bluuebunny/crossref_metadata_2025 huggingface dataset:
The Trypanocide Diminazene Aceturate Is Accumulated Predominantly through the TbAT1 Purine Transporter: Additional Insights on Diamidine Resistance in African Trypanosomes
Authors: de Koning Harry P. , Anderson Laura F. , Stewart Mhairi , Burchmore Richard J. S. , Wallace Lynsey J. M. , Barrett Michael P.
Published: April 2004

Resistance to diminazene aceturate (Berenil) is a severe problem in the control of African trypanosomiasis in domestic animals. It has been speculated that resistance may be the result of reduced diminazene uptake by the parasite. We describe here the mechanisms by which [
3
H]diminazene is transported by
Trypanosoma brucei brucei
bloodstream forms. Diminazene was rapidly accumulated through a single transporter, with a

K
m

of 0.45 ± 0.11 μM, which was dose dependently inhibited by pentamidine and adenosine. The

K
i

values for these inhibitors were consistent with this transporter being the P2/TbAT1 adenosine transporter. Yeast expressing
TbAT1
acquired the ability to take up [
3
H]diminazene and [
3
H]pentamidine.
TbAT1
-null mutants had lost almost all capacity for [
3
H]diminazene transport. However, this cell line still displayed a small but detectable rate of [
3
H]diminazene accumulation, in a nonsaturable manner. We conclude that TbAT1 mediates [
3
H]diminazene transport almost exclusively and that this explains the observed diminazene resistance phenotypes of
TbAT1
-null mutants and field isolates.
Broth Microdilution Susceptibility Testing forLeptospiraspp
Authors: Murray Clinton K. , Hospenthal Duane R.
Published: April 2004

Leptospirosis in humans has traditionally been treated with penicillin or doxycycline. The choice of therapy offered at the time of initial patient presentation is often empirical, as definitive diagnosis can take weeks. Determining the activity of numerous antimicrobial agents against a wide range ofLeptospiraserovars may broaden empirical therapeutic options. Various antimicrobials have been shown to be active against a limited number of serovars in in vitro studies, chiefly by the use of broth macrodilution techniques. We developed a broth microdilution technique using the commercially available growth indicator alamarBlue. MICs produced by this technique were compared to MICs and minimal bactericidal concentrations produced by the traditional broth macrodilution technique. The internal validity of our methods was assessed with 11 runs over numerous days with a single isolate ofLeptospira interrogansserovar Icterohaemorrhagiae. By either method, the MICs for these internal-validity runs fell within 2 dilutions of each other for more than 90% of antimicrobials. A broader application of these two techniques included 12 serovars (including seven species) ofLeptospiraand six antimicrobials (penicillin G, doxycycline, chloramphenicol, erythromycin, cefotaxime, and ciprofloxacin). Observed reproducibility fell within 2 dilutions for 99% of the duplicate result sets for the MIC microdilution method, compared to 89% for the MIC macrodilution method. The macrodilution method tended to have a higher MIC at which 90% of the isolates were inhibited (MIC90) than did the microdilution method, but the MIC90s of both methods were within 2 dilutions of each other for all six drugs. The macrodilution and microdilution techniques produced similar results, with microdilution allowing a faster, more streamlined method of producing MIC results.
Genetic and Molecular Characterization of β-Lactamase-Negative Ampicillin-Resistant
Haemophilus influenzae
with Unusually High Resistance to Ampicillin
Authors: Kaczmarek Frank S. , Gootz Thomas D. , Dib-Hajj Fadia , Shang Wenchi , Hallowell Shawn , Cronan Melissa
Published: April 2004

Previous studies with beta-lactamase-negative, ampicillin-resistant (BLNAR)
Haemophilus influenzae
from Japan, France, and North America indicate that mutations in
ftsI
encoding PBP3 confer ampicillin MICs of 1 to 4 μg/ml. Several BLNAR strains with ampicillin MICs of 4 to 16 μg/ml recently isolated from North America were studied. Pulsed-field gel electrophoresis identified 12 unique BLNAR strains; sequencing of their
ftsI
transpeptidase domains identified 1 group I and 11 group II mutants, as designated previously (K. Ubukata, Y. Shibasaki, K. Yamamoto, N. Chiba, K. Hasegawa, Y. Takeuchi, K. Sunakawa, M. Inoue, and M. Konno, Antimicrob. Agents Chemother.
45:
1693-1699, 2001). Geometric mean ampicillin MICs for several clinical isolates were 8 to 10.56 μg/ml. Replacement of the
ftsI
gene in
H. influenzae
Rd with the intact
ftsI
from several clinical isolates resulted in integrants with typical BLNAR geometric mean ampicillin MICs of 1.7 to 2.2 μg/ml. Cloning and purification of His-tagged PBP3 from three clinical BLNAR strains showed significantly reduced Bocillin binding compared to that of PBP3 from strain Rd. Based on these data, changes in PBP3 alone could not account for the high ampicillin MICs observed for these BLNAR isolates. In an effort to determine the presence of additional mechanism(s) of ampicillin resistance, sequencing of the transpeptidase regions of
pbp1a
, -
1b
, and -
2
was performed. While numerous changes were observed compared to the sequences from Rd, no consistent pattern correlating with high-level ampicillin resistance was apparent. Additional analysis of the resistant BLNAR strains revealed frame shift insertions in
acrR
for all four high-level, ampicillin-resistant isolates.
acrR
was intact for all eight low-level ampicillin-resistant and four ampicillin-susceptible strains tested. A knockout of
acrB
made in one clinical isolate (initial mean ampicillin MIC of 10.3 μg/ml) lowered the ampicillin MIC to 3.67 μg/ml, typical for BLNAR strains. These studies illustrate that BLNAR strains with high ampicillin MICs exist that have combined resistance mechanisms in PBP3 and in the AcrAB efflux pump.
Bis-Anthracycline Antibiotics Inhibit Human Immunodeficiency Virus Type 1 Transcription
Authors: Kutsch Olaf , Levy David N. , Bates Paula J. , Decker Julie , Kosloff Barry R. , Shaw George M. , Priebe W. , Benveniste Etty N.
Published: April 2004

The increasing numbers of human immunodeficiency virus type 1 (HIV-1) strains that exhibit resistance to antiretroviral agents used at present require the development of new effective antiretroviral compounds. Tat transactivation was recognized early on as an attractive target for drug interference. To screen for and analyze the effects of compounds that interfere with Tat transactivation, we developed several cell-based reporter systems in which enhanced green fluorescence protein is a direct and quantitative marker of HIV-1 expression or Tat-dependent long terminal repeat activity. Using these reporter cell lines, we found that the bis-anthracycline WP631, a recently developed DNA intercalator, efficiently inhibits HIV-1 expression at subcytotoxic concentrations. WP631 also abrogated acute HIV-1 replication in peripheral blood mononuclear cells infected with various primary virus isolates. We demonstrate that WP631-mediated HIV-1 inhibition is caused by the inhibition of Tat transactivation. The data presented suggest that WP631 could serve as a lead compound for a new type of HIV-1 inhibitor.
In Vivo Efficacy and Pharmacokinetics of AC98-6446, a Novel Cyclic Glycopeptide, in Experimental Infection Models
Authors: Weiss William J. , Murphy Timothy , Lenoy Eileen , Young Mairead
Published: April 2004

AC98-6446 is a novel semisynthetic derivative of a natural product related to the mannopeptimycins produced byStreptomyces hygroscopicus. Naturally occurring esterified mannopeptimycins exhibited excellent in vitro activity but only moderate in vivo efficacy against staphylococcal infection. The in vivo efficacy and pharmacokinetics of AC98-6446 were investigated in murine acute lethal, bacterial thigh and rat endocarditis infections. Pharmacokinetics were performed in mice, rats, monkeys, and dogs. Acute lethal infections were performed with several gram-positive isolates:Staphylococcus aureus(methicillin-susceptible and methicillin-resistant staphylococci), vancomycin-resistantEnterococcus faecalis, and penicillin-susceptible and -resistantStreptococcus pneumoniae. The 50% effective dose for all isolates tested ranged from 0.05 to 0.39 mg/kg of body weight after intravenous (i.v.) administration. Vancomycin was more than fivefold less efficacious against all of these same infections. Results of the thigh infection withS. aureusshowed a static dose for AC98-6446 of 0.4 mg/kg by i.v. administration. Reduction of counts in the thigh of >2 log10CFU were achieved with doses of 1 mg/kg. i.v. administration of 3 mg/kg twice a day for 3 days resulted in a >3 log10reduction in bacterial counts of vancomycin-susceptible and -resistantE. faecalisin a rat endocarditis model. Pharmacokinetics of AC98-6446 showed an increase in exposure (area under the concentration-time curve) from mouse to dog species. The i.v. half-life (t1/2) increased threefold between rodents and the higher species dosed. Efficacy of AC98-6446 has been demonstrated in several models of infection with resistant gram-positive pathogens. This glycopeptide exhibited bactericidal activity in these models, resulting in efficacy at low doses with reduction in bacterial load.
Natural Polymorphism of Cytomegalovirus DNA Polymerase Lies in Two Nonconserved Regions Located between Domains Delta-C and II and between Domains III and I
Authors: Fillet Anne-Marie , Auray Laetitia , Alain Sophie , Gourlain Karine , Imbert Berthe Marie , Najioullah Fatiha , Champier Gael , Gouarin Stéphanie , Carquin Jocelyne , Houhou Nadhira , Garrigue Isabelle , Ducancelle Alexandra , Thouvenot Danielle , Mazeron Marie-Christine
Published: April 2004

We described the natural polymorphism of cytomegalovirus DNA polymerase in 42 unrelated isolates susceptible to ganciclovir, foscarnet, and cidofovir. All variations, including an eight-amino-acid deletion, were located between domains delta-C and II and between domains III and I, suggesting that these specific residues are not involved in enzymatic functions.
Rapid Colorimetric Assay for Antimicrobial Susceptibility Testing of
Pseudomonas aeruginosa
Authors: Tunney Michael M. , Ramage Gordon , Field Tyler R. , Moriarty Thomas F. , Storey Douglas G.
Published: April 2004

A colorimetric assay based on the reduction of a tetrazolium salt {2,3-bis[2-methyloxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxanilide (XTT)} for rapidly determining the susceptibility of
Pseudomonas aeruginosa
isolates to bactericidal antibiotics is described. There was excellent agreement between the tobramycin and ofloxacin MICs determined after 5 h using the XTT assay and after 18 h using conventional methods. The data suggests that an XTT-based assay could provide a useful method for rapidly determining the susceptibility of
P. aeruginosa
to bactericidal antibiotics.
Variations in mixed-layer illite/smectite diagenesis in the rift and post-rift sediments of the Jeanne d'Arc Basin, Grand Banks offshore Newfoundland, Canada
Authors: Abid Iftikhar A , Hesse Reinhard , Harper John D
Published: April 2004

Mixed-layer illite/smectite (I/S) clays were analyzed from 22 deep exploration wells from the Jeanne d'Arc Basin on the Grand Banks offshore Newfoundland, the host of large commercial hydrocarbon accumulations discovered in the last two and a half decades. The fine fraction of the clays (<0.1 µm) consists mainly of mixed-layer I/S with minor amounts of kaolinite, illite, and chlorite. Smectite and (or) smectite-rich I/S clays were supplied to the Jeanne d'Arc Basin from Upper Jurassic to Tertiary times. Smectite-rich I/S clays occur only in shallow samples irrespective of geologic age. The proportion of illite in I/S mixed-layers, as well as the degree of ordering, increase with depth and temperature indicating that smectite-rich I/S clays have been progressively illitized in both rift and post-rift sediments of the Jeanne d'Arc Basin during burial. The transition from random to R1-ordered I/S occurs between subsurface depths of 1940 and 3720 m and crosses major stratigraphic boundaries. The transition from R1- to R3-ordered I/S generally occurs below 4000 m depth. Variable shapes of I/S depth profiles reflect the influence of temperature, fluid migration, subsidence history, basin structure, lithology, and salt diapirism on I/S diagenesis. Based on these variations, the basin can be subdivided into 4 regions with different illitization gradients. In the Southern Jeanne d'Ac Basin, advanced I/S diagenesis probably reflects uplift and denudation and (or) higher paleogeothermal gradients. Rapid increase of percent illite in I/S with depth in the Trans-Basinal Fault area is most likely controlled by upward flow of hot, K+-bearing fluids along faults. The migration of hydrocarbons probably followed the same pathways as the illitizing fluids. Delayed illitization in the Northern Jeanne d'Arc Basin and Central Ridge area reflects insufficient K+supply because of a lack of detrital K-feldspar in the host sediment, the absence of faulting, and the presence of thick shale intervals. These findings show that I/S depth profiles may vary within the same sedimentary basin due to a variety of geological factors. Single wells generally cannot be considered representative for the basin as a whole.
Using an individual-based model of fish assemblages to study the response of size spectra to changes in fishing
Authors: Shin Yunne-Jai , Cury Philippe
Published: April 2004

For most fish species, strong environmental constraints imposed by living in an aquatic medium have produced converging streamlined body forms without prehensile appendices. This similarity in body shapes highlights a common predation constraint: a predatory fish must have a jaw large enough to swallow its prey. Fish diets may then reflect local prey availability and predatorprey size ratios. Based on this size-based opportunistic predation process, the multispecies individual-based model OSMOSE (Object-oriented Simulator of Marine ecOSystem Exploitation) is used to investigate to what extent the size distribution of fish communities can contribute to better our understanding of the functioning of marine food webs and the ecosystem effects of fishing. Strong similarity in shape is found between simulated size spectra and those described in empirical studies. The existence of a curvature towards small size classes is discussed in the light of the size-based predation hypothesis, which implies that smaller fish may undergo higher predation mortality. Applying linear and quadratic regressions to the simulated size spectra allows the detection of variations in fishing pressure and the proposal of different ways to quantify them. In particular, it is shown that the slope of the size spectrum decreases quasilinearly with fishing mortality and that the curvature could help to detect ecosystem overexploitation.
Food web interactions between larval bluegill (Lepomis macrochirus) and exotic zebra mussels (Dreissena polymorpha)
Authors: Raikow David F
Published: April 2004

Food web interactions between native larval bluegill (Lepomis macrochirus), exotic invasive zebra mussels (Dreissena polymorpha), and zooplankton were examined with a mesocosm experiment. Hatchling larval bluegill collected from nests were reared in the presence of size-structured populations of zebra mussels in 1500-L limnocorrals suspended in an artificial pond for 2 weeks. Chlorophyll a, other limnological variables, and zooplankton abundance and biomass (including copepod nauplii and rotifers) were monitored over time. During their first 2 weeks of life, larval fish reared in the presence of mussels grew 24% more slowly than fish reared alone. Differential growth rates can be explained by competition between mussels and bluegill for food in the form of microzooplankton. Also likely was an indirect competition via starvation of the zooplankton community as zebra mussels consumed phytoplankton. Either direct or indirect trophic competition between zebra mussels and obligate planktivores may result in ecological harm as zebra mussels spread throughout inland lakes of North America.
Capturerecapture estimates of space used in streams (CRESUS) at the population scale: case study onZingel asper(percid), a threatened species of the Rhône catchment
Authors: Danancher Delphine , Labonne Jacques , Pradel Roger , Gaudin Philippe
Published: April 2004

In this study, capturemarkrecapture statistics were applied to spatial recapture histories to assess the intensity of fish restricted movements along the longitudinal axis of a river using a previously described model for survival and recruitment analysis. Adapting the stopover estimation method to spatial data, movement probabilities were then used to estimate space used at the population scale. This capturerecapture estimates of space used in streams (CRESUS) method may thus be seen as a complementary tool of classic home range methods and should be used to explore the consequence of behavioural strategies on population mechanisms. We propose a methodological example where movements and space use strategies of a Zingel asper (percid) population in the Beaume River (Ardèche, France) were directly estimated at the population scale taking account of the effects of different biotic or abiotic factors. Results showed differences in Z. asper space use patterns among sexes, periods of biological cycle (growing and spawning period), and types of mesohabitat. Downstream movements were more important during the spawning period and by the way the riffle was more intensively used.
Osmoregulatory plasticity of the glass eel ofAnguilla anguilla: freshwater entry and changes in branchial ion-transport protein expression
Authors: Wilson Jonathan Mark , Antunes José Carlos , Bouça Patricío Duro , Coimbra João
Published: April 2004

The glass-eel stage of the life history of Anguillid eels (Anguilla spp.) makes the important physiological transition from seawater (SW) to freshwater (FW) osmoregulation. Central to successful adaptation to fresh water is the switch from active hypoosmoregulation (ion excretion) to active hyperosmoregulation (ion uptake) to counter passive fluxes imposed by concentration gradients. Anguilla anguilla (L.) glass eels, captured from the lower Minho River estuary and maintained in brackish water (BW; 24), were fully capable of adapting to FW following acute transfer. In a comparison between SW- (34) and FW-adapted glass eels, gill Na+/K+-ATPase and Na+:K+:2Clcotransporter (NKCC) expression were both markedly reduced in the FW group. Branchial mitochondria-rich chloride cells (MRCs) were also significantly larger in SW-adapted glass eels. Apical CFTR Clchannel immunoreactivity associated with branchial MRCs was also only present in SW-adapted glass eels. The expression of these three ion-transport proteins is strongly associated with active ion excretion in SW teleost fishes. In FW-adapted glass eels, cortisol treatment increased branchial Na+/K+-ATPase expression but was without effect on NKCC expression. Glucocorticoid receptor blockade by RU-486 had no effect on Na+/K+-ATPase or NKCC expression.
Investigation of shear stiffness and rutting in asphalt concrete mixes
Authors: Bekheet Wael , Abd El Halim A O , Easa Said M , Ponniah Joseph
Published: April 2004

Field and laboratory testing programs were set up to evaluate the in-situ shear properties of asphalt concrete mixes using the newly developed in-situ shear stiffness testing (InSiSSTTM) facility versus the laboratory evaluation using the resilient modulus and torsion testing. The LTPP SPS-9A 870900 test site, which has six similar pavement sections with different AC surface mix properties, was tested in the field using the InSiSSTTM and core samples were extracted from the site and tested in the laboratory. The results of the testing program were correlated with the rutting of the test sections over a 4-year period. In this paper, the InSiSSTTM facility is briefly introduced and the interpretation of the data collected is presented. The experimental program and analysis procedures are then outlined. The analysis of variance was used to test the significance of the results, and a bivariate analysis was performed for correlating rutting (as a criterion variable) and the different laboratory and field measured material properties (as predictor variables). Finally, a regression analysis between the in-situ shear stiffness and pavement rutting is presented. The results of the study showed that the in-situ shear stiffness had the highest correlation coefficient with rutting rate, and this might be a suitable measure to characterize the asphalt mixes and evaluate the rutting potential of asphalt pavements. This important result should be useful to the pavement engineers interested in the evaluation of rutting using a simple field measure.Key words: in-situ testing, laboratory testing, shear stiffness, shear properties, asphalt concrete, pavements, rutting, long-term performance.
Quantified benefit of implementing enterprise resource planning through process simulation
Authors: Lee Sangyoub , Arif Ahsan Ullah , Jang Hyounseung
Published: April 2004

The enterprise resource planning (ERP) system can integrate the major business management functions of the enterprise with a single common database to allow sharing of all information and achieve efficient communications between management functions. Based on the needs of running a construction enterprise, ERP shows potential applicability to the construction industry. This paper sought to quantify the benefits of ERP systems when applied to construction materials procurement. Specifically, this paper briefly described the business processes involved in construction materials procurement and illustrated how ERP systems could be implemented and the efficiency of the construction materials management system consequently enhanced. The transformation from a non-ERP system into an ERP system through application integration, internal integration, external integration, and automation were simulated. Results show that the individual task improvements of models can increase the productivity of the materials management cycle by up to 5.2%, 18.2%, 27.8%, 13.5%, and 79.2% through internal integration, external integration, application integration, automation, and ERP system, respectively, by automating most of the repeated transactions and reducing manpower required to perform the tasks.Key words: enterprise resource planning, materials management system, productivity, simulation.
Numerical modeling of liquefaction and comparison with centrifuge tests
Authors: Byrne Peter M , Park Sung-Sik , Beaty Michael , Sharp Michael , Gonzalez Lenart , Abdoun Tarek
Published: April 2004

The prediction of liquefaction and resulting displacements is a major concern for earth structures located in regions of moderate to high seismicity. Conventional procedures used to assess liquefaction commonly predict the triggering of liquefaction to depths of 50 m or more. Remediation to prevent or curtail liquefaction at these depths can be very expensive. Field experience during past earthquakes indicates that liquefaction has mainly occurred at depths less than about 15 m, and some recent dynamic centrifuge model testing initially appeared to confirm a depth or confining-stress limitation on the occurrence of liquefaction. Such a limitation on liquefaction could greatly reduce remediation costs. In this paper an effective stress numerical modeling procedure is used to assess these centrifuge tests. The results indicate that a lack of complete saturation and densification at depth arising from the application of the high-acceleration field are largely responsible for the apparent limitation on liquefaction at depth observed in some centrifuge tests.Key words: liquefaction, dynamic centrifuge modeling, numerical modeling, depth limitation.
Triaxial tests on model sand columns in clay
Authors: Sivakumar V , McKelvey D , Graham J , Hughes D
Published: April 2004

Vibro-stone columns can improve the bearing capacity and reduce the settlement of foundations. Their performance depends on the strength of the column material, reinforcement method of column installation, type of in situ soil, area replacement ratio, and column length. This paper examines the behaviour of small laboratory specimens of soft clay (undrained shear strength ≈ 30 kPa) reinforced with sand columns when tested under known boundary stress conditions. Two series of tests were carried out on kaolin specimens (diameter 100 mm, height 200 mm) in a triaxial cell. In the first series, specimens were reinforced with a 32 mm diameter column of sand, 80, 120, 160, or 200 mm long. Columns were installed by (i) compacting moist sand into a prebored hole or (ii) freezing a column of moist sand before inserting it into a prebored hole. In the second series, columns were reinforced with geo-grids before installation. The specimens were subjected to (i) uniform loading in which the load was applied over the entire surface area of the specimen or (ii) foundation-type loading in which only a small area in the centre of the specimen was loaded. Under uniform loading, the specimens containing a full-depth column were significantly stronger than specimens without columns. Specimens with single, partially penetrating columns installed by wet compaction were weaker than specimens without columns. When frozen columns were installed, strengths increased progressively. Under foundation-type loading, bearing capacities increased with an increase in column length. Geo-grid reinforcement produced significant increases in load-carrying capacity.Key words: ground improvement, undrained shear strength, consolidation, stress path.
Disinfection of selected Aspergillus spp. using ultraviolet germicidal irradiation
Authors: Green Christopher F , Scarpino Pasquale V , Jensen Paul , Jensen Nancy J , Gibbs Shawn G
Published: April 2004

Aims: The efficacy of ultraviolet germicidal irradiation (UVGI) and the UVGI dose necessary to inactivate fungal spores on an agar surface for cultures of Aspergillus flavus and Aspergillus fumigatus were determined. Methods and results: A four-chambered UVGI testing unit with a 9-W, Phillips, low pressure, mercury UVGI lamp in each chamber was used in this study. An aperture was adjusted to provide 50, 100, 150, and 200 µW/cm2 of uniform flux to the surfaces of the Petri dish, resulting in a total UVGI dose to the surface of the Petri dishes ranging from 12 to 96 mJ/cm2. The UVGI dose necessary to inactivate 90% of the A. flavus and A. fumigatus was 35 and 54 mJ/cm2, respectively. Conclusions: UVGI can be used to inactivate culturable fungal spores. Aspergillus flavus was more susceptible than A. fumigatus to UVGI. Significance and impact of the study: These results may not be directly correlated to the effect of UVGI on airborne fungal spores, but they indicate that current technology may not be efficacious as a supplement to ventilation unless it can provide higher doses of UVGI to kill spores traveling through the irradiated zone.Key words: Aspergillus, ultraviolet germicidal irradiation, fungi.
Comparison of cultural and analytical methods for determination of aflatoxin production by Mississippi DeltaAspergillusisolates
Authors: Abbas Hamed K , Zablotowicz R M , Weaver M A , Horn B W , Xie W , Shier W T
Published: April 2004

This study compared cultural and analytical methods for detecting aflatoxin production by Aspergillus species. Aspergillus isolates were obtained from various Mississippi Delta crops (corn, peanut, rice, cotton) and soils. Most of the isolates (99%) were A. flavus and the remainder comprised A. parasiticus and A. nomius. The following three cultural methods were evaluated on potato dextrose agar: fluorescence (FL) on β-cyclodextrin-containing media (CD), yellow pigment (YP) formation in mycelium and medium, and color change after ammonium hydroxide vapor exposure (AV). Aflatoxins in culture extracts were confirmed by thin-layer chromatography (TLC) and quantified by enzyme-linked immunosorbent assay (ELISA). Of the 517 isolates, 314 produced greater than 20 ng/g of total aflatoxin based on ELISA, and 180 produced greater than 10 000 ng/g of aflatoxin in the medium. Almost all the toxigenic isolates (97%) were confirmed by TLC as producers. Of the toxigenic isolates, as determined by ELISA, 93%, 73%, and 70% gave positive FL, YP, and AV responses, respectively. Of the 203 isolates producing less than 20 ng/g of aflatoxin, 20%, 6%, and 0% of respective FL, YP, and AV methods gave false-positive responses. The 9% false-positive results from TLC fall within this range. This study showed good agreement among all tested cultural methods. However, these cultural techniques did not detect aflatoxin in all cultures that were found to produce aflatoxins by ELISA, LC/MS, and TLC. The best results were obtained when the AV color change and CD fluorescence methods were used together, yielding an overall success rate comparable to TLC but without the need for chemical extraction and the time and expense of TLC.Key words: aflatoxins, analytical methods, Aspergillus flavus, Aspergillus parasiticus, cultural methods, β-cyclodextrin, fluorescence enhancers, mycotoxins, yellow pigment.
Trematode behaviours and the perceptual worlds of parasites
Authors: Sukhdeo M V.K , Sukhdeo S C
Published: April 2004

There is a great deal of empirical data and theoretical predictions on the patterns and processes of trematode behaviour, particularly in relation to host-finding activities by the free-living stages and site-finding migrations by the parasitic stages within their hosts. Ecological and evolutionary models of trematode life histories often make explicit assumptions about how these organisms must perceive and respond to signals in their worlds as they move from host to host and as they parasitize each host. Nevertheless, it is unclear how natural selection shapes the parasites' behavioural strategies. In addition, at each stage in their life cycle, trematodes are adorned with elaborate sensory organs and possess sophisticated neuromuscular systems, but it is not clear how they use these complex machinery to perceive their worlds. The purpose of this review is to address this question through insights gathered from a century of research on trematode behaviour. Core theoretical assumptions from modern animal behaviour are used to provide the context for this analysis; a key concept is that all animals have unique perceptual worlds that may be inferred from their behaviours. A critical idea is that all animals possess complex patterns of innate behaviour which can be released by extremely specific signals from the environment. The evidence suggests that trematode parasites live in ecologically predictable aquatic and internal host environments where they perceive only small subsets of the total information available from the environment. A general conclusion is that host finding in miracidia and cercaria, and site-finding by trematodes migrating within their definitive hosts, is accomplished through the release of innate patterns of behaviours which are adaptive within the context of conditions in the worm's environment. Examples from empirical studies are used to support the contention that, despite the apparent complexity of their free-living and parasitic environments, the perceptual worlds of trematodes are impoverished, and complex patterns of behaviour may be released by only a few signals in their environment.
Molecular phylogeny of the Platyhelminthes
Authors: Baguñà Jaume , Riutort Marta
Published: April 2004

The phylum Platyhelminthes has traditionally been considered the most basal bilaterian taxon. The main difficulty with this placement is the lack of convincing synapomorphies for all Platyhelminthes, which suggest that they are polyphyletic. Recent molecular findings based on 18S rDNA sequence data and number and type of Hox genes strongly suggest that the majority of Platyhelminthes are members of the lophotrochozoan protostomes, whereas the Acoelomorpha (Acoela + Nemertodermatida) fall outside of the Platyhelminthes as the most basal bilaterian taxon. Here we review phylum-wide analyses based on complete ribosomal and other nuclear genes addressed to answer the main issues facing systematics and phylogeny of Platyhelminthes. We present and discuss (i) new corroborative evidence for the polyphyly of the Platyhelminthes and the basal position of Acoelomorpha; (ii) a new consensus internal tree of the phylum; (iii) the nature of the sister group to the Neodermata and the hypotheses on the origin of parasitism; and (iv) the internal phylogeny of some rhabditophoran orders. Some methodological caveats are also introduced. The need to erect a new phylum, the Acoelomorpha, separate from the Platyhelminthes (now Catenulida + Rhabditophora) and based on present and new morphological and molecular characters is highlighted, and a proposal made.
MINIMAL DUVAL EXTENSIONS
Authors: HARJU TERO , NOWOTKA DIRK
Published: April 2004

A word v=wu is a (nontrivial) Duval extension of the unbordered word w, if (u is not a prefix of v and) w is an unbordered factor of v of maximum length. After a short survey of the research topic related to Duval extensions, we show that, if wu is a minimal Duval extension, then u is a factor of w. We also show that finite, unbordered factors of Sturmian words are Lyndon words.
SCHEDULING TO MINIMIZE MAX FLOW TIME: OFF-LINE AND ON-LINE ALGORITHMS
Authors: MASTROLILLI MONALDO
Published: April 2004

We investigate the max flow time scheduling problem in the off-line and on-line setting. We prove positive and negative theoretical results. In the off-line setting, we address the unrelated parallel machines model and present the first known fully polynomial time approximation scheme, when the number of machines is fixed. In the on-line setting and when the machines are identical, we analyze the First In First Out (FIFO) heuristic when preemption is allowed. We show that FIFO is an on-line algorithm with a (3-2/m)-competitive ratio. Finally, we present two lower bounds on the competitive ratio of deterministic on-line algorithms.
PREDICTING SPATIAL DATA WITH RBF NETWORKS
Authors: HU TIANMING , SUNG SAM YUAN
Published: April 2004

Spatial prediction needs to account for spatial information, which makes conventional radial basis function (RBF) networks inappropriate, for they assume independent and identical distribution. In this paper, we fuse spatial information at different layers of RBF. Experiments show fusion at hidden layer gives the best result and suggest that the optimal value is around one for the coefficient, which is used in the linear combination at the output layer.
GAUSSIAN PROCESSES FOR MACHINE LEARNING
Authors: SEEGER MATTHIAS
Published: April 2004

Gaussian processes (GPs) are natural generalisations of multivariate Gaussian random variables to infinite (countably or continuous) index sets. GPs have been applied in a large number of fields to a diverse range of ends, and very many deep theoretical analyses of various properties are available. This paper gives an introduction to Gaussian processes on a fairly elementary level with special emphasis on characteristics relevant in machine learning. It draws explicit connections to branches such as spline smoothing models and support vector machines in which similar ideas have been investigated.

Gaussian process models are routinely used to solve hard machine learning problems. They are attractive because of their flexible non-parametric nature and computational simplicity. Treated within a Bayesian framework, very powerful statistical methods can be implemented which offer valid estimates of uncertainties in our predictions and generic model selection procedures cast as nonlinear optimization problems. Their main drawback of heavy computational scaling has recently been alleviated by the introduction of generic sparse approximations.13,78,31The mathematical literature on GPs is large and often uses deep concepts which are not required to fully understand most machine learning applications. In this tutorial paper, we aim to present characteristics of GPs relevant to machine learning and to show up precise connections to other "kernel machines" popular in the community. Our focus is on a simple presentation, but references to more detailed sources are provided.
NONLINEAR SYSTEM MODELLING VIA OPTIMAL DESIGN OF NEURAL TREES
Authors: CHEN YUEHUI , YANG BO , DONG JIWEN
Published: April 2004

This paper introduces a flexible neural tree model. The model is computed as a flexible multi-layer feed-forward neural network. A hybrid learning/evolutionary approach to automatically optimize the neural tree model is also proposed. The approach includes a modified probabilistic incremental program evolution algorithm (MPIPE) to evolve and determine a optimal structure of the neural tree and a parameter learning algorithm to optimize the free parameters embedded in the neural tree. The performance and effectiveness of the proposed method are evaluated using function approximation, time series prediction and system identification problems and compared with the related methods.
FRACTAL CHARACTERIZATION OF BPN WEIGHTS EVOLUTION
Authors: GUNASEKARAN S. , VENKATESH B. , SAGAR B. S. D.
Published: April 2004

Training methodology of the Back Propagation Network (BPN) is well documented. One aspect of BPN that requires investigation is whether or not the BPN would get trained for a given training data set and architecture. In this paper the behavior of the BPN is analyzed during its training phase considering convergent and divergent training data sets. Evolution of the weights during the training phase was monitored for the purpose of analysis. The evolution of weights was plotted as return map and was characterized by means of fractal dimension. This fractal dimensional analysis of the weight evolution trajectories is used to provide a new insight to understand the behavior of BPN and dynamics in the evolution of weights.
APPLICATION OF EXACT RENORMALIZATION GROUP TECHNIQUES TO THE NON-PERTURBATIVE STUDY OF SUPERSYMMETRIC FIELD THEORY
Authors: ARNONE STEFANO , YOSHIDA KENSUKE
Published: April 2004

A simple form of the exact renormalization group method is proposed for the study of supersymmetric gauge field theory. The method relies on the existence of ultraviolet-finite four dimensional gauge theories with extended supersymmetry. The resulting exact renormalization group equation crucially depends on the Konishi anomaly of N=1 super Yang–Mills. We illustrate our method by dealing with the NSVZ exact relation for the beta functions, the N=2 super Yang–Mills effective potential and the N=1 super Yang–Mills gluon superpotential (the so-called Veneziano–Yankielowicz potential).
ON THE STATISTICAL PHYSICS CONTRIBUTION TO QUANTITATIVE FINANCE
Authors: LOFFREDO MARIA I.
Published: April 2004

A short review is given of some research topics recently developed in the framework of quantitative finance and which can be referred to the effort of adapting methods and technologies of statistical physics to the analysis of economic systems. In particular we emphasize the role of a different, new perspective, in approaching financial problems, originated within the theory of complex systems and based on concepts like universality, scaling and correlation properties. Once applied to the time evolution of prices and volatility, this approach allows for the recognition of long-range and nonlinear effects in financial time series.
PATH INTEGRAL APPROACH IN QUANTUM-LIKE THEORY.
Authors: PUSTERLA M.
Published: April 2004

A formulation of the Quantum-like theory based on Feynman's propagator is presented for particle beams. Applications to betatronic oscillations of LHC and HIDIF show encouranging predictions.
FOUR REMARKS ON EIGENVALUES OF LAMÉ'S EQUATION
Authors: VOLKMER HANS
Published: April 2004

Four properties of eigenvalues of Lamé's differential equation are studied: interlacing of eigenvalues, behavior as k→1, width of stability bands and expansion in powers of k2.
AUTOMATED VIDEO SEGMENTATION USING COMPUTER VISION TECHNIQUES
Authors: YOO HUN-WOO , JANG DONG-SIK
Published: April 2004

A video segmentation method is proposed in this paper. For abrupt cut detection, inter-frame similarities are computed using gray-level and edge histograms and a cut is declared when the similarities are under the predetermined threshold value. Gradual shot boundary detection is decided based on the similarities between the current frame and the previous shot boundary frame. Correlation coefficients are used to obtain universal threshold values, which are applied to various video data. Experimental results show that the proposed method provides 95% recall and 80% precision rates for abrupt cuts, and 83% recall and 54% precision rates for gradual changes.
IDENTIFYING "BEST-BUYS" IN THE MARKET OF PREPAID MOBILE TELEPHONY: AN APPLICATION OF IMPRECISE DEA
Authors: SMIRLIS Y. G. , DESPOTIS D. K. , JABLONSKY J. , FIALA P.
Published: April 2004

Value-for-money is a widely used criterion to locate "best-buys" in a market of competitive products or services. The term "value" represents a composite measure of what a consumer gets from a product or service, while the term "money" is what the consumer pays for it. In the absence of individual preferences, the problem of identifying best-buys by the value-for-money criterion can be formulated as an imprecise DEA model with a single input (price) and multiple outputs (indices and performance estimates). In accordance with the DEA terminology, efficient units (products or services) are those that worth their price. As the price of a particular product can vary from dealer to dealer or due to different discount policies, it is usually known to lie within a bounded interval, between the lowest and the highest price recorded in the market. On the other hand, product outputs may be measured either by exact values or bounded intervals (overall evaluation judgments made by different experts, for example) or ordinal variables (product ratings obtained by experts or surveys). In this paper, we use the imprecise DEA model to classify prepaid mobile telephony packages in the Greek market by the value-for-money criterion.
Earlier Onset of Treatment or Increment in LT4 Dose in Screened Congenital Hypothyroidism: Which Was the More Important Factor for IQ at 7 Years?
Authors: Boileau Pascal , Bain Philippa , Rives Solange , Toublanc Jean-Edmond
Published: April 2004

Objective: To determine between timing and LT4 dose which was the more important factor for IQ at 7 years in screened congenital hypothyroidism (CH). Methods: 131 children with CH born from 1979 to 1994 and 30 controls were studied. Mean age at recall: 22.8 ± 1.1 days. Mean initial LT4: 5.6 ± 0.1 µg/kg/day. Results: Optimal global IQ (GIQ; 119.0 ± 1.8) was obtained for a recall ≤15 days. Results for a recall after 3 weeks were lower (107.7 ± 2.4). The IQ of infants treated before 21 days (117.1 ± 1.2) was identical to the IQ of controls (117.0 ± 2.3) whereas the IQ of those treated after this threshold was lower (108.6 ± 1.7). No significant differences for GIQ were observed with various initial LT4 doses. Infants treated with a dose of LT4 ≧6 µg/kg/day had a higher performance IQ (117.3 ± 1.8 vs. 112.8 ± 1.2) compared with those treated with a dose <6 µg/kg/day. The severity of CH and socio-economic levels were similar in all groups. Conclusion: In this study, timing appears to be the more important factor for the intellectual outcome.
Pigment Epithelium Endoscopic Laser Surgery for Treatment of Choroidal Neovascularization
Authors: Koch Frank H.J. , Quiroz-Mercado Hugo , Hattenbach Lars-Olof , Guerrero-Naranjo Jose Luis , Yesurun Itamr , Augustin Albert , Luloh K. Peter , Ohrloff Christian
Published: April 2004

Purpose: To present a new concept and technique for subretinal surgery. Methods: Twenty-four eyes of 24 patients with subfoveal choroidal neovascularization (CNV) were included in this study. Nine patients were operated on in Mexico City by one surgeon, 15 patients in Frankfurt by another surgeon. The retina at the posterior pole was detached and subretinal thermal photocoagulation of the CNVs was performed using a 20/19-gauge GRIN rod laser endoscope (Insight Instruments Inc., Sanford, Fla., USA). This procedure was termed PEELS (pigment epithelium endoscopic laser surgery). Results: In 7 patients (Mexico), moderate improvement or stabilization of vision over 6 months or longer was achieved. In 10 out of 12 patients (Frankfurt), stabilization of vision over a follow-up period of 6–18 months was achieved, at least. Serious complications were not observed. Four of the Frankfurt series patients improved their vision. Conclusion: PEELS can stabilize or improve vision.
A Modified Technique to Stain the Internal Limiting Membrane with Indocyanine Green
Authors: Schmidt Joerg C. , Rodrigues Eduardo B. , Meyer Carsten H. , Hoerle Steffen , Kroll Peter
Published: April 2004

Purpose: Peeling of the internal limiting membrane (ILM) has improved the outcomes in vitreoretinal surgery of macular diseases. Indocyanine green (ICG) is used to stain and improve the visualization of the ILM. This paper aims to describe a modified approach to stain and peel the ILM avoiding potential adverse side effects. Methods: After a core vitrectomy, 0.05 ml of ICG in a concentration of 5 mg/ml is quickly injected under water around the macular region. The tip of the syringe is positioned about 5 mm from the macular tissue, in a way that about a 3-mm diameter area around the fovea is stained by the ICG. Additional ICG is immediately removed by aspiration. Peeling of the ILM is accomplished with a forceps. Results: Neither residual ICG in the vitreous cavity nor any clinical signs of phototoxicity like retinal edema were detected in any patients operated by this technique. Conclusions: This modified technique to stain the ILM limits the amount and concentration of ICG. The locally limited contact of ICG with the retinal surface seems to be a safe procedure to stain the ILM.
Medical Treatment of Stage I Nasal Polyposis over a 3-Year Follow-Up Period
Authors: Bonfils Pierre , Norès Jean-Marc , Halimi Philippe , Avan Paul
Published: April 2004

Purpose: To determine the effects of a standardized therapeutic protocol (short-term oral administration of prednisolone and daily intranasal spray of beclometasone) on stage I nasal polyposis over a follow-up period of 3 years. Procedures: Assessments (evaluation of nasal function and drug consumption) were conducted at baseline and every 3 months on 54 consecutive patients with stage I nasal polyposis during 3 years. Results: Over the follow-up period of 3 years, this dual modality proved to be successful in 87% of the subjects; only 13% had to undergo surgery after its failure. The average symptom reduction reached an improvement rate varying from 66 to 94.8%, according to the symptom type. The daily dosage of prednisolone and beclometasone was progressively decreased, while the gain in nasal comfort was being preserved. Conclusion: Management of stage I nasal polyps should be primarily medical.
Synovial Sarcoma of the Neck
Authors: Ochi Naoki , Uozumi Masaki , Doi Kiyoshi , Tanimoto Hitoshi , Ohbayashi Chiho , Inagaki Hiroshi , Nibu Ken-ichi
Published: April 2004

Background: Synovial sarcoma is a soft tissue sarcoma rarely seen in the head and neck. Due to its rarity and morphologic variations, diagnosis is difficult in most cases. Method: A case of synovial sarcoma arising in the upper neck is presented. The detection of the specific chromosomal translocation t(X;18)(p11.2;q11.2) is also described. Result: A specific chimeric gene, the SSX-SYT fusion gene, was identified in the formalin-fixed paraffin-embedded surgical specimen using the reverse-transcription polymerase chain reaction (RT-PCR) technique. Conclusion: Synovial sarcoma contains a characteristic chromosomal translocation, which serves as a useful diagnostic tool. RT-PCR technique has enabled to detect this specific translocation not only in fresh tissues but also in archival paraffin-embedded specimens.