Diesel engine turbochargers are known to have operation into the self-excited unstable region. The operation in the nonlinear limit cycle has been tolerated on most applications to date. The need for a quieter and a smoother operation and in addition reduced emission levels have prompted new evaluations of the rotor bearing design for these systems. In this research, a commercial rotor-bearing dynamics computer program was used to evaluate the stability and transient response of a highspeed diesel engine turbocharger. Various models with varying bearing designs and properties were solved to obtain the linear stability threshold speeds and also the nonlinear transient response. The predicted whirl speed map shows two modes of instability and is very similar to recent on-engine test results conducted at Virginia Tech as part of a recent senior capstone design project. The development of the diesel engine test stand and the associated data acquisition system will be discussed. The results from the unloaded and the loaded engine testing will be compared to the analytical results. Future research will be devoted to the elimination of the large subsynchronous excitation.

We report null results on a 2 year photometric search for outburst predictors in SS Cyg. Observations in Johnson Vand Cousins I were obtained almost daily for multiple hours per night for two observing seasons. The accumulated data are put through various statistical and visual analysis techniques, but we fail to detect any outburst predictors. However, analysis of 102 years of AAVSO archival visual data has led to the detection of a correlation between a long term quasi-periodic feature at around 1000-2000 days in length and an increase in outburst rate.

We report null results on a two year photometric search for outburst predictors in SS Cyg. Observations in Johnson V and Cousins I were obtained almost daily for multiple hours per night for two observing seasons. The accumulated data are put through various statistical and visual analysis techniques but fails to detect any outburst predictors. However, analysis of 102 years of AAVSO archival visual data led to the detection of a correlation between a long term quasi-periodic feature at around 1,000-2,000 days in length and an increase in outburst rate.

Background: Metabolic bone disease of prematurity is characterised by impaired postnatal mineralisation of the rapidly growing infant skeleton. Objective: To longitudinally evaluate postnatal changes in tibial speed of sound (tSOS; which reflects cortical thickness and bone mineral density) and lower limb length (LLL; a measure of tibial growth) in very low birthweight preterm infants receiving contemporary neonatal care. Methods: tSOS and LLL were measured using a quantitative ultrasound device and an electronic neonatal knemometer, respectively, in the same limb, weekly, for a median period of four weeks (3–16 weeks) in 84 preterm infants (median gestation 26.8 weeks (range 23–35.2 weeks) and median birth weight 869.5 g (range 418–1481 g)). Results: Initial tSOS and LLL were correlated with gestation (r = 0.42, p<0.001; r = 0.76, p<0.001, respectively) and birth weight (r = 0.23, p = 0.038; r = 0.93, p<0.001, respectively). Postnatally, tSOS decreased (r = −0.15, p = 0.011) whereas LLL increased (r = 0.96, p<0.001) with age. The rate of postnatal change in LLL, but not in tSOS, was positively influenced by intake of calcium (p = 0.03), phosphorus (p = 0.01) and vitamin D (p = 0.03). Conclusions: The postnatal decline in tSOS, which is probably due to cortical thinning secondary to endocortical bone loss, and increase in LLL provide new insight into the development of long bones in preterm infants.

Bacterial integrons are a useful PCR amplification target in epidemiological surveys of bacterial antibiotic resistance, and a variety of primers have been published. We describe multiplex PCR methodology to test for classes 1, 2 and 3 integron-associated integrases in boiled lysates of Gram-negative bacteria. We report on performance in Acinetobacter spp. (n=50), Enterobacteriaceae (n=76), Pseudomonas aeruginosa (n=15), Bacteroidesspp. (n=69), and in undifferentiated mixed cultures derived from perineal swabs (n=50) and endotracheal aspirates (n=8). This method achieved 100% sensitivity and specificity in simple lysates made from a range of bacteria, without requiring DNA extraction, and is recommended as an efficient screening tool for surveys of integron cassettes.

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ABSTRACT A 44-year-old man with a bioprosthetic aortic valve suffered destructive endocarditis with severe embolic disease due to Bartonella henselae infection. Multilocus sequence typing was successfully performed with crude preparations of operative tissue as templates, and the infecting organism was determined to be typical of the Houston clonal group, although it was never cultured from blood or tissue. This is the first report of B. henselae infection in the South Pacific, and it reminds one that B. henselae is a cause of potentially lethal culture-negative endocarditis which may respond poorly to conventional empirical therapy. Nothing is known of the epidemiology of the infection in this region, but it is likely to be common and to contain representatives of both major clonal complexes. This study emphasizes the ease with which multilocus sequence typing can be used directly with tissue, which is important because of suggestions of strain-dependent clinical outcomes.

Bartonella henselae is a fastidious, Gram-negative bacterial pathogen of cats and humans. Previous workers have shown that serial passage in vitro leads to attenuation of virulence-associated attributes such as expression of pili, invasion of human epithelial cell lines and the stimulation of endothelial cell proliferation. In contrast to the published data, it was found that pilin expression is frequently preserved in organisms which have undergone phase variation in vitro. Transition from a slow-growing, dry agar-pitting (DAP) to a faster-growing, smooth non-agar-pitting (SNP) form appears to occur predictably and may reflect competition between two populations growing at different rates. Better survival of the slower-growing (DAP) form may explain its relatively easy retrieval from piliated SNP populations allowed to age on solid media. Pilin expression is associated with auto-agglutination in liquid suspension or broth cultures, and appears to be necessary but not sufficient for expression of the agar-pitting phenotype and for the formation of biofilms. Outer-membrane protein variation is seen in association with phase variation, but lipopolysaccharide expression is preserved in piliated as well as extensively passaged non-piliated isolates. The EagI/HhaI infrequent restriction site-PCR fingerprint, which has been previously used to discriminate between serotypes Marseille and Houston, is shown to alter with phase variation in vitro, and there is evidence that genetic change accompanies these events. The extent of genetic and phenotypic variability of phase-variant B. henselae has previously been underestimated. It may lead to new insights into the pathogenicity of this organism, and must be considered when interpreting data arising from such studies.

ABSTRACT A study of 59 isolates of Bartonella henselae reveals relatively limited diversity among those of human origin ( n = 28). Either of two distinct alleles of both gltA and 16S ribosomal DNA (rDNA) was found in all isolates, with a high level of congruity between 16S and gltA inheritance among proven human pathogens. Human isolates from all over Eastern Australia were most commonly 16S rDNA (Bergmans) type I, with the same gltA allele as the type strain (Houston-1). Comparable feline isolates were more commonly 16S type II, with less congruity of inheritance between 16S and gltA alleles. Previously described arbitrarily primed PCR and Eag I- Hha I infrequent restriction site PCR fingerprinting techniques separated Bartonella species effectively but lacked discriminating power within B. henselae. Examination of the 16-23S intergenic spacer region revealed for several strains several point mutations as well as a repeat sequence of unknown significance which is readily detected by Hae III restriction fragment length polymorphism analysis. The bacteriophage-associated papA gene was present in all isolates. Enterobacterial repetitive intergenic consensus PCR proved to be a useful and robust typing tool and clearly separated human isolates (including imported strains) from the majority of feline isolates. Our data are consistent with published evidence and with previous suggestions of intragenomic rearrangements in the type strain and suggest that human isolates come from a limited subset of B. henselae strains. They strengthen arguments for careful exploration of genotype-phenotype relationships and for the development of a multilocus enzyme electrophoresis and multilocus sequence typing-based approach to the phylogeny of B. henselae .

The ubiquitous feline intraerythrocytic pathogen Bartonella henselae causes a range of important human infections, and seroprevalence in blood donors in Australia is around 5% (6). Two antigenically distinct subtypes have been described, named for the type strain (Houston-1) and the more recently recognized Marseille strain (5), which have characteristic DNA sequences in the 16S rRNA gene (rDNA) and the gltA (citrate synthase) gene (2, 3, 5). Culture of this fastidious, gram-negative bacterium is difficult, and serology is a primary diagnostic approach. A recent report that Houston-like strains (including Houston-1, 90-615, and SA-2) may be distinguished from serologically distinct Marseille-like strains (including URBHLLY-8, URBHLIE-9, Fizz, and CAL-1) by the faster migration of a characteristic band (ca. 29 kDa) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis and immunoblotting of whole-cell lysates is therefore particularly noteworthy (7). However, the SDS-PAGE data appear to contrast with previous publications from the same laboratory (8, 9) and others (11). We therefore compared local human isolates with the Houston-1 and Marseille strains and also found two closely related genotypes with corresponding patterns on SDS-PAGE of whole-cell lysates (Fig. ​(Fig.1).1). All human strains appear to have either the 30-kDa band (Houston) or the 29-kDa band (Marseille), in agreement with earlier studies (10, 11). The agar-pitting colony phenotype and number of in vitro passages have no apparent influence (Fig. ​(Fig.11 and Table ​Table1).1). However, a local feline strain of the type II (Marseille-like) 16S rDNA genotype has the faster-migrating (29-kDa) band and a gltA gene sequence typical of Houston strains, consistent with the considerable diversity known to exist in feline strains (1, 10) and illustrating a dissociation of the accepted genotype-phenotype relationships. The strains in the recent study (7) were all human isolates and were assigned to genotypes by individual sequencing of several genes, including groEL (12) and the 16S rDNA (3). While the 29- to 30-kDa antigen(s) may yet prove useful for serotyping of human isolates, it thus seems unlikely that reported inconsistencies in the data can be easily explained by phase variation or genotype. In addition, we have no reason to assume that the more diverse feline strains are all nonpathogenic in humans. For both of thesereasons, we therefore urge caution in adopting this promising target as a basis for serotype distinction until the picture is clearer. FIG. 1. Marseille and Houston types. Coomassie-stained SDS-PAGE of whole-cell lysates harvested from chocolate agar plates (grown at 35°C in 5% CO2). High-molecular-weight (lane 1 and left border) and low-molecular-weight (right border) markers are shown, ... TABLE 1. B. henselae isolates used in this study

The use of the Lorentz gauge for 'low frequency' eddy current problems has been previously reported in the literature, and has proved to be a reliable method for these types of problem. In the present paper, the formulation is extended to solve the full set of Maxwell's equation, including both displacement and volume currents. The magnetic scalar potential cannot be used, since the displacement current is now present. The formulation therefore requires the use of the magnetic vector and electric scalar potentials throughout space.

Journal Article Conservative management of perforated duodenal ulcer Get access T E Keane, T E Keane Department of Surgery, The General Hospital, Portlaoise, Ireland Correspondence to: Mr T. E. Keane, North Tees General Hospital, Hardwick, Stockton-on-Tees TS19 8PE, UK Search for other works by this author on: Oxford Academic Google Scholar B Dillon, B Dillon Department of Surgery, The General Hospital, Portlaoise, Ireland Search for other works by this author on: Oxford Academic Google Scholar N H Afdhal, N H Afdhal Department of Surgery, The General Hospital, Portlaoise, Ireland Search for other works by this author on: Oxford Academic Google Scholar C J McCormack C J McCormack Department of Surgery, The General Hospital, Portlaoise, Ireland Search for other works by this author on: Oxford Academic Google Scholar British Journal of Surgery, Volume 75, Issue 6, June 1988, Pages 583–584, https://doi.org/10.1002/bjs.1800750629 Published: 08 December 2005 Article history Accepted: 26 August 1987 Published: 08 December 2005