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Abstract: The success of system-on-a-chip (SoC) hinges upon a well-concerted integrated approach from multiple disciplines, such as device, design, and application. From the device perspective, rapidly improving VLSI technology allows the integration of billions of transistors on a single chip, thus permitting a wide range of functions to be combined on one chip. From the application perspective, numerous killer applications have been identified, which can make full use of the aforementioned functionalities provided by a single chip. From the design perspective, however, with greater device integration, system designs become more complex and are increasingly challenging to design. Moving forward, novel approaches will be needed to meet these challenges. This paper explores several new design strategies, which represent the current design trends to deal with the emerging issues. For example, recognizing the stringent requirements on power consumption, memory bandwidth/latency, and transistor variability, novel power/thermal management, multi-processor SoC, reconfigurable logic, and design for verification and testing have now been incorporated into modern system design. In addition, we look into some plausible solutions. For example, further innovations on scalable, reusable, and reliable system architectures, IP deployment and integration, on-chip interconnects, and memory hierarchies are all anticipated in the near future.

Resistivity logs have been used by seismic interpreters for many years to construct seismograms, particularly in hydrocarbon gas fields where sonic logs are scarce or absent. The correlation between the conventional synthetic seismogram made from density and sonic logs and the pseudo-synthetic seismogram made from density and resistivity logs has not been very satisfactory in the past because many of the pseudo-synthetic seismograms do not include the ‘gas effect’. Our research team has developed a method to correct for the gas effect, and thereby to improve the overall quality of the pseudo-synthetic seismogram. We apply this method to a well and then compare the improved results to a conventional seismogram made from the same well. Our research should be of interest to researchers in New Zealand, Taiwan and other Pacific Rim countries because of the similarities in the tectonic setting of these nations.

This work is focused on the optimization of the synthesis conditions of a Pt sol phase containing suspended metallic Pt nanoparticles with the primary goal being to produce thin (ca. 1 monolayer) Pt films having the highest possible electroactive surface area per gram. This is gauged here by the surface roughness factor, determined from the magnitude of the Pt electrochemical response in sulfuric acid solution. Two Pt(IV) chloride compounds (H2PtCl6, Na2PtCl6) are shown to be the best Pt precursors, producing stable Pt nanoparticles with an average particle diameter of 1−3 nm. Sodium ethoxide and formic acid are found to be excellent reducing agents of the PtCl62-anion, although formaldehyde results in a lower yield of Pt nanoparticles. A ratio of sodium ethoxide to H2PtCl6of 2:1 and a 72 °C reflux in ethanol between 30 min and 5 h resulted in the highest Pt roughness factor (ca. 8). Transmission electron microscopy analysis has verified that all of the reducing agents produce Pt particles of a similar size and that the higher roughness factors are the result of a higher yield of Pt nanoparticles. The effect of time of storage of Pt sols formed using sodium ethoxide showed that only a minor aging effect is observed over long periods of time, likely minimized by the stabilization offered by PtCl3(C2H4)-, a species formed as a byproduct during the synthesis.

To improve the reliability of telephone-based speaker verification systems, channel compensation is indispensable. However, it is also important to ensure that the channel compensation algorithms in these systems surpress channel variations and enhance interspeaker distinction. This paper addresses this problem by a blind feature-based transformation approach in which the transformation parameters are determined online without any a priori knowledge of channel characteristics. Specifically, a composite statistical model formed by the fusion of a speaker model and a background model is used to represent the characteristics of enrollment speech. Based on the difference between the claimant's speech and the composite model, a stochastic matching type of approach is proposed to transform the claimant's speech to a region close to the enrollment speech. Therefore, the algorithm can estimate the transformation online without the necessity of detecting the handset types. Experimental results based on the 2001 NIST evaluation set show that the proposed transformation approach achieves significant improvement in both equal error rate and minimum detection cost as compared to cepstral mean subtraction and Znorm.

Paraunitary filter banks are important for several signal processing tasks, including coding, multichannel deconvolution and equalization, adaptive beamforming, and subspace processing. In this paper, we consider the task of adapting the impulse response of a multichannel paraunitary filter bank via gradient ascent or descent on a chosen cost function. Our methods are spatio-temporal generalizations of gradient techniques on the Grassmann and Stiefel manifolds, and we prove that they inherently maintain the paraunitariness of the multichannel adaptive system over time. We then discuss the necessary practical approximations, modifications, and simplifications of the methods for solving two relevant signal processing tasks: (i) spatio-temporal subspace analysis and (ii) multichannel blind deconvolution. Simulations indicate that our methods can provide simple, useful solutions to these important problems.

AbstractThe aim of the present study was to evaluate the impact of highly active antiretroviral therapy (HAART) on HIV viral load of plasma and intraocular fluids in AIDS patients with ophthalmic opportunistic infections. We further compared the treatment effect of HAART on these patients. From June 1997 to July 2003, we examined and followed up the ophthalmic conditions of 49 patients receiving HAART with ophthalmic diseases during this period. The method of reverse-transcriptase polymerase chain reaction was used to detect and monitor HIV load in plasma and/or aqueous humor of AIDS patients. Before HAART, the HIV levels in the plasma and aqueous humor in 8 AIDS patients with ophthalmic opportunistic infections were significantly higher than those in 6 patients with HIV-related retinopathy (p < 0.05). Compared to the eye findings and clinical improvement, HIV loads of aqueous humor in 10 of 14 AIDS patients (6 with HIV-related retinopathy, 5 with cytomegalovirus retinitis, 2 with toxoplasmic retinitis and 1 with cryptococcal chorioretinitis) declined to undetectable levels (<400 copies/ml) after 4–8 months of HAART. HIV virus levels in the plasma of AIDS patients were significantly decreased, and the CD4 counts of these patients were significantly increased (Wilcoxon test) after initiation of HAART.Copyright © 2004 S. Karger AG, Basel

Background: Gln is an important substrate for enterocyte and rapid proliferation cells. Studies have shown that parenteral supplementation of Gln maintains the intracellular Gln pool, improves nitrogen balance and shortens hospital stay. However, some studies showed Gln-supplemented TPN had no effect on restoring the Gln pool in critically ill patients. Objective: To evaluate the effect of glutamine (Gln) dipeptide supplementation of total parenteral nutrition (TPN) on postoperative nitrogen balance and immune response of patients undergoing surgery. Methods: This study is a prospective, randomized double-blind clinical trial. APACHE II score and TISS were used to evaluate the patients after admission. Forty-eight patients with major abdominal surgery were allocated to two groups to receive isonitrogenous (0.228 g nitrogen/kg/day) and isoenergetic (30 kcal/kg/day) TPN for 6 days. Two groups (Conv and Ala-Gln) were further divided to high (APACHE6) and low (APACHE <6) groups. Control group (Conv) received 1.5 g amino acids/kg/day, whereas the Ala-Gln group received 0.972 g amino acids/kg/day and 0.417 g of L -alanyl- L -glutamine (Ala-Gln)/kg/day. Blood samples were collected on day 1 and day 6 after surgery for plasma amino acid and CD4, CD8 cell and T lymphocyte analysis. Cumulative nitrogen balance were also measured on day 2, 3, 4, 5 postoperatively. Results: Although there was a tendency to have better cumulative nitrogen balance on the postoperative days in the Ala-Gln group, no significant difference was observed between two groups. However, a better significant cumulative nitrogen balance was observed on the 2nd, 3rd and 5th postoperative day in the Ala-Gln group than in the Conv group in patients with APACHE II <6, whereas no significant difference was noted in patients with APACHE II  6. No difference in urine 3-methylhistidine excretion were observed between the 2 groups. Patients in the Ala-Gln group had significant higher T lymphocyte and CD4 cells than did those in the Conv group. Conclusion: TPN supplemented with Gln dipeptide had beneficial effect on enhancing the immune response. However, the effect of Ala-Gln administration on improving nitrogen economy was only observed in patients with low APACHE II scores. These results may indicate that Gln required for reversing the catabolic condition may depend on the characteristics and severity of the diseases. Copyright 2002 Published by Elsevier Science Ltd.

This paper proposes a generalized multipath separability conditionfor subspace processing and derives a novel COD(Combined Oversampling and Displacement) algorithm to utilize both spatial and temporal diversities for path separation, DOA (Direction of Arrival) estimation and signal recovery. A unique advantage lies in its ability to cope with the situation where the number of multipaths is larger than that of antenna elements, which has not been treated in the traditional approaches. CODstrategy solves the antenna deficiency problem by combining vertical expansion with temporal oversamplingand horizontal expansion with spatial displacement. We provide a detailed analysis on the theoretical footings for CODfactorization and multipath separability conditions, which naturally leads to CODpath separation and DOA estimation algorithms. Another advantage of CODfactorization hinges upon its ability to generate a multiplicity of eigenvalues which greatly facilitates a SIMO channel equalization formulation useful for signal recovery. This paper also proposes a frequency-domain total-least-square algorithm for SIMO equalization procedure. Finally, simulation results on path separation, DOA estimation and signal recovery are demonstrated.

A mathematical model for a three-dimensional omnidirectional integral recording camera system that uses either circular- or hexagonal-based spherical surface microlens arrays is derived. The geometry of the image formation and recording process is fully described. Matlab is then used to establish the number of recorded micro-intensity distributions representing a single object point and their dependence on spatial position. The point-spread function for the entire optical process for both close and remote imaging is obtained, and the influence of depth on the point-spread dimensions for each type of microlens and imaging condition is discussed. Comparisons of the two arrangements are made, based on the illustrative numerical results presented.

This paper presents extensions of stochastic gradient independent component analysis (ICA) methods to the blind deconvolution task. Of particular importance in these extensions are the constraints placed on the deconvolution system transfer function. While unit-norm constrained ICA approaches can be directly applied to the prewhitened blind deconvolution task, an allpass filter constraint within the optimization procedure is more appropriate. We show how such constraints can be approximately imposed within gradient adaptive finite-impulse-response (FIR) filter implementations by proper extensions of gradient techniques within the Stiefel manifold of orthonormal matrices. Both on-line time-domain and block-based frequency-domain algorithms are described. Simulations verify the superior performance behaviors provided by our allpass-constrained algorithms over standard unit-norm-constrained ICA algorithms in blind deconvolution tasks.

This paper develops three approximate methods for the analysis of patch damping designs. Undamped natural frequencies and modal loss factors are calculated using the Rayleigh energy method and modal strain energy technique, respectively, without explicitly solving high order differential equations or complex eigenvalue problems. Approximate Method I is developed for sandwich beams assuming that damped mode shapes are given by the Euler beam eigenfunctions. The superposition principal is then used to accommodate any arbitrary mode shape, which may be obtained from modal experiments or the finite element method. In Method II, the formulation is further simplified with the assumption of a very compliant viscoelastic core. Finally, Method III considers a compact patch problem. The modal loss factor is then expressed as a product of terms related to material properties, layer thickness, patch size and patch performance. Approximate Methods II and III are also extended to rectangular plates. Formulations are verified by conducting analogous modal measurements and by comparing predictions with those obtained using the Rayleigh–Ritz method (without making any of the above mentioned assumptions). Several example cases are presented to demonstrate the validity and utility of approximate methods for patch damping design concepts.

The problem of unbiased spectral estimation of narrowband signals in additive noise, colored or white, is addressed in this paper. Both recursive and non-recursive methods are presented. First, a recursive method, the adaptive notch filter working directly on the data is developed. Certain features of its realization i.e. cascade, modified gradient etc. are highlighted. Next, a non-recursive method, the Toeplitz approximation method working on second order statistics i.e. autocovariance is proposed. A approximation procedure based on singular value decomposition is discussed.

Comparison of the DNA sequences of the rbcL gene from three Nicotiana species reveals a high degree of homology among the 1431 bp in the coding region. Only eight base pair differences are observed between N. otophora and N. tabacum, and between N. otophora and N. acuminata. Four base pair differences are observed between N. acuminata and N. tabacum. Most changes are in the third position of the codon resulting in only two amino acid alterations when N. otophora and N. acuminata are compared with N. tabacum. Evidence is presented demonstrating that the amino acid compositions of the LS derived from the DNA sequence are related to the IEF cluster pattern. A single charged residue is responsible for the difference in cluster pattern.

The polypeptide compositions of fraction I protein isolated from six collections of Nicotiana glauca and from ten cultivars of N. tabacum, as well as a polyploid series and a male sterile line, have been analyzed by isoelectric focusing in polyacrylamide gel slabs containing 8 m urea. Apart from the male sterile line, none of the plants showed any variation from the species pattern of polypeptides. Fraction I protein from the male sterile Burley 21 cultivar of N. tabacum contained the two small subunit polypeptides of N. tabacum and the three large subunit polypeptides of an Australian species, probably N. megalosiphon. This indicates a changed chloroplast genome in the male sterile line in comparison to the normal fertile N. tabacum.

Using the existing restriction map and probes from wheat and pea ct-DNA, seven protein genes have been localized in the chloroplast genome of N. tabacum. On the clock-like map, the location of each gene is indicated by its time zone: the 15.2 kD polypeptide of the cytochrome b/f complex at 3:15, cytochrome f at 4:30, LS of RuBPCase at 4:50, both ß and ? subunits of ATP synthase at or near 5:00, proton-translocating subunit of ATP synthase at 8:20, a subunit of ATP synthase at 8:40 and the 32 kD protein at 9:30. The genome organization of Nicotiana chloroplast DNA is similar to spinach.

RuBPCase, the enzyme responsible for carboxylation and oxidation of RuBP in a wide variety of photosynthetic organisms, is the major protein found in the chloroplast. Here we present the first evidence for direct expression in E. coli and B. subtilis of tobacco and Chlamydomonas ct-DNA sequences coding for the LS of RuBPCase as demonstrated by a simple in situ immunoassay.

A physical map containing six restriction sites of the Nicotiana tabacum chloroplast genome, together with the BamHI maps of N. tabacum, N. otophora and N. knightiana, and the SmaI maps of N. acuminata, N. plumbaginifolia, N. langsdorffii, N. otophora, N. tabacum, N. tomentosiformis and N. knightiana was constructed. In Nicotiana chloroplast genomes, the most frequently observed variations are point mutations. Deletions are also detected. Most of the observed changes are confined to one area of the large single copy region, which is designated as the “hot spot”. Based on the evidence obtained from Nicotiana chloroplast genomes, an origin of the inverted repeats in this genus is proposed. We suggest that the inverted repeats represent a vestige of what were once two identical, complete chloroplast genomes joined together in a head-to-head and tail-to-tail fashion, and that deletions generated the current chloroplast genome organization.

Under greenhouse conditions the dark green wild type (su/su) tobacco grows 2–3 times faster than the yellow mutant (Su/su) and contains five-fold more chlorophyll. On a fresh weight basis, however, both genotypes contain similar amounts of RuBPCase and fraction 11 protein in approximately equal proportion and have similar levels of 70s and 80s ribosomes. When seedlings are cultured on agar medium supplemented with sucrose and equal concentrations of IAA and kinetin or kinetin alone, a drastic reduction of RuBPCase and free 70s ribosomes, but not of chlorophyll content, were observed. Moreover, albino (Su/Su) seedlings developed on supplemented media still contain appreciable amounts of RuBPCase and free 70s ribosomes although chlorophyll levels are extremely low indicating no correlation between RuBPCase and chlorophyll content. RuBPCase crystallized from both wild type and yellow mutant plants seem to have identical composition and structure when examined by isoelectric focusing, amino acid analysis or peptide mapping techniques. The slow-growing yellow mutant is apparently deficient only in chlorophyll of the light harvesting chlorophyll-protein complex but with no alteration of the protein moiety or chlorophyll a/b ratio.

The chloroplast DNA restriction fragment patterns of several higher plants from different classes, subclasses, orders, and families were examined. Regardless of the restriction enzyme used, there were few similarities among these restriction patterns. Within the genus Nicotiana, however, most of the restriction fragments were common to all species examined. The few uncommon fragments remaining were distributable with respect to the taxonomic classification of Nicotiana species. Estimates of divergence between selected families, genera, and species were obtained using data gathered from several restriction enzyme patterns.

What we observe as an apparent superluminal motion is the resultant velocity of Hubble flow and a local ejection. Taking Hubble flow into account, one can explain, problems posed for the relativistic beaming model, such as the one-sidedness problem and the untolerable extension of the depromected structure of some superluminal sources; the misalignment of small-and large-scale jets can be analyzed more appropriately. A significant by-product of the present investigation is the initiation to find a new way to determine the value of the Hubble constantH0, provided that one can observe the superluminal motion at much longer wavelengths, say, meter wavelengths.

The maximum volume of the closed Friedmann universe is further investigated and is shown to be 2p2R3(t), instead of p2R3(t) as found previously. This discrepancy comes from the incomplete use of the volume formula of 3-dimensional spherical space in the astronomical literature. Mathematically, there exists the maximum volume at any cosmic timet in a 3-dimensional spherical case. However, the Friedmann closed universe in expansion reaches its maximum volume only at the timetm of the maximum scale factorR(tm). The particle horizon has no limitation for the farthest objects in the closed Friedmann universe if the proper distance of objects is compared with the particle horizon as it should be. It will lead to absurdity if the luminosity distance of objects is compared with the proper distance of the particle horizon.

Summary The polypeptide composition of Fraction I protein fromNicotiana digluta, a synthetic species which arose by chromosome doubling following the interspecific hybridization ofN.glutinosa andN.tabacum, has been examined by isoelectric focusing. The composition of the protein fromN.digluta, which was identical to the protein from the infertile F1 hybridN.glutinosa xN.tabacum, showed 3 polypeptides in the large subunit and 4 polypeptides in the small subunit. The large subunit polypeptides were identical to those fromN.glutinosa, the maternal parent in the original hybridization, whereas the small subunit polypeptides were a composite of the small subunit polypeptides from bothN.glutinosa andN.tabacum. This analysis demonstrates how the polypeptide composition of Fraction I protein evolves during the origin of new species ofNicotiana.

This paper advocates digital VLSI architectures for implementing a wide variety of artificial neural networks (ANNs). A programmable systolic array is proposed, which maximizes the strength of VLSI in terms of intensive and pipelined computing and yet circumvents the limitation on communication. The array is meant to be more general purpose than most other ANN architectures proposed. It may be used for a variety of algorithms in both the retrieving and learning phases of ANNs: e.g., single layer feedback networks, competitive learning networks, and multilayer feed-forward networks. A unified approach to modeling of existing neural networks is proposed. This unified formulation leads to a basic structure for a universal simulation tool and neurocomputer architecture. Fault-tolerance approach and partitioning scheme for large or non-homogeneous networks are also proposed. Finally, the implementations based on commercially available VLSI chips (e.g., Inmos T800) and custom VLSI technology are discussed in great detail.

Phorbol 12-myristate 13-acetate (PMA) uncaps a small number of the fast-growing (barbed) ends of actin filaments, thereby eliciting slow actin assembly and extension of filopodia in human blood platelets. These reactions, which also occur in response to immunologic perturbation of the integrin glycoprotein (GP) IIb-IIIa, are sensitive to the phosphoinositide 3-kinase inhibitor wortmannin. Platelets deficient in GPIIb-IIIa integrins or with GPIIb-IIIa function inhibited by calcium chelation or the peptide RGDS have diminished PMA responsiveness. The effects of PMA contrast with thrombin receptor stimulation by >/=5 microM thrombin receptor-activating peptide (TRAP), which causes rapid and massive wortmannin-insensitive actin assembly and lamellar and filopodial extension. However, we show here that wortmannin can inhibit filopod formation if the thrombin receptor is ligated using suboptimal doses (<1 microM) of TRAP. Phosphatidylinositol 3,4-bisphosphate inhibits actin filament severing and capping by human gelsolin in vitro. The findings implicate D3 polyphosphoinositides and integrin signaling in PMA-mediated platelet stimulation and implicate D3 containing phosphoinositides generated in response to protein kinase C activation and GPIIb-IIIa signaling as late-acting intermediates leading to filopodial actin assembly.

A new analytical, energy based approach that predicts the vibration characteristics of a rectangular plate with multiple viscoelastic patches is presented. This paper extends the method presented earlier by the authors that was applied to the determination of the eigensolutions of viscoelacstically damped beams. The method first relates all motion variables of a sandwich plate in terms of the flexural displacement of the base structure. Then the flexural shape function sets are incorporated in the Rayleigh–Ritz minimization scheme to obtain a complex eigenvalue problem. This method allows for the visualization of complex models of all deformations of the viscoelastic core that are the major contributors to the overall energy dissipation. Comparison with the work of three prior investigators on a simply supported plate validates the model for the limiting case of full coverage. Benchmark experimental measurements are made on a plate with free edges, and five damping cases are considered. Analytical predictions of natural frequencies, modal loss factors and complex modes for all cases are in excellent agreement with modal measurements. A normalization scheme for complex mode shapes has also been developed. Finally, simplified loss factor estimation procedures are presented to illustrate the additive effect of damping patches.

Herpesvirus saimiri is a lymphotropic herpesvirus capable of immortalizing and transforming T cells both in vitro and in vivo. Immortalized and transformed T cells harbor several copies of the viral genome as a persisting genome. The mapping of the cis-acting genetic cis-acting segment (oriP) required for viral episomal maintenance is reported here. Viral DNA fragments that potentially contain oriP were cloned into a plasmid that contains the hygromycin resistance gene. After several round of subcloning followed by transfection, oriP was mapped to a 1.955-kb viral segment. This viral fragment permits stable plasmid replication without deletion or rearrangement as well as episomal maintenance without integration or recombination. The function of oriP depends on a trans-acting factor(s) encoded by the viral genome. The 1.955-kb viral segment includes a dyad symmetry region located between two small nuclear RNA genes and is located upstream of the dihydrofolate reductase gene homolog. Therefore, this oriP contains novel elements distinct from those of other DNA viruses.

We present new high-resolution methods for the problem of retrieving sinusoidal processes from noisy measurements. The approach taken is by use of the so-called principal-components method, which is a singular-value-decomposition-based approximate modeling method. The low-rank property and the algebraic structure of both the data matrix and the covariance matrix (under noise-free conditions) form the basis of exact modeling methods. In a noisy environment, however, the rank property is often perturbed, and singular-value decomposition is used to obtain a low-rank approximant in factored form. The underlying algebraic structure of these factors leads naturally to least-squares estimates of the state-space parameters of the sinusoidal process. This forms the basis of the Toeplitz approximation method, which offers a robust Pisarenko-like spectral estimate from the covariance sequence. Furthermore, the principle of Pisarenko’s method is extended to harmonic retrieval directly from time-series data, which leads to a direct-data approximation method. Our simulation results indicate that favorable resolution capability (compared with existing methods) can be achieved by the above methods. The application of these principles to two-dimensional signals is also discussed.

Dynamic Programming (DP) applies to many signal and image processing applications including boundary following, the Viterbi algorithm, dynamic time warping, etc. This paper presents an array processor implementation of generic dynamic programming. Our architecture is a SIMD array attached to a host computer. The processing element of the architecture is based on an ASIC design opting for maximum speed-up. By adopting a torus interconnection network, a dual buffer structure, and a multilevel pipeline, the performance of the DP chip is expected to reach the order of several GOPS. The paper discusses both the dedicated hardware design and the data flow control of the DP chip and the total array.

This paper is devoted to VLSI implementation of a staged decoder for Block-Coded Modulation (BCM). We first review a general parallel and pipelined implementation of the decoder and we identify the parameters to be considered for optimization. A particular BCM scheme, based on the 8-PSK signal set, is chosen for a case study. Several ideas are described leading to a code-optimized design, and hardware implementation is shown. Next, we evaluate the performance of our design. In particular it is shown that, by exploiting regularity, a simple structure which achieves a throughput rate of 10 Mbps can be implemented by using 23 K transistors and 2Μstandard cells CMOS technology. Further optimization and simple stacking of ten processors on a single chip in a block-processing structure allows us to achieve a throughput rate of 100 Mbps with about 150 K transistors (38 K gates).

We present a fast and numerically advantageous algorithm for solving minimal design problems(MDP) and a new, simpler test for the existence of a proper solution of the MDP.

Nicotiana chloroplast genomes exhibit a high degree of diversity and a general similarity as revealed by restriction enzyme analysis. This property can be measured accurately by restriction enzymes which generate over 20 fragments. However, the restriction enzymes which generate a small number (about 10) of fragments are extremely useful not only in constructing the restriction maps but also in establishing the sequence of ct-DNA evolution. By using a single enzyme, Sma I, a elimination and sequential gain of its recognition sites during the course of ct-DNA evolution is clearly demonstrated. Thus, a sequence of ct-DNA evolution for many Nicotiana species is formulated. The observed changes are all clustered in one region to form a “hot spot” in the circular molecule of ct-DNA. The mechanisms involved for such alterations are mostly point mutations but inversion and deficiency are also indicated. Since there is a close correlation between the ct-DNA evolution and speciation in Nicotiana a high degree of cooperation and coordination betwen organellar and nuclear genomes is evident.

The corrosion resistance of several candidate furnace-wall materials was evaluated in a laboratory retort, simulating the reducing—sulfidizing combustion environment existing in PC-fired utility boilers burning coal substiochiometrically. These materials, including three alloys and nine coatings, were exposed to a mixed gas containing 400 ppm H2S, 100 ppm HC1, 900 ppm SO2, and other essential gaseous components at 800°F (°C) for 1000 hours with and without the coverage of a chloride-bearing ash deposit. The nine coatings consisted of three weld overlays, two diffusion coatings, and four thermal-spray coatings. The test results indicate that sulfidation was the primary mode of attack on unprotected low—Cr steels, such as SA213—T2. Furthermore, the role of 900 ppm SO2in the corrosion mechanism varied significantly with the Cr content in the alloys. A Cr concentration of approximately 9 wt% appeared to be a threshold, below which the scale surface favoured the catalytic conversion of SO2to H2S, thus increasing the local H2S concentration and gas corrosivity. Above this threshold, the SO2reacted with Cr in the alloy preferentially to form Cr2O3, resulting in a reduced sulfidation attack. With relatively high Cr concentrations, the weld overlays generally performed well in the simulated reducing—sulfidizing combustion environment. Both diffusion coatings also exhibited satisfactory resistance to the mixed gas under the test condition employed. However, the protectiveness of the thermal-spray coatings was limited by their porous coating microstructures, which allowed local penetration of sulfur into the base metal. The HVOF process appeared to produce a denser coating than the arc spray and thus provided better corrosion resistance. No effect was found from the addition of a small amount of HC1 to the mixed gas and chlorides to the ash on the furnace-wall corrosion. The probable corrosion mechanism is briefly discussed.

A new analytical, energy based approach is described that predicts the harmonic vibration response of a damped beam with multiple viscoelastic patches. Each damping patch consists of a metallic constraining layer and an adhesive viscoelastic layer with spectrally-varying material properties. Since this approach relates all deformation variables in various layers, only flexural shape functions need to be incorporated in the complex eigenvalue problem. Consequently flexural, longitudinal and shear deformation eigenvectors can be calculated. In particular, the shear deformation modes of the viscoelastic core provide useful information regarding the effect of patch damping. The proposed method has been validated by comparing predictions with modal measurements and with those published in the literature. Also, an estimation technique is developed that determines the shear modulus and loss factor properties of two different viscoelastic materials used in experimental studies. An uncertainty study is also performed to establish the error bounds of the estimated material loss factors. Effects of patch boundary conditions, patch cutouts and locations, and mismatched patch combinations are analytically and experimentally examined.

An insertion element, ISAE1, was discovered during the molecular analysis of mutants defective in the autotrophic growth (Aut-) of Alcaligenes eutrophus H1-4, a mitomycin C-generated derivative of strain H1. ISAE1 is 1,313 bp long, has 12-bp nearly perfect inverted terminal repeats, and contains an open reading frame that has a coding capacity of 408 amino acids. Direct repeats of 8 bp were generated by insertion of ISAE1 into chromosomes or plasmids. Most insertion were found in the AT-rich target sites. The distribution of ISAE1 is limited to A. eutrophus H1 (ATCC 17698) and H16 (ATCC 17699). Variants with newly transposed copies of ISAE1 could be isolated at an elevated frequency by changing the growth conditions.

Electrofocusing of carboxymethylated, crystalline Fraction I proteins in polyacrylamide gels containing 8 M urea resolves the large subunit into three major peptides and the small subunit into one or more peptides. Electrofocusing of proteins isolated from leaves of the reciprocal, F1, hybrids: N. glutinosa x N. tabacum, N. glauca x N. tabacum, N. glauca x N. langsdorfii and the parental species confirms that coding information for the large subunit is inherited only by the maternal line whereas both parents contribute coding information for the small subunit. The analysis shows that one or more of the three peptides of the large subunit of Fraction I proteins from different Nicotiana species differ in isoelectric point and therefore serve as phenotypic markers for chloroplast DNA genes.

The analysis of restriction patterns of chloroplast DNA (ct-DNA) generated by several enzymes reveals that there is a high frequency of ct-DNA alteration in the male sterile but not in the fertile cytoplasma of N. tabacum. The altered restriction patterns and maps suggest that recombination of ct-DNA may have occurred. However, other alternatives such as deletions, insertions, and/or point mutations cannot be ruled out.

Summary: A total of 27 out of 28 BamHI restriction fragments of N. otophora ct-DNA have been stably cloned into plasmid pBR322. Each cloned fragment was identified by its electrophoretic mobility. By using this cloned library and a second restriction enzyme, SmaI, a physical map of N. otophora ct-DNA, was also constructed. The genes for rRNA and the LS of RuBPCase have been localized in the clone and marked on the map. No unusual structural feature of Nicotiana ct-DNA was detected in this species. Attempts to perform the in vivo expression of the cloned fragments employing the plasmid-directed protein synthesis system in maxicells met with some success. It is clearly demonstrated that certain cloned ct-DNA fragments could direct the synthesis of chloroplast polypeptides in E. coli.

Summary: N. accuminata has a chloroplast genome of 171 Kb which is larger than 160 Kb reported for N. tabacum. A physical map of the former has been constructed by SalI, BglI, and PvuII enzymes in comparison with N. tabacum. They both share identical restriction map except in the extra segment of N. accuminata. This extra segment is located on the right-hand border of an inverted repeat in the large-single copy region of N. accuminata. It contains the following restriction sites: two for BglI and SmaI; three for SalI and XhoI. The size of inverted repeat measured by electron microscope is 22.67±0.78 Kb and 19.28±0.61 Kb for N. accuminata and N. tabacum, respectively. This is the first case where a larger inverted repeat region accompanied by a larger genome size was found among over 30 Nicotiana species studied thus far.