Atmospheric transport of polybrominated diphenyl ethers and polychlorinated biphenyls to the Baltic Sea

The atmospheric transport of polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) was compared by measuring concentrations in air and deposition on an island located in the central basin of the Baltic Sea. Median sigmaPBDE and sigmaPCB concentrations (gaseous + particle) were 8.6 and 7.4 pg m(-3), respectively. Airborne PCBs were mainly found in the gaseous phase, while most of the PBDEs were detected on particles, which agrees with predicted particle/gas distributions. SigmaPBDE levels were dominated by the decabrominated BDE209 followed bythe tetrabrominated BDE47 and pentabrominated BDE99. BDE209 is a marker for the environmental distribution of the commercial deca-BDE formulation (>99.5% BDE209), whereas BDE47 and BDE99 are markers for the commercial penta-BDE mixture. General correlations between PBDEs and PCBs suggested similarities in sources and transport mechanism, while more detailed examination of the data identified notable behaviors and exceptions. Differences in regression slopes among tetra-, penta-, and decabrominated PBDEs may reflect different transport processes and the change in usage pattern. Tetra- and pentabrominated PBDEs may originate from secondary sources such as air surface exchange in a manner similar to that of the PCBs, while the deca-BDE209 formulation still has primary sources. The tribrominated BDE17 was also detected and is proposed to be a breakdown product due to atmospheric debromination processes. PBDEs had higher washout ratios than PCBs, explaining their higher concentrations compared to PCBs in precipitation (median of 6.0 and 0.5 ng L(-1) for sigmaBDE and sigmaPCB concentrations ("dissolved" + particle), respectively) than in air. The calculated yearly deposition of PBDEs and PCBs indicated that the atmospheric input of PBDEs to the Baltic Proper is currently exceeding that of the PCBs by a factor of 40, while that of the PCBs is decreasing.     

Fully integrated CMOS limiting amplifier with offset compensation network

A fully integrated CMOS limiting amplifier (LA) is presented. Its novel implementation of the offset compensation circuit completely removes bulky off-chip RC components. The LA is designed using a 0.18 mum CMOS technology and it obtains a 40 dB gain with a bandwidth of 1.8 GHz. The total power consumption is only 18.39 mW under a 1.8 V voltage supply.     

A Carrier-Based Unipolar PWM Current Controller That Minimizes the PWM-Cycle Average Current-Error Using Internal Feedback of the PWM Signals

A carrier-based unipolar pulsewidth modulation (PWM) current controller is described using a one-phase PWM rectifier bridge as a test circuit. The controller PWM signal generator uses a sawtooth carrier signal to obtain both synchronized PWM waveforms and a constant switching frequency. A current-error signal and an amplitude modulation depth signal are used to create the input reference signal to the PWM signal generator. The amplitude modulation depth signal is obtained from the PWM-cycle average of the PWM signal generator output signals. This internal feedback is illustrated using a second-order low pass Butterworth filter. With an appropriately designed low-pass filter, the current-error signal is forced to be centered on zero over a PWM cycle. The maximum peak-peak magnitude of the current-error signal is used as a design guideline for deciding an appropriate gain constant in the controller current feedback loop. The low pass filter design is examined to determine a suitable gain and 20-dB attenuation frequency to minimize the current-error signal. The steady-state and transient operation of the proposed current controller is compared with a proportional-integral controller and an average current-error controller. SPICE simulations and experimental results are used to demonstrate the characteristics of the controller.     

Effectiveness of Explicit Stations Grouping in Crowded Wireless LANs

In this letter, we evaluate the effectiveness of a multi-stage contention scheme for wireless local area networks (WLANs) medium access control (MAC). Multi-stage contention schemes basically divide the stations into smaller groups to resolve the contention more efficiently. Previous researchers have proposed virtual grouping schemes for WLANs MAC. Here we quantitatively analyze what can be achieved with a simple grouping scheme, i.e. through multi-stage contention. Our analysis shows that the multi-stage scheme is efficient in resolving contention, making it a good alternative to the commonly used exponential backoff mechanism.     

Highly Flexible Graphene Oxide Nanosuspension Liquid‐Based Microfluidic Tactile Sensor

A novel graphene oxide (GO) nanosuspension liquid‐based microfluidic tactile sensor is developed. It comprises a UV ozone‐bonded Ecoflex–polydimethylsiloxane microfluidic assembly filled with GO nanosuspension, which serves as the working fluid of the tactile sensor. This device is highly flexible and able to withstand numerous modes of deformation as well as distinguish various user‐applied mechanical forces it is subjected to, including pressing, stretching, and bending. This tactile sensor is also highly deformable and wearable, and capable of recognizing and differentiating distinct hand muscle‐induced motions, such as finger flexing and fist clenching. Moreover, subtle differences in the handgrip strength derived from the first clenching gesture can be identified based on the electrical response of our device. This work highlights the potential application of the GO nanosuspension liquid‐based flexible microfluidic tactile sensing platform as a wearable diagnostic and prognostic device for real‐time health monitoring. Also importantly, this work can further facilitate the exploration and potential realization of a functional liquid‐state device technology with superior mechanical flexibility and conformability.     

Challenges in the capture and dissemination of measurements from high-speed networks

The production of a large-scale monitoring system for a high-speed network leads to a number of challenges. These challenges are not purely technical but also socio-political and legal. The number of stakeholders in such monitoring activity is large including the network operators, the users, the equipment manufacturers and, of course, the monitoring researchers. The MASTS project (measurement at all scales in time and space) was created to instrument the high-speed JANET lightpath network and has been extended to incorporate other paths supported by JANET(UK). Challenges the project has faced included: simple access to the network; legal issues involved in the storage and dissemination of the captured information, which may be personal; the volume of data captured and the rate at which these data appear at store. To this end, the MASTS system will have established four monitoring points each capturing packets on a high-speed link. Traffic header data will be continuously collected, anonymised, indexed, stored and made available to the research community. A legal framework for the capture and storage of network measurement data has been developed which allows the anonymised IP traces to be used for research purposes.     

Regional cerebral volume loss associated with verbal learning and memory in dementia of the Alzheimer type.

Twenty-seven research participants with dementia of the Alzheimer type were studied with the California Verbal Learning Test (D. C. Delis, J. H. Kramer, E. Kaplan, & B. A. Ober, 1987) and standardized volume measures of the mesial temporal cortical gray matter, neocortical gray matter, thalamus, and caudate nuclei, from magnetic resonance imaging. A pattern of atrophic brain changes in the mesial temporal lobes (MTL) and the thalamus, with relatively less severe atrophy in the neocortical gray matter, was associated with poorer learning of the word list. Similar patterns of brain atrophy were observed for measures of delayed recall and recognition hits. However, for delayed recall, neither contribution was statistically significant, and for recognition hits, MTL was only at the trend level for significance. These results provide evidence that the verbal memory deficit of Alzheimer's disease (AD) is associated not only with the mesial temporal limbic cortex, thought to be the site of earliest and most severe pathology in AD, but also with damage in the thalamus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Granular biomass capable of partial nitritation and anammox

A novel and efficient way of removing nitrogen from wastewater poor in biodegradable organic carbon, is the combination of partial nitritation and anoxic ammonium oxidation (anammox), as in the one-stage oxygen-limited autotrophic nitrification/denitrification (OLAND) process. Since anoxic ammonium-oxidizing bacteria grow very slowly, maximum biomass retention in the reactor is required. In this study, a lab-scale sequencing batch reactor (SBR) was used to develop granular, rapidly settling biomass. With SBR cycles of one hour and a minimum biomass settling velocity of 0.7 m/h, OLAND granules were formed in 1.5 months and the nitrogen removal rate increased from 50 to 450 mg N L(-1) d(-1) in 2 months. The granules had a mean diameter of 1.8 mm and their aerobic and anoxic ammonium-oxidizing activities were well equilibrated to perform the OLAND reaction. Fluorescent in-situ hybridization (FISH) demonstrated the presence of both beta-proteobacterial aerobic ammonium oxidizers and planctomycetes (among which anoxic ammonium oxidizers) in the granules. The presented results show the applicability of rapidly settling granular biomass for one-stage partial nitritation and anammox.     

Rumours greatly exaggerated: Allport and Postman's apocryphal study.

Assessed the potential impact of stereotypical information on memory, using 107 undergraduates. Ss saw a series of slides depicting a violent knifing incident between 2 men on the London Underground. Half were shown the altercation as occurring between 2 White men and half between a Black and a White man. In all cases, the critical slide in which the knife was presented showed it to be in the hand of the White man. After a distraction interval of 45 min Ss were given forced-choice recognition and recall tests. The latter required the Ss to write a brief account of the event while the former required Ss to choose between 2 slides. Results indicate that, when the recognition test preceded the recall test, Ss who had seen the slides with the Black and White protagonists were less accurate than those who had seen only White protagonists. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)