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Obstructive sleep apnoea (OSA) syndrome is a common sleep disorder in which recurrent apnoea and hypopnoea produce repeated episodes of hypoxemia followed by reoxygenation. We previously demonstrated that OSA was associated with telomere shortening and increased susceptibility to cell senescence [1]. The cyclin-dependent kinase inhibitor p21, the main effector of p53, is activated in response to DNA damage and telomere dysfunction but is down-regulated by certain clock genes. Sleep abnormalities also disrupt endogenous circadian clock genes, more specifically Rev-Erbα, a central transcriptional repressor of the molecular clock that downregulates p21 expression.

In this paper we consider PI-algebras Aover the real and complex numbers and address the question of whether it is possible to find a normed PI-algebra Bwith the same polynomial identities as A, and moreover, whether there is some Banach PI-algebra with this property. Our main theorem provides an affirmative answer for this question and moreover we also show the existence of a Banach Algebra with the same polynomial identities as A. As a byproduct we prove that if Ais a normed PI-algebra and its completion is nil, then Ais nilpotent.

Residual feed intake (RFI) and its relationship with reproductive traits was evaluated in growing bulls. Fifty-two growing Purunã bulls (11 mo initial age) were fed ad libitum in individual feedlot pens for 112 d. The animals were ranked for RFI and assigned to 3 feed efficiency groups: efficient (low RFI), intermediate (medium RFI), and inefficient (high RFI). Initial and final BW and ADG did not differ (P> 0.10) among the efficiency groups and were mean values of 254.6 (SD 44), 373.0 (SD 62), and 1.06 kg (SD 0.25), respectively. Mean values of 7.12 ± 0.28, 7.78 ± 0.28, and 8.04 ± 0.28 kg/d for DMI and −0.38 ± 0.04, −0.02 ± 0.04, and 0.51 ± 0.04 kg of DM/d for RFI were observed in the efficient, intermediate, and inefficient groups, respectively. Crude protein and ME intake were strongly correlated (r= 0.74, P< 0.001 for both variables) with RFI and were lower (P< 0.10) in the efficient group (13.6 ± 0.2 g DM/kg BW0.75∙d and 0.252 ± 0.003 Mcal/kg BW0.75∙d, respectively) and greater (P< 0.10) in the inefficient group (15.3 ± 0.2 g DM/kg BW0.75∙d and 0.282 ± 0.003 Mcal/kg BW0.75∙d, respectively). Testicular measures (width, length, volume, ultrasonogram pixel intensity, and scrotum perimeter) and serum testosterone were not correlated with RFI (P> 0.10) but showed moderate to strong correlations with initial BW (rranged from 0.36 to 0.51, P≤ 0.01), final BW (rranged from 0.36 to 0.64, P≤ 0.01), and ADG (rranged from 0.29 to 0.53, P< 0.05). All the reproductive traits (testicular measurements and concentrations of serum testosterone) showed similar values among the efficiency groups. During the growth phase, feed intake and protein and energy requirements were decreased in more efficient bulls in terms of RFI. However, both groups maintained similar BW and ADG. Regardless of their RFI classification, Purunã bulls had the same reproductive traits during the growth phase.

Type 1 diabetes (T1D) is a multifactorial disease that has a strong genetic component. The HLA-Gis a nonclassical HLAclass I locus that is associated with immunomodulatory functions, including downregulation of innate and adaptive immune responses and induction of immune tolerance. However, there is currently limited information about the involvement of HLA-Gin T1D susceptibility. This case-control study aims to investigate the T1D susceptibility association of alleles and genotypes of a widely investigated 14-bp insertion/deletion polymorphism in the HLA-Gand to provide further evidence of the frequency distribution of class II HLA-DR-DQ-risk genotypes in T1D children and adolescents in the Brazilian population. The deletion allele and the homozygous deletion genotype are associated with susceptibility to T1D and the insertion allele and the heterozygous deletion/insertion genotype are associated with protection from T1D. We also confirm that genetic susceptibility to T1D is associated with the DRB1*03:01-DQA1*05:01-DQB1*02:01and DRB1*04-DQA1*03:01-DQB1*03:02haplotypes in Brazilian northeast region. The DR3-DQ2/DR4-DQ8 genotype conferred the highest detected risk for T1D. Our results identify a novel association of the 14-bp deletion allele and the homozygous deletion genotype with T1D development and provide additional evidence of the importance of HLAclass II heterozygous DR3-DQ2/DR4-DQ8 genotype in T1D susceptibility.

This study was conducted to assess the effects of dietary energy in late pregnancy and hormone therapy at weaning on plasma metabolite profile, litter performance, reproductive parameters, and embryo viability in the second pregnancy. A total of 23 first-parity sows at 75 d of pregnancy were randomly allocated to 4 treatments. Treatments were factorial (2 × 2) combinations of 2 nutritional strategies [standard-energy feed (SEF) and high-energy feed (HEF)] and 2 hormone therapies [600 IU eCG and 2.5 mg swine LH 72 h later (HO) and no hormone (WH)]. Sows were weighed weekly from 75 d of pregnancy until 3 d before farrowing; 1 d after farrowing; 7, 14, and 21 d into lactation; and at weaning. Back fat (BF) was measured at 75 d of pregnancy, 3 d before farrowing, and at weaning. Average daily gain and ADFI were also calculated. Plasma metabolites were analyzed after 82, 89, 96, and 103 d of pregnancy, at farrowing, and after 7, 14, and 21 d of lactation. Embryo viability was assessed after 4.55 d of second pregnancy. During pregnancy, HEF-treated sows displayed greater BW (P < 0.05) compared with SEF-treated females, but no differences were observed during lactation. There were no differences in BW of the piglets caused by the treatments. High-energy-treated females showed superior BF (P > 0.05) in all periods; however, significant differences were detected only at the prefarrowing measurement (P < 0.05). No differences in ADFI were observed during lactation. The SEF group showed positive ADG, whereas the HEF group showed negative ADG (0.216 vs. -0.266 kg/d for SEF and HEF, respectively; P < 0.05). High-energy-treated sows presented greater concentrations of total cholesterol after 89 and 103 d of pregnancy and greater concentrations of high-density lipid cholesterol (HDL) after 89 and 96 d. At farrowing and 14 and 21 d of lactation, NEFA concentrations were greater (P < 0.05) in the HEF group. After hormone treatment, no differences were observed on weaning-to-estrus intervals and estrus duration. Greater mobilization of body reserves observed in the HEF group during lactation did not affect reproductive performance negatively, suggesting that metabolic status was adequate for the first lactational catabolism.

This paper describes the determination of diclofenac (DCF) in pharmaceutical formulations using flow injection method with multiple pulse amperometric detection. Unmodified boron‐doped diamond (BDD) is used as working electrode and 0.10 mol L−1sulfuric acid as supporting electrolyte. The system exhibited sharp current response peaks and excellent stability of the analytical signal (RSD=1.0 %, n=10). The linear response range from 5 to 50 µmol L−1was obtained by using an injected volume of 50 µL, with good correlation coefficient (R=0.998). The limits of detection (LOD) and quantification (LOQ) were found to be 0.14 and 0.46 µmol L−1, respectively. The sampling frequency was calculated about 135 injections h−1.

Nitrogen (N) is the primary limiting factor to increase wheat (Triticum aestivumL.) yield in Brazil, and the use of N‐fixing agents might be an alternative to increase wheat production. A field experiment was conducted in 2006 in São Paulo State, Brazil, with three N rates (0, 60, and 120 kg ha−1) and three endophytic bacteria (IAC‐HT‐11, IAC‐HT‐12, and IAC‐AT‐8) to evaluate their combined impact on biophysical (leaf area index [LAI] and grain yield) and spectral parameters (normalized difference vegetation index [NDVI], absorption band parameters) of wheat and to determine the spectral parameters that best correlated with LAI and grain yield. Leaf area index and canopy spectral reflectance measurements were made at jointing, heading, and ripening growth stages for this purpose. The statistical relationships between biophysical and spectral parameters were evaluated within and among the treatments. Statistical results showed that the N rates significantly affected biophysical and spectral parameters. Bacteria inoculation presented a significant effect only on grain yield, which is consistent with results reported in the literature. The NDVI, followed by absorption band parameters PBand ABat 1205 nm, provided the best estimates of LAI and grain yield during the heading stage, indicating that it may be the best stage for remote sensing–based yield mapping.

We theoretically and experimentally study changes with pump power in the polarization of an optical signal as it simultaneously experiences Kerr-effect-induced birefringence and four-wave-mixing-based parametric amplification from a copropagating pump in an optical fiber. It is shown that the changes caused by the two nonlinear optical effects are orthogonal to each other in the Stokes space. Results also show that the pump polarization state works as an attractor for signal polarization. The implications of this feature to fiber parametric amplifiers and entangled-photon sources are discussed, and a fiber polarization switch is demonstrated.

The aim of the present work was to determine the physical and chemical characteristics of salami produced through spontaneous fermentation. Fifty samples of sausages from different small manufacturers from South Brazil were analyzed. In relation to pH and water activity, the samples presented values from 4.35 to 6.92 and 0.80 to 0.95, respectively. The moisture content showed a remarkable variation, the sample with the lowest content had 20.97% and the highest content was 55.11% moisture. The amount of lipids in the samples varied from 7.44 to 48.83%, and for proteins the content varied from 11.32 to 41.27%. As for the mineral residue of the samples, the contents varied from 3.76 to 8.84. Various samples proved to have one or more parameters outside the limits established by the Technical Regulation for Sausage Identity and Quality, and only 46% of the salami samples fulfilled the maximum and minimum values established by Brazilian legislation.El objetivo de este trabajo fue determinar las caracteristicas fisicas y quimicas de salamis producidos por fermentacion espontanea. Se analizaron cincuenta muestras de salami de varias industrias pequenas del sur de Brasil. En relacion al pH y actividad de agua, las muestras presentaron valores de 4,35 a 6,92 y 0,80 a 0,95, respectivamente. La humedad vario considerablemente, la muestra con menor valor fue de 20,97% y la mayor de 55,11% de humedad. La cantidad de lipidos en las muestras vario de 7,44 a 48,83%, y para las proteinas fue de 11,32 a 41,27%. En relacion al residuo mineral de las muestras, los valores variaron de 3,76 a 8,84%. Varias muestras tuvieron uno o mas parametros fuera de los limites establecidos en el Reglamento Tecnico de Identidad y Calidad del Salame. Unicamente el 46% de las muestras de salamis cumplieron con los valores maximos o minimos permitidos por la Legislacion Brasilena.Palabras clave: Salami, caracteristicas fisicoquimicas, calidad, starter culture

The methods of dimensional control for solid surfaces are usually contact methods. However, in fragile and reduced hardness surfaces, these methods present critical disadvantages. The method presented in this work aims to offer resources for the optimization of graphite components machined with laser through the measurement of the channels’ depth and shape. In this scope, the laser triangulation technique demonstrated to be a very useful tool in the quality control of graphite diffusers plates for fuel cell prototyping and in their future production.

The atomic structure of the characteristic defects (Mg-rich hexagonal pyramids) in p-doped bulk and MOCVD GaN:Mg thin films grown with Ga polarity was determined at atomic resolution by direct reconstruction of the scattered electron wave in a transmission electron microscope. Small cavities were present inside the defects, confirmed also with positron annihilation. The inside walls of the cavities were covered by GaN of reverse polarity compared to the matrix. Annealing of the MOCVD layers lead to slight increase of the defect size and an increase of the room temperature photoluminescence intensity. Positron annihilation confirms presence of vacancy clusters of different sizes triggered by the Mg doping in as-grown samples and decrease of their concentration upon annealing at 900 and 1000 °C. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Lightly n-doped, 4H-SiC films implanted with 10²⁰ cm⁻³ Al or co-implanted with 10²⁰ cm⁻³ Al and 10²⁰ cm⁻³ C were examined in the unannealed state or annealed at 1300, 1400, 1500, 1600 or 1650 °C after they had been coated with an AlN cap. For a given annealing temperature, TA, the sheet resistance, Rsh, is smaller in the co-implanted samples at the lower TA's, but not at the higher ones because the C catalyzes the chemical reactions for the incorporation of Al into a Si site, and at the higher TA's the activation energies for these reactions no longer control the reaction kinetics. The CL peak created by a free electron recombining with a hole bound to an Al acceptor decreases in intensity as TA increases because the Al acceptors can be trapped by the deep donors related to the DI defect that increase in number as TA increases. However, the process must be more complicated because the temperature dependence of Rsh implies that the activation energy for conduction is much less than that of the 0.35 eV hole trap. The excellent temperature stability of the DI defect suggests it is likely to be associated with defects that nucleate and grow such as dislocation loops and/or stacking faults. This is consistent with decreased ion beam channeling at the higher TA's, and the small anisotropy of the EPR peak associated with implant damage. The higher energy peak in the DI doublet increases in intensity relative to the lower energy peak as TA increases, and for the same TA the relative intensity of the higher energy peak is larger in the co-implanted samples. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

A new vapor phase crystal growth technique was applied to fabricate single crystal AlN wafers up to 1.75-inch diameter. The wafers were sliced from AlN crystals and polished. Fabricated AlN wafers were investigated by X-ray diffraction, TEM, and cathodoluminescence. X-ray diffraction and TEM studies confirmed single crystal structure of grown material. High electrical resistivity of these AlN wafers was verified. AlN homoepitaxial layers exhibiting sharp near-band-edge emission were grown on fabricated AlN substrates. These results open the door for the commercialization of AlN substrates for advanced high-power mm-wave devices and optoelectronic devices based on Group III-nitride semiconductors. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The stress model of the hybrid finite element formulation is applied to the solution of dynamic elastoplastic structural problems. The stress field is approximated in the domain of the elements and the displacements on its boundary. The displacement, velocity and acceleration approximations in the domain of the element are implicit, in the sense that they result from a combination of the stress estimate with the time integration procedure that ensures that the equilibrium condition is locally satisfied. The finite elements are subdivided in plastic cells where a gradient dependent model is implemented using a hybrid formulation based on the approximation of the plastic parameter and the plastic radiation fields in the domain and on the boundary of the plastic cells, respectively. Generalized variables associated with orthogonal and naturally hierarchical bases are used. The resulting solving systems are symmetric, sparse, p-adaptive and well suited to parallel processing. The performance of the element is assessed using a representative set of testing problems. Copyright © 2001 John Wiley & Sons, Ltd.

The displacement model of the hybrid-Trefftz finite element formulation is applied to the shape optimization of linear elastostatic problems. The model is based on the direct approximation of the displacements in the domain of the element and of the tractions on its boundary. The independent description of the geometry is based on the parametric description of the shape of the element sides. The finite element solving system is symmetric and sparse. As the displacement approximation is extracted from the solution set of the governing differential equations, all structural matrices are defined by boundary integral expressions. The approximation bases are compact and naturally p-hierarchical. High-order approximations are implemented to obtain accurate solutions using coarse meshes of macro-elements. The sensitivities are determined analytically and remeshing is not implemented during the optimization procedure because the elements are weakly sensitive to gross shape distortion. Numerical testing is based on a standard set of two-dimensional linear elastostatic problems. Copyright © 2001 John Wiley & Sons, Ltd.

Objectives The evidence linking low levels of folic acid and orofacial clefting (OFC) is presently equivocal. There is stronger evidence for the role of folic acid supplementation in protection against the occurrence and recurrence of neural tube defects. The present investigation tested the hypotheses that cleft lip, cleft palate, or both are inversely associated with maternal intake of dietary and supplemental vitamins during the periconceptional period and first 4 months of pregnancy in a Brazilian population.Design A population-based, case-control study of cleft lip with or without cleft palate (CL(P)) and isolated cleft palate (CP) in a Brazilian population. In structured interviews, case histories were taken from the mothers of a consecutive sample of 450 infants born with nonsyndromic OFC.Results Mothers who had children with CL(P) were less likely to have been supplemented during the periconceptional period. The statistical significance of the difference in prevalence of the use of supplements between mothers of patients and of controls was greater for the CL(P) group: p < .05 for CP and p < .001 for CL(P). Multivariate analysis confirmed this finding of a protective effect for both types of orofacial cleft.Conclusions The use of vitamin supplements in the first 4 months of pregnancy was suggestive of a protective effect against the occurrence of CP and CL(P) in this population. The significance of an association between multivitamin supplementation and OFC and the possible role of gene/environment interaction are discussed.

Abstract: The Galerkin and collocation methods are combined in the implementation of a boundary integral formulation based on the Trefftz method for linear elastostatics. A finite element approach is used in the derivation of the formulation. The domain is subdivided in regions or elements, which need not be bounded, simply connected or convex. The stress field is directly approximated in each element using a complete solution set of the governing Beltrami condition. This stress basis is used to enforce on average, in the Galerkin sense, the compatibility and elasticity conditions. The boundary of each element is, in turn, subdivided into boundary elements whereon the displacements are independently approximated using Dirac functions. This basis is used to enforce by collocation the static admissibility conditions, which reduce to the Neumann conditions as the stress approximation satisfies locally the domain equilibrium condition. The resulting solving system is symmetric and sparse. The coefficients of the structural matrices and vectors are defined either by regular boundary integral expressions or determined by direct collocation of the trial functions.

Saccharomyces cerevisiae lacking copper-zinc superoxide dismutase (sod1) shows a series of defects, including reduced rates of aerobic growth in synthetic glucose medium and reduced ability to grow by respiration in glycerol-rich medium. In this work, we observed that addition of iron improved the respiratory growth of the sod1 mutant and in glucose medium total intracellular iron content was higher in the sod1 mutant than in wild type cells. Transcription of the high affinity iron transporter gene, FET3, was enhanced in the sod1 mutant, suggesting that iron transport systems were up-regulated. An sod1/fet3 double mutant showed increased sensitivity to oxygen and increased transcription of FET4, an alternative, low affinity, iron transporter. We propose that this increased iron demand in the sod1 mutant may be a reflection of the cells' efforts to reconstitute iron-sulfur cluster-containing enzymes that are continuously inactivated in conditions of excess superoxide.

The occurrence of silicon in two kinds of biomass (rice hulls and endocarp of babassu coconut) and the thermal transformations taking place in these materials under heat treatments are studied here. We report also the production, characterization, and study of carbonaceous materials with high SiC content through the carbothermal reduction of silica, using these natural precursors. X-ray diffraction, scanning electron microscopy, and ¹³C and ²⁹Si room temperature high-resolution solid-state NMR measurements are used in the characterization and study of the materials as well as the process of SiC formation. Important conclusions about the nature of silicon in these types of biomass and the effects of heat treatments on the structure of silicon-containing species are derived from the results presented. It is shown that silicon in these materials occurs in two distinct forms:  amorphous hydrated silica and organically bound silicon species. The influence of spin−lattice relaxation dynamics on the NMR spectra is discussed, evidencing the role played by the paramagnetic defects produced in the materials through pyrolysis.

The stress model of the hybrid-Trefftz finite element formulation is applied to the linear elastostatic analysis of solids. The stresses are approximated in the domain of the element and displacements on its boundary. Complete, linearly independent, hierarchical polynomial approximation functions are used in both domain and boundary approximations. The displacement basis is defined independently on each inter-element surface. Continuity at the edges and on the corners of the elements is not enforced a priori. The stress basis is constrained to solve locally the Beltrami governing differential equation. It is derived from the associated Papkovitch–Neuber elastic displacement solution. Generalized variables are used to ensure that the approximations are independent of the geometric description of the elements. The solving system is derived directly from the fundamental relations of elastostatics. The solving system is symmetric, when the same property applies to the local elasticity condition, sparse, described by boundary integral arrays and well suited to p-refinement and parallel processing. The numerical implementation of these equations is discussed and numerical tests are presented to illustrate the performance of the finite element formulation. Copyright © 2000 John Wiley & Sons, Ltd.

Abstract: Growth pressure has a dramatic influence on the grain size, transport characteristics, optical recombination processes, and alloy composition of GaN and AlGaN films. We report on systematic studies which have been performed in a close spaced showerhead reactor and a vertical quartz tube reactor, which demonstrate increased grain size with increased growth pressure. Data suggesting the compensating nature of grain boundaries in GaN films is presented, and the impact of grain size on high mobility silicon-doped GaN and highly resistive unintentionally doped GaN films is discussed. We detail the influence of pressure on AlGaN film growth, and show how AlGaN must be grown at pressures which are lower than those used for the growth of optimized GaN films. By controlling growth pressure, we have grown high electron mobility transistor (HEMT) device structures having highly resistive (105 Ω-cm) isolation layers, room temperature sheet carrier concentrations of 1.21013 cm−2 and mobilities of 1500 cm2/Vs, and reduced trapping effects in fabricated devices.

Summary: This paper reports on hybrid formulations being developed by the Structural Analysis Research Group of Instituto Superior Técnico. Three alternative sets of hybrid finite element formulations are presented. They are termed hybrid-mixed, hybrid and hybrid-Trefftz and differ essentially on the field conditions that the approximation functions are constrained to satisfy locally. Two models, namely the displacement and the stress models, are obtained for each formulation depending on whether the tractions or the boundary displacements are the field chosen to implement inter-element continuity. Because they are derived from a strict hybrid approach released from the conventional node conformity concepts, these formulations allow different fields to be independently approximated, within certain consistency criteria, and enhance the use of a wide range of approximation functions. For simplicity and objectivity, the description of the approach followed in the derivation of the alternative formulations and models is based on the elementary linear elastostatic problem of structural analysis. Their fundamental properties are identified and their patterns of convergence are analysed and compared.

The alternative stress and displacement models of the hybrid-Trefftz finite element formulation for the analysis of linear boundary value problems are derived in parallel form to emphasise the complementary nature of the fundamental concepts they develop from. In the stress model the stresses in the structural domain and the boundary displacements are independently approximated and inter-element stress continuity is enforced explicitly. Conversely, in the displacement model the displacements in the structural domain and the boundary tractions are independently approximated and inter-element linkage is enforced in the form of displacement continuity. In both models the approximation in the domain is constrained to satisfy locally all field equations, a feature typical of the Trefftz method. Duality is used to interpret physically the finite element equations, which are derived from the fundamental relations of elastostatics. Numerical tests are presented to compare the relative performance of the alternative stress and displacement models.

A tissue culture procedure was developed for growing winter wheat roots. This system was used to study bacterial-root interactions and root colonization by Pseudomonas cepacia strains R55 and R85, Azospirillum brasilense ATCC 29729 and Azotobacter chroococcum ATCC 9043. Axenic root tissue cultures were inoculated with bacteria and incubated at 25° C on a rotary shaker (150 rpm) for up to 3 weeks. At various intervals, root morphology and root hair development, bacterial colonization of root surfaces and nitrogenase activity were determined. As determined by plate counting techniques, bacterial attachment to the roots varied from 7.5 × 104 to 3.2 × 107 colony-forming units cm-1. Scanning electron microscopy of inoculated roots revealed that some rhizobacteria (e.g., P. cepacia R85) significantly enhanced root hair development, and others (e.g., P. cepacia R55) specifically colonized root exudation sites. Nitrogenase activity of roots inoculated with either A. brasilense ATCC 29729 or A. chroococcum ATCC 9043 was stimulated if the inorganic nitrogen sources in the medium were replaced with 300 µg glutamine ml-1. We propose that the use of root tissue culture systems will facilitate studies on plant root-microbe interactions.

The cases of 38 children with AVM seen at the Lariboisière Hospital since 1962 are reviewed. The clinical picture was often of sudden onset with impairment of motor function and/or subarachnoid hemorrhage. The diagnosis was usually made by myelography, but spinal arteriography is the key examination, since it confirms the diagnosis and is essential to determine the exact location of the angioma: whether it is extramedullary, intramedullary, or mixed. Angiotomography and angiomyelography with magnification are necessary to determine if the lesion is median, compact, and if it has long sulcocommissural arteries, details which have an important bearing on the prognosis. Operation should be performed as soon as possible after its feasibility has been demonstrated angiographically. But embolization with new materials has also been effective, either associated with operation or as an alternative.

Abstract: This paper presents a comparative study of the properties of GaN grown by organometallic vapor phase epitaxy, using both a GaN and A1N buffer layer, as a function of sapphire orientation (c-plane vs a-plane). Results are presented for varying the thickness of the buffer layer, varying the growth temperature of the GaN film, and also varying the ammonia/trimethylgallium mass flow ratio. The electron Hall mobilities of GaN films grown on an A1N buffer layer were, in general, higher compared to films grown using a GaN buffer layer. In addition, growth on a-plane sapphire resulted in higher quality films (over a wider range of buffer thicknesses) than growth on c-plane sapphire. The room temperature electron mobilities were also found to be dependent on, not only the growth temperature, but also the ammonia/trimethylgallium mass flow ratio.

Abstract: Native defects and dopants in GaN grown by organometallic chemical vapor deposition have been studied with photoluminescence and optically detected magnetic resonance. For undoped samples, the combined results indicate the presence of residual shallow donors and acceptors and deep donors. A model for the capture and recombination among these defects is developed. For Mg-doped samples, the experiments reveal shallow and perturbed acceptors and shallow and deep donors. Hence, shallow and deep states for the native donor or donors appear in all samples. The Mg-acceptor is perturbed from its effective-mass state by nearby point defects.

Abstract: 18F fluoride ion is produced by bombarding18O enriched water using an 11 MeV negative ion Radioisotope Delivery System (RDS-112) cyclotron by18O(p,n)18F reaction. During the synthesis of18F-FDG, a gaseous effluent containing18F is released. To quantitate the loss of18F during the synthesis, the18F activity at the end of bombardment delivered to chemical process control unit (CPCU), the amount of18F-FDG produced, the residual activity in CPCU, the activity trapped in charcoal filter, reaction vessels, cartridge and resin column were measured. A dose calibrator was used to assay total18F delivered to the CPCU and FDG produced. All other measurements were with a calibrated ionization chamber in a fixed geometry. The amount of gaseous18F released was calculated. For routine productions, conversion of18F into FDG was 46.0±4.0%. In six production runs without a charcoal filter, the mean gaseous release of18F was 10.6±1.0%. With an activated charcoal filter retrofitted to the exhaust of the CPCU, then mean gaseous18F activity released was 1.2±1.2%. The residual activity in the synthesis unit was 12.9±3.5%. The remaining activity i.e. 33.1±4.2%, was in the reaction vessels, cartridges and in the resin column. The efficiency of a charcoal filter for trapping18F gaseous effluent during synthesis was found to be >99.0%.

Abstract: The ability of phosphate-solubilizing rhizobacteria to enhance the growth and phosphorus uptake of canola (Brassica napus L., cv. Legend) was studied in potted soil experiments in the growth chamber. One hundred and eleven bacteria isolated from the rhizosphere of field-grown plants, and a collection of nine bacteria known to be effective plant growth-promoting rhizobacteria (PGPR), were screened for P-solubilization in vitro. All rhizobacteria were identified using whole-cell fatty acids methyl ester (FAME) profiles. The best P-solubilizing isolates were two Bacillus brevis strains, B. megaterium, B. polymyxa, B. sphaericus, B. thuringiensis, and Xanthomonas maltophilia (PGPR strain R85). The P-solubilizers were tested for their effects on growth and P-uptake of canola plants in a P-deficient soil amended with rock phosphate. Although some of the P-solubilizing rhizobacteria significantly increased plant height or pod yield, none increased P-uptake. The most effective inoculant was a B. thuringiensis isolate which significantly increased the number and weight of pods and seed yield without rock phosphate. Xanthomonas maltophilia increased plant height, whereas the other bacilli increased the number on weight of pods. These results demonstrate the potential use of these P-solubilizing rhizobacteria as inoculants for canola, but indicate that P-solubilization was not the main mechanism responsible for positive growth response.

The stress model of the hybrid finite element formulation is applied to the analysis of quasi-static, gradient-dependent elastoplastic structural problems. The finite element approximation consists in the direct estimate of the stress and plastic multiplier fields in the domain of the element and of the displacements and plastic multiplier gradients on its boundary. The finite element equations are derived directly from the relevant fundamental structural conditions, namely equilibrium, compatibility, elasticity and gradient-dependent plasticity. The finite element solving system for the finite step incremental analysis is encoded as a recursive sequence of symmetric parametric linear complementarity problems (SPLCP). The sequence of SPLCP is solved using a direct extension of the restricted basis linear programming algorithm. The implementation of the formulation and of the algorithm is illustrated with numerical applications. © 1998 John Wiley & Sons, Ltd.

Little is known about the composition and diversity of the bacterial community associated with plant roots. The purpose of this study was to investigate the diversity of bacteria associated with the roots of canola plants grown at three field locations in Saskatchewan, Canada. Over 300 rhizoplane and 220 endophytic bacteria were randomly selected from agarâ€solidified trypticase soy broth, and identified using fatty acid methyl ester (FAME) profiles. Based on FAME profiles, 18 bacterial genera were identified with a similarity index >0.3, but 73% of the identified isolates belonged to four genera: Bacillus(29%), Flavobacterium(12%), Micrococcus(20%) and Rathayibacter(12%). The endophytic community had a lower Shannonâ€Weaver diversity index (1.35) compared to the rhizoplane (2.15), and a higher proportion of Bacillus, Flavobacterium, Micrococcusand Rathayibactergenera compared to rhizoplane populations. Genera identified in the endophytic isolates were also found in the rhizoplane isolates. Furthermore, principal component analysis indicated three clusters of bacteria regardless of their site of origin, i.e., rhizoplane or endophytic. In addition, the rhizoplane communities of canola and wheat grown at the same site differed significantly. These results indicate that diverse groups of bacteria are associated with fieldâ€grown plants and that endophytes are a subset of the rhizoplane community.

Abstract: The sensitivity and specificity of heart rate variability (HRV) in the corroboration of brain death diagnosis in patients with acute traumatic intracranial lesions was evaluated in 20 patients with clinical criteria of brain death, nine patients in deep coma (Glasgow scale <7) and 18 normal controls, all age matched. The electrocardiogram was sampled at 650 Hz and several parameters of HRV were calculated, in both time and frequency domains. The HRV parameters were significantly lower in the brain death group compared with the deep coma group. Linear discriminant analysis between brain death and deep coma patients was performed on a data set made of nine randomly selected patients with clinical criteria of brain death and nine patients in deep coma. Cross-validation was performed on the remaining 11 patients with clinical criteria of brain death. All patients in the data set were correctly classified (sensitivity and specificity of 100%). All patients in the cross-validation set were correctly classified (sensitivity of 100%). Further studies are necessary to evaluate the specificity of the method in the independent set of deep coma patients and in the follow-up of comatose and vegetative patients to identify irreversibility of HRV. Nevertheless, these results suggest that HRV analysis constitutes a fully sensitive and specific method for assessing brain death in potential organ donors with acute traumatic lesions of the brain. This fast, quantitative and bedside method seems very promising for the early confirmation of brain death, which is an important factor for the success of transplantation procedures and could have a high predictive value of brain death in comatose patients with brain injuries without fully diagnostic criteria.

Esophageal motility was studied in 21 patients with Sjögren's syndrome, and in 25 normal volunteers, in order to record the prevalence and type of esophageal motor abnormalities. Esophageal motor abnormalities were detected in seven of the 21 patients (33.3%). These esophageal abnormalities did not correlate with the presence of dysphagia, the extraglandular involvement, or the presence of autoantibodies.