Optimal receive filters for the suppression of ISI and adjacentchannel interference

A new efficient method for the design of finite impulse response (FIR) digital receive filters is proposed. The authors formulate a cost function which minimises the total mean square error and thus reduces the effect of channel noise, intersymbol interference (ISI), and adjacent channel interference (ACI) simultaneously. Also, arbitrary fractional-sample delay can be compensated. The resulting filters are analysed in terms of bit error rate (BER) and implementation loss (IL) performance     

Mammalian Auditory Responses to 3.0 GHz Microwave Pulses

A study of the effects of 3.0 GHz microwave pulses on the auditory systems of a number of mammalian species was conducted. Some human subjects heard a distinct "click" when irradiated with a sufficiently intense individual microwave pulse. Microwave induced auditory evoked responses were measured in the cat, dog, and chinchilia. The microwave peak power density levels at the threshold of producing an auditory response were determined for a number of human subjects in addition to the smaller animals. The inability of some of the human subjects to bear short microwave pulses was correlated with hearing losses above 8 kHz in frequency.     

Challenges in the Verification of Mobile <Emphasis Type="Italic">Ad Hoc</Emphasis> Networking Systems

Mobile Ad Hoc Network (MANET) techniques are critical to the success of emerging modern warfare concepts and are required to support communications for mobile military platforms, including ships, aircrafts, and ground vehicles operating in a highly dynamic and mobile tactical communications network without fixed infrastructure. Research in Mobile Ad Hoc Networking has increased dramatically over the last few years with significant work in hardware architectures, media access and routing protocols. Until now, most of the work has been in simulation and small-scale laboratory demonstrations due to the significant resources required to implement an actual network with sufficient nodes to fully exercise the capabilities of both the hardware and software. There is significant need to develop testbeds to fully understand the behavior of ad hoc networks, performance under real-world application scenarios. This paper describes a testbed for a real system application exercised in an outdoor environment which approximates very closely the physical operational environment. The ad hoc network performance results include throughput and delay under conditions of mobility and foliage.     

Amine-quinone polyurethanes. I. Preparation of polyurethane block copolymers containing 2,5–bis(N-2-hydroxyethyl-N-methylamino)-1,4–benzoquinone diol monomer

The amine-quinone monomer, 2,5–bis(N-2-hydroxyethyl-N-methylamino)-1,4-benzoqui-none (AQM-1), was prepared by the multiple-step condensation of 2-(N-methylam-ino)ethanol with benzoquinone in the presence of oxygen. This crystalline monomer was used to prepare a series of amine-quinone polyurethanes by condensation polymerization, either in the melt or in solution (THF or DMF), with a diisocyanate (MDI, TDI, or IPDI) and an oligomeric diol [poly(caprolactone) or poly(1,2-butylene glycol)]. The amine-quinone functional group was stable under the polymerization conditions, and was incorporated into the main chain, giving red-brown polyurethanes that had molecular weights in the range of 11,000–90,000 and were soluble in THF, MEK, DMF, and DMSO. The thermal properties were consistent with a two-phase morphology with an amorphous soft segment, containing the oligomeric diol, and a microcrystalline hard segment, containing AQM-1. The polymers having a low hard segment content (<50%) were rubbery (soft segment T_g <?25°C); polymers having a high hard segment content (>50%) were thermoplastic (hard segment T_g>150°C). © 1995 John Wiley & Sons, Inc.     

Phosphorous-filled nanobrick wall multilayer thin film eliminates polyurethane melt dripping and reduces heat release associated with fire

Unique trilayer (TL) thin films of sodium montmorillonite (MMT), poly(allylamine hydrochloride) (PAH) and poly(sodium phosphate) (PSP) are prepared via layer-by-layer (LbL) assembly. This three-component nanocoating completely shuts down melt dripping and reduces heat release of open-celled flexible polyurethane (PU) foam when exposed to direct flame due to a synergistic interaction between PSP and the thermally shielding clay platelets in the condensed phase. Post burn scanning electron microscopy reveals the nanocoating's swollen morphology is able to maintain foam shape, cellular structure, and porosity. Cone calorimetry reveals that 4 TL coated foams (<3 wt% addition) have a peak heat release rate that is reduced by 54% relative to the uncoated control. Using LbL assembly, this work combines two common flame-retarding mechanisms (thermal shielding clay and intumescing PAH/PSP) in a single coating system and provides a foundational platform for new environmentally-benign flame retardant strategies for various substrates (e.g., foam found in home furnishings).     

Analysis of free and bound phenolics in wine and grapes by GC–MS after automated SPE

The results of validation of a method for the analysis of free and bound phenolics in wine and grapes are presented. Wine and grape extracts are fractionated by automated solid-phase extraction on Bond Elut PPL cartridges to give free and bound phenolic fractions. Bound fractions are subjected to acid hydrolysis, and the phenolics released are recovered by solid-phase extraction on Bond Elut PPL cartridges. The fractions are further purified by automated solid-phase extraction on Bond Elut silica cartridges. After derivatisation to form trimethylsilyl ethers, the phenolics are determined by gas chromatography–mass spectrometry with selected ion monitoring. The method is suitable for robust, high-throughput monitoring of the concentrations of phenolics that can affect the palatability of wine.     

Metal-sensitive and thermostable trypsin from the crevalle jack (<Emphasis Type="Italic">Caranx hippos</Emphasis>) pyloric caeca: purification and characterization

Background

Over the past decades, the economic development and world population growth has led to increased for food demand. Increasing the fish production is considered one of the alternatives to meet the increased food demand, but the processing of fish leads to by-products such as skin, bones and viscera, a source of environmental contamination. Fish viscera have been reported as an important source of digestive proteases with interesting characteristics for biotechnological processes. Thus, the aim of this study was to purify and to characterize a trypsin from the processing by-products of crevalle jack (Caranx hippos) fish.

Results

A 27.5 kDa trypsin with N-terminal amino acid sequence IVGGFECTPHVFAYQ was easily purified from the pyloric caeca of the crevalle jack. Its physicochemical and kinetic properties were evaluated using N-α-benzoyl-_DL-arginine-p-nitroanilide (BApNA) as substrate. In addition, the effects of various metal ions and specific protease inhibitors on trypsin activity were determined. Optimum pH and temperature were 8.0 and 50°C, respectively. After incubation at 50°C for 30 min the enzyme lost only 20% of its activity. K _m , k_cat, and k _cat /K _m values using BApNA as substrate were 0.689 mM, 6.9 s^-1, and 10 s^-1 mM^-1, respectively. High inhibition of trypsin activity was observed after incubation with Cd²⁺, Al³⁺, Zn²⁺, Cu²⁺, Pb²⁺, and Hg²⁺ at 1 mM, revealing high sensitivity of the enzyme to metal ions.

Conclusions

Extraction of a thermostable trypsin from by-products of the fishery industry confirms the potential of these materials as an alternative source of these biomolecules. Furthermore, the results suggest that this trypsin-like enzyme presents interesting biotechnological properties for industrial applications.

     

Ultrashort laser pulse bioeffects and safety.

Recent studies of retinal damage due to ultrashort laser pulses have shown that less energy is required for retinal damage for pulses shorter than 1 ns than that for longer pulses. It has also been shown that more energy is required for near-infrared (NIR) wavelengths than in the visible because the light focuses behind the retina, requiring more energy to produce a damaging fluence on the retina. We review the progress made in determining the trends in retinal damage from laser pulses of 1 ns to 100 fs in the visible and NIR wavelength regimes. We have determined the most likely damage mechanism(s) operative in this pulse width regime.