bluuebunny/crossref_metadata_2025 huggingface dataset:
Rabbit Model of
Candida albicans
Biofilm Infection: Liposomal Amphotericin B Antifungal Lock Therapy
Authors: Schinabeck Matthew K. , Long Lisa A. , Hossain Mohammad A. , Chandra Jyotsna , Mukherjee Pranab K. , Mohamed Sotohy , Ghannoum Mahmoud A.
Published: April 2004

Catheter-related infections due to
Candida albicans
biofilms are a leading cause of fungal nosocomial bloodstream infection. In this paper, we describe the development of a model of catheter-associated infection with
C. albicans
biofilms and show that antifungal lock therapy with liposomal amphotericin B is an effective treatment strategy for these infections. Silicone catheters surgically placed in New Zealand White rabbits were infected with
C. albicans
, and the rabbits were randomized into three groups: (i) untreated controls, (ii) liposomal amphotericin B lock, and (iii) fluconazole lock. Upon completion of therapy, blood cultures were obtained and the catheters were removed for quantitative culture and scanning electron microscopic analyses. Quantitative cultures revealed that catheters treated with liposomal amphotericin B yielded 0 CFU, which was significant compared to the untreated controls (
P
< 0.001) and the fluconazole-treated group (
P
= 0.0079). Although fluconazole treatment tended to have lower CFU compared to untreated controls, there was no difference in mean colony counts between these two groups (1.128 ± 0.764 and 1.841 ± 1.141 log
10
CFU/catheter segment, respectively;
P
= 0.297). Scanning electron microscopy revealed abundant biofilm in the control and fluconazole groups, while the liposomal amphotericin B group was virtually cleared. These findings suggest a possible treatment strategy for the successful salvage of catheters infected with
C. albicans
biofilms and describe an animal model that may play an important role in the further study of
C. albicans
biofilm pathogenesis and evaluation of potential antibiofilm agents.
Trypanocidal Activity of Melamine-Based Nitroheterocycles
Authors: Stewart Mhairi L. , Bueno Gorka Jimenez , Baliani Alessandro , Klenke Burkhard , Brun Reto , Brock Janice M. , Gilbert Ian H. , Barrett Michael P.
Published: April 2004

A series of nitroheterocyclic compounds were designed with linkages to melamine or benzamidine groups that are known substrates of the P2 aminopurine and other transporters in African trypanosomes of the brucei group. Several compounds showed in vitro trypanotoxicity with 50% inhibitory concentrations in the submicromolar range. Although most compounds interacted with the P2 transporter, as judged by their ability to inhibit adenosine transport via this carrier, uptake through this route was not necessary for activity since
TbAT1
-null mutant parasites, deficient in this transporter, retained sensitivity to these drugs. One compound, a melamine-linked nitrofuran, also showed pronounced activity against parasites in mice. Studies into the mode of action of this compound indicated that neither reductive, nor oxidative, stress were related to its trypanocidal activity ruling out a genotoxic effect in
T. brucei
, distinguishing it from some other, mammalian cell toxic, trypanocidal nitroheterocycles.
Activities of Benzimidazole
d
- and
l
-Ribonucleosides in Animal Models of Cytomegalovirus Infections
Authors: Kern Earl R. , Hartline Caroll B. , Rybak Rachel J. , Drach John C. , Townsend Leroy B. , Biron Karen K. , Bidanset Deborah J.
Published: April 2004

Since human cytomegalovirus (HCMV) does not infect or replicate in nonhuman cells and tissues, there are few animal models currently available for evaluation of antiviral therapies for these infections. In the present studies, we utilized two different models in which severe combined immunodeficient (SCID) mice were implanted with human fetal tissue that was subsequently infected with HCMV. In one model, human fetal retinal tissue was implanted into the anterior chamber of the SCID mouse eye, and in the second, human fetal thymus and liver (thy/liv) tissues were implanted under the kidney capsule. After the implants were established, they were infected with 2,000 to 9,000 PFU of HCMV. To determine the efficacy of three benzimidazole nucleosides, 2-bromo-5,6-dichloro-(1-β-
d
-ribofuranosyl)benzimidazole (BDCRB), GW275175X (175X), and GW257406X (1263W94, maribavir [MBV]) treatment was initiated 24 h after infection of the implants and continued for 28 days. Treatment consisted of either placebo, 25 mg of ganciclovir (GCV)/kg of body weight administered intraperitoneally (i.p.) twice daily, 33 or 100 mg of BDCRB/kg administered i.p. twice daily, or 75 mg of either MBV or 175X/kg administered orally twice daily. GCV was effective in both models, inhibiting HCMV infection by 5- to 3,000-fold. In the retinal tissue model, MBV and BDCRB reduced HCMV replication about fourfold through 21 days postinfection compared with results for the vehicle control. In the thy/liv tissue model, all three benzimidazole nucleosides were effective in inhibiting HCMV replication by approximately 30- to 3,000-fold in comparison to the vehicle control. These data indicate that the benzimidazole nucleosides were efficacious in these animal models and suggest that this class of compounds should be active against the various HCMV infections that occur in the immunocompromised host.
Outcomes of Patients with Melioidosis Treated with Meropenem
Authors: Cheng Allen C. , Fisher Dale A. , Anstey Nicholas M. , Stephens Dianne P. , Jacups Susan P. , Currie Bart J.
Published: April 2004

Melioidosis, an infection due to
Burkholderia pseudomallei
, is endemic in southeast Asia and northern Australia. We reviewed our experience with meropenem in the treatment of severe melioidosis in 63 patients over a 6-year period. Outcomes were similar to those of ceftazidime-treated patients (
n
= 153) despite a deliberate selection bias to more-unwell patients receiving meropenem. The mortality among meropenem-treated patients was 19%. One patient had a possible drug fever associated with the use of meropenem. We conclude that meropenem (1 g or 25 mg/kg every 8 h intravenously for ≥14 days) is an alternative to ceftazidime and imipenem in the treatment of melioidosis. The use of meropenem may be associated with improved outcomes in patients with severe sepsis associated with melioidosis.
Clinical Strains of
Pseudomonas aeruginosa
Overproducing MexAB-OprM and MexXY Efflux Pumps Simultaneously
Authors: Llanes Catherine , Hocquet Didier , Vogne Christelle , Benali-Baitich Dounia , Neuwirth Catherine , Plésiat Patrick
Published: April 2004

Simultaneous overexpression of the MexAB-OprM and MexXY efflux systems was demonstrated by real-time reverse transcription-PCR and immunoblotting experiments for 12 multiresistant clinical isolates of
Pseudomonas aeruginosa
. DNA sequencing analysis showed that nine of these strains (named
agrZ
mutants) harbored mutations in
mexZ
, the product of which downregulates the expression of the
mexXY
operon. In addition, 8 of the 12 strains exhibited mutations in genes known to control transcription of the
mexAB-oprM
operon. Four of them were
nalB
mutants with alterations in the repressor gene
mexR
, three of them appeared to be
nalC
mutants deficient in gene
PA3721
and overexpressing gene
PA3720
, and one strain was a
nalB nalC
double mutant. For MexAB-OprM as well as for MexXY, no clear correlation could be established between (i) the types of mutations, (ii) the expression level of
mexA
or
mexX
, and (iii) resistance to effluxed antibiotics. Finally, three isolates, named
agrW
mutants, overproduced MexXY and had an intact
mexZ
gene, and four strains overproduced MexAB-OprM and had intact
mexR
and
PA3721
genes (
nalD
mutants). These data show that clinical isolates are able to broaden their drug resistance profiles by coexpressing two Mex efflux pumps and suggest the existence of additional regulators for MexAB-OprM and MexXY.
Novel, Rapid, and Inexpensive Cell-Based Quantification of Antimalarial Drug Efficacy
Authors: Bennett Tyler N. , Paguio Michelle , Gligorijevic Bojana , Seudieu Clement , Kosar Andrew D. , Davidson Eugene , Roepe Paul D.
Published: April 2004

We report on the development of a new SYBR Green I-based plate assay for analyzing the activities of antimalarial drugs against intraerythrocytic
Plasmodium falciparum
. This assay is considerably faster, less labor-intensive, and less expensive than conventional radiotracer (e.g., [
3
H]hypoxanthine and [
3
H]ethanolamine)-based assays or
P. falciparum
lactate dehydrogenase activity-based assays. The assay significantly improves the pace at which antimalarial drug discovery efforts may proceed.
Novel Non-
mecA
-Containing Staphylococcal Chromosomal Cassette Composite Island Containing
pbp4
and
tagF
Genes in a Commensal Staphylococcal Species: a Possible Reservoir for Antibiotic Resistance Islands in
Staphylococcus aureus
Authors: Mongkolrattanothai Kanokporn , Boyle Susan , Murphy Trudy V. , Daum Robert S.
Published: April 2004

Among methicillin-resistant
Staphylococcus aureus
isolates, a staphylococcal chromosomal cassette containing the
mecA
gene (SCC
mec
) is integrated into the chromosome at a unique site. SCC
mec
also contains unique
ccrAB
recombinase genes mediating its integration and excision from the genome and is flanked by characteristic left and right direct- and inverted-repeat sequences. A few non-
mecA
-containing SCC elements that have the other molecular features described above have recently been described. The origin of these cassettes is not clear. We have identified two new members of the SCC family integrated within
orfX
in
Staphylococcus epidermidis
strain ATCC 12228, neither of which carries
mecA
. One is a 57-kb element flanked by a unique 28-bp SCC direct repeat. It was called the SCC composite island (SCC-CI) because it carries a 19-kb SCC element (SCC
pbp4
) nested within it. SCC
pbp4
contains
pbp4
and
tagF
genes, as well as one pair of
ccrAB
genes (allotype 2) flanked by classical SCC-specific terminal repeats. External to SCC
pbp4
, SCC-CI contains a second pair of
ccrAB
genes (allotype 4), three IS
431
elements, and genes mediating resistance to heavy metals. Genes mediating restriction-modification that may facilitate horizontal transfer are also present within SCC-CI, both within and outside SCC
pbp4.
Several novel arrangements of the SCC direct and inverted repeats were identified. Several long stretches of homology with other SCCs were found within and outside SCC
pbp4
. In view of the fact that SCC-CI was found in a commensal species, it may represent a reservoir for sequences involved in genetic shuffling between staphylococci and may contribute to the diversity found in SCC elements.
Inhibitory Activity of Alkoxyalkyl and Alkyl Esters of Cidofovir and Cyclic Cidofovir against Orthopoxvirus Replication In Vitro
Authors: Keith Kathy A. , Wan William B. , Ciesla Stephanie L. , Beadle James R. , Hostetler Karl Y. , Kern Earl R.
Published: April 2004

A new series of ether lipid esters of cidofovir (CDV) were evaluated against vaccinia and cowpox viruses. Activity was dependent on number of atoms in the alkyl or alkoxyalkyl chain, the linker moiety, and the presence of a double bond in the alkoxyalkyl chains linked to the phosphonate moiety of CDV.
Activities of Telithromycin against 13,874
Streptococcus pneumoniae
Isolates Collected between 1999 and 2003
Authors: Farrell David J. , Felmingham David
Published: April 2004

Telithromycin MICs for 13,874
Streptococcus pneumoniae
isolates collected in the first 3 years of the global PROTEKT study (1999 to 2003) were studied. There was no change in the distribution of telithromycin MICs over this period, even in countries where telithromycin is in use. The telithromycin MICs for 10 isolates (0.07%) were ≥4 μg/ml, and these 10 isolates contained
erm
(B); there was no evidence of reproducible clonal spread between centers.
Differential Expression Levels of MRP1, MRP4, and MRP5 in Response to Human Immunodeficiency Virus Infection in Human Macrophages
Authors: Jorajuria Sylvie , Dereuddre-Bosquet Nathalie , Naissant-Storck Karen , Dormont Dominique , Clayette Pascal
Published: April 2004

Multidrug resistance proteins (MRPs) have been reported to be involved in the efflux of some anti-human immunodeficiency virus (HIV) drugs. We show here that MRP1, MRP4, and MRP5 are expressed at the mRNA level in human monocyte-derived macrophages. HIV infection caused increased transcription of these MRPs; however, temporal differences in stimulation are reported.
Iron Blocks the Accumulation and Activity of Tetracyclines in Bacteria
Authors: Avery Angela M. , Goddard Helen J. , Sumner Edward R. , Avery Simon V.
Published: April 2004

The apparent sensitivities of several bacterial pathogens to tetracyclines varied by up to 128-fold with the medium content of Fe, but not of other metals. The effect of Fe was independent of superoxide dismutase activity and of intracellular Fe, but accumulation of tetracyclines was blocked in high-Fe medium. Thus, synergistic suppression of bacterial growth in the presence of a low Fe concentration and tetracyclines arises because of elevated antibiotic accumulation.
Effects of Maribavir and Selected Indolocarbazoles on Epstein-Barr Virus Protein Kinase BGLF4 and on Viral Lytic Replication
Authors: Gershburg Edward , Hong Ke , Pagano Joseph S.
Published: April 2004

The human cytomegalovirus (HCMV) homolog of the Epstein-Barr virus (EBV) protein kinase (PK), UL97, is inhibited by maribavir (1263W94) and selected indolocarbazoles. Here we show that only one of these indolocarbazoles (K252a), but not maribavir, inhibits autophosphorylation of the EBV PK, BGLF4. However, maribavir and another indolocarbazole, NGIC-I, do inhibit EBV DNA synthesis, suggesting that although these last compounds inhibit both HCMV and EBV, they seem to operate through differ-ent pathways.
Pharmacokinetics of Indinavir Combined with Low-Dose Ritonavir in Human Immunodeficiency Virus Type 1-Infected Children
Authors: Bergshoeff A. S. , Fraaij P. L. A. , van Rossum A. M. C. , Verweel G. , Wynne L. H. , Winchell G. A. , Leavitt R. Y. , Nguyen B.-Y. T. , de Groot R. , Burger D. M.
Published: April 2004

So far, no pediatric doses for indinavir combined with ritonavir have been defined. This study evaluated the pharmacokinetics of 400 mg of indinavir/m2combined with 125 mg of ritonavir/m2every 12 h (q12h) in 14 human immunodeficiency virus type 1-infected children. The area under the concentration-time curve from 0 to 24 h and the minimum concentration of drug in serum for indinavir were similar to those for 800 mg of indinavir-100 mg of ritonavir q12h in adults, while the maximum concentration of drug in serum was slightly decreased, with geometric mean ratios (90% confidence intervals in parentheses) of 1.1 (0.87 to 1.3), 0.96 (0.60 to 1.5), and 0.80 (0.68 to 0.94), respectively.
In Vitro Activity of Anidulafungin against Selected Clinically Important Mold Isolates
Authors: Odabasi Zekaver , Paetznick Victor L. , Rodriguez Jose R. , Chen Enuo , Ostrosky-Zeichner Luis
Published: April 2004

In this study, we evaluated the in vitro activity of anidulafungin against selected mold isolates. Anidulafungin showed promising activity against
Bipolaris spicifera
,
Exophiala jeanselmei
,
Fonsecaea pedrosoi
,
Madurella mycetomatis
,
Penicillium marneffei
,
Phialophora verrucosa
,
Pseudallescheria boydii
,
Sporothrix schenckii
, and
Wangiella dermatitidis.
Stratigraphy, palynology, and provenance of the Colorado Creek basin, Alaska, USA: Oligocene transpressional tectonics along the central Denali fault system
Authors: Trop Jeffrey M , Ridgway Kenneth D , Sweet Arthur R
Published: April 2004

New sedimentologic, biostratigraphic, and compositional data from a 415-m-thick section of siliciclastic and volcanic strata document Oligocene synthrusting sedimentation south of the McKinley segment of the Denali fault system. Strata of the Colorado Creek basin are presently exposed on the south side of the central Alaska Range in the footwalls of north-dipping thrust faults. New measured sections define a three-part stratigraphy. Lowermost strata consist of a ~30-m-thick unit of marine sandstone and mudstone that contain Late Cretaceous dinoflagellate taxa. The middle unit consists of ~330 m of conglomerate, sandstone, and mudstone interpreted as braided stream and floodplain deposits. This middle unit contains early Oligocene pollen and spore assemblages. The upper unit is 55 m thick and contains lava flows, tuff, and pumice interpreted as the product of subaerial volcanic eruptions. Direct age data are lacking from the upper unit. Compositional data from the middle unit indicate that detritus was derived from sedimentary and igneous source terranes exposed on both the north and south side of the McKinley fault. Matching source lithologies north of the McKinley fault with conglomerate clast types in the Colorado Creek basin implies 3033 km of maximum post-early Oligocene dextral displacement along the fault. We interpret the Oligocene strata of the Colorado Creek basin as a product of transpressional deformation that produced north-dipping thrust faults associated with strike-slip displacement on the central Denali fault. Our data from the Colorado Creek basin, in combination with previous studies, document a major episode of middle Eocene  late Oligocene synorogenic sedimentation along the Denali fault from British Columbia to southwestern Alaska.
Endostromatolites from permafrost karst, Yukon, Canada: paleoclimatic proxies for the Holocene hypsithermal
Authors: Clark Ian , Lauriol Bernard , Marschner Mark , Sabourin Nicolas , Chauret Yanie , Desrochers André
Published: April 2004

A remarkable biogenic calcite precipitate forms carpets of finely laminated ~1 mm diameter columns lining fissures within limestone bedrock in the permafrost regions of the northern Yukon. This material, "endostromatolite," for its laminated morphology and growth hidden within the carbonate rock, is ubiquitous within limestone terrains of the Arctic and grew during the early Holocene hypsithermal. Dissolution on the interior fissure faces is accompanied by biomineralization of the opposing faces; a previously unrecognized weathering process in permafrost regions. Occurrence is restricted to outcrops with a southern orientation in permafrost regions, in this case, from the Ogilvie Mountains, northern Yukon. Growth occurs in water-saturated talik during periods of permafrost degradation during insolation maxima. Their enriched δ13C values (1.7 to 11.4) are generated in a methanogenic environment during anaerobic degradation of soil-derived organic carbon. A paleotemperature signal extracted from the δ18O values demonstrates that growth occurred during a hypsithermal period with an average summer air temperature 7 ± 2 °C higher than today. Corrected radiocarbon age measurements of the calcite and organic matter preserved within the endostromatolites indicate that biomineralization occurred during the late Pleistocene  early Holocene hypsithermal event. Profiles along the columns document late Pleistocene climate improvement, with maximum warmth coincident with the insolation maximum for 65°N, followed by cooling and end of growth in the mid to late Holocene.
A reevaluation of the enigmatic Permian synapsidWatongiaand of its stratigraphic significance
Authors: Reisz Robert R , Laurin Michel
Published: April 2004

The enigmatic synapsid Watongia, initially described on the basis of fragmentary remains from the Chickasha Formation of Oklahoma as an early therapsid (a gorgonopsian), is redescribed and is shown to represent the largest known varanopid synapsid. Its assignment to the Varanodontinae (Varanopidae: Synapsida) is supported by several diagnostic features, including a strongly recurved marginal dentition with both posterior and anterior, unserrated, cutting edges, quadratojugal with two discrete superficial rami, a large lateral tuberosity on the postorbital, short, deep excavations on the neural arches, and a broad, short radiale. The presence in Watongia of a posterolateral process of the frontal precludes therapsid or sphenacodontid affinities. The previously described preparietal that provided the strongest evidence of therapsid affinities for Watongia is shown to be based on misinterpreted skull fragments that were incorrectly assembled. The presence of a varanopid in the Chickasha Formation is consistent with a Guadalupian age (Middle Permian), and in the absence of large sphenacodontids and therapsids, Watongia was probably the top predator of its terrestrial vertebrate community.
Consumption of juvenile herring (Clupea harengus) by cod (Gadus morhua) in the Barents Sea: a new approach to estimating consumption in piscivorous fish
Authors: Johansen Geir Odd , Bogstad Bjarte , Mehl Sigbjørn , Ulltang Øyvind
Published: April 2004

Consumption of different age groups of juvenile, Norwegian, spring-spawning herring (Clupea harengus) by northeast Arctic cod (Gadus morhua) in the Barents Sea in 19921997 is estimated using cod stomach content data. We present a new approach to the problem of estimating consumption by fish. The new method is based on the estimation of digestion time for single prey items based on the difference between fresh weight at ingestion and weight in the stomach at time of sampling. Estimation is based on a gastric evacuation model for cod and area-specific sea temperatures. This is used to estimate the time (tmax) it takes for a prey to become digested to a stage where length is no longer measurable. Predation rate is then estimated for all prey with digestion time ≤tmax as number of prey eaten in the time range defined by tmax. This rate is combined with estimates of the proportion of the cod stock consuming the prey and area-specific abundance of cod, giving consumption of herring on a seasonal and yearly basis. The consumption estimates differ from those obtained using current methods. Predation mortality of herring is estimated directly from the consumption estimates by combining them with acoustic herring abundance data.
Energy utilization and metabolism in spawning migrating Early Stuart sockeye salmon (Oncorhynchus nerka): the migratory paradox
Authors: Kiessling Anders , Lindahl-Kiessling Kerstin , Kiessling Karl-Heinz
Published: April 2004

Sockeye salmon (Oncorhynchus nerka) were followed during their 1400-km-long migration from cessation of feeding outside British Columbia, Canada, up the Fraser River to spawning. Enzymatic capacity (indicative of glycolysis, β-oxidation, and respiratory chain ATP formation), muscle fibre size distribution, body and muscle conformation, and gross chemical composition in different parts of red and white muscle were monitored to determine energy strategies throughout the migration. The mobilization of extramuscular lipid depots was also monitored. The most conspicuous change in white muscle, concomitant with a large decrease in protein content, was an ordered reduction in muscle fibre size and lipid depots with distance covered, resulting in an accumulation of fibres with a cross section between 2000 and 6000 µm2and a maintained level of 4% intramuscular fat. A peak in oxidative capacity was noted in red muscle during the strenuous passage of Fraser Canyon. In white muscle, glycolytic capacity was maintained at least until passage of the Fraser Canyon. Enzymatic capacity was higher in the caudal than rostral part of the muscle. Differences were also found between lateral and dorsal parts of the white muscle, indicating significant differences in the timing and magnitude of enzymatic capacity of red and white muscle.
Short-term decisions of small-scale fishers selecting alternative target species: a choice model
Authors: Salas Silvia , Sumaila Ussif Rashid , Pitcher Tony
Published: April 2004

The complexity of small-scale fisheries makes it difficult to predict the allocation of fishing effort among alternative target species in mixed fisheries, resulting in limitation for fisheries management. One reason for the difficulty is that fishing effort has been assumed as an aggregate of different components, without consideration of fishers' decisions. In this paper, we use discrete choice models to identify factors involved in fishers' decisions about selecting target species on a daily basis. We analyze catch data, by species and fisher, from three fishing communities of Yucatan, Mexico, to contrast the following models: (i) random selection, (ii) economic motivation, and (iii) changes in resource availability. Our results show that fishers do not operate at random but consider information on resource availability and revenues generated from previous trips before selecting or shifting a target. We compare the results among communities and also use the proposed models to predict changes in fishing effort levels given changes in species price and catch per unit effort. We stress the importance of understanding fishers' behavior when it comes to developing appropriate management policies.
Radiocarbon in otoliths of yelloweye rockfish (Sebastes ruberrimus): a reference time series for the coastal waters of southeast Alaska
Authors: Kerr Lisa A , Andrews Allen H , Frantz Brian R , Coale Kenneth H , Brown Thomas A , Cailliet Gregor M
Published: April 2004

Atmospheric testing of thermonuclear devices during the 1950s and 1960s created a global radiocarbon (14C) signal that has provided a useful tracer and chronological marker in oceanic systems and organisms. The bomb-generated 14C signal retained in fish otoliths can be used as a time-specific recorder of the 14C present in ambient seawater, making it a useful tool in age validation of fishes. The goal of this study was to determine 14C in otoliths of the age-validated yelloweye rockfish (Sebastes ruberrimus) to establish a reference time series for the coastal waters of southeast Alaska. Radiocarbon values from the first year's growth of 43 yelloweye rockfish otoliths plotted against estimated birth year produced a 14C time series (19401990) for these waters. The initial rise of 14C occurred in 1958 and 14C levels rose to peak values (6070) between 1966 and 1971, with a subsequent declining trend through the end of the record in 1990 (3.2). In addition, the 14C data confirmed the longevity of the yelloweye rockfish to a minimum of 44 years and strongly support higher age estimates. This 14C time series will be useful for the interpretation of 14C accreted in biological samples from these waters.
Odor-evoked field potentials as indicators of sublethal neurotoxicity in juvenile coho salmon (Oncorhynchus kisutch) exposed to copper, chlorpyrifos, or esfenvalerate
Authors: Sandahl Jason F , Baldwin David H , Jenkins Jeffrey J , Scholz Nathaniel L
Published: April 2004

The sublethal effects of three different pesticides (a metal, organophosphate, and pyrethroid) on juvenile coho salmon (Oncorhynchus kisutch) were evaluated using paired electrophysiological recordings from the olfactory epithelium and the olfactory bulb. Animals were exposed to copper (520 µg·L1), chlorpyrifos (0.6252.5 µg·L1), or esfenvalerate (0.050.20 µg·L1) for 7 days. Sublethal neurotoxicity was examined by recording odor-evoked field potentials from the sensory epithelium and olfactory forebrain using two natural odorants (taurocholic acid or L-serine). Copper and chlorpyrifos decreased the amplitudes of the epithelial and bulbar responses to both odorants in a concentration-dependent manner. Benchmark concentrations for a 20% loss of sensory function were 4.4 µg·L1 for copper and 0.72 µg·L1 for chlorpyrifos. Esfenvalerate did not affect the amplitude of odor-evoked field potentials. However, in the olfactory bulbs of coho exposed to 0.2 µg esfenvalerate·L1, L-serine evoked distinct and irregular bursts of postsynaptic activity in the olfactory bulb, possibly indicating sublethal excitotoxicity to central networks. Collectively, these data indicate that periodic, non-point source contamination of salmon habitats with current-use pesticides could interfere with olfactory function and, by extension, olfactory-mediated behaviors that are important for the survival and migration of salmonids.
Behavior of concrete columns confined by carbon composite tubes
Authors: Hong Won-Kee , Kim Hee-Cheul
Published: April 2004

The carbon composite tube can play an important role in replacing or complementing longitudinal and transverse reinforcing steels by providing ductility and strength for conventional columns. In this study, both experimental and analytical investigations of axial behavior of large-scale circular and square concrete columns confined by carbon composite tubes are presented. The specimens are filament-wound carbon composite with 90° + 90°, 90° ± 60°, 90° ± 45°, and 90° ± 30° winding angles with respect to a longitudinal axis of a tube. The instrumented large-scale concrete-filled composite tubes are subjected to monotonic axial loads exerted by a 10 000 kN universal testing machine (UTM). The influence of transverse dilation, winding angle, thickness of a tube, as well as shape of the column section on stress–strain relationships of the confined columns is identified and discussed. Proposed equations to predict both strength and ductility of confined columns by carbon composite tubes demonstrate good correlation with test data obtained from large-scale specimens.Key words: carbon composites, glass fibers, strength, filament winding.
Impulse response evaluation of drilled shafts with pile caps: modeling and experiment
Authors: Baxter S C , Islam M O , Gassman S L
Published: April 2004

Impulse response, a nondestructive surface reflection technique, offers a way to assess the quality and integrity of deep foundations. While the impulse response test is a straightforward method to implement, interpretation of the data is often difficult. The response of a shaft will be affected by construction conditions, accessibility and quality of the concrete, as well as by gross defects in geometry. As a result, test responses seldom resemble the ideal theoretical response. The difficulty is increased when the accessibility of the shaft is limited by the presence of a pile cap or other structures. This study progressively develops and builds two-dimensional (2-D) and three-dimensional (3-D) finite element models of experimentally tested shafts to identify key structural features that can be modeled and captured experimentally. For shafts with pile caps, the model helped confirm previous interpretations of the experimental data presented in this paper, identifying the shaft base, a defect, and the base of the pile cap.Key words: nondestructive testing, quality assessment, quality assurance, impulse response.
Performance of double skin-profiled composite shear walls — experiments and design equations
Authors: Hossain K M. Anwar , Wright H D
Published: April 2004

The novel form of composite walling system consists of two skins of profiled steel sheeting with an infill of concrete. The knowledge of the behaviour of such walling under shear loading is important to use this system as shear elements in a steel framed building. Currently design provisions for this novel form of framed shear walling do not exist. This paper presents the results of tests on one-sixth scale models of the composite wall and its components, manufactured from very thin sheeting and microconcrete. The heavily instrumented small-scale tests provided information on the load–deflection response, strength, stiffness, strain condition, sheet–concrete interaction, and failure modes. Analytical models for the shear strength and stiffness of the wall are derived. The adequacy of design equations is validated through experimental results and finite element modelling.Key words: composite wall, design equation, profiled sheeting, shear strength, shear stiffness, strain, buckling, finite element, interface, microconcrete.
Analytical methods to reduce uncertainty in tunnel construction projects
Authors: Ruwanpura J Y , AbouRizk S M , Allouche M
Published: April 2004

This paper presents a method to quantify uncertainty using simulation techniques and approximate geotechnical methods. Unknown soil conditions are major contributors to uncertainty in any underground construction project. Soil conditions are unknown because generally soil samples taken from vertical boreholes show only the soils present in the discrete borehole locations. The soil profiles between the boreholes therefore contribute to project uncertainty, and construction practitioners must make assumptions about these soil profiles for construction planning and scheduling purposes. Analytical and simulation methods are presented to accurately predict soil profiles between boreholes and reduce uncertainty in a "rough and ready" fashion. These methods use existing borehole data to create an analytical model for soil prediction, which is then incorporated with a process interaction simulation model of the construction project using special purpose simulation concepts and advanced geotechnical characterization techniques. The application of these methods to an Edmonton tunnel construction project is also detailed. Construction engineers or managers can use these simulation methods to strengthen the geological data obtained for the construction project.Key words: borehole data, construction, risk, soil families, soil profiles, soil transitions, special purpose simulation, tunnelling, uncertainty.
Modelling pavement temperature for winter maintenance operations
Authors: Sherif Aly , Hassan Yasser
Published: April 2004

Road and highway maintenance is vital for the safety of citizens and for enabling emergency and security services to perform their essential functions. Accumulation of snow and (or) ice on the pavement surface during the wintertime substantially increases the risk of road crashes and can have negative impact on the economy of the region. Recently, road maintenance engineers have used pavement surface temperature as a guide to the application of deicers. Stations for road weather information systems (RWIS) have been installed across Europe and North America to collect data that can be used to predict weather conditions such as air temperature. Modelling pavement surface temperature as a function of such weather conditions (air temperature, dew point, relative humidity, and wind speed) can provide an additional component that is essential for winter maintenance operations. This paper uses data collected by RWIS stations at the City of Ottawa to device a procedure that maximizes the use of a data batch containing complete, partially complete, and unusable data and to study the relationship between the pavement surface temperature and weather variables. Statistical models were developed, where stepwise regression was first applied to eliminate those variables whose estimated coefficients are not statistically significant. The remaining variables were further examined according to their contribution to the criterion of best fit and their physical relationships to each other to eliminate multicollinearities. The models were further corrected for the autocorrelation in their error structures. The final version of the developed models may then be used as a part of the decision-making process for winter maintenance operations.Key words: winter maintenance, pavement temperature, statistical modelling, RWIS.
Prévision hydrologique distribuée pour la gestion des barrages publics du Québec
Authors: Turcotte Richard , Lacombe Pierre , Dimnik Corrine , Villeneuve Jean-Pierre
Published: April 2004

The development of a flow forecasting system for public dam management in southern Quebec is presented. The system is based on distributed hydrological models using 3-h time steps to correctly perform short-term forecasts on small watersheds, located upstream of these dams, with quick hydrological responses. The contribution of models in the complete process of forecast evaluation is also studied. A numerical application, using the flood of the Chaudière river in July 2001, illustrated that distributed models with short time steps are needed despite the added complexity in the installation, calibration, and operation of the forecasting system. Also, the analysis of flow forecasted for the Spring 2003 flood shows that interpretation of model runs can lead the operational forecaster to better forecasting of results and can be improved by the use of distributed models.Key words: hydrology, flow forecast, distributed hydrological model, flood.
Cefotaximases (CTX-M-ases), an expanding family of extended-spectrum β-lactamases
Authors: Walther-Rasmussen Jan , Høiby Niels
Published: April 2004

Among the extended-spectrum β-lactamases, the cefotaximases (CTX-M-ases) constitute a rapidly growing cluster of enzymes that have disseminated geographically. The CTX-M-ases, which hydrolyze cefotaxime efficiently, are mostly encoded by transferable plasmids, and the enzymes have been found predominantly in Enterobacteriaceae, most prevalently in Escherichia coli, Salmonella typhimurium, Klebsiella pneumoniae, and Proteus mirabilis. Isolates of Vibrio cholerae, Acinetobacter baumannii, and Aeromonas hydrophila encoding CTX-M-ases have also been reported. The CTX-M-ases belong to the molecular class A β-lactamases, and the enzymes are functionally characterized as extended-spectrum β-lactamases. This group of β-lactamases confers resistance to penicillins, extended-spectrum cephalosporins, and monobactams, and the enzymes are inhibited by clavulanate, sulbactam, and tazobactam. Typically, the CTX-M-ases hydrolyze cefotaxime more efficiently than ceftazidime, which is reflected in substantially higher MICs to cefotaxime than to ceftazidime. Phylogenetically, the CTX-M-ases are divided into four subfamilies that seem to have descended from chromosomal β-lactamases of Kluyvera spp. Insertion sequences, especially ISEcp1, have been found adjacent to genes encoding enzymes of all four subfamilies. The class I integron-associated orf513 also seems to be involved in the mobilization of blaCTX-M genes. This review discusses the phylogeny and the hydrolytic properties of the CTX-M-ases, as well as their geographic occurrence and mode of spread.Key words: extended-spectrum β-lactamases, cefotaximases, phylogeny, dissemination, hydrolytic properties.
Isolation of a strain of Agrobacterium tumefaciens (Rhizobium radiobacter) utilizing methylene urea (ureaformaldehyde) as nitrogen source
Authors: Koivunen Marja E , Morisseau Christophe , Horwath William R , Hammock Bruce D
Published: April 2004

Methylene ureas (MU) are slow-release nitrogen fertilizers degraded in soil by microbial enzymatic activity. Improved utilization of MU in agricultural production requires more knowledge about the organisms and enzymes responsible for its degradation. A Gram-negative, MU-degrading organism was isolated from a soil in Sacramento Valley, California. The bacterium was identified as Agrobacterium tumefaciens (recently also known as Rhizobium radiobacter) using both genotypic and phenotypic characterization. The pathogenic nature of the organism was confirmed by a bioassay on carrot disks. The MU-hydrolyzing enzyme (MUase) was intracellular and was induced by using MU as a sole source of nitrogen. The bacterial growth was optimized in NH4Cl, urea, or peptone, whereas the production and specific activity of MUase were maximized with either NH4Cl or urea as a nitrogen source. The result has a practical significance, demonstrating a potential to select for this plant pathogen in soils fertilized with MU.Key words: methylene urea, ureaformaldehyde, slow-release fertilizer, soil, nitrogen, isolation, Agrobacterium tumefaciens, Rhizobium radiobacter.
Weathering of phlogopite by Bacillus cereus and Acidithiobacillus ferrooxidans
Authors: tyriaková Iveta , Bhatti Tariq M , Bigham Jerry M , tyriak Igor , Vuorinen Antti , Tuovinen Olli H
Published: April 2004

The purpose of this study was to assess the weathering of finely ground phlogopite, a trioctahedral mica, by placing it in contact with heterotrophic (Bacillus cereus) and acidophilic (Acidithiobacillus ferrooxidans) cultures. X-ray diffraction analyses of the phlogopite sample before and after 24 weeks of contact in B. cereus cultures revealed a decrease in the characteristic peak intensities of phlogopite, indicating destruction of individual structural planes of the mica. No new solid phase products or interlayer structures were detected in B. cereus cultures. Acidithiobacillus ferrooxidans cultures enhanced the chemical dissolution of the mineral and formed partially weathered interlayer structures, where interlayer K was expelled and coupled with the precipitation of K-jarosite [KFe3(SO4)2(OH)6].Key words: Acidithiobacillus ferrooxidans, Bacillus cereus, mica, phlogopite, weathering.
EPISTURMIAN WORDS: SHIFTS, MORPHISMS AND NUMERATION SYSTEMS
Authors: JUSTIN JACQUES , PIRILLO GIUSEPPE
Published: April 2004

Episturmian words, which include the Arnoux-Rauzy sequences, are infinite words on a finite alphabet generalizing the Sturmian words and sharing many of their same properties. This was studied in previous papers. Here we gain a deeper insight into these properties. This leads in particular to consider numerations systems similar to the Ostrowski ones and to give a matrix formula for computing the number of representations of an integer in such a system. We also obtain a complete answer to the question: if an episturmian word is morphic, which shifts of it, if any, also are morphic ?
INSTANCE-SPECIFIC SOLUTIONS FOR ACCELERATING THE CKY PARSING OF LARGE CONTEXT-FREE GRAMMARS
Authors: BORDIM JACIR L. , IBARRA OSCAR H. , ITO YASUAKI , NAKANO KOJI
Published: April 2004

The main contribution of this paper is an FPGA-based implementation of an instance-specific hardware which accelerates the CKY (Cocke-Kasami- Younger) parsing of context-free grammars. Given a context-free grammar G and a string x, the CKY parsing determines whether G derives x. We developed a hardware generator that creates a Verilog HDL source to perform the CKY parsing for any fixed context-free grammar G. The generated source is embedded in an FPGA using the design software provided by the FPGA vendor. The results show that our instance-specific hardware solution attains an astonishing speed-up factor of up to 3,700 over traditional software solutions.
Several Generalizations of Shamir's Secret Sharing Scheme
Authors: Lai Chun-Pong , Ding Cunsheng
Published: April 2004

A secret sharing scheme is a system designed to share a piece of information or the secret among a group of people such that only authorized people can reconstruct the secret from their shares. Since Blakley and Shamir proposed threshold secret sharing schemes in 1979 independently, many secret sharing schemes have been constructed. In this paper, we present several threshold schemes that are generalizations of Shamir's secret sharing scheme.
EQUILIBRIUM STATES WITH MACROSCOPIC CORRELATIONS
Authors: BASILE GIADA , JONA-LASINIO GIOVANNI
Published: April 2004

We show that the equilibrium macroscopic entropy of a generic non-reversible Kawasaki–Glauber dynamics is a non-local functional of the density. This implies that equilibrium correlations extend to macroscopic distances.
TOWARDS A THEORY OF DECOHERENCE
Authors: DELL'ANTONIO GIANFAUSTO
Published: April 2004

Consider a quantum particle of mass M in R3, described at time 0 by a wave function ϕ(x) with dispersion Δ, interacting independently with a collection of N particles of mass m. Using only Schroedinger's Quantum Mechanics we prove that when N becomes large and m/M becomes small, and if the information at time t>0 about the N particles of small mass in negleted, the system admits a "classical" description, i.e. a description in which the coherence of the wave function over distances of the order of mM-1N-1Δ have disappeared. We consider this a first step towards proving that most "sufficiently large" quantum systems interacting with an uncontrolled environment admit a classical description at least for position measurements.
THE JOOS-ZEH FORMULA AND THE ENVIRONMENT–INDUCED DECOHERENCE
Authors: FIGARI RODOLFO , CARLONE RAFFAELE , TETA ALESSANDRO
Published: April 2004

We recall the classical picture about the decoherence effects induced on a quantum sub-system by the interaction with a macroscopic environment. We discuss the need of a rigorous treatment, in mathematically reasonable models, of the dynamical process bringing the system in an entangled state with the environment. We consider a simple system consisting of two particles interacting via a two-body potential and we discuss a rigorous derivation of the asymptotic wave function of the system in the limit of small mass ratio. We apply the result to the explicit computation of the decoherence effect induced on the heavy particle, in concrete examples of quantum evolution.
ON THE PROBABILITY DISTRIBUTION OF THE OVERLAP IN SPIN GLASSES
Authors: PARISI GIORGIO
Published: April 2004

In this paper we review the predictions of the replica approach on the probability distribution of the overlaps among replicas and on the sample to sample fluctuations of this probability. We stress the role of replica equivalence in obtaining relations that do not depend on the form of replica symmetry breaking. A comparison is done with the results obtained with a different rigorous approach. The role of the ultrametricity and of other algebraic properties in discussed.
CLASSICAL CHAOTIC TRAJECTORIES IN QUANTUM FIELD THEORY
Authors: VITIELLO GIUSEPPE
Published: April 2004

Trajectories in the space of the unitarily inequivalent representations of the canonical commutation relations are shown to be classical trajectories. Under convenient conditions, they may exhibit properties typical of chaotic behavior in classical nonlinear dynamics. Quantum noise in fluctuating random force in the system–environment coupling and system–environment entanglement is also discussed.
INHOMOGENEOUS PLANCHEREL–PÔLYA INEQUALITIES ON SPACES OF HOMOGENEOUS TYPE AND THEIR APPLICATIONS
Authors: DENG DONGGAO , HAN YONGSHENG , YANG DACHUN
Published: April 2004

In this paper, the authors establish the inhomogeneous Plancherel–Pôlya inequalities on spaces of homogeneous type by use of the inhomogeneous discrete Calderón reproducing formulas. As an application, the authors prove that the Lebesgue norms of the inhomogeneous Littlewood–Paley g-function and S-function on spaces of homogeneous type are equivalent. All results are new even for ℝn.
ON THE GIERER–MEINHARDT SYSTEM WITH SATURATION
Authors: WEI JUNCHENG , WINTER MATTHIAS
Published: April 2004

We consider the following shadow Gierer–Meinhardt system with saturation: [Formula: see text] where ∊>0 is a small parameter, τ≥0, k>0 and Ω⊂Rnis smooth bounded domain. The case k=0 has been studied by many authors in recent years. Here we give some sufficient conditions on k for the existence and stability of stable spiky solutions. In the one-dimensional case we have a complete answer to the stability behavior. Central to our study are a parameterized ground-state equation and the associated nonlocal eigenvalue problem (NLEP) which is solved by functional analysis arguments and the continuation method.
SOBOLEV CLASSES AND HORIZONTAL ENERGY MINIMIZERS BETWEEN CARNOT–CARATHÉODORY SPACES
Authors: TAN KANG-HAI
Published: April 2004

The notion of horizontal energy minimizers between C-C spaces is introduced. We prove the existence of such energy minimizers when the domain is a C2, noncharacteristic bounded open set in a C-C space and the target is a C-C space of Carnot type.
SOME PROPERTIES OF LEGENDRE FUNCTIONS
Authors: JONES D. S.
Published: April 2004

Some integral representations involving Legendre functions are given. Some are related to Bessel functions and their products. Others are concerned with zeros of Legendre functions and may provide a suitable basis for computational purposes.