bluuebunny/crossref_metadata_2025 huggingface dataset:
A comparison of sediment reflection coefficient measurements to elastic and poro-elastic models
Authors: Camin H. John , Isakson Marcia J.
Published: November 2006

This work compared three plane wave reflection coefficient models to laboratory sediment reflection measurements collected using a spherical source and receiver. Plane wave decomposition was used to modify the reflection coefficient models to include the inherent spherical effects such as lateral wave interference for direct comparison with the data. Sets of data at two transducer separation distances (1.27 and 0.25m) were collected to compare the range dependence of the spherical effects. Bandpass filtered linear frequency-modulated chirps from 30 to 160kHz were used to measure frequency dependence. Grazing angles from 5° to 75° were measured to compare angle dependence. Each set of data was collected along approximately 3m of smoothed sediment for spatial averaging. Unavoidable experimental effects including transducer response, beam pattern, and spherical spreading were accounted for in order to compare the reflection coefficient measurements with the modified models. Significant spherical wave effects were measured in the data. Three reflection coefficient models were considered: the viscoelastic model, the grain shearing model [M. Buckingham, J. Acoust. Soc. Am. 108, 1796–2815 (2000)] and the effective density fluid model [K. Williams, J. Acoust. Soc. Am. 110, 2276–2281 (2001)]. The viscoelastic and grain shearing models predicted values for the reflection coefficient that were not within the 95% confidence interval for low frequencies. The data exhibited high variance which was frequency and angle dependent. This variance is not likely to be caused by variations in bulk properties as defined by the fluid or viscoelastic models. The cause of the variance will be considered in subsequent publications.
Development and the role of internal noise in detection and discrimination thresholds with narrow band stimuli
Authors: Buss Emily , Hall Joseph W. , Grose John H.
Published: November 2006

The experiments reported here examine the role of internal noise in the detection of a tone in narrow band noise and intensity discrimination for narrow band stimuli in school-aged children as compared to adults. Experiment 1 used 20-Hz wide bands of Gaussian and low-fluctuation noise centered at 500Hz to assess the role of stimulus fluctuation in detection of a 500-Hz pure tone. Additional conditions tested whether performance was based on level and∕or level-independent cues. Children’s thresholds were elevated with respect to adults, and whereas adults benefited from the reduced fluctuation of low-fluctuation noise, children did not. Results from both groups were consistent with the use of a level cue. Experiment 2 estimated intensity increment thresholds for a narrow band Gaussian noise or a pure tone, either with or without a presentation-by-presentation level rove, an additional source of level variability. Stimulus variability was found to have a larger effect on performance of adults as compared to children, a rather counterintuitive finding if one thinks of children as more prone to informational masking introduced by stimulus variability. Both tone-in-noise and intensity discrimination data were consistent with the hypothesis that children’s performance is limited by greater levels of internal noise.
Multiload procedure to measure the acoustic scattering matrix of a duct discontinuity for higher order mode propagation conditions
Authors: Sitel Azzedine , Ville Jean-Michel , Foucart Felix
Published: November 2006

A procedure for measuring the acoustic scattering matrix coefficients of a duct discontinuity for higher order acoustic duct mode propagation conditions is described and tested. The technique requires measurement of pressure waves per mode coming in and out of the discontinuity. Assuming N cut-on modes, the (2N)2 scattering matrix coefficients are determined after repeating the experiment for N linearly independent pressure distributions for at least two load configurations. Experiments were conducted for a straight duct and a reactive chamber. A good agreement was found between experiment and theory except near cut-off frequencies. The overdetermination method based on four loads was shown to improve the results. An analytical simulation of the experiment was developed to compute the influence on the [S] calculation of an error in temperature and total modal pressure assumed to be representative of a real measurement situation. This simulation with a discussion explains the discrepancies between experiment and theory. The test with the chamber shows that the load method fails as expected in determining the coefficients associated to the wave coming in the discontinuity from the open end side because of the property of the middle duct to filter modes making the results very sensitive to uncertainties.
A fast near-field method for calculations of time-harmonic and transient pressures produced by triangular pistons
Authors: Chen Duo , Kelly James F. , McGough Robert J.
Published: November 2006

Analytical expressions are demonstrated for fast calculations of time-harmonic and transient near-field pressures generated by triangular pistons. These fast expressions remove singularities from the impulse response, thereby reducing the computation time and the peak numerical error with a general formula that describes the near-field pressure produced by any triangular piston geometry. The time-domain expressions are further accelerated by a time-space decomposition approach that analytically separates the spatial and temporal components of the numerically computed transient pressure. Applied to a Hanning-weighted input pulse, time-space decomposition converts each spatio-temporal integral into six spatial integral evaluations at each field point. Time-harmonic and transient calculations are evaluated for an equilateral triangle with sides equal to four wavelengths, and the resulting errors are compared to pressures obtained with exact and approximate implementations of the impulse response method. The results show that the fast near-field method achieves smaller maximum errors and is consistently faster than the impulse response and methods that approximate the impulse response.
Anomalous negative dispersion in bone can result from the interference of fast and slow waves
Authors: Marutyan Karen R. , Holland Mark R. , Miller James G.
Published: November 2006

The goal of this work was to show that the apparent negative dispersion of ultrasonic waves propagating in bone can arise from interference between fast and slow longitudinal modes, each exhibiting positive dispersion. Simulations were carried out using two approaches: one based on the Biot-Johnson model and one independent of that model. Results of the simulations are mutually consistent and appear to account for measurements from many laboratories that report that the phase velocity of ultrasonic waves propagating in cancellous bone decreases with increasing frequency (negative dispersion) in about 90% of specimens but increases with frequency in about 10%.
Properties of an electrostatic transducer
Authors: Medley A. P. , Billson D. R. , Hutchins D. A. , Davis L. A. J.
Published: November 2006

A thin and flexible transducer design for use in air is described. It is fabricated from three or more layers of material to form an electrostatic device with many interesting properties. The new acoustic source has an excellent high-frequency response and can be used as an acoustic radiator over a wide range of frequencies, in both the audible and ultrasonic frequency ranges. The frequency response and directivity are both modeled and compared to theory, where it is demonstrated that the device operates in a manner consistent with a plane piston source.
Nanoparticle Polymer Composites: Where Two Small Worlds Meet
Authors: Balazs Anna C. , Emrick Todd , Russell Thomas P.
Published: November 2006

The mixing of polymers and nanoparticles is opening pathways for engineering flexible composites that exhibit advantageous electrical, optical, or mechanical properties. Recent advances reveal routes to exploit both enthalpic and entropic interactions so as to direct the spatial distribution of nanoparticles and thereby control the macroscopic performance of the material. For example, by tailoring the particle coating and size, researchers have created self-healing materials for improved sustainability and self-corralling rods for photovoltaic applications. A challenge for future studies is to create hierarchically structured composites in which each sublayer contributes a distinct function to yield a mechanically integrated, multifunctional material.
In Quest of Virtual Tests for Structural Composites
Authors: Cox Brian , Yang Qingda
Published: November 2006

The difficult challenge of simulating diffuse and complex fracture patterns in tough structural composites is at last beginning to yield to conceptual and computational advances in fracture modeling. Contributing successes include the refinement of cohesive models of fracture and the formulation of hybrid stress-strain and traction-displacement models that combine continuum (spatially averaged) and discrete damage representations in a single calculation. Emerging hierarchical formulations add the potential of tracing the damage mechanisms down through all scales to the atomic. As the models near the fidelity required for their use as virtual experiments, opportunities arise for reducing the number of costly tests needed to certify safety and extending the design space to include material configurations that are too complex to certify by purely empirical methods.
The Impact of Boreal Forest Fire on Climate Warming
Authors: Randerson J. T. , Liu H. , Flanner M. G. , Chambers S. D. , Jin Y. , Hess P. G. , Pfister G. , Mack M. C. , Treseder K. K. , Welp L. R. , Chapin F. S. , Harden J. W. , Goulden M. L. , Lyons E. , Neff J. C. , Schuur E. A. G. , Zender C. S.
Published: November 2006

We report measurements and analysis of a boreal forest fire, integrating the effects of greenhouse gases, aerosols, black carbon deposition on snow and sea ice, and postfire changes in surface albedo. The net effect of all agents was to increase radiative forcing during the first year (34 Â± 31 Watts per square meter of burned area), but to decrease radiative forcing when averaged over an 80-year fire cycle (â2.3 Â± 2.2 Watts per square meter) because multidecadal increases in surface albedo had a larger impact than fire-emitted greenhouse gases. This result implies that future increases in boreal fire may not accelerate climate warming.
Reversible, Metal-Free Hydrogen Activation
Authors: Welch Gregory C. , Juan Ronan R. San , Masuda Jason D. , Stephan Douglas W.
Published: November 2006

Although reversible covalent activation of molecular hydrogen (H
2
) is a common reaction at transition metal centers, it has proven elusive in compounds of the lighter elements. We report that the compound (C
6
H
2
Me
3
)
2
PH(C
6
F
4
)BH(C
6
F
5
)
2
(Me, methyl), which we derived through an unusual reaction involving dimesitylphosphine substitution at a para carbon of tris(pentafluorophenyl) borane, cleanly loses H
2
at temperatures above 100°C. Preliminary kinetic studies reveal this process to be first order. Remarkably, the dehydrogenated product (C
6
H
2
Me
3
)
2
P(C
6
F
4
)B(C
6
F
5
)
2
is stable and reacts with 1 atmosphere of H
2
at 25°C to reform the starting complex. Deuteration studies were also carried out to probe the mechanism.
N-Linked Glycosylation of Folded Proteins by the Bacterial Oligosaccharyltransferase
Authors: Kowarik Michael , Numao Shin , Feldman Mario F. , Schulz Benjamin L. , Callewaert Nico , Kiermaier Eva , Catrein Ina , Aebi Markus
Published: November 2006

N-linked protein glycosylation is found in all domains of life. In eukaryotes, it is the most abundant protein modification of secretory and membrane proteins, and the process is coupled to protein translocation and folding. We found that in bacteria, N-glycosylation can occur independently of the protein translocation machinery. In an in vitro assay, bacterial oligosaccharyltransferase glycosylated a folded endogenous substrate protein with high efficiency and folded bovine ribonuclease A with low efficiency. Unfolding the eukaryotic substrate greatly increased glycosylation. We propose that in the bacterial system, glycosylation sites are located in flexible parts of folded proteins, whereas the eukaryotic cotranslational glycosylation evolved to a mechanism presenting the substrate in a flexible form before folding.
Optimized FaeG Expression and a Thermolabile Enterotoxin DNA Adjuvant Enhance Priming of an Intestinal Immune Response by an FaeG DNA Vaccine in Pigs
Authors: Melkebeek V. , Sonck E. , Verdonck F. , Goddeeris B. M. , Cox E.
Published: November 2006

One of the problems hindering the development of DNA vaccines is the relatively low immunogenicity often seen in humans and large animals compared to that in mice. In the present study, we tried to enhance the immunogenicity of a pcDNA1/
faeG
19 DNA vaccine in pigs by optimizing the FaeG expression plasmid and by coadministration of the plasmid vectors encoding the A and B subunits of the
Escherichia coli
thermolabile enterotoxin (LT). The insertion of a Kozak sequence and optimization of vector (cellular localization and expression) and both vector and codon usage were all shown to enhance in vitro FaeG expression compared to that of pcDNA1/
faeG
19. Subsequently, pcDNA1/
faeG
19 and the vector-optimized and the vector-codon-optimized construct were tested for their immunogenicity in pigs. In line with the in vitro results, antibody responses were better induced with increasing expression. The LT vectors additionally enhanced the antibody response, although not significantly, and were necessary to induce an F4-specific cellular response. These vectors were also added because LT has been described to direct the systemic response towards a mucosal immunoglobulin A (IgA) response in mice. Here, however, the intradermal FaeG DNA prime-oral F4 boost immunization resulted in a mainly systemic IgG response, with only a marginal but significant reduction in F4
+
E. coli
fecal excretion when the piglets were primed with pWRGFaeGopt and pWRGFaeGopt with the LT vectors.
Initiation of Heat-Induced Replication Requires DnaA and the L-13-mer of
oriC
Authors: González-Soltero Rocío , Botello Emilia , Jiménez-Sánchez Alfonso
Published: November 2006

An upshift of 10°C or more in the growth temperature of an
Escherichia coli
culture causes induction of extra rounds of chromosome replication. This stress replication initiates at
oriC
but has functional requirements different from those of cyclic replication. We named this phenomenon

h

eat-

i

nduced

r

eplication (HIR). Analysis of HIR in bacterial strains that had complete or partial
oriC
deletions and were suppressed by F integration showed that no sequence outside
oriC
is used for HIR. Analysis of a number of
oriC
mutants showed that deletion of the L-13-mer, which makes
oriC
inactive for cyclic replication, was the only mutation studied that inactivated HIR. The requirement for this sequence was strictly correlated with Benham's theoretical stress-induced DNA duplex destabilization.
oriC
mutations at DnaA, FIS, or IHF binding sites showed normal HIR activation, but DnaA was required for HIR. We suggest that strand opening for HIR initiation occurs due to heat-induced destabilization of the L-13-mer, and the stable oligomeric DnaA-single-stranded
oriC
complex might be required only to load the replicative helicase DnaB.
Characterization of the Carboxysomal Carbonic Anhydrase CsoSCA from
Halothiobacillus neapolitanus
Authors: Heinhorst Sabine , Williams Eric B. , Cai Fei , Murin C. Daniel , Shively Jessup M. , Cannon Gordon C.
Published: November 2006

In cyanobacteria and many chemolithotrophic bacteria, the CO
2
-fixing enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO) is sequestered into polyhedral protein bodies called carboxysomes. The carboxysome is believed to function as a microcompartment that enhances the catalytic efficacy of RubisCO by providing the enzyme with its substrate, CO
2
, through the action of the shell protein CsoSCA, which is a novel carbonic anhydrase. In the work reported here, the biochemical properties of purified, recombinant CsoSCA were studied, and the catalytic characteristics of the carbonic anhydrase for the CO
2
hydration and bicarbonate dehydration reactions were compared with those of intact and ruptured carboxysomes. The low apparent catalytic rates measured for CsoSCA in intact carboxysomes suggest that the protein shell acts as a barrier for the CO
2
that has been produced by CsoSCA through directional dehydration of cytoplasmic bicarbonate. This CO
2
trap provides the sequestered RubisCO with ample substrate for efficient fixation and constitutes a means by which microcompartmentalization enhances the catalytic efficiency of this enzyme.
pH-Dependent Activation of the BarA-UvrY Two-Component System inEscherichia coli
Authors: Mondragón Verónica , Franco Bernardo , Jonas Kristina , Suzuki Kazushi , Romeo Tony , Melefors Öjar , Georgellis Dimitris
Published: November 2006

ThebarAanduvrYgenes ofEscherichia coliencode a two-component sensor kinase and a response regulator, respectively. Although this system plays a major role in the regulation of central carbon metabolism, motility, and biofilm formation by controlling the expression of the CsrB and CsrC noncoding RNAs, the environmental conditions and the physiological signal(s) to which it responds remain obscure. In this study, we explored the effect of external pH on the activity of BarA/UvrY. Our results indicate that a pH lower than 5.5 provides an environment that does not allow activation of the BarA/UvrY signaling pathway.
Evidence for Recombination inMycobacterium tuberculosis
Authors: Liu Xiaoming , Gutacker Michaela M. , Musser James M. , Fu Yun-Xin
Published: November 2006

Due to its mostly isolated living environment,Mycobacterium tuberculosisis generally believed to be highly clonal, and thus recombination between different strains must be rare and is not critical for the survival of the species. To investigate the roles recombination could have possibly played in the evolution ofM. tuberculosis, an analysis was conducted on previously determined genotypes of 36 synonymous single nucleotide polymorphisms (SNPs) in 3,320M. tuberculosisisolates. The results confirmed the predominant clonal structure of theM. tuberculosispopulation. However, recombination between different strains was also suggested. To further resolve the issue, 175 intergenic SNPs and 234 synonymous SNPs were genotyped in 37 selected representative strains. A clear mosaic polymorphic pattern ahead of the MT0105 locus encoding a PPE (Pro-Pro-Glu) protein was obtained, which is most likely a result of recombination hot spot. Given that PPE proteins are thought to be critical in host-pathogen interactions, we hypothesize that recombination has been influential in the history ofM. tuberculosisand possibly a major contributor to the diversity observed ahead of the MT0105 locus.
The Cation-Responsive Protein NhaR of
Escherichia coli
Activates
pgaABCD
Transcription, Required for Production of the Biofilm Adhesin Poly-β-1,6-
N
-Acetyl-
d
-Glucosamine
Authors: Goller Carlos , Wang Xin , Itoh Yoshikane , Romeo Tony
Published: November 2006

The
pgaABCD
operon of
Escherichia coli
is required for production of the biofilm adhesin poly-β-1,6-
N
-acetyl-
d
-glucosamine (PGA). We establish here that NhaR, a DNA-binding protein of the LysR family of transcriptional regulators, activates transcription of this operon. Disruption of the
nhaR
gene decreased biofilm formation without affecting planktonic growth. PGA production was undetectable in an
nhaR
mutant strain. Expression of a
pgaA
′-′
lacZ
translational fusion was induced by NaCl and alkaline pH, but not by CaCl
2
or sucrose, in an
nhaR
-dependent fashion. Primer extension and quantitative real-time reverse transcription-PCR analyses further revealed that NhaR affects the steady-state level of
pga
mRNA. A purified recombinant NhaR protein bound specifically and with high affinity within the
pgaABCD
promoter region; one apparent binding site overlaps the −35 element, and a second site lies immediately upstream of the first. This protein was necessary and sufficient for activation of in vitro transcription from the
pgaA
promoter. These results define a novel mechanism for regulation of biofilm formation in response to environmental conditions and suggest an expanded role for NhaR in promoting bacterial survival.
Wall Teichoic Acid Polymers Are Dispensable for Cell Viability in
Bacillus subtilis
Authors: D'Elia Michael A. , Millar Kathryn E. , Beveridge Terry J. , Brown Eric D.
Published: November 2006

An extensive literature has established that the synthesis of wall teichoic acid in
Bacillus subtilis
is essential for cell viability. Paradoxically, we have recently shown that wall teichoic acid biogenesis is dispensable in
Staphylococcus aureus
(M. A. D'Elia, M. P. Pereira, Y. S. Chung, W. Zhao, A. Chau, T. J. Kenney, M. C. Sulavik, T. A. Black, and E. D. Brown, J. Bacteriol. 188:4183-4189, 2006). A complex pattern of teichoic acid gene dispensability was seen in
S. aureus
where the first gene (
tarO
) was dispensable and later acting genes showed an indispensable phenotype. Here we show, for the first time, that wall teichoic acid synthesis is also dispensable in
B. subtilis
and that a similar gene dispensability pattern is seen where later acting enzymes display an essential phenotype, while the gene
tagO
, whose product catalyzes the first step in the pathway, could be deleted to yield viable mutants devoid of teichoic acid in the cell wall.
Horizontal Gene Transfer in a Polyclonal Outbreak of Carbapenem-ResistantAcinetobacter baumannii
Authors: Valenzuela Jubelle K. , Thomas Lee , Partridge Sally R. , van der Reijden Tanny , Dijkshoorn Lenie , Iredell Jon
Published: November 2006

In the last few years, phenotypically carbapenem resistantAcinetobacterstrains have been identified throughout the world, including in many of the hospitals and intensive care units (ICUs) of Australia. Genotyping of Australian ICU outbreak-associated isolates by pulsed-field gel electrophoresis of whole genomic DNA indicated that different strains were cocirculating within one hospital. The carbapenem-resistant phenotype of these and other Australian isolates was found to be due to carbapenem-hydrolyzing activity associated with the presence of theblaOXA-23gene. In all resistant strains examined, theblaOXA-23gene was adjacent to the insertion sequence ISAba1in a structure that has been found inAcinetobacter baumanniistrains of a similar phenotype from around the world;blaOXA-51-like genes were also found in allA. baumanniistrains but were not consistently associated with ISAba1, which is believed to provide the promoter required for expression of linked antibiotic resistance genes. Most isolates were also found to contain additional antibiotic resistance genes within the cassette arrays of class 1 integrons. The same cassette arrays, in addition to the ISAba1-blaOXA-23structure, were found within unrelated strains, but no common plasmid carrying these accessory genetic elements could be identified. It therefore appears that antibiotic resistance genes are readily exchanged between cocirculating strains in epidemics of phenotypically indistinguishable organisms. Epidemiological investigation of major outbreaks should include whole-genome typing as well as analysis of potentially transmissible resistance genes and their vehicles.
Vaccinia Virus Interactions with the Cell Membrane Studied by New Chromatic Vesicle and Cell Sensor Assays
Authors: Orynbayeva Z. , Kolusheva S. , Groysman N. , Gavrielov N. , Lobel L. , Jelinek R.
Published: November 2006

The potential danger of cross-species viral infection points to the significance of understanding the contributions of nonspecific membrane interactions with the viral envelope compared to receptor-mediated uptake as a factor in virus internalization and infection. We present a detailed investigation of the interactions of vaccinia virus particles with lipid bilayers and with epithelial cell membranes using newly developed chromatic biomimetic membrane assays. This analytical platform comprises vesicular particles containing lipids interspersed within reporter polymer units that emit intense fluorescence following viral interactions with the lipid domains. The chromatic vesicles were employed as membrane models in cell-free solutions and were also incorporated into the membranes of epithelial cells, thereby functioning as localized membrane sensors on the cell surface. These experiments provide important insight into membrane interactions with and fusion of virions and the kinetic profiles of these processes. In particular, the data emphasize the significance of cholesterol/sphingomyelin domains (lipid rafts) as a crucial factor promoting bilayer insertion of the viral particles. Our analysis of virus interactions with polymer-labeled living cells exposed the significant role of the epidermal growth factor receptor in vaccinia virus infectivity; however, the data also demonstrated the existence of additional non-receptor-mediated mechanisms contributing to attachment of the virus to the cell surface and its internalization.
Incorporation of Glycosylphosphatidylinositol-Anchored Granulocyte- MacrophageColony-Stimulating Factor or CD40 Ligand Enhances Immunogenicity of Chimeric Simian Immunodeficiency Virus-Like Particles
Authors: Skountzou Ioanna , Quan Fu-Shi , Gangadhara Sailaja , Ye Ling , Vzorov Andrei , Selvaraj Periasamy , Jacob Joshy , Compans Richard W. , Kang Sang-Moo
Published: November 2006

The rapid worldwide spread of human immunodeficiency virus (HIV) mandates the development of successful vaccination strategies. Since live attenuated HIV is not accepted as a vaccine due to safety concerns, virus-like particles (VLPs) offer an attractive safe alternative because they lack the viral genome yet they are perceived by the immune system as a virus particle. We hypothesized that adding immunostimulatory signals to VLPs would enhance their efficacy. To accomplish this we generated chimeric simian immunodeficiency virus (SIV) VLPs containing either glycosylphosphatidylinositol (GPI)-anchored granulocyte-macrophage colony-stimulating factor (GM-CSF) or CD40 ligand (CD40L) and investigated their biological activity and ability to enhance immune responses in vivo. Immunization of mice with chimeric SIV VLPs containing GM-CSF induced SIV Env-specific antibodies as well as neutralizing activity at significantly higher levels than those induced by standard SIV VLPs, SIV VLPs containing CD40L, or standard VLPs mixed with soluble GM-CSF. In addition, mice immunized with chimeric SIV VLPs containing either GM-CSF or CD40L showed significantly increased CD4+- and CD8+-T-cell responses to SIV Env, compared to standard SIV VLPs. Taken together, these results demonstrate that the incorporation of immunostimulatory molecules enhances humoral and cellular immune responses. We propose that anchoring immunostimulatory molecules into SIV VLPs can be a promising approach to augmenting the efficacy of VLP antigens.
Identification of a Ribonucleoprotein Intermediate of Tomato Mosaic Virus RNA Replication Complex Formation
Authors: Komoda Keisuke , Mawatari Natsuki , Hagiwara-Komoda Yuka , Naito Satoshi , Ishikawa Masayuki
Published: November 2006

The replication of eukaryotic positive-strand RNA virus genomes occurs in the membrane-bound RNA replication complexes. Previously, we found that the extract of evacuolated tobacco BY-2 protoplasts (BYL) is capable of supporting the translation and subsequent replication of the genomic RNAs of plant positive-strand RNA viruses, including
Tomato mosaic virus
(ToMV). Here, to dissect the process that precedes the formation of ToMV RNA replication complexes, we prepared membrane-depleted BYL (mdBYL), in which the membranes were removed by centrifugation. In mdBYL, ToMV RNA was translated to produce the 130-kDa and 180-kDa replication proteins, but the synthesis of any ToMV-related RNAs did not occur. When BYL membranes were added back to the ToMV RNA-translated mdBYL after the termination of translation with puromycin, ToMV RNA was replicated. Using a replication-competent ToMV derivative that encodes the FLAG-tagged 180-kDa replication protein, it was shown by affinity purification that a complex that contained the 130-kDa and 180-kDa proteins and ToMV genomic RNA was formed after translation in mdBYL. When the complex was mixed with BYL membranes, ToMV RNA was replicated, which suggests that this ribonucleoprotein complex is an intermediate of ToMV RNA replication complex formation. We have named this ribonucleoprotein complex the “pre-membrane-targeting complex.” Our data suggest that the formation of the pre-membrane-targeting complex is coupled with the translation of ToMV RNA, while posttranslationally added exogenous 180-kDa protein and replication templates can contribute to replication and can be replicated, respectively. Based on these results, we discuss the mechanisms of ToMV RNA replication complex formation.
SNP-based markers for discriminating olive (Olea europaea L.) cultivars
Authors: Reale S. , Doveri S. , Díaz A. , Angiolillo A. , Lucentini L. , Pilla F. , Martín A. , Donini P. , Lee D.
Published: November 2006

A set of 11 polymorphic markers (1 cleaved amplified polymorphic sequence (CAPS), 2 sequence-characterized amplified regions (SCARs), and 8 single-nucleotide polymorphism (SNP) - derived markers) was obtained for olive cultivar identification by comparing DNA sequences from different accessions. Marker development was more efficient, using sequences from the database rather than cloning arbitrary DNA fragments. Analyses of the sequences of 3 genes from 11 diverse cultivars revealed an SNP frequency of 1 per 190 base pairs in exons and 1 per 149 base pairs in introns. Most mutations were silent or had little perceptible effect on the polypeptide encoded. The higher incidence of transversions (55%) suggests that methylation is not the major driving force for DNA base changes. Evidence of linkage disequilibrium in 2 pairs of markers has been detected. The set of predominantly SNP-based markers was used to genotype 65 olive samples obtained from Europe and Australia, and was able clearly to discriminate 77% of the cultivars. Samples, putatively of the same cultivar but derived from different sources, were revealed as identical, demonstrating the utility of these markers as tools for resolving nomenclature issues. Genotyping data were used for constructing a dendrogram by UPGMA cluster analysis using the simple matching similarity coefficient. Relationships between cultivars are discussed in relation to the route of olive's spread.
Dietary intake, weight gain, and birth outcomes of physically active pregnant women: a pilot study
Authors: Giroux Isabelle , Inglis Stuart D. , Lander Susan , Gerrie Shannon , Mottola Michelle F.
Published: November 2006

Pregnant women have increased energy and nutrient needs. Exercise also increases energy and glucose demands. This pilot study examined whether women who were physically active during pregnancy met their dietary needs, gained weight adequately, avoided hypoglycemia, and had normal birth outcomes. Based on a convenience sample, 11 active women were studied from 18 weeks gestation to delivery. They exercised for 40 min at 70% VO2 peak, 3–4 times per week. Weekly measures included capillary blood glucose concentrations, body mass, and food records. Birth outcome measures included baby mass, length, and activity, pulse, grimace, appearance, and respiration (APGAR) scores. Our findings suggest that these subjects had lower average energy intake (8680 ± 490 kJ/d) than recommended for the 2nd and 3rd trimesters (13 020 ±185 kJ/d; 13 480 ± 185 kJ/d, respectively, p < 0.0001). Protein requirements for pregnancy were exceeded. Average intakes of iron (19 ± 2 mg/d) and folate (356 ± 33 μg/d) were lower than Recommended Dietary Allowances (RDAs) (27 mg/d and 600 μg/d, respectively) and milk products consumed were less than the recommended daily servings. Four women gained less weight per week than recommended for pregnancy. No hypoglycemia occurred post-exercise. Birth outcome measures were within normal ranges. Comparative studies with a larger number of subjects are required to determine if active pregnant women have adequate nutrient intakes and weight gain.
Hydrothermal treatment and recycling of organic by-products from sludge – confirmation of by-products availability for biological nutrient removal
Authors: Shanableh A , Jomaa S
Published: November 2006

The main objective of this study was to confirm the technical feasibility of using hydrothermal processing of sludge to combine partial treatment and generation of useful organic by-products for internal recycling to support biological nutrient removal (BNR). The experimental program involved assessing hydrothermal sludge treatment and production of organic by-products containing volatile fatty acids, especially acetic acid, under a variety of reaction temperatures, durations, and uses of oxidant. Three sludge types were treated; primary, secondary, and a mixture of the primary and secondary. The organic by-products were then used to provide the main carbon source to support BNR in two short sets of sequencing batch reactor experiments. The results confirmed the bio-availability of the by-products to support simultaneous biological phosphorus removal and denitrification. The BNR microorganisms readily used the dissolved by-products, especially acetic acid, for active biological phosphorus release and uptake and denitrification. Mass balance analysis confirmed that hydrothermal generation of by-products from sludge can be adequate for internal recycling in BNR wastewater treatment plants. Key words: wastewater sludge, hydrothermal treatment, recycling of organic by-products, organic carbon source, volatile fatty acids, acetic acid, biological nutrient removal, phosphorus removal, denitrification.
Removal of cadmium (II) ions from aqueous solution by Tamrix gallica leaves
Authors: Zaggout Farid R , Al-Subu Mohamed M , El-Ghoti Tysser
Published: November 2006

Removal of cadmium from aqueous solutions by Tamrix gallica leaves has been investigated. The effect of several factors on the removal has been studied, including metal ions concentration, Tamrix leaves concentration, pH, presence of competing ions, agitation, crushing, and drying. Removal of cadmium by Tamrix leaves was found to be dependant on pH and the maximum removal of cadmium by Tamrix leaves was found at pH 5. The cadmium removal by Tamrix leaves has been found to depend on both the concentration of leaves and the concentration of cadmium in solution. The presence of foreign ions along with cadmium ions in water reduce the removal of cadmium in the order Cu > Pb > Ni > Na > K. Applicability of the Freundlich adsorption isotherm has been examined and the parameters of this isotherm have been calculated. The order of reaction between cadmium ions and Tamrix gallica leaves with respect to cadmium has been found to be first order and a mechanism based on adsorption of cadmium on leaves has been suggested. Key words: cadmium removal, water, Tamrix leaves, adsorption isotherm.
A field study of the use of methoprene for West Nile virus mosquito control
Authors: Des Lauriers Angelune , Li James , Sze Kevin , Baker Stacey L , Gris Greg , Chan Jack
Published: November 2006

The occurrence of vector-borne West Nile virus in Canada has resulted in the use of larvicides for widespread urban mosquito control. To determine the fate of larvicides in storm drainage systems, three catch basins in Toronto, Ontario were treated with methoprene (Altosid) pellets three times over the summer of 2003, at the recommended mosquito control dose of 0.7 g per catch basin. Daily monitoring included: methoprene concentration analysis, precipitation in the area, the presence of mosquito larvae, and the chemical composition of catch basin sumps. A model catch basin in the laboratory was also dosed with methoprene pellets and sampled daily to observe concentration over time under quiescent conditions. It was found that (1) the methoprene concentration at the catch basins fell below the minimum lethal concentration after one or two weeks after treatment; (2) rainfall flushed methoprene from the catch basins to the storm sewer outfall at concentrations lower than the level that may cause ecosystem damage; and (3) the methoprene concentrations in the experiments exhibited a double peak decay pattern. Key words: methoprene, Altosid, West Nile virus, larvicide, catch basin, Toronto.
Electrochemically formed passive layers on titanium — Preparation and biocompatibility assessment in Hank's balanced salt solution
Authors: Zhao Baodong , Jerkiewicz Gregory
Published: November 2006

Uniform and crack-free passive layers on Ti are prepared using AC voltage in 7.5 wt.% aq. NH4·BF4 at 25 °C. The passive layers possess coloration (wide spectrum of colors) that depends on the experimental conditions. The biocompatibility of such prepared passive layers is evaluated using corrosion science and analytical techniques. Their corrosion behavior, Ti-ion release, surface roughness, and wettability in Hank's Balanced Salt Solution (HBSS) at 37 °C are the main focus of this work. Open-circuit potential and polarization measurements demonstrate that the corrosion potential (Ecorr) of the passive layers becomes more positive than that of the untreated Ti. The value of Ecorr increases as we increase the AC voltage (VAC). Their corrosion rate (CR) is lower than that of the untreated Ti, and they reduced the Ti-ion release level from 230 to 15 ppb. An increase in the AC voltage frequency (f) leads to a slightly higher level of the Ti-ion release (~50 ppb). Surface profilometry, optical microscopy, and scanning electron microscopy (SEM) analyses show that prolonged exposure of the passive layers to HBSS results in changes to their surface topography. The passive layers prepared by the application of AC voltage are rougher and more hydrophilic than the untreated Ti. Our methodology of preparing biocompatible passive layers on Ti might be applied as a new surface treatment procedure for Ti implants.Key words: titanium, metal surface treatment, surface roughness, corrosion, metal ion release, contact angle.
Synthesis and evaluation of methyl 2-methoxycarbonyl-3-phenylpropionate derivatives as a new type of angiotensin converting enzyme inhibitors
Authors: Cai Xiao-hua , Xie Bing , Guo Hui
Published: November 2006

Methyl 2-methoxycarbonyl-3-phenylpropionate derivatives were prepared, and their inhibitory activities for angiotensin converting enzyme (ACE) were evaluated. Compounds 5b (IC50 = 0.0039 µmol/L), 5d (IC50 = 0.0027 µmol/L), 5e (IC50 = 0.0021 µmol/L), and5f (IC50 = 0.0052 µmol/L) exhibited more potent ACE inhibitiory activity than the control drug Captopril® (IC50 = 0.0075 µmol/L).Key words: hypertension, 2-methoxycarbonyl-3-phenyl propionate derivative, ACE inhibitor.
Biocontrol of wood-rotting fungi withStreptomyces violaceusnigerXL-2
Authors: Shekhar Nilanshu , Bhattacharya Debaditya , Kumar Dishant , Gupta Rajinder K
Published: November 2006

During the previous decade, chitinases have received increased attention because of their wide range of applications. Chito-oligomers produced by enzymatic hydrolysis of chitin have been of interest in recent years because of their broad applications in medical, agricultural, and industrial applications, such as antibacterial, antifungal, hypo cholesterolemic, and antihypertensive activity, and as food quality enhancer. Fungal cell walls being rich in chitin also enable the use of chitinases in biocontrol of fungal pathogens, as bio-fungicides. An actinomycete was isolated from the bark of trees of Dehradun in India and was later identified as Streptomyces violaceusniger. This strain exhibits strong antagonism towards various wood-rotting fungi, such as Phanerochaete chrysosporium, Postia placenta, Coriolus versicolor, and Gloeophyllum trabeum. Further, studies showed an extracellular bioactive compound was responsible for the antagonism. The conditions for the production of this biocontrol agent were optimized, and the effects of various stress factors (like nitrogen-deficient media, carbon-deficient media, etc.) were studied. The presence of chitin in the growth media was found to be an essential factor for the active production of the biocontrol agent. The pH and temperature optima for the biocontrol agent were determined. Purification and characterization of this specific biocontrol agent was performed through anion exchange chromatography using a DEAE–cellulose column, and a single protein band was obtained on a 10% sodium dodecyl sulfate – polyacrylamide gel. The protein was later identified as a 28 kDa endo chitinase by MALDI–TOF (matrix-assisted laser desorption ionization – time of flight) and by a chitobiose activity assay.Key words: actinomycetes, biocontrol agents, Streptomyces violaceusniger, chitinase.
ThemviNhomolog inBurkholderia pseudomalleiis essential for viability and virulence
Authors: Ling Jessmi M.L , Moore Richard A , Surette Michael G , Woods Donald E
Published: November 2006

The virulence factors of Burkholderia pseudomallei, the causative agent of melioidosis, are not fully understood. We have identified a gene with homology to the Salmonella typhimurium mouse virulence gene, mviN, a member of the mouse virulence factor family. Expression studies with an insertional mutant containing a lux operon demonstrated that the expression of the gene is influenced by free-iron availability in the media and by growth phase. The mutant displayed an increased LD50value in the hamster infection model and a loss of the ability to invade human lung epithelial cells. The mutant has a slower growth rate than that of the wild type. Both defects were restored to various degrees when complemented in trans with the mviN gene. The mutant contains an insertion at 1229 bp of the 1548 bp gene, resulting in a truncated protein that is presumably responsible for the defects. Deletion mutants of the entire B. pseudomallei mviN gene were obtained only in the presence of the complement vector. This result and the inability of the complemented deletion mutant to lose the plasmid in the absence of antibiotic selection suggest that the gene is essential to B. pseudomallei.Key words: Burkholderia pseudomallei, mviN, virulence, essential gene.
Are there ventricle-specific postnatal maturational differences in myocardial β-adrenoceptors?
Authors: Wittnich Carin , Belanger Michael P. , Bandali Karim
Published: November 2006

Newborn hearts have restricted functional reserve and variable responsiveness to inotropes that could be partly due to differences in myocardial β-adrenoceptors (β-AR). To clarify this issue, this study documented ventricle-specific changes in myocardial β-AR density and affinity during postnatal maturation. In vivo left and right ventricle (LV and RV, respectively) biopsies were obtained from newborn (3-day-old, n = 11), immature (14-day-old, n = 7), and adult (n = 6) pigs. Total β-AR density (Bmax, fmol/g) and dissociation constant (Kd, pmol/L) were determined by radioligand binding with I125 iodocyanopindolol. Overall, β-AR Bmax in the LV significantly decreased with maturation. Interestingly, newborn animal hearts (LV and RV) subdivided into 2 groups: an adult-like low Kd group with low Bmax and a fetal-like high Kd group with high Bmax, which were significantly different from one another. The high Kd newborn group also had significantly higher Kd and Bmax than both immature and adult hearts. Newborns had similar Bmax but higher Kd in the LV than the RV, whereas immature and adult hearts did not have ventricular differences. During maturation, β-AR density decreased, whereas LV β-AR binding affinity increased. Variable β-AR maturity was also identified immediately post partum, which could potentially explain the newborn heart’s variable responsiveness to inotropes. The subset of newborn hearts with lower binding affinity (reduced responsiveness) could also contribute to the newborn heart’s overall reduction in functional reserve.
Effect of fasudil on macrovascular disorder-induced endothelial dysfunction
Authors: Shah Dhvanit I. , Singh Manjeet
Published: November 2006

The present study has been designed to investigate the effect of fasudil (Rho-kinase inhibitor) in hypercholesterolemia- and hypertension-induced endothelial dysfunction. High fat diet (8 weeks) and desoxycortisone acetate (DOCA) (40 mg·kg–1) were administered (s.c.) to rats to produce hypercholesterolemia and hypertension (mean arterial blood pressure > 120 mmHg), respectively. Endothelial dysfunction was assessed using isolated aortic ring, electron microscopy of thoracic aorta, and serum concentration of nitrite/nitrate. The expression of mRNA for p22phox and eNOS was assessed by using RT-PCR. Serum thiobarbituric acid reactive substances concentration and aortic superoxide anion concentration were estimated to assess oxidative stress. Fasudil (30 mg·kg–1, p.o.) and atorvastatin (30 mg·kg–1, p.o.) treatments markedly prevented hypercholesterolemia- and hypertension-evoked attenuation of acetylcholine-induced endothelium-dependent relaxation, impairment of vascular endothelial lining, decrease in expression of mRNA for eNOS and serum nitrite/nitrate concentration, and an increase in expression of mRNA for p22phox, superoxide anion, and serum thiobarbituric acid reactive substances. The ameliorative effect of fasudil was prevented by L-NAME. In conclusion, fasudil-induced inhibition of Rho-kinase may improve hypercholesterolemia- and hypertension-induced endothelial dysfunction.
VERTICALLY ALIGNED CARBON NANOTUBES AT DIFFERENT TEMPERATURES BY SPRAY PYROLYSIS TECHNIQUES
Authors: AFRE RAKESH A. , SOGA T. , JIMBO T. , KUMAR MUKUL , ANDO Y. , SHARON M.
Published: November 2006

Vertically aligned arrays of multi-walled carbon nanotubes (VACNTs) were grown by spray pyrolysis of turpentine oil and ferrocene mixture at temperatures higher than 700°C. Using this simple method, we report the successful growth of vertically aligned nanotubes of ~300μm length and diameter in the range of ?20–80 nm on Si (100) substrate. The ferrocene acts as an in situ Fe catalyst precursor, forming the nano-sized metallic iron particles for formation of VACNTs on the Si substrate. The morphological characteristics of VACNTs are confirmed by SEM, TEM and Raman spectroscopy and growth mechanism is discussed in short.
Where's the evidence that active learning works?
Authors: Michael Joel
Published: November 2006

Calls for reforms in the ways we teach science at all levels, and in all disciplines, are wide spread. The effectiveness of the changes being called for, employment of student-centered, active learning pedagogy, is now well supported by evidence. The relevant data have come from a number of different disciplines that include the learning sciences, cognitive psychology, and educational psychology. There is a growing body of research within specific scientific teaching communities that supports and validates the new approaches to teaching that have been adopted. These data are reviewed, and their applicability to physiology education is discussed. Some of the inherent limitations of research about teaching and learning are also discussed.