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.     

Consumer assessment of the effect of electrical stimulation on the colour and colour stability of Semimembranosus muscles

The influence of effective low voltage electrical stimulation on the colour stability of beef topside (semimembranosus) muscles, during storage and retail display was studied using objective measurements and subjective assessments. Earlier results obtained from objective measurements demonstrated that during a three day retail display period, stimulated topsides had a greater loss of colour than non-stimulated topsides, and primal cuts aged for 33 days at 0 °C before display suffered faster changes to colour during retail presentation than cuts aged for 5 days. To relate results obtained using objective methods to consumer perceptions of meat quality, consumer perceptions of samples of meat displayed for 3 days in the retail cabinets of a major local supermarket were recorded. A total of 960 consumers were asked to evaluate topside steaks for meat and fat colour, meat discolouration and acceptability. During 3 days of retail display, consumers did not perceive differences in the extent of discolouration of topside steaks from electrically stimulated and non-stimulated carcasses; for the majority of the treatment groups (high or low pH muscles, 5 or 33 day ageing, 1-3 day retail display) there were no significant differences, for any of the scored attributes, between stimulated and non-stimulated samples. However, for samples in the fresh (5 days ageing), high pH (5.8-6.0) treatments group, lean meat colour and acceptability for the stimulated samples were, on some of the days on display, given significantly (P < 0.05) better ratings by the consumers than those from corresponding non-stimulated samples.     

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.<>     

Crystallographic orientation dependence of the growth rate for GaAs low pressure organometallic vapor phase epitaxy

The complete crystallographic orientation dependence of the growth rate for GaAs low pressure organometallic vapor phase epitaxy (LPOMVPE) is determined using a previously described semi-empirical model. A set of LPOMVPE growth rate polar diagrams is presented for reactor temperatures near 550°C as well as near 700°C. Also, the variation of the growth rate polar diagrams as a function of process variables is given. The experimental data utilized in the semiempirical model was attained using a typical horizontal reactor LPOMVPE system and typical LPOMVPE process parameters.     

Efficient representation of object shape for silhouetteintersection

A new shape representation-the radial intersection set (RIS)-is presented. The RIS is an object-centred model in which 2-D and 3-D boundaries are represented via their intersection with radial lines from some specific origin. The RIS representation allows efficient 3-D reconstruction using silhouette intersection from an arbitrary number of 2-D perspective views. The relationship between the visual hull (Laurentini, 1994) of the 3-D object and the silhouettes it may generate is defined as a set intersection operator. This operator allows the direct generation of 3-D RIS models from silhouettes. The RIS method is shown to compare favourably, in terms of both speed and storage, with existing octree techniques. Examples of images rendered from RIS models are presented. These show high visual fidelity     

Electronic Stabilization of Continuous-Wave and Pulsed Lasers Based on Macroscopic Rate-Equation Modelling

We present a macroscopic laser rate-equation model based on measurable laser parameters, allowing easy system identification. A numerical simulation based on the model is used in the design and testing of electronic laser feedback systems for intensity noise suppression and Q-switched pulse stabilization. A novel pulse energy control scheme is also presented, including experimental results.