The politics of conservative elites and the 'liberal media' argument

Recent evidence suggests that conservative elites' claims of a liberal media are having an impact upon public perceptions of news coverage. With this in mind, we examined two related questions in the context of the 1988, 1992, and 1996 presidential elections. First, what factors may be prompting conservative elites to make allegations of liberal media bias? Second, what factors may influence when news media report these criticisms during presidential campaigns? Findings suggest that these criticisms of news media are at least partly strategic and reflect a dynamic relationship between political elites and journalists during a presidential campaign.     

Creating an intelligent optical network worldwide interoperability demonstration

The Optical Internetworking Forum (OIF) conducted a world interoperability demonstration in conjunction with SUPERCOMM held in Chicago June 22-24, 2004. The demonstration was executed on a global stage with seven carriers across three continents internetworking through an intelligent control plane in a multivendor environment of 15 vendor participants. OIF's demonstration successfully included dynamic end-to-end connection management between client devices and transport network elements in a multidomain, multinode environment. The global connectivity included network elements (NEs) that incorporated the OIF optical user-to-network interface (UNI) and external network-to-network interfaces (E-NNI) among various vendors. Furthermore, carriers were able to test the new Ethernet over synchronous optical network/synchronous digital hierarchy (SONET/SDH) capabilities utilizing the generic framing procedure (GFP-F), virtual concatenation (VCAT), and the link capacity adjustment scheme (LCAS), based on International Telecommunication Union - Telecommunication Standardization Sector (ITU-T) recommendations. This article described the technical approach and execution of this demonstration.     

T-Ray Sensing and Imaging

T-ray wavelengths are long enough to pass through dry, nonpolar objects opaque at visible wavelengths, but short enough to be manipulated by optical components to form an image. Sensing in this band potentially provides advantages in a number of areas of interest to security and defense such as screening of personnel for hidden objects and the retection of chemical and biological agents. Several private companies are developing smaller, reliable cheaper systems allowing for commercialization and this motivates us to review a number of promising applications within this paper. While there are a number of challenges to be overcome there is little doubt that T-ray technology will play a significant role in the near future for advancement of security, public health, and defense.     

Tractography gone wild: probabilistic fibre tracking using the wild bootstrap with diffusion tensor MRI

Diffusion tensor magnetic resonance imaging (DT-MRI) permits the noninvasive assessment of tissue microstructure and, with fibre-tracking algorithms, allows for the 3-D trajectories of white matter fasciculi to be reconstructed noninvasively. Probabilistic algorithms allow one to assign a "confidence" to a given reconstructed pathway--but often rely on a priori assumptions about sources of uncertainty in the data. Bootstrap methods have been proposed as a way of circumventing this problem, deriving the uncertainty from the data themselves--but acquisition times for data amenable to precise and robust bootstrapping are clinically prohibitive. By combining the wild bootstrap, recently introduced to the DT-MRI literature, with tractography, we show how confidence can be assigned to reconstructed trajectories using data collected in a fraction of the time required for regular bootstrapping. We compare in vivo wild bootstrap tracking results with regular tracking results and show that results are comparable. This approach therefore allows users who have collected data sets for use with deterministic tracking algorithms, rather than those specifically designed for bootstrapping, to be able to apply bootstrap analyses and retrospectively assign confidence to their reconstructed trajectories with minimum additional effort.     

The detection of polyphosphate in broiler chicken breast muscle

The relationship between the concentration of sodium and phosphorus (as P₂O₅) in commercially processed broiler chicken breast muscle as a result of injection of various levels of sodium polyphosphate and sodium chloride has been studied and a routine analytical method which can confirm the presence or absence of the addition of these chemicals has been developed. The method is applicable to frozen, thawed or cooked broilers and is independent of moisture and protein content. Since polyphosphates may contain potassium as well as sodium salts, the relationship between these two elements in untreated commercially processed broiler breast muscle has also been measured and compared with treated birds. The analytical procedure has been applied to a survey of deep frozen broilers purchased from three local supermarkets.     

The 802.11n MIMO-OFDM Standard for Wireless LAN and Beyond

An overview is given of the new IEEE 802.11n standard. This is the first wireless LAN standard based on MIMO-OFDM, a technique pioneered by Airgo Networks to give a significant performance increase in both range and rate relative to conventional wireless LAN. Performance results show that net user throughputs over 100 Mbps are achievable, which is about four times larger than the maximum achievable throughput using IEEE 802.11a/g. For the same throughput, MIMO-OFDM achieves a range that is about 3 times larger than non-MIMO systems. This significant improvement in range-rate performance makes MIMO-OFDM the ideal solution not only for wireless LAN, but also for home entertainment networks and 4G networks. Richard van Nee received the M.Sc. degree in Electrical Engineering from Twente University in Enschede, the Netherlands, in 1990. In May 1995, he received the PhD degree from Delft University of Technology. From 1995 to 2000, he worked for Lucent Technologies Bell Labs on wireless LAN transmission techniques. He was one of the original proposers of the CCK and OFDM modulation techniques which were adopted by the IEEE 802.11b and IEEE802.11a wireless LAN standards. In 2001, he cofounded Airgo Networks that developed the first MIMO-OFDM modem for wireless LAN and which techniques form the basis of the IEEE 802.11n standard. Together with Ramjee Prasad, he wrote a book on OFDM, entitled ‘OFDM for Mobile Multimedia Communications.’ In 2002 he received the Dutch Veder award for his contributions to standardization of wireless communications.     

Pilotless Frame Synchronization via LDPC Code Constraint Feedback

In traditional receiver architectures, frame synchronization is performed using pilot symbols and a correlation rule. In this paper we show that outputs from the constraint node side of a bipartite decoding graph can be used to achieve frame synchronization in a pilotless low-density parity-check (LDPC) coded transmission, thereby avoiding the bandwidth cost inherent in use of pilot symbols. The complexity of the frame synchronizer is kept relatively low due to its XOR-based approach.     

Genetic design of linear antenna arrays

Discusses a way to optimize both the topology and the numerical parameters of an antenna design. The approach relies on an “antenna language” to define how antennas are constructed, and a genetic algorithm to create new designs using this language. The grammatical rules of a language can be very vague or very specific, depending on the purpose of the designer. With a vague grammar, genetic algorithms search a very large design space, and can occasionally find unexpected solutions to a design problem. Other times, they completely fail to find a reasonable solution because of the vastness of the search space. In this case, including knowledge about the problem into the grammar narrows the search to a region expected to yield good results. This yields more conventional design solutions that usually perform reasonably well. In an example, two languages were used to design a linear antenna array. The general language allowed a wide variety of designs, while the Yagi-log language confined the search to topologies known to perform well. The performance of the antennas produced by both languages was superior to that of a conventional log-periodic design. Further, the Yagi-log design was more fit than the unconventional design from the general language, illustrating the benefits of including knowledge in the grammar     

The properties of MOVPE grown 1.3 μm DFB MQW lasers infilled with semi-insulating InP fabricated on semi-insulating substrates

The use of optoelectronic integrated circuits (OEICs) is now emerging as a practical technology for a variety of applications, particularly in advanced telecommunications. OEICs consist of a range of devices such as lasers, waveguides, modulators, amplifiers, transistors, detectors, etc. fabricated on the same substrate. When a semi-insulating substrate is used, these devices can be electrically isolated by channel etching, resulting in a low capacitance structure with reduced electrical interference between the subcomponents. One of the devices which is particularly advantageous for this type of integration scheme is the distributed feedback (DFB) laser. The laser can be made to function more efficiently by minimizing the current flowing outside the active region. This can be achieved by surrounding the active region with semi-insulating iron doped InP. This work describes for the first time, the MOVPE growth, fabrication, and device characterization of 1.3 um buried heterostructure DFB MQW lasers, which combine the advantages of using both a semi-insulating substrate and a semi-insulating infill region in the same device structure. The potential advantage of this design scheme is improved OEIC performance as a result of, reduced capacitance and electrical crosstalk, enhanced laser output power, higher speed, increased efficiency, wider operating temperature and reduced threshold current. The laser active region consists of 8 x 140 Å quantum wells of GalnAsP (λ = 1.3 μm) and 110 Åbarriers of GalnAsP (λ= 1.07 μm). Single mode 1.3 urn devices of length 250 μm operating at room temperature produced threshold currents of 8 mA, efficiencies of up to 25%, output powers of 18 mW at 80 mA (pulsed), and a frequency response greater than 12GHz. The parasitic capacitance was estimated to be less than 3 pF.     

DC and large-signal time-dependent electron transport in heterostructure devices: an investigation of the heterostructure barrier varactor

The DC and large-signal time-dependent electron transport properties of Heterostructure Barrier Varactors (HBVs) are investigated using a physical model which combines drift-diffusion current transport through the heterostructure bulk with thermionic and thermionic-field emission currents imposed at the abrupt heterointerfaces in a fully self-consistent manner. A fast and accurate hydrodynamic device simulator for generic unipolar InGaAs-InAlAs on InP, InGaAs-InP on InP, and GaAs-InGaAs-AlGaAs on GaAs HBVs has been developed based on this model. The experimentally observed current-voltage and capacitance-voltage characteristics of GaAs-AlGaAs and GaAs-InGaAs-AlGaAs HBVs are compared with the simulated results over a wide range of DC bias. Large-signal time-dependent simulations at a pump frequency of 100 GHz confirm the odd-harmonic operation of these devices and indicate that multiple barrier HBVs should provide efficient frequency multiplication, especially in high order frequency multipliers, broadband frequency triplers, and quasi-optical tripler arrays.<>