Prevalence of Helicobacter pylori infection in asymptomatic children

OBJECTIVE: To determine the prevalence of Helicobacter pylori infection in a sample of asymptomatic Australian children. METHODOLOGY: A prospective observational study, during a 3 month period, of consecutive children aged 0 to 14 years undergoing minor elective surgical procedures in a Day Surgical Unit at a Melbourne paediatric hospital. Subjects without gastrointestinal symptoms or a family history of peptic ulcers had sociodemographic data recorded and serum collected. Serum anti-H. pylori immunoglobulin G antibodies were measured by an enzyme immunoabsorbent assay previously validated in children from the same population. RESULTS: H. pylori antibodies were present in 21/147 (14.3%) children aged 3 months to 14 years. Prevalence was not influenced by age or sex, but was greatest in children whose parents migrated from developing nations and lowest in children with Caucasian Australian or Western European parents (25.8 vs 5.9%; P < 0.001). An inverse relationship between social class and infection was also observed (P = 0.02). Multivariate analysis demonstrated the father's ethnic background as the only significant independent risk factor for H. pylori infection (P = 0.002). CONCLUSIONS: Although seroprevalence of H. pylori appears to be lower in Australian children than in developing countries there are some ethnic groups at substantially greater risk for the acquisition of H. pylori infection and its complications.     

An integrated content and metadata based retrieval system for art

A new approach to image retrieval is presented in the domain of museum and gallery image collections. Specialist algorithms, developed to address specific retrieval tasks, are combined with more conventional content and metadata retrieval approaches, and implemented within a distributed architecture to provide cross-collection searching and navigation in a seamless way. External systems can access the different collections using interoperability protocols and open standards, which were extended to accommodate content based as well as text based retrieval paradigms. After a brief overview of the complete system, we describe the novel design and evaluation of some of the specialist image analysis algorithms including a method for image retrieval based on sub-image queries, retrievals based on very low quality images and retrieval using canvas crack patterns. We show how effective retrieval results can be achieved by real end-users consisting of major museums and galleries, accessing the distributed but integrated digital collections.     

Design guidelines for granular particles in a conical centrifugal filter

Essential design criteria for successful drying of granular particles in a conical continuous centrifugal filter are developed in a dimensionless fashion. Four criteria are considered: minimum flow thickness (to ensure sliding bulk flow rather than particulate flow), desaturation position, output dryness and basket failure. The criteria are based on idealised physical models of the machine operation and are written explicitly as functions of the basket size l_out, spin velocity Ω and input flow rate of powder Q_p. The separation of sucrose crystals from liquid molasses is taken as a case study and the successful regime of potential operating points (l_out, Ω) is plotted for a wide range of selected values of flow rate Q_p. Analytical expressions are given for minimum and maximum values of the three independent parameters (l_out, Ω, Q_p) as a function of the slurry and basket properties. The viable operating regime for a conical centrifugal filter is thereby obtained as a function of the slurry and basket properties.     

Damage-free passivation of InAlAs/InGaAs HFETs by use of ECR-deposited SiN

Silicon nitride deposited by electron-cyclotron resonance has been used to fully passivate InAlAs/InGaAs HFETs. The passivation process did not increase the gate leakage current, and passivated 1 mu m HFETs had a breakdown voltage of 15 V. These results illustrate the potential of ECR nitride for passivation of InP-based semiconductor devices.<>     

Rotational hysteresis in polycrystalline alloys

Rotational hysteresis has been studied at very low rotational speeds in nearly isotropic polycrystalline materials. Measurements were made on disc shaped samples of pure iron, 1.2% C steel and mild steel. The magnitude and direction of the moment were measured as the disc was rotated starting from an initial magnetization parallel to the external field. For large angles of rotation the measurements give the usual hysteresis loss measured in continually rotating specimens. However it was also possible to measure the approach to the steady state and the response of the moment to small changes in the direction of the external field. The results are explained in terms of two models, one appropriate to low fields, below the maximum in the rotational loss curve, the other to the high field regime. At low fields the losses are due to domain wall motion, and the model predicts that the ratio of alternating to rotational loss ispisqrt{2}. At high fields the loss is thought to be due to a mechanism not present in alternating fields. This is the unstable rotation of the magnetization in each grain past its direction of difficult magnetization. To test the model Barkhausen noise measurements were made under alternating and rotating conditions. The results are compared with numerical calculations on the behaviour of 25 interacting dipoles.     

Relationships between magnetic tape properties and magnetic oxide concentration

A series of tapes were coated in which the concentration of the magnetic ferric oxide was essentially the sole variable. Magnetic and electroacoustic properties were evaluated as a function of magnetic oxide concentration. The intrinsic coercivity was found to increase slightly with decreasing oxide concentration but not to the extent predicted by the simple packing factor law. Biasing current changed in approximately the same ratio as coercivity. The sensitivity was directly proportional to the remanent flux density but the saturation output was proportional to the remanent flux. The linear range of the recording process increased appreciably with increasing oxide concentration. Frequency response decreased very slightly. Signal-to-noise ratio increased with increasing magnetic oxide concentration. Particle interactions had a strong effect upon the signal-to-print-through ratio. A decrease in magnetic oxide concentration to 50 percent of normal increased this ratio by 4 dB although coercivity was increased only slightly more than 5 percent.     

STD patient compliance with the syndromic management therapeutic regimen

Nurses spend time and effort making referral appointments for families who do not comply. Nurses can ensure that families will comply with referrals by following the recommendations contained in this article. These recommendations include the education of families about the reason for the referral and emphasis on the importance of keeping the appointment as paramount to the success of the referral. Families must be permitted to select referral sites based on location, appointment scheduling, and payment policies to enhance their compliance. Nurses must be cognizant of their legal obligation to protect patient confidentiality, especially that of adolescents, when making referrals and monitoring noncompliance. Families who do not keep referrals for serious conditions require that the nurse diligently contact them about compliance, recording all attempted and established communications with the family, such as certified letters. Continued noncompliance may require the nurse to file a medical neglect report.     

Bronchoalveolar lavage or oropharyngeal cultures to identify lower respiratory pathogens in infants with cystic fibrosis

As collections of lower respiratory tract specimens from young children with cystic fibrosis (CF) are difficult, we determined whether oropharyngeal cultures predicted lower airway pathogens. During 1992-1994, 75 of 90 (83%) infants with CF diagnosed by neonatal screening had 150 simultaneous bronchoalveolar lavage (BAL) and oropharyngeal specimens collected for quantitative bacterial culture at a mean age of 17 months (range, 1-52). Ten children undergoing bronchoscopy for stridor served as controls. Total and differential cell counts and interleukin-8 concentrations were measured in BAL fluid. A subset of bacterial pathogens were typed by pulsed field gel electrophoresis. A non-linear relationship with inflammatory markers supported a diagnosis of lower airway infection when > or = 10(5) colony-forming units/ml were detected. This criterion was met in 47 (31%) BAL cultures from 37 (49%) children. Staphylococcus aureus (19%), Pseudomonas aeruginosa (11%), and Hemophilus influenzae (8%) were the major lower airway pathogens. In oropharyngeal cultures, S. aureus (47%), Escherichia coli (23%), H. influenzae (15%), and P. aeruginosa (13%) predominated. The sensitivity, specificity, and positive and negative predictive values of oropharyngeal cultures for pathogens causing lower respiratory infections were 82%, 83%, 41%, and 97%, respectively. When there was agreement between paired oropharyngeal and BAL cultures, genetic fingerprinting showed some strains of the same organism were unrelated. We conclude that oropharyngeal cultures do not reliably predict the presence of bacterial pathogens in the lower airways of young CF children.