Highly integrated direct conversion receiver for GSM/GPRS/EDGE with on-chip 84-dB dynamic range continuous-time /spl Sigma//spl Delta/ ADC

This paper describes a highly digitized direct conversion receiver of a single-chip quadruple-band RF transceiver that meets GSM/GPRS and EDGE requirements. The chip uses an advanced 0.25-/spl mu/m BiCMOS technology. The I and Q on-chip fifth-order single-bit continuous-time sigma-delta (/spl Sigma//spl Delta/) ADC has 84-dB dynamic range over a total bandwidth of /spl plusmn/135 kHz for an active area of 0.4 mm/sup 2/. Hence, most of the channel filtering is realized in a CMOS IC where digital processing is achieved at a lower cost. The systematic analysis of dc offset at each stage of the design enables to perform the dc offset cancellation loop in the digital domain as well. The receiver operates at 2.7 V with a current consumption of 75 mA. A first-order substrate coupling analysis enables to optimize the floor plan strategy. As a result, the receiver has an area of 1.8 mm/sup 2/.     

Incidence of neoplasms in ages 0-19 y in parts of Sweden with high 137Cs fallout after the Chernobyl accident

An experiment was conducted to elucidate the origin of tetraploids (2n = 4x = 44) of Paragonimus westermani that occur together with diploid (2n = 2x = 22) and triploid (2n = 3x = 33) types in Liaoning Province, the People's Republic of China. Metacercariae of the diploid type, obtained from Hyogo Prefecture, Japan, and those of the triploid type from Tsushima, Nagasaki Prefecture, Japan, were mixed and inoculated into dogs and cats. The following results were obtained. The flukes were found in pairs within cysts in random combinations of 2x + 2x, 2x + 3x, and 3x + 3x (7:15:7). Oocytes in the oviduct were at stages from diplotene to metaphase. In a triploid fluke encysted with a diploid fluke, the primary oocytes were intruded by sperms from the diploid fluke. In the primary oocytes of diploid as well as triploid flukes, from diplotene to diakinesis, the homologues of the nucleolar chromosomes were heteromorphic as far as the size of the short arm was concerned. This implies that the triploid is an autotriploid generated in an ancestral diploid population that was polymorphic for the nucleolar chromosome.     

Node cooperation in hybrid ad hoc networks

A hybrid ad hoc network is a structure-based network that is extended using multihop communications. Indeed, in this kind of network, the existence of a communication link between the mobile station and the base station is not required: A mobile station that has no direct connection with a base station can use other mobile stations as relays. Compared with conventional (single-hop) structure-based networks, this new generation can lead to a better use of the available spectrum and to a reduction of infrastructure costs. However, these benefits would vanish if the mobile nodes did not properly cooperate and forward packets for other nodes. In this paper, we propose a charging and rewarding scheme to encourage the most fundamental operation, namely packet forwarding. We use "MAC layering" to reduce the space overhead in the packets and a stream cipher encryption mechanism to provide "implicit. authentication" of the nodes involved in the communication. We analyze the robustness of our protocols against rational and malicious attacks. We show that-using our solution-collaboration is rational for selfish nodes. We also show that our protocols thwart rational attacks and detect malicious attacks.     

Application of particle swarm optimization in epileptic spike EEG source localization

Surgical therapy has become an important therapeutic alternative for patients with medically intractable epilepsy. Correct and anatomically precise localization of an epileptic focus is essential to decide if resection of brain tissue is possible. The inverse problem in EEG-based source localization is to determine the location of the brain sources that are responsible for the measured potentials at the scalp electrodes. We propose a new global optimization method based on particle swarm optimization (PSO) to solve the epileptic spike EEG source localization inverse problem. In a forward problem a modified subtraction method is proposed to reduce the computational time. The good accuracy and fast convergence are demonstrated for 2D and 3D cases with realistic head models. The results from the new method are promising for use in the pre-surgical clinic in the future.     

Simulations of time series of atmospherically distorted wave fronts

A comparatively simple way to generate time series of atmospherically distorted wave fronts is described and tested. Temporal power spectra of Zernike aberrations, extracted from the time series, agree very well with theoretical predictions. A method for generation of longer time series is also shown to give results in accordance with theory, except for the lowest temporal frequencies modeled. A way to superimpose several time series of wave fronts to generate a multilayer model of the atmosphere is briefly discussed.     

Predicting the electrospinnability of polymer solutions with electromechanical simulation

The number of polymers successfully electrospun is increasing, and methods are needed predict the electrospinnability of polymers. With such methods, researchers should consider the polymer solution parameters and perform measurements in conditions that mimic the electrospinning process. A novel test method based on the electromechanical simulation of the fiber formation was developed. We formed fibers by mechanically dragging a conductive ball from the solution at an applied voltage and measuring the electrical current. The changes in the time of the electrical current (the ball current) reflect the fiber‐formation process, which depended on certain polymer solution properties (e.g., viscosity, surface tension, liquid flow) and on the influence of charges on the fiber surface. The data obtained with the proposed method was compared with experimental data from electrospinning trials with the spinneret and bubble electrospinning. The results demonstrate that the ball‐current method made it possible to predict the polymer solution behavior in the electrospinning process. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41091.     

Distribution of bacteria in a domestic hot water system in a Danish apartment building

Bacterial growth in hot water systems seems to cause problems such as bad odor of the water, skin allergies and increased heat transfer resistance in heating coils. In order to establish a basis for long-term suppression of bacterial growth, we studied the distribution of bacteria in a Danish domestic hot water system. Heterotrophic plate counts (HPC) were measured in both water and biofilm samples from various sampling sites in the system. In hot water samples, where the temperature was 55-60 degrees C, the HPC were 10(3)-10(4)CFU/mL at incubation temperatures of 25 degrees C or 37 degrees C and 10(5)CFU/mL at 55 degrees C or 65 degrees C. In the cold water (10 degrees C) supplying the hot water system, the HPC at 25 degrees C or 37 degrees C was lower than in the hot water, and no bacteria were found after incubation at 55 degrees C or 65 degrees C. HPC constituted from 38% to 84% of the AODC results in hot water but only 2% in cold water, which showed a high ratio of culturable bacteria in hot water. Biofilm samples from the hot water tank and the inner surface of the pipes in the cold and hot water distribution system were collected by specially designed sampling devices, which were exposed in the system for 42 days. The quasi-steady-state number of bacteria in the biofilm, measured as the geometric mean of the HPC obtained between 21 and 42 days, was five-fold higher in the hot water pipe (13x10(5)CFU/cm(2) at 55 degrees C) than in the cold water pipe (2.8x10(5)CFU/cm(2) at 25 degrees C). There was no significant difference between the number of bacteria in the biofilm samples from the top, middle and bottom of the hot water tank, and the number of bacteria in the biofilm counted at 55 degrees C ranged from 0.6x10(4) to 1.7x10(4)CFU/cm(2). The surfaces of the sacrificial aluminum anodes and the heating coils in the hot water tank also contained high bacterial numbers. The measured number of bacteria in water and biofilm samples was related to the dimensions of the hot water system, and calculations showed that the majority of bacteria (72%) were located in the biofilm especially in the distribution system, which accounts for the greatest surface area. Free-living bacteria accounted for 26% and only a minor part of the bacteria were in the sludge in the hot water tank (2%).     

Studies of the wetting characteristics of liquid iron on dense alumina by the X-ray sessile drop technique

In the present work, the reaction between a molten iron drop and dense alumina was studied using the X-ray sessile-drop method under different oxygen partial pressures in the gas atmosphere. The changes in contact angles between the iron drop and the alumina substrate were followed as functions of temperature and varying partial pressures of oxygen in the temperature range 1823 to 1873 K both in static and dynamic modes. The results of the contact angle measurements with pure iron in contact with dense alumina in extremely well-purified argon as well as under different oxygen partial pressures in the gas atmosphere showed good agreement with earlier measurements reported in the literature. In the dynamic mode, when argon was replaced by a CO-CO₂-Ar mixture with a well-defined in the gas, the contact angle showed an initial decrease followed by a period of nearly constant contact angle. At the end of this period, the length of which was a function of the imposed, a further steep decrease in the contact angle was noticed. An intermediate layer of FeAl₂O₄ was detected in the scanning electron microscope (SEM) analysis of the reacted substrates. An interesting observation in the present experiments is that the iron drop moved away from the site of the reaction once the product layer covered the interface. The results are analyzed on the basis of the various forces acting on the drop.     

Joint High-Resolution Fundamental Frequency and Order Estimation

In this paper, we present a novel method for joint estimation of the fundamental frequency and order of a set of harmonically related sinusoids based on the multiple signal classification (MUSIC) estimation criterion. The presented method, termed HMUSIC, is shown to have an efficient implementation using fast Fourier transforms (FFTs). Furthermore, refined estimates can be obtained using a gradient-based method. Illustrative examples of the application of the algorithm to real-life speech and audio signals are given, and the statistical performance of the estimator is evaluated using synthetic signals, demonstrating its good statistical properties.