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BACKGROUND Hepatitis B viruses (HBV) harboring mutations in the a-determinant of the Hepatitis B surface antigen (HBsAg) are associated with reduced reactivity of HBsAg assays. OBJECTIVES To evaluate the sensitivity and specificity of three HBsAg point-of-care tests for the detection of HBsAg of viruses harboring HBsAg mutations. STUDY DESIGN A selection of 50 clinical plasma samples containing HBV with HBsAg mutations was used to evaluate the performance of three HBsAg point-of-care tests (Vikia(®), bioMerieux, Marcy-L'Etoile, France. Alere Determine HBsAg™, Iverness Biomedical Innovations, Koln, Germany. Quick Profile™, LumiQuick Diagnostics, California, USA) and compared to the ARCHITECT HBsAg Qualitative(®) assay (Abbott Laboratories, Sligo, Ireland). RESULTS The sensitivity of the point-of-care tests ranged from 98% to 100%. The only false-negative result occurred using the Quick Profile™ assay with a virus harboring a D144A mutation. CONCLUSIONS The evaluated point-of-care tests revealed an excellent sensitivity in detecting HBV samples harboring HBsAg mutations.

Background Molecular methods based on phylogenetic differences in the 16S rRNA gene are able to characterise the microbiota of the respiratory tract in health and disease. Objectives Our goals were (1) to characterise bacterial communities in lower and upper airways of patients with interstitial lung disease (ILD) and (2) to compare the results with the microbiota of patients with Pneumocystis pneumonia (PCP) and normal controls. Methods We examined the upper and lower respiratory tract of 18 patients with ILD of whom 5, 6, and 7 had idiopathic interstitial pneumonia (IIP), non-IIP and sarcoidosis, respectively. In addition, six immune-compromised patients with PCP and nine healthy subjects were included as controls. Exclusion criteria were recent bacterial/viral respiratory tract infection, HIV-positivity and subjects receiving antibiotic therapy. Bronchoalveolar lavage fluid and oropharyngeal swabs were simultaneously collected, and microbiota was characterised by ultra-deep 16S rRNA gene sequencing. Results The microbiota in lower airways of the majority of patients (30; 90%) primarily consisted of Prevotellaceae, Streptococcaceae and Acidaminococcaceae. α and β diversity measurements revealed no significant differences in airway microbiota composition between the five different groups of patients. Comparison of bacterial populations in upper and lower respiratory tract showed significant topographical discontinuities for 7 (23%) individuals. Conclusions IIP, non-IIP and sarcoidosis are not associated with disordered airway microbiota and a pathogenic role of commensals in the disease process is therefore unlikely. Nevertheless, molecular analysis of the topographical microbiota continuity along the respiratory tract may provide additional information to assist management of individual patients.

Background Chronic hepatitis B virus (HBV) infection affects up to 7 % of the European population. Specific HBV genotypes are associated with rapid progression to end-stage liver disease and sub-optimal interferon treatment responses. Although the geographic distribution of HBV genotypes differs between regions, it has not been studied in Switzerland, which lies at the crossroads of Europe. Methods In a retrospective analysis of 465 HBV samples collected between 2002 and 2013, we evaluated the HBV genotype distribution and phylogenetic determinants, as well as the prevalence of serological evidence of hepatitis delta, hepatitis C and HIV infections in Switzerland. Baseline characteristics of patients were compared across their region of origin using Fisher’s exact test and ANOVA, and risk factors for HBeAg positivity were assessed using logistic regression. Results The Swiss native population represented 15.7 % of HBV-infected patients living in Switzerland. In the overall population, genotype D was most prevalent (58.3 %), whereas genotype A (58.9 %) was the predominant genotype among the Swiss native population. The prevalence of patients with anti-HDV antibodies was 4.4 %. Patients of Swiss origin were most likely to be HBeAg-positive (38.1 %). HBV genotypes of patients living in Switzerland but sharing the same original region of origin were consistent with their place of birth. Conclusions The molecular epidemiology of HBV infection in Switzerland is driven by migration patterns and not by the genotype distribution of the native population. The prevalence of positive anti-HDV antibodies in our cohort was very low. Electronic supplementary material The online version of this article (doi:10.1186/s12879-015-1234-z) contains supplementary material, which is available to authorized users.

Background: Haemodynamically significant congenital heart disease (CHD) is a risk factor for severe respiratory syncytial virus (RSV) disease in young children. Population based data on the incidence of RSV hospitalisations in CHD patients are needed to estimate the potential usefulness of RSV immunoprophylaxis using palivizumab. Aims: (1) To obtain population based RSV hospitalisation rates in children

During the past decade mumps outbreaks have occurred in several European countries with universal vaccination programs probably due to poor efficacy of the Rubini vaccine strain. However, the evolution of vaccine escape mutants has also been considered. A phylogenetic analysis was undertaken on 69 clinical mumps isolates obtained from 39 vaccinated and 22 non-vaccinated mumps cases (and six cases with unknown vaccination status) during an outbreak in 1998–2000. Two major strain clusters (SWI-H, SWI-C) with two subgroups each (SWI-H1/2, SWI-C1/2) were identified, which belonged to genotypes C and H. No association between viral clusters and vaccination status or a specific vaccine strain (Jeryl-Lynn or Rubini) was found. Cluster SWI-C1 occurred more frequently in the Western part of Switzerland (P

Background: The annual respiratory syncytial virus (RSV) epidemics vary in time and severity. The aims of this study were (1) to describe the time-related pattern of RSV epidemics in Switzerland and (2) to deduce the most effective time period for administration of prophylactic measures to high-risk patients. Patients and Methods: Descriptive study of (1) RSV hospitalizations between 1997 and 2001 at a pediatric hospital serving a population of 1 million and (2) of national RSV detection rates reported by diagnostic laboratories between 1988 and 1999. Results: 497 RSV hospitalizations and 8,574 reported RSV detections occurring during four and 12 epidemics, respectively, were analyzed. There was fixed alternation of minor and major epidemics differing in the number of RSV infections (two to fourfold), evolution (median interval from onset to peak 13 weeks, range 4–13 weeks vs 8 weeks, range 7–10 weeks; p = 0.065) and median duration (26 weeks, range 24-29 weeks vs 19.5 weeks, range 18–21 weeks; p = 0.005). For minor epidemics it was estimated that a maximum of 85.6% (range, 79.4–86.6%) of annual RSV infections could be covered by a standard five-dose regimen of the monoclonal anti-RSV antibody palivizumab, if initiated in week 50. During major epidemics the most effective time of initiation would be week 43 (88.7%; range 81.9–94.6%). Conclusion: RSV epidemiology in Switzerland is characterized by fixed biannual variation. In the absence of active RSV surveillance, such periodicity is useful for scheduling RSV prophylaxis and for hospital resources management.

Advanced neutron detectors for experiments at new spallation sources will require greater counting rate capabilities than previously attainable. This necessitates careful design of both detector and readout electronics. As part of a new instrument for protein crystallography at LANSCE, we are constructing a detector whose concept was described previously (IEEE Trans. Nucl. Sci. NS-46 (1999) 1916). Here, we describe the signal processing circuit, which is well suited for 3He detectors with a continuous interpolating readout. The circuit is based on standard charge preamplification, transmission of this signal over 20 meters or so, followed by sample and hold using a second order gated baseline restorer. This latter unit provides high rate capability without requiring pole-zero and tail cancellation circuits. There is also provision for gain-adjustment. The circuits are produced in surface mounted technology.

Recent results from the Front-End electronics of the Detector of Internally Reflected Cerenkov light (DIRC) for the BaBar experiment at SLAC (Stanford, USA) are presented. It measures to better than 1 ns the arrival time of Cerenkov photoelectrons detected in a 11000 phototubes array and their amplitude spectra. It mainly comprises 64-channel DIRC Front-End Boards (DFB) equipped with eight full-custom analog chips performing zero-cross discrimination with 2 mV threshold and pulse shaping, four full-custom digital time to digital chips (TDC) for timing measurements with 500 ps binning and a readout logic selecting hits in the trigger window, and DIRC Crate Controller cards (DCC) serializing the data collected front up to 16 DFBs onto a 1.2 Gb/s optical link. Extensive test results of the pre-production chips are presented, as well as system tests.

Enteroviruses (EV) are among the most common causes of aseptic meningitis. Standard diagnostic techniques are often too slow and lack sensitivity to be of clinical relevance. EV RNA can be detected within 5 h by a commercially available reverse transcription-PCR (RT-PCR) test kit. Cerebrospinal fluid (CSF) samples from 68 patients presenting with aseptic meningitis during a summer outbreak in Switzerland were examined in parallel with cell culture and commercial RT-PCR. RT-PCR was positive in all 16 CSF specimens positive by cell culture (100%). In addition, 42 of 52 (80%) CSF samples negative by cell culture were PCR positive. In 26 of these 42 (62%) patients, viral culture from other sites (throat swab or stool) was also positive. The CSF virus culture took 3 to 7 days to become positive. Echovirus 30 was the type most often isolated in this outbreak. The sensitivity of CSF RT-PCR based on clinical diagnosis during this aseptic meningitis outbreak in patients with negative bacterial culture results was 85%, i.e., considerably higher than the sensitivity of CSF virus culture (24%). We conclude that this commercial RT-PCR assay allows a positive diagnosis with minimal delay and may thus influence clinical decisions.

An analog chip is designed to receive from a PM, through a 50 Ω coaxial cable, signals rising in 3 ns, falling in 8 ns, and to provide: • digital signals for timing purposes, • multiplixed analog output, proportional to the input, for spectral measurements; there are 8 channels per chip with a common gain adjustment for the preamplifier, and individual control for the offset and threshold setting. The discriminator sensitivity is 2 mV. The dynamic range is from 2 to 100 mV. The noise equivalent at the input is ≈100 μV. The RMS time dispersion is less than 550 ps for 3 mV threshold. The shaping amplifier is of bipolar shape with 80 ns peaking time and 2.5 V mean output voltage. The cross talk between channels is less than 2%.

An 8-channel preamplifier-shaper circuit for use with detectors having a capacitance in the range 20–50 pF has been designed in 1.2 μ CMOS AMS technology. The shaper is designed so that the peaking time can be adjusted, by steps, in the range 200 ns–2 μs by simple digital control. The pole-zero cancellation circuit uses an original method of sensing the preamplifier feedback capacitor discharging current and producing an identical current to discharge the capacitance of the pole-zero cancellation circuit. The series noise resistance r s = 415 Ω has been measured (270 Ω of which is the protection resistor). The input capacitance of the preamplifier is 10 pF + the strays of the test box 10 pF for a total of 20 pF. The input PMOS transistor has a gm of 5 mA/V (from simulation) at 210 μA drain current. The cross-talk between channels is less than 1%.

Novel configurations of current and voltage-sensitive preamplifiers in DMILL technology intended for calorimetry applications are discussed. A broad set of noise characterisation tests, including room temperature, cryogenic operation and radiation effects, is given. It is shown that in cryogenic conditions the noise behaviour is considerably less current dependent than at room temperature.

Background Cytomegalovirus (CMV) infection is associated with significant morbidity and mortality in transplant recipients. Resistance against ganciclovir is increasingly observed. According to current guidelines, direct drug resistance testing is not always performed due to high costs and work effort, even when resistance is suspected. Objectives To develop a more sensitive, easy applicable and cost-effective assay as proof of concept for direct drug resistance testing in CMV surveillance of post-transplant patients. Study design Five consecutive plasma samples from a heart transplant patient with a primary CMV infection were analyzed by quantitative real-time polymerase chain reaction (rtPCR) as a surrogate marker for therapy failure, and by direct drug resistance detection assays such as Sanger sequencing and the novel primer extension (PEX) reaction matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) based method. Results This report demonstrates that PEX reaction followed by MALDI-TOF analysis detects the A594V mutation, encoding ganciclovir resistance, ten days earlier compared to Sanger sequencing and more than 30 days prior to an increase in viral load. Conclusion The greatly increased sensitivity and rapid turnaround-time combined with easy handling and moderate costs indicate that this procedure could make a major contribution to improve transplantation outcomes.

We evaluated four tests for the detection of rubella virus-specific immunoglobulin M antibodies. Primarily, consecutive serum samples were tested by two different assays. Selected panels of sera from patients with proven or likely recent rubella and false-positive and true-negative results in the two primary assays were further tested with two recently developed, fully automated techniques. The four tests were comparable in overall accuracy, but their dynamic ranges may differ considerably. Ways to optimize the predictive values are discussed. We conclude that automated assays may be used without causing significant changes in diagnostic accuracy or distortions in notifications of the incidence of rubella compared with the use of established tools.

A prototype liquid argon preshower detector with a strip granularity of 2.5 mm has been tested at the CERN SPS in front of a liquid argon Accordion calorimeter. For charged tracks a signal-to-noise ratio of 9.4 and a space resolution of 340 μm were measured; the rejection power against overlapping photons produced in the decay of 50 GeV π 0 's is larger than 3; the precision on

The design and first results from double-sided silicon microstrip detectors designed for use in the DELPHI experiment at LEP are presented. The detectors are AC-coupled on both the n- and p-side. A novel readout scheme using a second metal layer has been implemented, allowing the readout of both coordinates on the same edge of the detector. The detectors have been tested in a high energy beam at the CERN SPS. Results on spatial resolution, pulse-height correlation and charge division are presented. The spatial resolution of the n-side has been measured as a function of the beam particle incident angle from 0 to 60°.

Some modification concerning the microplex MX3 128 channels chip (made by Rutherford Group) have been done. The noise is reduced by a factor of 3. The evaluation method and the new geometry are presented. This chip will be used for the DELPHI μ-vertex detector.

Background Polymerase chain reaction (PCR) is a sensitive tool for detection of respiratory picornaviruses. However, the clinical relevance of picornavirus detection by PCR is unclear. Immunofluorescence (IF), widely used to detect other respiratory viruses, has recently been introduced as a promising detection method for respiratory picornaviruses. Objectives To compare the clinical manifestations of respiratory picornavirus infections detected by IF with those of respiratory picornavirus infections detected by xTAG multiplex PCR in hospitalized children. Study design During a 1-year period, nasopharyngeal aspirates (NPA) from all children hospitalized due to an acute respiratory infection were prospectively analyzed by IF. All respiratory picornavirus positive IF samples and 100 IF negative samples were further tested with xTAG multiplex PCR. After exclusion of children with co-morbidities and viral co-infections, monoinfections with respiratory picornaviruses were detected in 108 NPA of 108 otherwise healthy children by IF and/or PCR. We compared group 1 children (IF and PCR positive, n = 84) with group 2 children (IF negative and PCR positive, n = 24) with regard to clinical manifestations of the infection. Results Wheezy bronchitis was diagnosed more often in group 1 than in group 2 (71% vs. 46%, p = 0.028). In contrast, group 2 patients were diagnosed more frequently with pneumonia (17% vs. 6%, p = 0.014) accompanied by higher levels of C-reactive protein (46 mg/l vs. 11 mg/l, p = 0.009). Conclusions Picornavirus detection by IF in children with acute respiratory infection is associated with the clinical presentation of wheezy bronchitis. The finding of a more frequent diagnosis of pneumonia in picornavirus PCR positive but IF negative children warrants further investigation.

Measurements are presented of the cross section ratios Rℓ = σℓ(e+e-→ℓ+ℓ -)/σhh(e+e-→hadrons) for ℓ = e, μ and τ using data taken from a scan around the Z0. The results are Re = (5.09±0.32±0.18)%, Rμ = (4.96±0.35±0.17)% and Rτ,=(4.72±0.38± 0.29)% where, for the ratio Re, the t-channel contribution has been subtracted. These results are consistent with the hypothesis of lepton universality and test this hypothesis at the energy scale s ∼ 8300 GeV2. The absolute cross sections σℓ(e+e-→ℓ +ℓ-) have also been measured. From the cross sections the leptonic partial widths Γe = (83.2±3.0±2.4) MeV, (ΓeΓμ) 1/2=(84.6±3.0±2.4) MeV and (ΓeΓτ) 1/2=(82.6±3.3±3.2) MeV have been extracted. Assuming lepton universality the ratio Γℓ/Γh=(4.89±0.20± 0.12) × 10-2 was obtained, together with Γℓ=(83.6±1.8±2.2) MeV. The number of light neutrino species is determined to be Nv=3.12±0.24±0.25. Al the data are consistent with the predictions of the standard model., 0, SCOPUS: ar.j, info:eu-repo/semantics/published

Rapid detection of enterovirus (EV) infections is essential in the management of aseptic meningitis. Molecular approaches have opened the way to such rapid, but also specific and sensitive, diagnostic tests. The aim of this study was to compare the performance of the CE marked NucliSens EasyQ Enterovirus assay with an in-house two-step RT-PCR assay using cerebrospinal fluid (CSF) and throat swab samples. In addition, specificity was tested with clinical isolates positive for viruses with clinical importance in CSF samples. For nucleic acid extraction, the NucliSens miniMAG and NucliSens magnetic extraction reagents were used. Subsequently real-time nucleic acid sequence-based amplification (NASBA) RNA amplification was performed using NucliSens EasyQ basic kit reagents and NucliSens EasyQ Enterovirus reagents. An EV-specific internal homologous control (IC) RNA was used to monitor the entire NucliSens EasyQ procedure at the individual sample level. No IC but an external inhibition control was available for the RT-PCR method. For the NucliSens EasyQ procedure, amplification and real-time detection reactions were carried out in the NucliSens EasyQ analyzer. The real-time NASBA enterovirus detection was based on NASBA amplification and real-time molecular beacon technology. Data were analyzed using the manufacturer's software on the NucliSens EasyQ analyzer. For the in-house assay, RT-PCR amplicons were detected using agarose gel analysis. The analysis of clinical samples positive for HSV-1, HSV-2, adenovirus, CMV, VZV, mumps and rhinovirus were all negative by NucliSens EasyQ Enterovirus assay. Three rhinovirus samples were, however, strongly positive in RT-PCR. A total of 141 clinical samples were retrospectively tested, including 126 cerebrospinal fluid (CSF) samples and 15 throat swabs. The 91 CSF samples were negative by both methods, 31 CSF samples and 14 throat swab samples were positive by both methods. The four CSF samples were positive by RT-PCR only. One throat swab sample was negative in NucliSens EasyQ but positive in RT-PCR. The sensitivity and specificity of both methods seem to be more or less comparable. However, the in-house RT-PCR assay appears to amplify some rhinovirus strains and should therefore not be used for throat swab samples. NucliSens EasyQ Enterovirus assay gave more invalid results than the in-house RT-PCR, which is obvious taken into account the difference in quality control between the CE marked NucliSens EasyQ Enterovirus assay and the in-house enterovirus assay. The NucliSens EasyQ procedure can be completed within 5h versus 9.5h for the RT-PCR. NucliSens EasyQ Enterovirus assay showed to be a standardized, rapid, specific, sensitive and reliable procedure for the detection of enterovirus RNA.

During the past decade mumps outbreaks have occurred in several European countries with universal vaccination programs probably due to poor efficacy of the Rubini vaccine strain. However, the evolution of vaccine escape mutants has also been considered. A phylogenetic analysis was undertaken on 69 clinical mumps isolates obtained from 39 vaccinated and 22 non-vaccinated mumps cases (and six cases with unknown vaccination status) during an outbreak in 1998-2000. Two major strain clusters (SWI-H, SWI-C) with two subgroups each (SWI-H1/2, SWI-C1/2) were identified, which belonged to genotypes C and H. No association between viral clusters and vaccination status or a specific vaccine strain (Jeryl-Lynn or Rubini) was found. Cluster SWI-C1 occurred more frequently in the Western part of Switzerland (P0.001). Isolates causing complicated disease tended to cluster more frequently with SWI-H1 (P = 0.11). Wild-type strains homologous or similar to the Rubini vaccine strain (isolated in Switzerland in 1974) were no longer circulating. Therefore, there was no evidence for vaccine escape mutants. Strain redistribution may have occurred during the past decades. Continuous monitoring of circulating mumps virus populations is needed.

The TRIPLEX, a 128 channel integrated circuit, intended for use with the DELPHI Si-strip microvertex detector is described. It includes a sensitive differential discriminator per channel for participation in the DELPHI trigger. The discriminators, which compare sampled signals from before and after beam crossing, are servo-stabilized between beam crossings to provide uniform thresholds. The preamplifier noise (90 electrons+8 electrons per pF for a 1.5 microsecond peaking time) is compatible with a trigger threshold of less than 1/4 MIP. The 128 discriminator outputs are connected in wired-OR to the trigger output. An automatic mechanism is included to disconnect noisy channels from the trigger. >

Summary form only given. A research and development program is being conducted in view of realizing an electromagnetic and hadronic calorimeter for the Large Hadron Collider (LHC). The authors report on tests on fast electronics, coupled to an electromagnetic prototype calorimeter built with an accordion structure. Three different types of preamplifiers have been used. In two (Si and GaAs hybrids), the preamplifier is operated in liquid argon. In the third one, a common based (Si JFET or GaAs) transistor is in the liquid, the charge preamplifier being outside the cryostat, after about 6 m of 50- Omega cable. The shaping amplifier uses RC-CR filtering. The response to a short current pulse peaks after about 20 ns. When the system is connected to the calorimeter, the liquid argon signals peak, as expected, after 30 ns. Noise, linearity, and cross-talk between channels were investigated. First results from an exposure of the calorimeter to electrons of energy 30 to 175 GeV were obtained. >

An analog chip is designed to receive from a PM, trough a 50 /spl Omega/ coaxial cable signals rising in 3 ns, falling in 8 ns, and to provide: (i) digital signals for timing purposes, (ii) multiplexed analog output, proportional to the input, for spectral measurements. There are 8 channels per chip with a common gain adjustment for the preamplifier, and individual control for the offset and threshold setting. The discriminator sensitivity is 2 mV. The dynamic range is from 2 mV to 100 mV. The noise equivalent at the input is /spl cong/100 /spl mu/V. The RMS time dispersion is less than 500 ps for 3 mV threshold. The shaping amplifier is of bipolar shape with 80 ns peaking time and 2.5 V mean output voltage. The crosstalk between channels is less than 2%.

(1) To evaluate serum C-reactive protein (CRP) concentrations in children with adenovirus infection, and (2) to compare CRP concentrations in adenovirus and influenza virus infection.Retrospective, comparative single-center study conducted in Emergency Department patients of a paediatric tertiary care center. Comparison of CRP in adenovirus infection and influenza was performed in patient groups stratified according to age and duration of fever.In 87 children with adenovirus infection (median age, 1.5 years; interquartile range, 0.9-3.0), CRP levels of2 mg/L,10 mg/L, and100 mg/L were found in 4 (4%), 12 (13%), and 66 (76%) patients, respectively. Median CRP in the children with adenovirus infection and in 130 children with influenza was 49 mg/L (21-96) and 9 mg/L (3-20), respectively (p = 0.001). A statistically significant difference remained when these 2 patient groups were stratified according to age (/=2 vs.2 years) and duration of fever (/=3 vs.3 days) (p0.001). In adenovirus infection CRP concentrations were unrelated to age, duration of fever and severity of illness, as judged by the extent of mucosal involvement and by the frequency and duration of hospitalisation.Paediatric adenovirus infection is associated with substantially elevated CRP concentrations in the absence of secondary bacterial infection. CRP levels were independent of the duration of illness, indicating that adenoviruses trigger an immediate inflammatory host response resembling invasive bacterial infection.

Palivizumab is approved in Switzerland for prevention of hospitalisation for RSV infection in children with one of the following risk factors: (1) history of prematurityor = 35 weeks and ageor = 6 months or (2) chronic lung disease and ageor = 1 year. Regional data on the expected effectiveness of this monoclonal antibody are not available.(1) Retrospective, descriptive, single-site study on the characteristics of RSV hospitalisations during two consecutive seasons. (2) Extrapolation of data to generate population-based estimates on the impact of palivizumb if used according to the approved indications.Of 242 RSV hospitalisations, 216 (89.3%) and 26 (10.7%) occurred in children without and with risk factors, respectively. Patients without and with risk factors had similar clinical courses with respect to ICU admission rate (11.6 vs. 11.5%) and rate of mechanical ventilation (3.2 vs. 3.8%). Of a total of 28 ICU admissions, 13 (46%) occurred among infants agedor = 1 month without risk factors. Former premature infants were significantly older than patients with longer gestation (median age 7.5 vs. 3.7 months, p = 0.026). Applying the approved age criteria would have excluded 10 of 26 patients (38.5%) from eligibility for palivizumab. During the 1999/2000 RSV season, 36% of hospitalisations occurred after April 1, 2000. None of them may have been preventable had prophylaxis been started before November 1, 1999 and carried out for 5 months as recommended. In an annual birth cohort of 10,000, palivizumab as indicated would be expected to prevent between 5 and 7 RSV hospitalisations.The impact of palivizumab on the prevention of RSV hospitalisations in the Canton of Bern, Switerland, is expected to be small, and the approved indications may not target infants at greatest risk for severe disease.

AIMS: To assess the performance of 2-sucrose-phosphate based transport medium (2-SP) for the detection of Chlamydia trachomatis and Neisseria gonorrhoeae by an automated commercial polymerase chain reaction (PCR) and ligase chain reaction (LCR) compared to centrifugation culture on McCoy cells for C trachomatis. Second, to compare both amplification systems for initial diagnostic testing of a low prevalence population for sexually transmitted diseases. METHODS: Four hundred and eighty one consecutive urogenital and conjunctival specimens were examined. All tests were performed on the same specimen collected with a dacron swab and transported in 2-SP medium. Samples that were positive by culture or by both PCR and LCR were considered to be true positives. RESULTS: The prevalences of C trachomatis and of N gonorrhoeae were 2.7% and 0.4%, respectively. PCR had a resolved sensitivity and specificity of 100% and 99.8%, respectively, for C trachomatis, and 100% and 98.9%, respectively, for N gonorrhoeae. LCR was 100% sensitive and specific for both pathogens. The resolved sensitivity of the shell vial assay was 85%. No culture positive sample would have been missed by PCR or LCR. The inhibition rate for PCR was 4.8%. CONCLUSIONS: 2-SP medium proved to be suitable for both PCR and LCR. It is not limited to any one test manufacturer and allows the performance of amplification techniques and viral and chlamydia culture from the same specimen. The LCR was more reliable than PCR on initial testing. However, hands on time is longer, and no amplification control is available for LCR.

We evaluated immunoglobulin M (IgM) and IgA assays that could improve the predictive value for recently acquired toxoplasma infection for patients with positive screening test results. Follow-up sera were collected from 82 patients whose initial serum specimen had a reactive anti-Toxoplasma gondii IgM result. According to the evolution of the immune response, patients were divided retrospectively into two groups: one in which a recent infection was unlikely and the other one with an evolving immune response suggestive of recent toxoplasma infection. All IgM and one of three IgA assays used in the study are suitable for screening pregnant patients, with a negative predictive value of 100%. The predictive value of positive results is much lower because of the low prevalence of acute toxoplasmosis in pregnant women and the long persistence of IgM after acute infection. In the present study, all except one IgM enzyme immunoassay remained positive well beyond 6 months after the initial sample was tested. The IgM immunofluorescence test had the shortest persistence of positivity in most cases. IgA tests were either too insensitive or remained reactive too long to be useful for screening pregnant patients. Interpreting enzyme immunoassays with modified cutoff values and the combination of two tests could improve the predictive value of positive results to about 80% in terms of recent infection.

A novel geometry liquid argon calorimeter with accordion-shaped electrodes and converter plates has been recently conceived. Such a design allows for a fast readout and for a high granularity over large volumes with minimal dead spaces, properties which are considered essential for operation at the future hadron colliders. The first electromagnetic prototype based on this scheme has been built and tested at the CERN SPS. For a response peaking time of 140 ns an energy resolution of 10%/√ E (GeV) and a space resolution of 4.4 mm/√ E (GeV) with 2.7 cm cell size were achieved for electrons. A few preliminary results from a test with fast readout (response peaking time of less than 40 ns) are also presented.

Testing for specific anti-EBV antibodies is frequently used to obtain serological evidence for acute EBV infection. To date this is predominantly performed by indirect immunofluorescence staining of infected cells or by ELISAs based on the cell culture-derived antigen material. However, these assays are difficult to standardize and the variability of culture systems as well as the complexity of the phase-specific antigens do not support their use for large-scale production. The utilization of recombinant EBV antigens might overcome the aforementioned difficulties and improve the serodiagnosis of EBV infection.

Very fast multiwire proportional chambers of low mass for very high counting rates were developed. The anode signals have an effective duration of 8 ns after pulse shaping and a time jitter of only 4 ns fwhm. This performance was achieved with gas mixtures of CF4 and hydrocarbons at atmospheric pressure in MWPCs with small interelectrode distances. Gas mixtures with high primary specific ionization density and low noise fast signal processing provide full efficiency at gas gains of a few times 104. At these conditions, the chambers can operate at rates of several times 107 s−1 cm−2. Various gas mixtures and chamber geometries were explored and test results are reported.

A relation has been established between the number of effective granules in a superheated superconducting detector and the noise factor of the electronic channel which is expressed in terms of the magnetic flux involved. Consequences for detector design are discussed.

A low noise amplifier system capable of operating at high counting rates with the small signals from silicon telescopes is described. The signal-to-noise ratio degradation resulting from multiple differentiation or baseline restoration is avoided by using a dc coupled system which is periodically reset during the intervals between the accelerator bursts.

We describe a system of cathode read-out multiwire proportional chambers which performs the trigger of a spectrometer installed at the CERN S.P.S. to study high mass dimuon pairs. These chambers, associated with fast ECL circuitry, allow to select particles with high tranverse momentum in less than 110 ns. A further development of the electronics will permit to trigger on high dimuon masses with a response time of the order of 170 ns.

An analysis is presented of the behaviour of the common base configuration current amplifier. Some noise relations are developed taking into account the noise generated in the first and second stage of the amplifier. Simplified expressions for the equivalent noise charge are given in order to be able to determine the noise contribution from various circuit components.

The properties of bipolar transistors as input devices for low noise head-amplifiers for high energy applications of silicon detectors are discussed. Theoretical and experimental investigations have been carried out for three different configurations of head amplifiers. The results show that under the particular constraints of high energy experiments, the bipolar transistor has some features that make it competitive, if not even superior to the so far widely employed junction field-effect transistors. These constraints are the short processing times that have to be used to cope with the very high counting rates and the large detector capacitances of some experiments. It emerges from the analysis that the bipolar transistor appears to be an attractive input device for head amplifiers intended for large acquisition systems associated with silicon detectors.

A low noise, wide bandwidth preamplifier and signal processing filter were developed for high counting rate proportional counters. The filter consists of a seven pole Gaussian integrator with symmetrical weighting function and continuously variable shaping time, τ s , of 8–50 ns (fwhm) preceded by a second order pole zero circuit which cancels the long (1/ t ) tails of the chamber signals. The preamplifier is an optimized common base input design with 2 ns rise time and an equivalent noise input charge /lt 2000 r.m.s. electrons, when connected to a chamber with 10 pF capacitance and at a filtering time, τ s , of 10 ns.

An apparatus which has been used to study the 3 He( γ , π + ) 3 H reaction around the 3-3 resonance is presented. The beam arrangement and the target are described. A magnetic spectrometer, followed by a wire chamber, analysed the momentum of the outgoing pions and defined their emission angle. The tritons emerging from the target are detected in coincidence with the pions by two methods: a telescope of thin plastic scintillators inside the vacuum of the scattering chamber for a triton energy below 40 MeV; or a magnetic spectrometer followed by a series of plastic scintillators for larger energies.

Low-cost linear chain for MWPC cathode strip charge read out is described. Some simple relations for noise calculation of the preamplifier (which is a fast low-noise current amplifier) are given. Due to space restriction on the detector, hybrid technique for the preamplifier realization is adopted. The problems of transmission of linear signals (60 m) using twisted pairs, are discussed. 0.2 % of cross-talk is achieved. Fast differential input line receiver with shortening filter is used in order to compensate the integration of the transmission line. The cross-talk and the noise pick-up are reduced by assuming a good symmetry and using charge sensing ADC for digitalization of the analog signals.

Using a balanced dual-channel polarimeter and fast photodiodes coupled to low-noise charge integrators, we demonstrate precise polarization detection of individual light pulses in the nanosecond time-scale, with a noise very close to the shot noise limit. This result has important implications for various precision measurements such as atomic parity violation, squeezing at short time scales, and possibly parity violation with squeezed light.

Theoretical and experimental investigation has been carried out to determine the best working conditions of single or parallel combinations of field-effect or bipolar transistors in low noise preamplifiers for processing times in the 10 ns range. The effects of diffusion capacitance and base spreading resistance in bipolar transistors have been put into evidence and a way of reducing the noise due to the latter is suggested and experimentally demonstrated.

The dark mutagenicity of 4,5',8-trimethylpsoralen (4,5',8-TMP), 5-methoxypsoralen (5-MOP), 8-methoxypsoralen (8-MOP), 3-carbethoxypsoralen (3-CPs) and two new pyridopsoralens (PyPs and MePyPs) was tested using the Ames Salmonella plating assay in the absence of metabolic activation. 4,5',8-TMP, 8-MOP and the two pyridopsoralens were found to be weak frameshift mutagens in strain TA1537 whereas 5-MOP and 3-CPs did not demonstrate any significant mutagenic activity. These findings support the notion that the genetic risks of these psoralens in the dark may be considered to be negligible.

The central tracking device of the DELPHI experiment is a time projection chamber (TPC) with an active volume of 2*1.34 m in length and 2.22 m in diameter. Since spring 1988 the TPC has undergone extensive tests in a cosmic ray setup. It has been equipped with its final readout electronics for one complete sector ( approximately 2000 channels) and has been operated since with cosmic rays as well as with the laser system and all the other calibration devices. First results indicate that the TPC behaves as expected, but more work and analysis is needed to quote final numbers. It will be installed in the LEP tunnel by early 1989. The authors describe the construction, the readout electronics, and the contribution of the TPC to the Delphi trigger. Emphasis is given to novel features which are not used in similar detectors. >

Transition radiation from a radiator of 650 lithium foils has been studied in a MWPC filled with a xenon-Co 2 mixture for two experimental configurations. With the chamber immediately behind the radiator, particle discriminations comparable to those reported in the literature (90% efficiency for electrons, 10% for hadrons) have been observed. With magnetic bending between the radiator and the xenon chamber typical efficiencies of 87% for electrons and less than 0.4% for hadrons have been measured. The discrimination obtained is at least a factor 20 better than for the more conventional configuration. In the latter case, synchrotron radiation has also been observed.

The influence of input and weight voltage variations, on channel width is examined. To obtain a mathematical expression for the differential linearity, the channel width is treated as a function of L t n - the channel width defined by the weights only. In a second step, L t n is supposed to be variable. To avoid errors due to the nonideal stretcher and transients during weights setting, the method of supplementary tests is examined. This method leads to improvements of very fast successive approximation ADC's.

The considerable influence of the pulse stretcher on the differential linearity of a weighted converter is shown and discussed. Theoretical histograms are derived from the relationship between the channel-width and the stretcher slope. Finally, we describe a circuit which carries out a new sequence of successive comparisons, entirely eliminating the influence of the stretcher on the differential linearity. Experimental spectra obtained through this method confirm the theoretical predictions.

Some practical examples are given for circuits enabling simultaneous conversion of several correlated or noncorrelated parameters with one ADC. The analog memories (stretchers) used as buffers introduce a dispersion due to the nonideal stretcher, when noncorrelated parameters are converted. A method of calculation is given to evaluate the dispersion introduced by the circuit. In the case of an important dispersion a symmetrisation of the data around the correct value is proposed so that the dispersion is reduced by a factor two.