bluuebunny/crossref_metadata_2025 huggingface dataset:
Mechanism of Increased Fluconazole Resistance in
Candida glabrata
during Prophylaxis
Authors: Bennett John E. , Izumikawa Koichi , Marr Kieren A.
Published: April 2004

Candida glabrata
can become resistant to fluconazole, causing persistent colonization and invasive infection during prolonged exposure to the drug. To determine the mechanism of resistance in this setting, weekly oropharyngeal cultures for
C. glabrata
were obtained over a 2-year period from hematopoietic stem cell transplant recipients who were receiving fluconazole prophylaxis. In 20 patients from whom at least two isolates of the same karyotype were obtained more than two weeks apart, fluconazole MICs doubled every 31 days on average. The mechanism of fluconazole resistance in isolates from the 14 of the 20 patients studied in whom MICs changed at least fourfold was studied. Cellular resistance was accompanied by increased drug efflux as measured by decreased accumulation of fluconazole and rhodamine 6G and increased abundance of transcripts from two drug transporters,
CgCDR1
and
PDH1.
The rapidity and regularity of the rising resistance indicated that
C. glabrata
is able to upregulate drug efflux without losing the ability to maintain colonization.
Membrane Sphingolipid-Ergosterol Interactions Are Important Determinants of Multidrug Resistance in
Candida albicans
Authors: Mukhopadhyay Kasturi , Prasad Tulika , Saini Preeti , Pucadyil Thomas J. , Chattopadhyay Amitabha , Prasad Rajendra
Published: April 2004

In this study, we examined the importance of membrane ergosterol and sphingolipids in the drug susceptibilities of
Candida albicans
. We used three independent methods to test the drug susceptibilities of
erg
mutant cells, which were defective in ergosterol biosynthesis. While spot and filter disk assays revealed that
erg2
and
erg16
mutant cells of
C. albicans
became hypersensitive to almost all of the drugs tested (i.e., 4-nitroquinoline oxide, terbinafine,
o
-phenanthroline, itraconazole, and ketoconazole), determination of the MIC at which 80% of the cells were inhibited revealed more than fourfold increase in susceptibility to ketoconazole and terbinafine. Treatment of wild-type
C. albicans
cells with fumonisin B1 resulted in 45% inhibition of sphingolipid biosynthesis and caused cells to become hypersensitive to the above drugs. Although
erg
mutants displayed enhanced membrane fluidity and passive diffusion, these changes alone were not sufficient to elicit the observed hypersusceptibility phenotype of
erg
mutants. For example, the induction in vitro of a 12% change in the membrane fluidity of
C. albicans
cells by a membrane fluidizer, benzyl alcohol, did not affect the drug susceptibilities of
Candida
cells. Additionally, the surface localization of green fluorescent protein-tagged Cdr1p, a major drug efflux pump protein of
C. albicans
, revealed that any disruption in ergosterol and sphingolipid interactions also interfered with its proper surface localization and functioning. A 50% reduction in the efflux of the Cdr1p substrate, rhodamine 6G, in
erg
mutant cells or in cells with a reduced sphingolipid content suggested a strong correlation between these membrane lipid components and this major efflux pump protein. Taken together, the results of our study demonstrate for the first time that there is an interaction between membrane ergosterol and sphingolipids, that a reduction in the content of either of these two components results in a disruption of this interaction, and that this disruption has deleterious effects on the drug susceptibilities of
C. albicans
cells.
Simple and Inexpensive Fluorescence-Based Technique for High-Throughput Antimalarial Drug Screening
Authors: Smilkstein Martin , Sriwilaijaroen Nongluk , Kelly Jane Xu , Wilairat Prapon , Riscoe Michael
Published: April 2004

Radioisotopic assays involve expense, multistep protocols, equipment, and radioactivity safety requirements which are problematic in high-throughput drug testing. This study reports an alternative, simple, robust, inexpensive, one-step fluorescence assay for use in antimalarial drug screening. Parasite growth is determined by using SYBR Green I, a dye with marked fluorescence enhancement upon contact with
Plasmodium
DNA. A side-by-side comparison of this fluorescence assay and a standard radioisotopic method was performed by testing known antimalarial agents against
Plasmodium falciparum
strain D6. Both assay methods were used to determine the effective concentration of drug that resulted in a 50% reduction in the observed counts (EC
50
) after 48 h of parasite growth in the presence of each drug. The EC
50
s of chloroquine, quinine, mefloquine, artemisinin, and 3,6-bis-ε-(
N
,
N
-diethylamino)-amyloxyxanthone were similar or identical by both techniques. The results obtained with this new fluorescence assay suggest that it may be an ideal method for high-throughput antimalarial drug screening.
Anti-Respiratory Syncytial Virus (RSV) Neutralizing Antibody Decreases Lung Inflammation, Airway Obstruction, and Airway Hyperresponsiveness in a Murine RSV Model
Authors: Mejías Asunción , Chávez-Bueno Susana , Ríos Ana María , Saavedra-Lozano Jesús , Fonseca Aten Mónica , Hatfield Jeanine , Kapur Payal , Gómez Ana María , Jafri Hasan S. , Ramilo Octavio
Published: April 2004

Numerous studies have described a strong association between respiratory syncytial virus (RSV) infection in infancy and the development of recurrent wheezing and airway hyperresponsiveness. We evaluated the effect of an anti-RSV neutralizing monoclonal antibody (palivizumab) on different aspects of RSV disease by using a murine model. BALB/c mice were intranasally inoculated with RSV A2. Palivizumab or an isotype-matched control antibody was administered once at 24 h before inoculation, 1 h after inoculation, or 48 h after inoculation. Regardless of the timing of administration, all mice treated with the neutralizing antibody showed significantly decreased RSV loads in bronchoalveolar lavage (BAL) and lung specimens compared with those of infected controls. Pulmonary histopathologic scores, airway obstruction measured by plethysmography, and airway hyperresponsiveness after methacholine challenge were significantly reduced in mice treated with the anti-RSV antibody 24 h before inoculation compared with those for untreated controls. Concentrations of interferon-gamma, interleukin-10, macrophage inflammatory protein 1α, regulated on activation normal T-cell expressed and secreted (RANTES), and eotaxin in BAL fluids were also significantly reduced in mice treated with palivizumab 24 h before inoculation. This study demonstrates that reduced RSV replication was associated with significant modulation of inflammatory and clinical markers of acute disease severity and significant improvement of the long-term pulmonary abnormalities. Studies to determine whether strategies aimed at preventing or reducing RSV replication could decrease the long-term morbidity associated with RSV infection in children should be considered.
Biochemical Characterization of
Streptococcus pneumoniae
Penicillin-Binding Protein 2b and Its Implication in β-Lactam Resistance
Authors: Pagliero Estelle , Chesnel Laurent , Hopkins Julie , Croizé Jacques , Dideberg Otto , Vernet Thierry , Di Guilmi Anne Marie
Published: April 2004

Extensive use of β-lactam antibiotics has led to the selection of pathogenic streptococci resistant to β-lactams due to modifications of the penicillin-binding proteins (PBPs). PBP2b from
Streptococcus pneumoniae
is a monofunctional (class B) high-molecular-weight PBP catalyzing the transpeptidation between adjacent stem peptides of peptidoglycan. The transpeptidase domain of PBP2b isolated from seven clinical resistant (CR) strains contains 7 to 44 amino acid changes over the sequence of PBP2b from the R6 β-lactam-sensitive strain. We show that the extracellular soluble domains of recombinant PBP2b proteins (PBP2b*) originating from these CR strains have an in vitro affinity for penicillin G that is reduced by up to 99% from that of the R6 strain. The Thr446Ala mutation is always observed in CR strains and is close to the key conserved motif (S
443
SN). The Thr446Ala mutation in R6 PBP2b* displays a 60% reduction in penicillin G affinity in vitro compared to that for the wild-type protein. A recombinant R6 strain expressing the R6 PBP2b Thr446Ala mutation is twofold less sensitive to piperacillin than the parental
S. pneumoniae
strain. Analysis of the Thr446Ala mutation in the context of the PBP2b CR sequences revealed that its influence depends upon the presence of other unidentified mutations.
Virulence of Metallo-β-Lactamase-Producing
Pseudomonas aeruginosa
In Vitro and In Vivo
Authors: Aoki S. , Hirakata Y. , Kondoh A. , Gotoh N. , Yanagihara K. , Miyazaki Y. , Tomono K. , Yamada Y. , Kohno S. , Kamihira S.
Published: April 2004

We evaluated the virulence of
Pseudomonas aeruginosa
carrying
bla
IMP
, a metallo-β-lactamase gene, and the efficacy of ceftazidime, imipenem-cilastatin, and ciprofloxacin in the endogenous bacteremia model. The presence of
bla
IMP
did not practically change the virulence of the parent strain, and ciprofloxacin was effective against infection with
P. aeruginosa
carrying
bla
IMP
.
Development of a Liposome Formulation of Ethambutol
Authors: Wiens Theresa , Redelmeier Thomas , Av-Gay Yossef
Published: April 2004

A liposomal formulation capable of encapsulating 76 to 92% of the antimycobacterial drug ethambutol and showing prolonged in vitro release kinetics is described. In vitro efficacy is equivalent to that of the free drug, suggesting that encapsulation of ethambutol has the potential to shorten the current regimens for tuberculosis.
A bimodal volcanicplutonic system: the Zarembo Island extrusive suite and the Burnett Inlet intrusive complex
Authors: Lindline Jennifer , Crawford William A , Crawford Maria Luisa
Published: April 2004

The Zarembo Island volcanic rocks and the Burnett Inlet plutonic complex in central southeastern Alaska were investigated to determine if they are genetically related. The Zarembo Island volcanic suite consists of basalt, andesite, and rhyolite lava flows, which exhibit features that suggest simultaneous eruptions of mafic and felsic lavas. Five kilometres to the southeast, the broadly layered Burnett Inlet plutonic complex consists of gabbrodiorite and granite plutons that also show characteristics of contemporaneous mafic and felsic magmatism. These bimodal volcanic and plutonic rocks are similar in age, ranging from 18.5 to 21.5 Ma. Both suites show a gap in silica concentration between 60 and 65 wt.% and have similar major, trace, and rare-earth element composition. Both suites also show igneous layering, either as interlayered basalt and rhyolite flows or as alternating gabbro and granite sheets. Additionally, both groups contain magma mingling and mixing textures, including mafic enclaves in felsic members and quartz xenocrysts rimmed by clinopyroxene in enclaves. These characteristics suggest that the Burnett Inlet intrusive complex and the Zarembo Island volcanic suite represent an eroded, shallow-level plutonic center and its eruptive cover. The style of volcanism and the bimodal nature of magmatism suggest that igneous activity occurred during crustal extension and thinning that accompanied strike-slip tectonic motion in southeastern Alaska during the Tertiary. The volcanicplutonic rock associations now exposed at the surface indicate that at least 7° of post-20 Ma crustal tilting has affected the region and can help to explain aberrant paleomagnetic poles in mid-Cretaceous intrusions of the Cordillera Coast belt.
Geology and UPb geochronology of the Kipawa Syenite Complex  a thrust related alkaline pluton  and adjacent rocks in the Grenville Province of western Quebec
Authors: Breemen O van , Currie K L
Published: April 2004

The Kipawa Syenite Complex, a thin, folded sheet of amphibole syenite, quartz syenite and minor nepheline syenite, lies along a west-vergent thrust separating a lower slice comprising the Kikwissi granodiorite and biotite tonalite dated at 2717 +1511 Ma, and unconformably overlying metasedimentary rocks from an overlying slice containing the Red Pine Chute orthogneiss, an alkali granite gneiss, and the Mattawa Quartzite. The syenite complex, dated at 1033 ± 3 Ma, lies within the lower slice but has metasomatically altered the overlying slice. Texturally guided UPb spot analyses on partially metasomatised zircons from the alkali granite gneiss yield a cluster of 207Pb/206Pb ages at 1389 ± 8 Ma, interpreted as the time of igneous crystallization and four ages overlapping the time of syenite emplacement, interpreted as in situ, metasomatic growth. The highest structural slice comprises garnet amphibolite separated from lower slices by the Allochthon Boundary Thrust. Metamorphic grade increases upward from greenschist grade in the biotite tonalite to amphibolite grade (690 °C, 9 kbar (1 kbar = 100 MPa)) at the lower boundary of the alkali granite. Emplacement of the Kipawa Syenite Complex took place after assembly of the thrust stack had begun and after emplacement of the allochthon or hot slab responsible for the inverted metamorphic gradient. Origin of the syenite is tentatively ascribed to anatexis of material metasomatized by flow of alkaline solutions along a major shear surface. Crystallization of new zircon in the margins of the syenite shows that metasomatism continued from ca. 1035 to 990 Ma, redistributing alkalies, fluorine, rare-earth elements and zirconium.
Effects of the abundance of spawning sockeye salmon (Oncorhynchus nerka) on nutrients and algal biomass in forested streams
Authors: Johnston N T , MacIsaac E A , Tschaplinski P J , Hall K J
Published: April 2004

We used natural variation in sockeye salmon (Oncorhynchus nerka) spawner biomass among sites and years in three undisturbed, forested watersheds in interior British Columbia to test the hypotheses that salmon were a major source of particulate organic matter inputs to the streams and that carcass biomass determined stream-water nutrient concentrations and epilithic algal production. Sockeye carcasses were retained at the spawning sites, primarily (7580%) by large woody debris (LWD) or pools formed by LWD. The abundance and distribution of sockeye salmon determined stream-water nutrient concentrations and epilithic chlorophyll a concentrations during late summer and early fall when most primary production occurred in the oligotrophic streams. Periphyton accrual rates were elevated at sites with high salmon biomass. Peak chlorophyll a concentration increased with increasing carcass biomass per unit discharge above a threshold value to reach maxima 10-fold greater than ambient levels. Epilithic algae were dominated by a few common, large diatom taxa. Salmon carcasses were the dominant source of particulate organic carbon in low gradient stream reaches. Nutrient budget modeling indicated that most of the salmon-origin nutrients were exported from the spawning streams or removed to the terrestrial ecosystem; diffuse impacts may extend over a much larger area than simply the sites used for spawning.
Environmental factors influencing freshwater survival and smolt production in Pacific Northwest coho salmon (Oncorhynchus kisutch)
Authors: Lawson P W , Logerwell E A , Mantua N J , Francis R C , Agostini V N
Published: April 2004

Climate variability is well known to affect the marine survival of coho salmon (Oncorhynchus kisutch) in Oregon and Washington. Marine factors have been used to explain up to 83% of the variability in Oregon coastal natural coho salmon recruitment, yet about half the variability in coho salmon recruitment comes from the freshwater life phase of the life cycle. This seeming paradox could be resolved if freshwater variability were linked to climate and climate factors influencing marine survival were correlated with those affecting freshwater survival. Effects of climate on broad-scale fluctuations in freshwater survival or production are not well known. We examined the influence of seasonal stream flows and air temperature on freshwater survival and production of two stock units: Oregon coastal natural coho salmon and Queets River coho salmon from the Washington Coast. Annual air temperatures and second winter flows correlated strongly with smolt production from both stock units. Additional correlates for the Oregon Coast stocks were the date of first fall freshets and flow during smolt outmigration. Air temperature is correlated with sea surface temperature and timing of the spring transition so that good freshwater conditions are typically associated with good marine conditions.
Population genetics and phylogeography of the blue rockfish (Sebastes mystinus) from Washington to California
Authors: Cope Jason M
Published: April 2004

Blue rockfish (Sebastes mystinus) are a major component of nearshore ecology and fisheries on the west coast of the United States, but the extent of spatial structuring between localized populations is unknown. I sampled 245 blue rockfish at eight locations from Washington to California and sequenced a 498 base pair portion of the mitochondrial DNA control region to describe genetic diversity, population structure, and phylogeography. Haplotype diversity was high, but nucleotide diversity was low, indicating historically unstable population dynamics. Significantly high levels of population differentiation were detected among sample sites (maximum pairwise FST: full sequence = 0.25, reduced sequence = 0.74, P < 0.001), with a distinct break (ΦCT: full sequence = 0.12; reduced sequence = 0.36, P < 0.05) north and south of Cape Mendocino and no overall trend between geographic and genetic distances. Cape Mendocino may prove an important biogeographic barrier to other marine organisms, but it has not been extensively explored as such. The northern subpopulation derived from the southern subpopulation, but little contact has been made between the populations for potentially thousands of years. Therefore, repopulation of a depleted southern subpopulation is unlikely to come from the less-fished northern subpopulation.
Flexural behaviour of concrete beams strengthened with prestressed carbon fibre reinforced polymer sheets subjected to sustained loading and low temperature
Authors: El-Hacha Raafat , Green Mark F , Wight R Gordon
Published: April 2004

This paper presents results of an experimental investigation that examined concrete beams post-tensioned with bonded carbon fibre reinforced polymer (CFRP) sheets and then exposed to either room (+22 °C) or low (-28 °C) temperatures. The primary objective of this investigation was to assess the flexural behaviour of the strengthened beams after sustained loadings at both room and low temperatures. The strengthened beams showed significant increases in flexural stiffness and ultimate capacity as compared with the control-unstrengthened beams. Failure of the strengthened beams was by tensile rupture of the prestressed CFRP sheets. Test results showed that the long-term and low temperature effects did not adversely affect the strength of the beams. Long-term loading and low temperature exposure caused prestress losses in the CFRP sheets. The loaddeflection behaviour of the long-term beams was predicted accurately by an analytical model. These results suggest that bonded prestressed CFRP sheets could be used to increase the strength of damaged prestressed concrete girders under extreme environmental conditions.Key words: strengthening, anchorage, low temperature, long-term, prestress losses, sustained load, carbon fibre reinforced polymer sheet.
Evaluation of moment equation in the 2000 Canadian highway bridge design code for soil–metal arch structures
Authors: Choi Dong-Ho , Kim Gi-Nam , Byrne Peter M
Published: April 2004

This paper evaluates the moment equation in the 2000 Canadian highway bridge design code (CHBDC) for soil–metal arch structures. This equation is adopted from Duncan's moment equation (1978), which is based on his finding from finite element analyses that the maximum moment occurs at the quarter point of soil-metal structures. However, finite element analyses carried out for this study demonstrate that the maximum moment in soil–metal arch structures with spans greater than approximately 11 m occurs at the crown point. In this study, the location and magnitude of the maximum moment was examined for soil–metal arch structures having spans of 6–20 m under three construction stages; backfill up to the crown, backfill up to the cover depth, and live loading. Based on the location of the maximum moment, two sets of moment equations dependant on span length were found necessary. Moment coefficients and moment reduction factors in moment equations are proposed from the results of numerous finite element analyses for semi-circular arch and part-arch types of soil–metal structures considering the various design variables, such as span length, structural shapes, section properties, and backfill conditions. The validity of the coefficients and reduction factors in the moment equation of the 2000 CHBDC is investigated by comparison with those proposed in this study. The comparison demonstrates that the moment equation of the 2000 CHBDC is still valid and a little conservative. The effects of design variables on the variations of moments of soil–metal arch structures during construction stages are also examined.Key words: soil–metal arch structures, moment equations, CHBDC, soil-structure interaction.
Étude du biais dans le modèle log-linéaire d'estimation régionale
Authors: Girard Claude , Ouarda Taha B.M.J , Bobée Bernard
Published: April 2004

Log-linear models are frequently used in hydrology, especially for the regional estimation of flood volumes based on the physiographic data of a set of basins. A log-linear model describes a linear relationship between the log of a dependant variable and independent variables which are functions of parameters, of which the value remains to be determined. It is determined by using a set of basins with known values of dependant and independent variables. The model is then used to obtain a prediction for the dependant variable logarithm of a basin of interest, based on the known values of independent variables in the model. This prediction is unbiased with relation to the log of the target variable. However, the exponential value of this prediction is biased with relation to the target variable. This paper addresses the measures to correct the bias in the prediction, which is introduced by exponentiation; the impacts on the variance of the ensuing predictions is also discussed. Key words: bias, transformation, log-linear model.[Journal translation]
Une nouvelle approche pour la caractérisation des aléas et l'évaluation des vulnérabilités des réseaux de support à la vie
Authors: Petit Frédéric , Robert Benoît , Rousselle Jean
Published: April 2004

Life support networks are vital structures, as they are significant in size and essential in nature for the entire society. A network failure may thus involve serious consequences. The analysis of the needs of those in charge of emergency measures has established that the behaviour of life support networks had to be studied not only for extreme events but also for all possible situations of failure. In this context, the role of civil engineers is crucial, since they must assure the safety of infrastructures from design to dismantling. The proposed approach consists of characterizing networks according to the importance and efficiency of their missions, operations, and essential infrastructures. This allows approaching network vulnerabilities from an exhaustive and global perspective. Based on the degree of efficiency of a mission, it is possible to identify the dysfunctioning operations and infrastructures, from which the internal and external causes of faults or failures could be defined. Instead of starting from a hazard and asking the question "What-if", as is currently done, this new approach aims at determining the vulnerabilities of a network by asking the question "Why". Once the potentialities of failures are defined, it will be possible, by using a global method of fusion, to determine the vulnerabilities of the various components of a life support network (missions, operations, infrastructures). This paper describes this new approach and the required criteria for the development of a global methodology for the assessment of anthropic hazard. Our article illustrates this approach with an application to a hydroelectric facility.Key words: risk, vulnerability, reliability, life support network, hydropower.
Microbial community structure and biomass in developing drinking water biofilms
Authors: Keinänen Minna M , Martikainen Pertti J , Kontro (Suutari) Merja H
Published: April 2004

Traditional techniques to study microbes, such as culturable counts, microbial biomass, or microbial activity, do not give information on the microbial ecology of drinking water systems. The aim of this study was to analyze whether the microbial community structure and biomass differed in biofilms collected from two Finnish drinking water distribution systems (A and B) receiving conventionally treated (coagulation, filtration, disinfection) surface water. Phospholipid fatty acid methyl esters (PLFAs) and lipopolysaccharide 3-hydroxy fatty acid methyl esters (LPS 3-OH-FAs) were analyzed from biofilms as a function of water residence time and development time. The microbial communities were rather stabile through the distribution systems, as water residence time had minor effects on PLFA profiles. In distribution system A, the microbial community structure in biofilms, which had developed in 6 weeks, was more complex than those grown for 23 or 40 weeks. The microbial communities between the studied distribution systems differed, possibly reflecting the differences in raw water, water purification processes, and distribution systems. The viable microbial biomass, estimated on the basis of PLFAs, increased with increasing water residence time in both distribution systems. The quantitative amount of LPS 3-OH-FAs increased with increasing development time of biofilms of distribution system B. In distribution system A, LPS 3-OH-FAs were below the detection limit.Key words: biofilm, distribution system, 3-hydroxy fatty acid, microbial community, PLFA.
Role of the tegument and gut in nutrient uptake by parasitic platyhelminths
Authors: Dalton John P , Skelly Patrick , Halton David W
Published: April 2004

The ease of procuring nutrient is probably the main selection pressure that drives and maintains the host–parasite relationship. The feeding activities of the ectoparasitic monogeneans exhibit similarities with the predatory turbellarians, with certain monopisthocotylean members feeding by means of a protrusible pharynx. These parasites degrade fish skin by secreting enzymes extracorporeally, but most of the digestion is carried out intracellularly in cells lining a well-differentiated gut. Some polyopisthocotylean monogeneans, however, living within the vascularized gill chamber, took advantage of the availability of a more highly nutritious, consistent, and renewable diet in the form of blood, and this represented a major step in the evolution of endoparasitism. Blood provides a rich source of carbohydrates for the production of energy and amino acids and fatty acids for the synthesis of parasite molecules and for egg production. The external surfaces of all parasitic flatworms depart from turbellarian character and are composed of a multifunctional syncytial tegument that is permeable to a variety of small organic solutes. Glucose and amino acid transporter molecules situated in the tegumental surface and basal membranes of trematodes and cestodes function in the uptake of these molecules and their distribution to the parasite tissues. Cestodes are bereft of any vestige of a gut, but their tegument has become elaborated into a highly efficient digestive–absorptive layer that competes with the vertebrate mucosa for nutrients. The patterns of energy metabolism in adult flatworm parasites are generally anaerobic and based on glycogen, with abbreviated metabolic pathways and the loss of biosynthetic capacities. In contrast to the tegument, the role of the gut is to digest host macromolecules and subsequently absorb the soluble products. However, the switch to blood as the major source of nutrient necessitated development of a means of overcoming the problems of blood clotting, attack by immune effector mechanisms, and the intracellular accumulations of haematin pigment. Digenean trematode, in contrast to monogeneans, digest blood extracellularly and their secretions include molecules capable of lysing erythrocytes and preventing blood clotting. Digestion of the ingested proteins is generally rapid, involving a range of cathepsin-like cysteine and aspartic proteases, which reduce the blood meal to absorbable peptides that are most likely further catabolized to amino acids by intracellular aminopeptidases. The parasites dispose of accumulated haematin by simply emptying the contents of their blind-ended gut.
Trematodes and snails: an intimate association
Authors: Lockyer Anne E , Jones Catherine S , Noble Leslie R , Rollinson David
Published: April 2004

Trematode parasites share an intimate relationship with their gastropod intermediate hosts, which act as the vehicle for their development and transmission. They represent an enormous economic and medical burden in developing countries, stimulating much study of snail–trematode interactions. Laboratory-maintained snail–trematode systems and in vitro cell cultures are being used to investigate the molecular dialogue between host and parasite. These dynamic and finely balanced antagonistic relationships, in which parasites strongly influence the physiology of the host, are highly specific and may occasionally demonstrate co-speciation. We consider the mechanisms and responses deployed by trematodes and snails that result in compatibility or rejection of the parasite, and the macroevolutionary implications that they may effect. Although for gastropods the fossil record gives some insight into evolutionary history, elucidation of trematode evolution must rely largely upon molecular approaches, and for both, such techniques have provided fresh and often surprising evidence of their origins and dispersal over time. Co-evolution of snails and trematodes is becoming increasingly apparent at both cellular and population levels; the implications of which are only beginning to be understood for disease control. Untangling the complex interactions of trematodes and snails promise fresh opportunities for intervention to relieve the burden of parasitic disease.
Immunology of the host–parasite relationship in fasciolosis (Fasciola hepaticaandFasciola gigantica)
Authors: Piedrafita D , Raadsma H W , Prowse R , Spithill T W
Published: April 2004

The protective resolution of liver fluke (Fasciola hepatica and Fasciola gigantica) infection is a dynamic interplay between the host's effector responses and the parasite's defence and immunomodulatory systems. The evidence suggests that the juvenile or immature parasite is the target of protective host immune responses but the effector mechanisms employed vary between hosts. Moreover, F. hepatica and F. gigantica differ in their susceptibility to these killing mechanisms. In the rat, in vitro killing of juvenile F. hepatica involves an antibody-dependent cell cytotoxicity mediated by nitric oxide produced by activated monocytes and (or) macrophages. However, monocytes and (or) macrophages from Indonesian sheep do not produce nitric oxide yet can effectively kill juvenile F. gigantica in vitro and in vivo by a mechanism that is ineffective against F. hepatica. These data show that disease progression or resolution in fasciolosis is determined both by biochemical differences between Fasciola species and by host-dependent factors. Understanding the genetic basis for these differences is a key question for the future. Fasciola hepatica and F. gigantica actively modulate the host immune response, downregulating type 1 responses during infection. It is important to determine whether such modulation of the immune response by Fasciola spp. directly leads to enhanced parasite survival in the various hosts.
Platyhelminth parasite reproduction: some general principles derived from monogeneans
Authors: Tinsley R C
Published: April 2004

Despite the importance of reproduction in platyhelminth parasite biology, there is generally only sketchy information on key parameters; many studies lack documentation on variation and there is limited application of laboratory studies to natural events. This review focuses on case studies involving monogeneans (species of the genera Polystoma, Protopolystoma, Pseudodiplorchis, Discocotyle, and Gyrodactylus) where laboratory experimental data are linked with fieldwork to produce exact measurements of life-history traits. Data are characterized by wide variation and sensitivity to limiting factors. In contrasting patterns of reproductive biology, controls are imposed by the external environment and by density, but there is consistent evidence of powerful regulation by host factors; most reproductive parameters, including prepatent period, egg production rate, and life-span, are negatively affected. Alongside rate-limiting effects, host factors operating during prereproductive development inflict massive mortality; this strongly regulates the size of the adult parasite population contributing to future recruitment. High fecundity is traditionally viewed as compensating for losses that occur as a result of the hazards of transmission, but this review suggests that parasite reproductive adaptations have their most significant role in countering the additional losses that occur post invasion. Regulation of parasite reproductive potential by host immunity and the reproductive specializations that counter this constraint represent a distinguishing characteristic of parasitism.
ON THE PALINDROMIC COMPLEXITY OF INFINITE WORDS
Authors: BRLEK S. , HAMEL S. , NIVAT M. , REUTENAUER C.
Published: April 2004

We study the problem of constructing infinite words having a prescribed finite set P of palindromes. We first establish that the language of all words with palindromic factors in P is rational. As a consequence we derive that there exists, with some additional mild condition, infinite words having P as palindromic factors. We prove that there exist periodic words having the maximum number of palindromes as in the case of Sturmian words, by providing a simple and easy to check condition. Asymmetric words, those that are not the product of two palindromes, play a fundamental role and an enumeration is provided.
A PROOF PROCEDURE FOR TEMPORAL LOGIC PROGRAMMING
Authors: GERGATSOULIS MANOLIS , NOMIKOS CHRISTOS
Published: April 2004

In this paper, we propose a new resolution proof procedure for the branching-time logic programming language Cactus. The particular strength of the new proof procedure, called CSLD-resolution, is that it can handle, in a more general way, open-ended queries, i.e. goal clauses that include atoms which do not refer to specific moments in time, without the need of enumerating all their canonical instances. We also prove soundness, completeness and independence of the computation rule for CSLD-resolution. The new proof procedure overcomes the limitations of a family of proof procedures for temporal logic programming languages, which were based on the notions of canonical program and goal clauses. Moreover, it applies directly to Chronolog programs and it can be easily extended to apply to multi-dimensional logic programs as well as to Chronolog(MC) programs.
MECHANISMS OF AGGREGATION OF PHYSICAL SYSTEMS: POSSIBLE UNIVERSAL LAWS
Authors: CAPOZZIELLO SALVATORE , DE MARTINO SALVATORE , DE SIENA SILVIO , ILLUMINATI FABRIZIO
Published: April 2004

In this paper we deduce, by general hypotheses, phenomenological relations which allow to compute in order of magnitude, but with sensible accuracy, the sizes of all the observed astrophysical and cosmological structures in terms of two microscopic quantities (the radius and the mass of a nucleon), and of two fundamental constants (the gravitational constant and the velocity of the light). Moreover, we show that similar phenomenological relations could rule the mechanisms of aggregations of a large class of physical systems.
CONVEX REPLICA SYMMETRY BREAKING FROM POSITIVITY AND THERMODYNAMIC LIMIT
Authors: CONTUCCI PIERLUIGI , GRAFFI SANDRO
Published: April 2004

Consider a correlated Gaussian random energy model built by successively adding one particle (spin) into the system and imposing the positivity of the associated covariance matrix. We show that the validity of a recently isolated condition ensuring the existence of the thermodynamic limit forces the covariance matrix to exhibit the Parisi replica symmetry breaking scheme with a convexity conditions on the matrix elements.
DYNAMICAL CONTROL OF THE HALO IN PARTICLE BEAMS: A STOCHASTIC–HYDRODYNAMIC APPROACH
Authors: PETRONI NICOLA CUFARO , DE MARTINO SALVATORE , DE SIENA SILVIO , ILLUMINATI FABRIZIO
Published: April 2004

In this paper we describe the beam distribution in particle accelerators in the framework of a stochastic–hydrodynamic scheme. In this scheme the possible reproduction of the halo after its elimination is a consequence of the stationarity of the transverse distribution which plays the role of an attractor for every other distribution. The relaxation time toward the halo is estimated, and a few examples of controlled transitions toward a permanent halo elimination are discussed.
PATH INTEGRALS FOR QUBITS
Authors: DE ANGELIS GIAN FABRIZIO
Published: April 2004

Feynman started the theory of quantum computation by observing that quantum mechanical amplitudes cannot be simulated efficiently on a computer, since path integrals are computationally hard. Path integrals are heuristic tools for Schrödinger's hamiltonians, at least for real time dynamics. On the contrary they have a rigorous mathematical meaning for quantum systems which are worth a finite but no matter how large number of qubits.
MESOSCOPIC DESCRIPTION OF DYNAMICAL SYSTEMS: HIERARCHY OF RECURSIVE EQUATIONS FOR THE MOMENTS OF THE DENSITY DISTRIBUTION WITH AN APPLICATION TO CHARGED PARTICLE BEAM DYNAMICS
Authors: DE MARTINO SALVATORE , DE SIENA SILVIO , FEDELE RENATO , TZENOV STEPHAN
Published: April 2004

The quantumlike formalism in the form of Madelung fluid has been applied to describe the collective dynamics of a mesoscopic aggregate of particles in a potential field. The scheme has been specialized to the one-degree-of-freedom dynamics of a charged particle beam in an accelerator in the presence of high-order multipole nonlinearities. A hierarchy of recursive equations satisfied by the moments of the density distribution has been obtained. It has been shown that the recursion relations can be in principle solved if a finite number of the first several moments is known. Beam dynamics in the presence of octupole and decapole nonlinearities has been studied as an example, demonstrating the above scheme. It has been shown that an appropriate mechanism can be introduced to control stability and coherence of states when high-order nonlinearities have to be taken into account.
STABILITY OF ASYNCHRONOUS STATES OF SPIKING NEURONS
Authors: SHCHERBINA MARIYA , TIROZZI BRUNELLO
Published: April 2004

We consider a system of N spiking neurons with random synaptic connections which take values ±1 with equal probability. The resulting system of equations has a stationary solution equal to 1 for the fraction of neurons having potential x at time t. This solution describes an asynchronous state. We study the stability of such a state in a perturbative way and find a threshold for the parameters of the model such that for values larger than this threshold the stationary asynchronous state is stable otherwise it is unstable. In other terms the stability of the asynchronous state holds only for relatively small random perturbations.
MULTIPLE SIGN CHANGING SOLUTIONS OF A QUASILINEAR ELLIPTIC EIGENVALUE PROBLEM INVOLVING THE p-LAPLACIAN
Authors: BARTSCH THOMAS , LIU ZHAOLI
Published: April 2004

We consider the eigenvalue problem [Formula: see text] where Ω⊂ℝN is a bounded smooth domain and Δpu denotes the p-Laplacian, 1
0 is a parameter. The nonlinearity f is required to have an oscillatory behaviour. We prove the existence of multiple positive, multiple negative, and in particular, of multiple sign changing solutions depending on λ.
DEGENERATION OF KÄHLER–EINSTEIN MANIFOLDS I: THE NORMAL CROSSING CASE
Authors: RUAN WEI-DONG
Published: April 2004

In this paper we prove that the Kähler–Einstein metrics for a degeneration family of Kähler manifolds with ample canonical bundles converge in the sense of Cheeger–Gromov to the complete Kähler–Einstein metric on the smooth part of the central fiber when the central fiber has only normal crossing singularities inside smooth total space. We also prove the incompleteness of the Weil–Peterson metric in this case.
DISCRETE INTEGRABLE SYSTEMS ASSOCIATED WITH THE UNITARY MATRIX MODEL
Authors: McLEOD J. B. , WANG C. B.
Published: April 2004

The orthogonal polynomials on the unit circle associated with the unitary matrix model have various interesting properties, and have been studied in connection with different applications, such as double scaling, Riemann–Hilbert problems and integrable Fredholm operators. In this paper, we study the orthogonal polynomials on the unit circle with the weight function [Formula: see text]. We use the orthogonality of the polynomials to show that the orthogonal polynomials on the unit circle satisfy the linear problems associated with the discrete PainlevéII hierarchy, alternate discrete PainlevéII hierarchy and the discrete MKdV hierarchy. Thus the isomonodromy deformation method can be used to study the unitary matrix model. Typically, we focus on the orthogonal polynomials with the weight function exp {s(z+z-1)}. The recursion formula z(pn+vnpn-1)=pn+1+unpn (derived from Szegö's equation) for the orthogonal polynomials pn(z,s) is proved to be equivalent to the discrete AKNS-ZS system which is the base equation in the linear problem for the discrete equations. The variable xn=pn(0,s) satisfies the discrete PainlevéII equation and the discrete MKdV equation; un, vn satisfy the alternate discrete PainlevéII equation; 1/un-1=-xn-1/xn satisfies the PainlevéIII equation; and [Formula: see text] satisfies the PainlevéV equation. Also, we discuss the continuum limits of the discrete equations by using the double scaling method. Further, we present a procedure for finding the linear equations for the orthogonal polynomials and the consistency conditions of the linear equations by using the orthogonality of the polynomials.
REPUTATION, UTILITY AND TECHNOLOGICAL INNOVATION STRATEGIES
Authors: XIAO TIAOJUN , YU GANG , SHENG ZHAOHAN
Published: April 2004

In order to study the optimal R&D strategies of a firm in a dynamic environment, this paper introduces a reputation model on two-stage R&D decision-making by employing signaling games based on Schumpeter's process of creative destruction. There are two players in the game. One is a sender with private information on its own synthesized capability of type H (high) and L (low), and the other is a receiver without private information. The reputation model studies the type L sender on whether there is an incentive to build reputation in first phase. We solve the game model without considering reputation by applying adverse induction method and compare the results with that of using reputation. We show that the optimal signal of the type L sender is larger in phase two if it builds up reputation in phase one. The utility of the type L sender is less in phase one if it builds up reputation in phase one. However, it will receive higher utility in phase two. Our results can be applied to setting marketing and sales strategies.
A MATHEMATICAL FRAMEWORK FOR ENTERPRISE ARCHITECTURE REPRESENTATION AND DESIGN
Authors: GOIKOETXEA AMBROSE
Published: April 2004

This paper presents a new mathematical framework for the representation and design of enterprise information architectures (EIA), also known as simply enterprise architectures (EA). Set theory is used to represent an EA as an 8-tuple consisting of a set of requirements, a set of business processes, a set of business systems, a set of data elements, a set of applications, a set of technologies, a set of constraints and business rules, and a set of architectural metrics and their values. These sets are then used to represent their respective architectural views, i.e. the Business Process Architectural View, the Business Systems Architectural View, etc. Next, it is shown that these multiple architectural views are all subsets of the same design point in the resource space. Design considerations leading to a Pareto efficient design point are discussed. Finally, the concept of Pareto design optimality is illustrated with one example in aircraft design and one example in database design.
Labour of Love
Authors: Jarrett Kylie
Published: April 2004

In the discourses of the electronic commerce (e-commerce) industry, consumers are alleged to be empowered by the affective relations they establish in online communities. This article investigates this claim using a Foucauldian archaeological framework. It seeks to identify the key social and historical conditions that have enabled this representation to appear and to become a viable characterization. The question it examines is not whether consumers are actually empowered by e-commerce, but why it is deemed important to interrogate online consumers’ affective activity in terms of power.
Divergent Narratives in the Imagining of the Home amongst Middle-Class Consumers
Authors: Woodward Ian
Published: April 2004

Sociological research on consumption has typically emphasized the social ‘work’ done by consuming things, showing how consumption expresses social identities, symbolizes class and status, and assists in delineating cultural boundaries and networks. In contrast, there are relatively few studies that explore consumption from the viewpoint of actors, seeking to expose the strategies, narratives and accounts that literally constitute the consumption act. Using interview data collected from a sample of middle-class Australian householders on practices of home decoration, this article explores the way consumption practice is linked to imagination and narrative. While the style and design features of the home have been a site for frenetic commodification within Australia, these data demonstrate that people’s desires with regard to how their home is presented and understood differ markedly, with some respondents emphasizing conspicuousness and style, and others comfort and relaxation. These narratives are interpreted as markers that socially mediate symbolic boundaries of self.
Love Yourself
Authors: Hazleden Rebecca
Published: April 2004

The rise of psy discourse has been the subject of considerable academic attention, but one of its most popular and visible forms, the self-help book, has received comparatively little attention. This article provides a Foucauldian analysis of a selection of relationship manuals; it examines the ways in which they set up a relation of the reader’s self to itself, and it explores the ethical valorizations and teleologies therein. The emphasis on the relationship with the self, and the development of mastery over the emotions advocated in the books, is related to the values held in liberal democratic societies.
A Social Justice Agenda
Authors: Speight Suzette L. , Vera Elizabeth M.
Published: April 2004

This commentary highlights the innovative inclusion of social action groups in the 2001 Houston Conference and expands on their significance to the conference and the field. If the 2001 Houston Conference has correctly forecast a (re)establishment of social action as a mainstay of counseling psychology, then an in-depth exploration of how we train students, conduct research, and engage in practice is warranted. Given the political nature of social action and its inextricable connection to social justice, the implications of such a stance for the future of the profession are discussed.