacity of the glass is reduced. A higher wind speed decreases the evaporation and condensation processes. The energy fractions within the solar still have also been analyzed. The simulations and the experiments conclude that the glass components handle the bulk of the heat transferred in a solar still, namely, radiation, evaporation, and condensation, and thus the distillation efficiency is enhanced by improving the thermal and optical properties of the glass.     

On the SQH Method for Solving Differential Nash Games

Journal of Dynamical and Control Systems - A sequentialquadratic Hamiltonian schemefor solving open-loop differential Nash games is proposed and investigated. This method is formulated in the...     

Current-mode body-biased switch to increase performance of linear charge pumps

This letter introduces a novel scheme to improve charge transfer switches in linear charge pumps. The proposed approach relies on the reduction of the threshold voltage of the transistor implementing each charge transfer switch by forcing a current into its bulk junction. Simulation results using a 130-nm standard complementary metal-oxide semiconductor (CMOS) technology confirm the effectiveness of the proposed method.     

Three-dimensional simulation of the thermohaline-driven buoyancy of a brine parcel

We provide three-dimensional numerical simulations of the thermohaline-driven buoyancy of a brine “parcel” immersed in an initially homogeneous porous medium of hydrological interest. Our purpose is to improve our understanding of the thermohaline flow through the 3D visualization of the evolving patterns generated by the distributions of brine, temperature, and fluid density in the porous medium. We propose a possible physical interpretation of our results, which are obtained within the approximations usually employed in the context of density- and temperature-driven flow.     

Global impedance attenuation network for multistage OTAs driving a broad range of load capacitor

Advanced multistage amplifiers suffer from load-dependent stability issues, which limit the load capacitor range they can drive. In this work, the concept of global impedance attenuation (GIA) network is introduced to improve an amplifier's stability in the presence of significant load capacitor variations. Composed of multiple parallel resistor-capacitor (RC) branches, the equivalent high-frequency output impedance of gain stages is shaped by the GIA network such that a desired frequency spectrum is obtained over a wide range of load capacitor. The parasitic poles at the output of the gain stages are nullified by the proposed network, thereby simplifying the amplifier's transfer function and reducing the minimum load capacitor it can drive. The idea is applied to design a three-stage operational transconductance amplifier (OTA) with cascode global impedance attenuation (CGIA). Small-signal analysis shows that the OTA is stable regardless of the load capacitor, and it can drive very small to ultra-large load capacitors. This feature is verified by the post-layout simulations of a CGIA amplifier in 0.18-μm complementary metal-oxide semiconductor (CMOS) process. The core occupies a die area of 0.0053 mm² while consuming a static current of 10.97 μA from 1.8-V voltage supply. The unity-feedback configuration is unconditionally stable for any load capacitor higher than 10 pF. To the best of our knowledge, this corresponds to the widest range of load capacitance reported for prior-art three-stage amplifiers.     

Linear distribution of capacitance in Dickson charge pumps to reduce rise time

This paper introduces a design strategy to reduce rise time of charge pumps maintaining equal the silicon area, which is effective when the load capacitance is lower than the total charge pump capacitance. The strategy relies on an unconventional pumping capacitors sizing, which set them not equal and follows a linear distribution. The approach is based on a theoretical analysis and is validated through post-layout simulations using a 130-nm complementary metal-oxide semiconductor (CMOS) standard technology. The simulations demonstrate the advantages of the proposed design strategy and the accuracy of the theory.