bluuebunny/crossref_metadata_2025 huggingface dataset:
Fault tolerant deployment and topology control in wirelessad hocnetworks
Authors: Li Xiang‐Yang , Wan Peng‐Jun , Wang Yu , Yi Chih‐Wei
Published: February 2004

We consider a large‐scale of wirelessad hocnetworks whose nodes are distributed randomly in a two‐dimensional region Ω (more specifically, a unit square). Givennwireless nodesV, each with transmission rangern, the wireless networks are often modeled by graphG(V,rn) in which two nodes are connected if and only if their Euclidean distance is no more thanrn. We first consider how to relate the transmission range with the number of nodes in a fixed area such that the resulted network can sustainkfault nodes in its neighborhood with high probability when all nodes have the same transmission range. We show that, for a unit‐area square region Ω, the probability that the networkG(V,rn) isk‐connected is at least${\rm e}^{-{\rm e}^{-\alpha}}$when the transmission radiusrnsatisfies$n \pi r_n^2 \ge {\rm ln}\ n \,+ (2k - 3) {\rm ln}\, {\rm ln}\, n - 2 \,{\rm ln}(k - 1)! + 2 \alpha \ {\rm for} \, k >\,1$andnsufficiently large. This result also applies to mobile networks when the moving of wireless nodes always generates randomly distributed positions. We also conduct extensive simulations to study the practical transmission range to achieve certain probability the network beingk‐connectivity, when the number of nodesnis not large enough. The relation between the minimum node degree and the connectivity of graphG(V,r) is also studied. Setting the transmission range of all nodes tornguarantees thek‐connectivity with high probability, but some nodes may have excessive number of neighbours in the graphG(V,rn). We then present a localized method to construct a subgraph of the network topologyG(V,rn) such that the resulting subgraph is stillk‐connected but with much fewer communication links maintained. We show that the constructed topology has onlyO(k · n) links and is a length spanner. Here a graphH ⊆ Gis spanner for graphG, if for any two nodes, the length of the shortest path connecting them inHis no more than a small constant factor of the length of the shortest path connecting them inG. Finally, we conduct some simulations to study the practical transmission range to achieve certain probability ofk‐connected whennis not large enough. Copyright © 2004 John Wiley & Sons, Ltd.
Performance of adaptive bridge scheduling in a scatternet with a slave–slave bridge
Authors: Mišić Vojislav B. , Mišić Jelena , Chan Ka Lok
Published: February 2004

End‐to‐end packet delays in a Bluetooth scatternet with a Slave–Slave (SS) bridge can be minimized by adjusting the bridge residence times in accordance with traffic intensity and locality. This paper presents two algorithms to do so. One of these uses a fixed value of the bridge residence time, while the other adjusts the residence time dynamically according to the instantaneous intensity of inter‐piconet traffic. We discuss the performance of these algorithms and show that the adaptive algorithm offers better performance than the fixed residence time one, provided the parameters are chosen appropriately. We also consider the stability of both algorithms and show that they have comparable stability limits. Copyright © 2004 John Wiley & Sons, Ltd.
Performance analysis and evaluation of IEEE 802.11e EDCF
Authors: Kim Jong‐Deok , Kim Chong‐Kwon
Published: February 2004

Recently, the IEEE 802.11 working group has announced a new distributed access mechanism called Enhanced DCF (EDCF) to provide service differentiation among traffic classes defined as access category. With the increasing demand for supporting Quality of Service (QoS) in IEEE 802.11 wireless LANs, the EDCF is now attracting many researchers' attention due to its practical worth as a standard mechanism. In this paper, we focus on the analytical approach to evaluate the performance of the EDCF. An analytical model is presented to estimate the throughput of the EDCF in saturation (asymptotic) conditions by substantially revising and extending the analytical model developed by Bianchi for the performance analysis of the DCF. Extensive simulation studies based on the NS‐2 simulator have been carried out for the validation of the analysis, and they show that it estimates the throughput of the EDCF accurately. By utilizing the analytical model, we evaluate the performance of the EDCF. Specifically, we concentrate on discovering the characteristics of the EDCF parameters, such as CWmin, CWmax and AIFS, in the way that they influence on the performance of the EDCF. Copyright © 2004 John Wiley & Sons, Ltd.
How does Xenopus oocyte acquire its competence to undergo meiotic maturation?
Authors: Jessus Catherine , Ozon René
Published: February 2004

Summry— During Xenopus oogenesis, the follicle‐enclosed oocyte, arrested at the diplotene stage of meiotic prophase, accumulates pre‐MPF. Pre‐MPF is an heterodimer formed of cyclin B2 and Cdc2 protein kinase, which is maintained inactive by inhibitory phosphorylations on Thr14 and Tyr15. When the oocyte reaches its full size, it becomes competent to respond to progesterone and to activate MPF through a positive feedback loop. In this paper, we present experimental data indicating that the molecular network involved in the autoamplification loop of MPF is progressively established during late oogenesis.
Test‐retest Validity of Acoustic Pharyngometry Measurements
Authors: Kamal Ibrahim
Published: February 2004

BACKGROUND

Acoustic reflectometry is a relatively new technique that quantifies upper airway obstruction. The oropharyngeal airway is geometrically complex and variable; therefore establishing a standard operating protocol and understanding the possible sources of artifacts are of great importance in obtaining reliable results. This work aims at assessing the repeatability of pharyngeal cross‐sectional area measurements obtained from normal and snoring individuals.

METHODS

Twenty adult normal volunteers (16 men and 4 women; mean age, 35.9 years) and 10 adult snorers (9 men and 1 woman; mean age, 36.4 years) were examined by acoustic reflectometry following the developed standard operating protocol.

RESULTS

Measurements of pharyngeal cross‐sectional area are analyzed in 2 groups. In normal subjects where mean pharyngeal cross‐sectional area in the first session was 3.187 cm2, in the second session (same‐day test‐retest), the mean pharyngeal cross‐sectional area was 3.239 cm2, and in the third session 7 to 10 days later (day‐to‐day test‐retest), it was 3.245 cm2 (P > 0.4). In a second group of snoring patients where mean pharyngeal cross‐sectional area in the first session was 2.244 cm2, in the second session, mean pharyngeal cross‐sectional area was 2.237 cm2, and mean pharyngeal cross‐sectional area in the third session (7 to 10 days later) was 2.238 cm2 (P > 0.9).

CONCLUSIONS

These results show that repeatability of acoustic reflection results can be achieved following the standard operating protocol.

SIGNIFICANCE

The study results add to the reliability of this technique in assessing the pharyngeal airway in patients with snoring and obstructive sleep apnea.
Allergic Fungal Sinusitis: Expanding the Clinicopathologic Spectrum
Authors: Thakar Alok , Sarkar Chitra , Dhiwakar Muthuswamy , Bahadur Sudhir , Dahiya Sonika
Published: February 2004

OBJECTIVE

We sought to determine whether histologic tissue invasion occurs in allergic fungal sinusitis (AFS) and, if so, to identify clinical indicators for the same.

STUDY DESIGN AND SETTING

We conducted a retrospective case record review of all 28 AFS cases identified by histology over a 32‐month period at a tertiary care referral center. All histologic specimens were reevaluated for features of invasive pathology, and case records were correlated for clinical, radiologic, or laboratory parameters associated with such invasion.

RESULTS

In addition to the universal finding of the characteristic allergic mucin with fungal elements on histopathologic examination of the sinus luminal contents, 6 cases (21%) had additional evidence of mucosal invasion as indicated by granulomatous inflammation and branching septate fungal hyphae in the submucosal tissues. Such coexistent invasion was associated with advanced disease as indicated by a higher incidence of orbital involvement on clinical evaluation (P = 0.024), and extra‐sinus spread (intraorbital or intracranial spread) on the computed tomography evaluation (P = 0.003). The single death that occurred on follow‐up was in a patient with coexistent invasion.

CONCLUSION

Advanced AFS may be complicated by histologic evidence of tissue invasion.

SIGNIFICANCE

The noninvasive and invasive forms of fungal sinusitis are not necessarily discrete and may coexist in the same patient. Clinical features of orbital involvement or computed tomography manifestations of extrasinus spread should alert the clinician to the possibility of invasion.
Differential Expression of Myosin Heavy Chain Isoforms between Abductor and Adductor Muscles in the Human Larynx
Authors: Li Zhao‐Bo , Lehar Mohamed , Nakagawa Hideki , Foon Yoong Hoh Joseph , Flint Paul W.
Published: February 2004

OBJECTIVE

This study examines the differential expression of myosin heavy chain (MyHC) components in human laryngeal muscle groups.

STUDY DESIGN

A battery of monospecific monoclonal antibodies in Western blots was used to determine expression of IIX, extraocular‐specific (EOM), and IIB MyHCs for the thyroarytenoid (TA), vocalis (VOC), lateral cricoarytenoid (LCA), cricothyroid (CT), and posterior cricoarytenoid (PCA) muscles obtained from fresh cadaver specimens.

RESULTS

Fast IIX MyHC was only expressed in the TA, VOC, and LCA muscles. Fast IIA and slow MyHCs were expressed in all laryngeal muscles including the CT and PCA. The CT with mixed phonatory and respiratory function and the PCA with respiratory function did not express IIX MyHC. The 2 MyHC isoforms associated with the highest speeds of contraction in rat laryngeal muscle, namely, the EOM MyHC and IIB MyHC, were not detected in human laryngeal muscles. Novel MyHC bands were not detected in SDS‐PAGE gels or Western blots using a broad specificity MyHC antibody.

CONCLUSION

The profile of MyHC expression in human laryngeal muscles differs from that observed in human extraocular and masticator muscles, and other mammalian species. Our data demonstrate that IIX MyHC expression is associated primarily with muscles affecting glottic closure and is absent in CT and PCA.

SIGNIFICANCE

A higher percentage of IIX MyHC is expected to impart a high speed of shortening to the TA and LCA muscles. The absence of IIX MyHC in muscles with respiratory (PCA) and mixed respiratory/phonatory function (CT) further supports the inference that the physiologic difference between laryngeal muscles is reflected in the molecular composition of contractile protein.
Effect of Nitric Oxide on Mucin Production in Experimental Otitis Media
Authors: Martin Paul , Choi Duk‐Joo , Jinn Tae‐Hoon , Cohen Joshua G. , John Earnest O. , Moorehead Morrill T. , Kaura Claire S. , Kaura Samantha H. , Jung Timothy T.K.
Published: February 2004

OBJECTIVE

The purpose of this study was to determine the role of nitric oxide (NO) in the pathogenesis of mucold otitis media (OM) in lipopolysaccha‐ride (LPS)‐induced OM.

METHODS

OM was induced in chinchillas by injecting S‐nitroso‐N‐acetylpenicillamine (SNAP), LPS, and LPS + SNAP into the superior bullae. Auditory brainstem response thresholds were measured every 24 hours. Samples of middle ear fluid were collected and analyzed for mucin by the periodic acid‐Schiff method. At the end of each experiment, temporal bones were harvested for histopathologic study.

RESULTS

Mucin concentration was greatest in the LPS + the SNAP group and least in the SNAP‐alone group. Auditory brainstem response threshold was highest in the LPS group and lowest in the SNAP group, although not significantly. Histopathology showed the greatest mucosal thickening and inflammation in the LPS + SNAP group.

CONCLUSION

The addition of NO in LPS‐induced OM increased the mucin concentration in middle ear fluid and increased mucosal thickness and inflammation in middle ear mucosa.

SIGNIFICANCE

In the OM disease process, NO may contribute to the pathogenesis of mucold OM.
Endoscopy‐Assisted Surgery of the Petrous Apex
Authors: Mattox Douglas E.
Published: February 2004

OBJECTIVE

Five large petrous apex lesions, 4 cholesterol granulomas and 1 cholesteatoma, were managed with a combination of microsurgical and endoscopic techniques.

STUDY DESIGN AND SETTING

Retrospective review of clinical experience in an academic medical center. Traditional microsurgical approaches, infra‐cochlear and/or retrofacial, were used in all cases, followed by endoscopic examination and debridement of the interior of the cysts. In all cases residual disease or fibrous septae within the cysts were found endoscopically that were not evident through use of the operating microscope.

RESULTS

In all cases, the lesions were successfully managed without operative complications.

CONCLUSIONS

The addition of endoscopic visualization to traditional microsurgical approaches allowed exposure of recesses within the lesions, removal of debris and inspissated secretions, and identification and removal of septae and fibrous bands within the petrous apex lesions that would not have been identified with the operating microscope alone. No surgical or postsurgical complications occurred in any of the cases, including facial weakness, hearing loss, or cerebrospinal fluid (CSF) leak.
A hypothesis to explain division site selection in Escherichia coli by combining nucleoid occlusion and Min
Authors: Norris Vic , Woldringh Conrad , Mileykovskaya Eugenia
Published: February 2004

The positioning of the site of cell division in Escherichia coli results, it is generally believed, from the operation of nucleoid occlusion in combination with the Min system. Nucleoid occlusion prevents division over the nucleoids and directs it by default to the mid‐cell region between segregating nucleoids or to polar regions while the Min system prevents division in polar regions. Unresolved questions include how these systems interact to control the earliest known event in division, the assembly at the membrane of the tubulin‐like protein, FtsZ, and, more importantly, what exactly constitutes a division site. Evidence exists that (1) the coupled transcription, translation and insertion of proteins into membrane (transertion), can structure the cytoplasmic membrane into phospholipid domains, (2) the MinD protein can convert vesicles into tubes and (3) a variety of membranous structures can be observed at mid‐cell. These data support a model in which transertion from the segregating daughter chromosomes leads to the formation of a distinct proteolipid domain between them at mid‐cell; the composition of this domain allows phospholipid tubes to extend like fingers into the cytoplasm; these tubes then become the substrate for the dynamic assembly and disassembly of FtsZ which converts them into the invaginating fold responsible for division; the Min system inhibits division at unwanted sites and times by removing these tubes especially at the cell poles.
Analysis of an activated ABI5 allele using a new selection method for transgenic Arabidopsis seeds
Authors: Bensmihen Sandra , To Alexandra , Lambert Guillaume , Kroj Thomas , Giraudat Jérôme , Parcy François
Published: February 2004

The Arabidopsis abscisic acid (ABA) insensitive (ABI)5 transcription factor participates in the ABA‐dependent induction of late embryogenesis abundant (LEA) genes in the final stages of seed development. We tested whether the VP16 transcriptional activation domain is sufficient to provide ABI5 with the ability to activate the AtEm LEA genes in vegetative tissues. We took advantage of a new transgenic seed selection assay based on green fluorescent protein (GFP) fluorescence and found that VP16‐ABI5 triggered growth retardation and ABA‐independent induction of AtEm1 in seedlings. These results indicate that ABI5 activation potential is a limiting step and might be a target for ABA signaling.
Glucosylceramides in Colletotrichum gloeosporioides are involved in the differentiation of conidia into mycelial cells
Authors: da Silva André F.C , Rodrigues Marcio L , Farias Sandra E , Almeida Igor C , Pinto Márcia R , Barreto-Bergter Eliana
Published: February 2004

Glucosylceramides (GlcCer) were extracted from the plant pathogen Colletotrichum gloeosporioides and purified by several chromatographic steps. By using electrospray ionization mass spectrometry and nuclear magnetic resonance, GlcCer from C. gloeosporioides were identified as N‐2′‐hydroxyoctadecanoyl‐1‐β‐D‐glucopyranosyl‐9‐methyl‐4,8‐sphingadienine and N‐2′‐hydroxyoctadecenoyl‐1‐β‐D‐glucopyranosyl‐9‐methyl‐4,8‐sphingadienine. Monoclonal antibodies against these structures were produced and used as tools for the evaluation of the role of GlcCer in the morphological transition of C. gloeosporioides. In the presence of antibodies to GlcCer, the differentiation of conidia into mycelia was blocked. Since GlcCer is present in several plant pathogens, the inhibitory activity of external ligands recognizing these structures may be applicable in other models of fungal infections.
Novel sites in the p65 subunit of NF‐κB interact with TFIIB to facilitate NF‐κB induced transcription
Authors: Xia Chulin , Watton Sandra , Nagl Sylvia , Samuel Jane , Lovegrove Jenny , Cheshire John , Woo Patricia
Published: February 2004

Nuclear factor κB (NF‐κB) transcription factors regulate a large number of genes in response to inflammation, infection and stressful conditions. In this study, we investigated whether NF‐κB p65 regulates the transcription of target genes by interacting with components of the basal transcription machinery. We examined the interaction of p65 with the basal transcription factor IIB (TFIIB). Glutathione S‐transferase pull down assays showed that the Rel homology domain of p65 is important for binding to TFIIB. Molecular modelling, together with the generation of specific point mutants, revealed that residues 41 R and 42 S in the Rel homology domain of p65 facilitate the interaction with TFIIB. Mutation of these residues showed a decrease in p65 induced transcription, suggesting that they are involved in a functional interaction with TFIIB.
α‐Chimaerin exists in a functional complex with the Cdk5 kinase in brain
Authors: Qi Robert Z , Ching Yick-Pang , Kung Hsiang-Fu , Wang Jerry H
Published: February 2004

Cyclin‐dependent kinase 5 (Cdk5) in association with its neuronal activators p35 and p39 shows a complex involvement in the control of neurocytoskeletal dynamics. Here we show that α‐chimaerin, a GTPase‐activating protein specific for Rac and Cdc42, is a p35‐binding protein. The interaction domains of p35 and α‐chimaerin were delineated. In transfected HeLa cells, p35 and α‐chimaerin displayed an overlapping distribution pattern and they could be co‐immunoprecipitated from the cell lysate. As α‐chimaerin has a regulatory function in actin repolymerization, these results suggested that the regulation of neurocytoskeleton dynamics by Cdk5 is mediated at least in part via α‐chimaerin.
Multi‐class cancer subtype classification based on gene expression signatures with reliability analysis
Authors: Fu Li M , Fu-Liu Casey S
Published: February 2004

Differential diagnosis among a group of histologically similar cancers poses a challenging problem in clinical medicine. Constructing a classifier based on gene expression signatures comprising multiple discriminatory molecular markers derived from microarray data analysis is an emerging trend for cancer diagnosis. To identify the best genes for classification using a small number of samples relative to the genome size remains the bottleneck of this approach, despite its promise. We have devised a new method of gene selection with reliability analysis, and demonstrated that this method can identify a more compact set of genes than other methods for constructing a classifier with optimum predictive performance for both small round blue cell tumors and leukemia. High consensus between our result and the results produced by methods based on artificial neural networks and statistical techniques confers additional evidence of the validity of our method. This study suggests a way for implementing a reliable molecular cancer classifier based on gene expression signatures.
Managing the Workflow of a High-Throughput Organic Synthesis Laboratory: A Marriage of Automation and Information Management Technologies
Authors: Goodman Burton A.
Published: February 2004

The production of high quality, individually characterized libraries of compounds requires a well-developed strategy, along with robust, user-friendly data and automation systems to support this strategy. We developed a workflow process to improve the efficiency of producing greater than 50,000 individual compounds per year. Our workflow process eliminates bottlenecks in traditional procedures and thus ensures a steady, predictable compound production rate. Initially, virtual library creation allowed for the determination of the physio-chemical properties of libraries as well as the ability to calculate the needed amounts of reagents and solvents for a production campaign. At this point, we registered all samples into our library database. Production of libraries began with loading the appropriate linkers onto resins, followed by complete characterization of the resin-linker intermediate. The resins were then loaded into IRORI MiniKans™ and sorted using the IRORI Autosort™ 10Kx sorting workstation. Chemistry was then performed using standard laboratory glassware. Additional sorting and chemistry steps were then performed until the compound was ready for cleavage off of the resin. The MiniKans were then sorted into Bohdan MiniBlocks™ and treated with the appropriate cleavage cocktail. Collection into 48-position racks was followed by removal of cleavage solution through vacuum centrifugation. The concentrate was then dissolved in a solvent mixture that allowed for standard liquid handling automation to create 96 well plates for analysis by high throughput flow inject NMR and LC/MS. Compounds 80% pure by LC/MS and presenting a >80% overall yield, as determined by NMR, were automatically flagged “acceptable” in the database. Compounds that failed to pass these analytical criteria were flagged “fail” in the database and were examined for trends that could be corrected in future library production. Finally, acceptable compounds were reformatted from the original source plates into master plates.
SMIRP-A Systems Approach to Laboratory Automation
Authors: Bradley Jean-Claude , Samuel Benjamin
Published: February 2004

SMIRP (Standard Modular Integrated Research Protocols), a web-based laboratory management system, will be described. SMIRP uses a protocol-experiment-parameter data representation system for all components of laboratory operations, including knowledge acquisition, laboratory data generation and analysis, and document production. Data tractability is inherent to the use of the system, permitting rapid browser-based navigation through linked information. The implementation of SMIRP in an academic research environment is discussed.
High Throughput Screening at the Nano Scale
Authors: Gentsch Juerg , Bruttger Oliver , Daffertshofer Martin , Fiedli Bernard , Malin Cosmas
Published: February 2004

Aunique approach to master sample screening at the nano scale was launched as a joint venture project between Evotec Biosystems AG Germany and Novartis Pharma AG. The application, which provides a fully automated nano-screening platform, is composed of three module units: HPLC Nano-Fraction Collection, Micro to Nano Pipetting, and Screening. Process simulation and 3D design tools were used to evaluate not only the most performing module design, but also to reach an outstanding automation and robotic concept. The uniqueness of this application is the combination of miniaturized assay format and single molecule detection read-out, having major beneficial consequences for assay biology.

Miniaturization of assays which have been shown to lead to significant savings in assay reagents and test samples. An additional benefit is the physical layout of the 2080-well Nano-Titre-Plate (NTP), which enables screening of rare compounds at low volume and an easy and fast shipment of chemical libraries to different screening sites.
Systemic pneumococcal disease in Norway 1995–2001: capsular serotypes and antimicrobial resistance
Authors: PEDERSEN M. K. , HØIBY E. A. , FRØHOLM L. O. , HASSELTVEDT V. , LERMARK G. , CAUGANT D. A.
Published: February 2004

A total of 4624 pneumococcal isolates from episodes of systemic pneumococcal disease were received at the Norwegian Institute of Public Health during the period 1995–2001. All isolates were serotyped and tested for susceptibility to benzylpenicillin, lincomycin, erythromycin, tetracycline and trimethroprim–sulphamethoxazole. The proportion of strains resistant to these antimicrobial agents remained stable at a low level, ranging from 0·1% for benzylpenicillin to 2·5% for erythromycin. The distribution of serotypes was also stable over the 7 years: serotypes 1, 4, 9, 14, 7, 6 and 23 were the most frequent, representing 70·5% of isolates. Overall, 95·8% of the isolates were of serotypes/groups included in the current 23-valent polysaccharide vaccine, 52·2% were of serotypes/groups included in the 7-valent conjugated vaccine and 85·5% were of serotypes/groups included in the 11-valent conjugated vaccine.
Costs of gastroenteritis in The Netherlands
Authors: VAN DEN BRANDHOF W. E. , DE WIT G. A. , DE WIT M. A. S. , VAN DUYNHOVEN Y. T. H. P.
Published: February 2004

In order to target the most important cost components of gastroenteritis in The Netherlands and to indicate which change of policy yields the largest decrease in costs, the cost of illness of gastroenteritis and the number of Disability Adjusted Life Years (DALYs) in the Dutch population in 1999 were determined. The costs of gastroenteritis were estimated using data mainly from a community-based cohort study. For calculating DALYs, data on the number of deaths due to gastroenteritis were used from Statistics Netherlands. On average, the costs for gastroenteritis were 77 Euro (€) per case. For all patients in The Netherlands, the costs were estimated at €345 million (ranging between €252 and €531 million). Indirect costs made up 82% of this total. An estimate of costs for patients with campylobacter, salmonella or norovirus infections was, in total, 10–17% of the costs of gastroenteritis. Gastroenteritis was associated with a loss of approximately 67 000 DALYs.
Bacteria–host interactions of Salmonella Paratyphi B dT+ in poultry
Authors: VAN IMMERSEEL F. , MEULEMANS L. , DE BUCK J. , PASMANS F. , VELGE P. , BOTTREAU E. , HAESEBROUCK F. , DUCATELLE R.
Published: February 2004

In recent years, a dramatic increase in incidence of the dextro-rotatory tartrate-positive variant (dT+) of Salmonella enterica subspecies enterica serovar Paratyphi B has been observed in poultry and poultry products. In the present study the interactions of this bacterium with the host were studied in vivo and in vitro in an attempt to explain the preferential association of this serotype with poultry. The ability of this organism to invade and multiply in chicken intestinal epithelial cells and the intracellular behaviour in chicken macrophages was studied in vitro using chicken cell lines. In vivo challenge experiments in specific pathogen-free chickens were carried out to determine the level of colonization of caeca and internal organs early after experimental infection. An in vivo trial with commercial broiler chickens, using a seeder model, was performed to determine whether S. Paratyphi B dT+ could persist and spread in broilers until slaughter. S. Paratyphi B dT+ invaded and multiplied in the chicken epithelial cell line and survived in a chicken macrophage cell line. The strain used colonized caeca and internal organs of chickens to a high extent 1 week after infection with a low-dose inoculum. Moreover, the strain was efficiently transmitted within a group of broilers and persisted until slaughter. It was concluded that S. Paratyphi B dT+ was well adapted to poultry and therefore it is suggested that specific control measures against this serotype should be considered.
A diagnostic strategy to determine the Shiga toxin-producing Escherichia coli O157 status of pens of feedlot cattle
Authors: SMITH D. R. , GRAY J. T. , MOXLEY R. A. , YOUNTS-DAHL S. M. , BLACKFORD M. P. , HINKLEY S. , HUNGERFORD L. L. , MILTON C. T. , KLOPFENSTEIN T. J.
Published: February 2004

Although cattle are reservoirs, no validated method exists to monitor Shiga toxin-producing Escherichia coli O157 (STEC O157) on farms. In 29 Midwestern United States feedlot pens we compared culturing faeces from the individual cattle to: (1) culturing rope devices that cattle rub or chew; and (2) culturing a composite of faecal pats. Eighty-six per cent (68–96%) of pens were classified correctly using rope devices to detect pens with at least 16% of the cattle shedding STEC O157 [sensitivity=82% (57–96%); specificity=92% (62–100%)]. Ninety per cent of pens (73–98%) were classified correctly using composite faeces to detect pens with at least 37% of the cattle shedding STEC O157 [sensitivity=86% (42–100%); specificity=91% (71–99%)]. Ranking pens into three risk levels based on parallel interpretation of the pen-test results correlated (Spearman's r=0·76, P<0·0001) with the pen's prevalence. This strategy could identify pens of cattle posing a higher risk to food safety.
Molecular epidemiology and population genetics of Salmonella subspecies diarizonae in sheep in Norway and Sweden
Authors: ALVSEIKE O. , VARDUND T. , LINDSTEDT B. , HEIR E. , ERIKSSON E. , KAPPERUD G.
Published: February 2004

Fifty-four isolates of Salmonella enterica subsp. diarizonae (IIIb) in Norway, Sweden, England, the United States, France and Australia were characterized by pulsed-field gel electrophoresis (PFGE). This study focuses on serovar 61:k:1,5,(7) [S. IIIb 61:k:1,5,(7)] isolated from sheep. Digestion of the bacterial DNA with restriction enzyme XbaI yielded 15 distinct PFGE profiles comprising 12–16 fragments in the range 48·5–630·5 kbp. Four different profiles were identified in Norwegian sheep isolates and a single profile in Swedish isolates. The spatial and temporal distribution of profiles is discussed.
Retrospective characterization of Newcastle Disease Virus Antrim '73 in relation to other epidemics, past and present
Authors: O'DONOGHUE K. , LOMNICZI B. , McFERRAN B. , CONNOR T. J. , SEAL B. , KING D. , BANKS J. , MANVELL R. , WHITE P. S. , RICHMOND K. , JACKSON P. , HUGH-JONES M.
Published: February 2004

In November 1973 Newcastle disease suddenly appeared in Northern Ireland, where the viscerotropic disease had not been seen in 3½ years and the two Irelands had been regarded as largely disease free for 30 years. It was successfully controlled with only 36 confirmed affected layer flocks, plus 10 more slaughtered as ‘dangerous contacts’. Contemporary investigations failed to reveal the source of the Irish epidemic. Using archival virus samples from most of the affected flocks, RT–PCR was conducted with primers selected for all six NDV genes. Phylogenetic analyses of three genes, HN, M and F, confirmed vaccine as the cause of one of the outbreaks. The other six samples were identical and closely related to previous outbreaks in the United States and western Europe initiated by infected imported Latin American parrots. The probable cause of the epidemic followed from the importation from The Netherlands of bulk feed grains contaminated with infected pigeon faeces.
Genetic diversity of Streptococcus agalactiae strains colonizing the same pregnant woman
Authors: PÉREZ-RUIZ M. , RODRÍGUEZ-GRANGER J. M. , BAUTISTA-MARÍN M. F. , ROMERO-NOGUERA J. , ROSA-FRAILE M.
Published: February 2004

Pulsed-field gel electrophoresis (PFGE) of SmaI–DNA digests and serotyping was performed on 15 colonies of Streptococcus agalactiae (GBS) from each of 30 vaginal–rectal colonized women. Five distinct GBS serotypes were observed among the 30 specimens (Ia, Ib, II, III and V). In 29 of the 30 samples, the same serotype was observed among all 15 colonies; in the remaining specimen, the 15 colonies yielded two serotypes (II and V). The PFGE profiles of all colonies in 27 of the 30 subjects were indistinguishable within each subject. In the remaining women, different DNA profiles were identified among the colonies in each specimen, one of whom carried two different serotypes. Furthermore, strains of the same serotype belonging to different women were genetically heterogeneous.
Waterborne outbreak of gastroenteritis in a religious summer camp in Norway, 2002
Authors: NYGÅRD K. , VOLD L. , HALVORSEN E. , BRINGELAND E. , RØTTINGEN J. A. , AAVITSLAND P.
Published: February 2004

In July 2002 an outbreak of acute gastroenteritis occurred in a camp facility in western Norway during a 10-day seminar, with around 300 guests staying overnight and several day-time visitors. Environmental and epidemiological investigations were conducted to identify and eliminate the source of the outbreak, prevent further transmission and describe the impact of the outbreak. Of 205 respondents, 134 reported illness (attack rate, 65%). Multivariate analysis showed drinking water and taking showers at the camp-site to be significant risk factors. Secondary person-to-person spread among visitors or outside of the camp was found. Norovirus was identified in 8 out of the 10 stool samples analysed. Indicators of faecal contamination were found in samples from the private untreated water supply, but norovirus could not be identified. This outbreak investigation illustrates the importance of norovirus as a cause of waterborne illness and the additional exacerbation through person-to-person transmission in closed settings. Since aerosol transmission through showering contributed to the spread, intensified hygienic procedures such as isolation of cases and boiling of water may not be sufficient to terminate outbreaks with norovirus.
Herpes simplex virus latency
Authors: Lachmann Robin
Published: February 2004

Herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are ubiquitous human pathogens. They share with other herpesviruses the ability to establish lifelong latent infection of the host. Periodic reactivation from latency is responsible for most of the clinical disease burden of HSV infection. This review focuses on what we have learned from molecular studies in model systems of HSV latency, and the implications these findings have for treating recurrent HSV disease.
Molecular aetiology of primary hyperoxaluria and its implications for clinical management
Authors: Danpure Christopher J. , Rumsby Gill
Published: February 2004

The primary hyperoxalurias type 1 (PH1) and type 2 (PH2) are autosomal recessive calcium oxalate kidney stone diseases caused by deficiencies of the metabolic enzymes alanine:glyoxylate aminotransferase (AGT) and glyoxylate/hydroxypyruvate reductase (GR/HPR), respectively. Over 50 mutations have been identified in the AGXT gene (encoding AGT) in PH1, associated with a wide variety of effects on AGT, including loss of catalytic activity, aggregation, accelerated degradation, and peroxisome-to-mitochondrion mistargeting. Some of these mutations segregate and interact synergistically with a common polymorphism. Over a dozen mutations have been found in the GRHPR gene (encoding GR/HPR) in PH2, all associated with complete loss of glyoxylate reductase enzyme activity and immunoreactive protein. The crystal structure of human AGT, but not human GR/HPR, has been solved, allowing the effects of many of the mutations in PH1 to be rationalised in structural terms. Detailed analysis of the molecular aetiology of PH1 and PH2 has led to significant improvements in all aspects of their clinical management. Enzyme replacement therapy by liver transplantation can provide a metabolic cure for PH1, but it has yet to be tried for PH2. New treatments that aim to counter the effects of specific mutations on the properties of the enzymes could be feasible in the not-too-distant future.
Lyme borreliosis (Lyme disease): molecular and cellular pathobiology and prospects for prevention, diagnosis and treatment
Authors: Auwaerter Paul G. , Aucott John , Dumler J. Stephen
Published: February 2004

Lyme borreliosis is a systemic infection caused by the spirochaete Borrelia burgdorferi, which is transmitted by tick bites and maintained in a delicately balanced ecological cycle. Recent increases in the population densities of tick hosts, the abundance of ticks and the proximity of man to natural tick habitats have led to an escalating worldwide incidence of Lyme borreliosis, and nonspecific clinical manifestations have yielded significant misunderstanding of the disease. After entry, B. burgdorferi activates local inflammation, yet evades host defences and facilitates dissemination by potentially masquerading with host components such as plasmin and complement. The extent of tissue injury is determined by the aggressiveness of host inflammation and immunological reactions, as well as by genetic attributes of the spirochaete. The clinical presentation can be highly varied, including early manifestations that are limited to erythema migrans and ranging to disseminated infection with arthritis, carditis, cranial nerve palsy, peripheral neuropathy, meningitis, or other manifestations. Diagnostic tests have improved, but are unhelpful during certain stages of infection. Therapy varies depending on the degree of involvement, and recovery is usually rapid and complete. Post-treatment clinical manifestations in the absence of evidence for active infection are still poorly understood. The understanding of how B. burgdorferi survives in the environment and interacts with human and mammalian hosts has improved. However, further advances in prevention and therapy depend on continued investigation of the ecological risks and improved understanding of the pathobiology of this obligate bacterial parasite.
Fracture closure in extension and mechanical interaction of parallel joints
Authors: Germanovich Leonid N. , Astakhov Dmitriy K.
Published: February 2004

It is well known that in many cases rock permeability depends upon in situ stress conditions and on the pressure of the flowing fluid. Parallel and quasi‐parallel joints represent one of the most often observed permeability structures. Frequently, joint sets are closely spaced and although joint mechanical interaction could significantly affect their aperture, the interaction is usually ignored in the evaluation of permeability. In this paper, on the basis of accurate computations of the interaction between the parallel fractures and conducted physical experiments, we suggest that the internal pressure can, in fact, close the pressurized joints. In general, there is a critical spacing between the parallel fractures below which their surfaces start contacting under the extensional load. However, the two edge fractures (end members) in the set remain widely open because they are not suppressed from one side. These effects dramatically change rock permeability and the fluid flow pattern.
Multimode surface wave tomography for the Australian region using a three‐stage approach incorporating finite frequency effects
Authors: Yoshizawa K. , Kennett B. L. N.
Published: February 2004

A three‐stage inversion technique for surface wave tomography is applied to the Australian region. The inversion procedure consists of three independent processes. In the first stage, path‐specific one‐dimensional (1‐D) shear velocity profiles are derived from multimode waveform inversion to provide dispersion information. The information from all paths is then combined to produce multimode phase speed maps as a function of frequency. The first version of these phase speed maps is derived from linearized inversion based on the assumption of surface wave propagation along great circle paths. Subsequently, the 2‐D phase speed maps are updated by including ray tracing and finite frequency effects through the influence zone around the surface wave paths over which the phase is coherent. Finally, in the third stage the 3‐D shear wave speed distribution is reconstructed from the set of updated multimode phase speed maps. This three‐stage inversion of surface waves has significant benefits because it is possible to incorporate multimode dispersion, off‐great circle propagation, and finite frequency effects for surface waves in a common framework. The final 3‐D model, which includes the effects of ray bending and finite frequency, shows improvement in the definition of the model in regions with high gradients in shear velocity, such as near tectonic boundaries, especially in eastern Australia. Despite the natural smoothing imposed by considering the influence zone around the surface wave paths, the final models still require rapid change in shear wave properties in the neighborhood of the edge of the craton.
Examination of reference concentration under waves and currents on the inner shelf
Authors: Lee Guan‐hong , Dade W. Brian , Friedrichs Carl T. , Vincent Chris E.
Published: February 2004

We examine reference concentration using three different data sets of near‐bed suspended sediment concentration observed under combined waves and currents. The data include observations made at 15 and 20 m depth off Dounreay, Scotland, UK, and observations obtained at 13 m depth off Duck, North Carolina, USA. These data accommodate different dynamic conditions (from wave‐dominated conditions at Dounreay to wind‐driven, current‐dominated conditions at Duck) and sediment properties (median size of bed sediment ranging from 120 to 350 μm). Near‐bed concentration profiles to elevations of about 80 cm were obtained using acoustic backscatter sensors with 1 cm resolution. The reference concentrations (Cr) at 1 cm were then evaluated by regressing the observed suspended sediment concentrations against a Rouse‐type model. Bed shear stresses associated with each estimate of Cr were estimated using the wave‐current interaction model of Grant and Madsen. Existing equations for reference concentration based on shear stress alone fail to accommodate all Cr estimates from different environments. We introduce a new empirical relationship between Cr and the product of Shields and inverse Rouse numbers. These dimensionless parameters represent the ratio of bed shear stress and submerged particle weight and the ratio of shear velocity and particle settling velocity, respectively. The new formula adjusts the amount of mobile sediment at the bed (related to the Shields number) to that available for suspension at the reference height (related to the inverse Rouse number). The new formula for reference concentration accommodates observations from different environments, suggesting that it may have wide applicability on sandy inner shelves.
Equatorial spread F irregularity characteristics over São Luís, Brazil, using VHF radar and GPS scintillation techniques
Authors: Rodrigues F. S. , de Paula E. R. , Abdu M. A. , Jardim A. C. , Iyer K. N. , Kintner P. M. , Hysell D. L.
Published: February 2004

Multitechnique observations may considerably improve our understanding of factors responsible for the generation, growth, and dynamics of the destabilized nighttime equatorial F region plasma irregularities. In order to investigate the dynamics of plasma density irregularities of different scale sizes, a campaign of observations was conducted during 11–20 November 2001 at the Brazilian magnetic equatorial station São Luís (2.57°S, 44.21°W, dip latitude 1.73°S). We carried out observations using VHF coherent backscatter radar, two spaced GPS‐based scintillation monitors, and one digisonde. Range type spread F on ionograms and radar plume signatures on range‐time‐intensity maps of the VHF radar started at similar times. In order to compare GPS L1 (1.575 GHz) scintillations and radar plumes we used the scintillation S4 index computed for the signal transmitted by the highest elevation satellite. GPS scintillations were not observed during the initial bottom‐type layer shown by the radar; however, stronger scintillations (higher S4 values) were observed concurrently to stronger radar echoes. Although the time duration of GPS scintillation is longer than the duration of the plumes observed by the radar, ionosonde spread F is still much longer than scintillation occurrence, confirming that smaller scale‐size irregularities decay faster. Zonal and vertical velocities of 5‐m irregularities measured by the radar were analyzed jointly with the apparent zonal velocity of ∼400‐m irregularities measured by the spaced‐receiver scintillation method. Larger values of the zonal velocity measured by the scintillation technique were found during the explosive growth phase of radar plumes associated with large values of vertical drifts measured by the radar.
Insights into the growth of basement uplifts deduced from a study of fracture systems in the San Rafael monocline, east central Utah
Authors: Fischer Mark P. , Christensen Ryan D.
Published: February 2004

We examined networks of joints, small faults, and minor cleavage exposed in the lower parts of the Jurassic Carmel Formation along the San Rafael monocline in east central Utah. By collecting data from the same 3 m stratigraphic interval we effectively guaranteed that variations in the architecture of fracture systems that we examined were not caused by influences that could be attributed to stratigraphic variables like lithology or environmental variables such as burial depth. We consequently interpret that the spatial variability of fracture system architecture we observe was due to local variations in fold kinematics or mechanics. Steeply dipping portions of the monocline contain suborthogonal sets of dominant strike‐normal and strike‐parallel joints. Shallowly dipping portions of the monocline contain multiple joint sets with no single dominant set and evidence for shear reactivation of joints. Sets of small offset conjugate faults are present throughout the monocline and are used to determine the orientation of paleostresses that caused them. This stress inversion yields a thrust faulting configuration with maximum compression bearing between 285° and 312°. There is a systematic 27° clockwise rotation of these stress directions from north to south along the monocline. We interpret the spatial variability in fracture systems in the monocline as a consequence of local cylindrical or noncylindrical folding associated with three‐dimensional flexure of the sedimentary cover during dominantly dip‐slip motion on the underlying basement fault. This interpretation suggests that the monocline did not grow laterally but evolved with fixed tips in response to a northwest‐southeast compression that is kinematically incompatible with accepted Laramide convergence directions.