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R Zimmermann

Publications and source records attributed to R Zimmermann.

At least 37 records · Page 2Linked to original sources
PubMed2005

On-line analysis of gas-phase composition in the combustion chamber and particle emission characteristics during combustion of wood and waste in a small batch reactor.

The emission of particulate matter and gaseous compounds during combustion of wood and refuse-derived fuel in a small batch reactor is investigated by laser mass-spectrometric on-line measurement techniques for gas-phase analysis and simultaneous registration of physical aerosol properties (number size distribution). The gas-phase composition is addressed by a laser-based mass spectrometric method, namely, vacuum-UV single-photon ionization time-of-flight mass spectrometry (VUV-SPI-TOFMS). Particle-size distributions are measured with a scanning mobility particle sizer. Furthermore, a photoelectric aerosol sensor is applied for detection of particle-bound polycyclic aromatic hydrocarbons. The different phases of wood combustion are distinguishable by both the chemical profiles of gas-phase components (e.g., polycyclic aromatic hydrocarbons, PAH) and the particle-size distribution. Furthermore, short disturbances of the combustion process due to air supply shortages are investigated regarding their effect on particle-size distribution and gas-phase composition, respectively. It is shown that the combustion conditions strongly influence the particle-size distribution as well as on the emission of particle-bound polycyclic aromatic hydrocarbons.

Aerosols↗
PubMed2005

Magnetic resonance imaging of the feto-placentar unit after fetoscopic laser coagulation for twin-to-twin transfusion syndrome.

Twin-to-twin transfusion syndrome (TTTS) is a severe complication in monochorionic twin pregnancies that results from a hemodynamical imbalance of placentar vascular anstomoses that connect the circulation of both fetuses. In TTTS, a poly/oligohydramnios sequence with high fetal morbidity and mortality rates occurs. Fetoscopic laser coagulation of the placentar anastomoses can limit or prevent fetal injury. The purpose of this report is to present and discuss fetal magnetic resonance imaging as a postoperative imaging tool after fetoscopic laser coagulation.

Adult↗
PubMed2005

Hepatitis B virus vaccination of blood donors--what costs may be expected?

Although the risk of transfusion-transmitted hepatitis B virus (TT-HBV) infection is very low, it still exists. Therefore, introduction of further precautions to reduce this risk is discussed at present. However, so far no data are available about the HBV vaccination status among blood donors (BDs). We compared HBV vaccination status of apheresis donors (ADs) of a university based and whole BDs (WBDs) of a Red Cross blood donation service using a standardized questionnaire. On the basis of these data, the estimated costs over 10 years for HBV vaccination were calculated for two different strategies and compared with the costs for HBV nucleic acid amplification technology (NAT) testing. 22.3% of the WBDs and 41.2% of the ADs indicated having received at least one HBV vaccine dose. This difference was related to the different demographic structures of the two BD populations (BDPs). With regard to the primary costs for the blood donation service, HBV vaccination of BDs could be an alternative to HBV NAT testing, especially for BDPs with an already high HBV vaccination rate and a high donation frequency.

Adult↗
PubMed2005

Hyperconcentrated platelets stored in additive solution: aspects on productivity and in vitro quality.

BACKGROUND AND OBJECTIVES: New platelet (PLT) additive solutions (PASs) allow a plasma carryover of < 30% in PLT concentrates. This implicates the need to collect apheresis PLT concentrates at very high PLT concentrations: so-called dry PLTs (DPs). We used the TRIMA, with software version 4 (TRIMA V4), to collect such DPs and investigated the in vitro quality of these PLTs when stored in the new modified PAS-III (PAS-IIIM). MATERIALS AND METHODS: TRIMA V4 was programmed to collect 6.0 x 10(11) PLTs at a concentration of 5000 x 10(3) PLTs/microl. Two DPs were pooled, split into four equal parts and diluted to obtain secondary pools (SPs) consisting of 70% PAS-III/30% plasma, 70% PAS-IIIM/30% plasma, 80% PAS-IIIM/20% plasma or 100% plasma. In vitro testing was performed on days 0, 1, 5 and 7. Collection efficiency (CE), collection rate (CR) and PLT yield were calculated for each donation. RESULTS: Thirty-two runs with TRIMA V4 were performed, collecting 6.58 +/- 0.74 x 10(11) PLTs at a concentration of 4255 +/- 914 x 10(3)/microl in 99 +/- 19.9 min, resulting in a CE of 65.3 +/- 8.2% and a CR of 6.92 +/- 1.6 x 10(9) PLTs/min. On day 0, 34-37% of the PLTs in the units prepared for storage were already activated. PLTs stored in 70% or 80% PAS-IIIM showed superior in vitro quality compared to PLTs stored in PAS-III. CONCLUSIONS: TRIMA V4 is a suitable device for the collection of DPs. Nevertheless, improvements are desirable to further increase the ability to concentrate PLTs at very high levels. The storage of apheresis-derived PLTs in PAS III-M is a very promising approach, even at a plasma carryover of < 30%.

Blood Platelets↗
PubMed2005

[Morbidity of dilatation and evacuation in the second trimester: an analysis].

OBJECTIVE: To compare the rates of complications of dilatation and evacuation (D&E) in the second trimester of pregnancy. STUDY DESIGN: Retrospective analysis of early complications after D&E in the second trimester (group A: 1988-1994) in comparison with D&E in the first trimester (group B: 1997) and with the induction of abortion by extra-amniotic application of prostaglandins in the second trimester of pregnancy (literature). RESULTS: The overall complication rate of D&E was statistically significantly higher in the second than in the first trimester (p < 0.0001). The most frequent complication in both groups was a blood loss > 500 ml (p < 0.009). As with blood loss, there was a statistically significant increase in the incidence of postoperative bleeding (p < 0.001) and fever > 38 degrees C (p = 0.042) with rising gestational age, too. We registered similar rates for incomplete abortion, infection, cervical injury, uterine perforation and thrombosis. CONCLUSION: Second-trimester pregnancy termination with D&E is associated with higher morbidity rates than in the first trimester. Overall, the rates of complications of D&E in our study were acceptable and comparable with the results of previous studies. Compared with the induction of abortion by extra-amniotic prostaglandins, D&E shows lower morbidity rates. In particular, the advantages of D&E are in the early second trimester.

Abortion, Induced↗
PubMed2004

Discrimination of three tobacco types (Burley, Virginia and Oriental) by pyrolysis single-photon ionisation-time-of-flight mass spectrometry and advanced statistical methods.

Pyrolysis single-photon ionisation (SPI)-time-of-flight mass spectrometry (TOFMS) and statistical analysis techniques have been applied to differentiate three major tobacco types, Burley, Virginia and Oriental, by means of the gas phase. SPI is known as a soft ionisation technique that allows fast and comprehensive on-line monitoring of a large variety of aliphatic and aromatic substances without fragmentation of the molecule ions. The tobacco samples were pyrolysed at 800 degrees C in a nitrogen atmosphere. The resulting pyrolysis gas contained signals from more than 70 masses between m/z 5 and 170. Mass spectra obtained were analysed by principal component analysis (PCA) and linear discriminant analysis (LDA) to distinguish between different tobacco types. Prior variable reduction of the data set was carried out by calculation of the Fisher ratios. Results achieved give information about chemical composition and characteristics of the smoke derived from each tobacco type and enable conclusions on plant cultivation to be drawn. Based on LDA, a model for tobacco type recognition of unknown samples was established, which was cross-checked by additional measurements of each tobacco type. Furthermore, first results on the recognition of tobacco mixtures based on principal component regression (PCR) are presented.

Mass Spectrometry↗
PubMed2004

MEG and EEG show different sensitivity to myogenic artifacts.

Simultaneous measurements of EEG, MEG and EMG were performed during randomized blocks with higher and lower muscular stress in comparison to baseline condition. Power spectral density PSD was analyzed separately for five intervals (theta, delta, alpha, beta, gamma). During increased muscular stress, a significant increase could be observed in most bands of EEG while MEG showed no significant changes. Topography of maximum effects for the EEG render cortical generators implausible and point instead to myogenic sources. This was confirmed by correlating changes in EEG with those in EMG. During reduced muscular stress, only gamma activity of the MEG showed significant amplitude reduction. Modeling myogenic activity, its portion could be estimated to be approximately 10 percent in the spontaneous MEG brain signal.

Adult↗
PubMed2004

Dephasing in quantum dots: quadratic coupling to acoustic phonons.

A microscopic theory of optical transitions in quantum dots with a carrier-phonon interaction is developed. Virtual transitions into higher confined states with acoustic phonon assistance add a quadratic phonon coupling to the standard linear one, thus extending the independent boson model. Summing infinitely many diagrams in the cumulant, a numerically exact solution for the interband polarization is found. Its full time dependence and the absorption line shape of the quantum dot are calculated. It is the quadratic interaction which gives rise to a temperature-dependent broadening of the zero-phonon line, calculated here for the first time in a consistent scheme.

Journal Article↗
PubMed2004

Mobile resonance enhanced multiphoton ionisation-time-of-flight mass spectrometer with a novel hybrid laser desorption/molecular beam ion source for rapid detection of aromatic trace compounds from gas phase and solid samples.

A mobile, field applicable resonance enhanced multiphoton ionisation-time-of-flight mass spectrometer (REMPI-TOFMS) for direct-inlet gas-phase analysis as well as for characterisation of solid samples, has been developed. For solid-sample analysis, laser desorption (LD) with IR-laser pulses is used for volatilisation of the neutral analytes from a target in the ion source prior to REMPI-TOFMS analysis. For direct inlet gas-phase analysis, a needle gas inlet is used and the formed molecular beam is REMPI-ionised directly in the ion source. A special ion source was developed, which can be rapidly interchanged between the REMPI-TOFMS and the LD-REMPI-TOFMS modes. The system is equipped with a tuneable optical parametrical oscillator (OPO)-laser system. The analytical properties are characterised for both modes of operations. In both cases, analytical performance is similar to that achieved with instruments specifically designed for either gas-phase or solid-phase characterisation. Results from field measurements of a wood combustion flue gas of a 174 kW bio mass furnace are given. Gas-phase analysis was applied for time-resolved on-line REMPI-TOFMS of the semi-volatile aromatic flue gas constituents. The low-volatile aromatic compounds, which were precipitated with the particulate matter in the filtering unit of the sampling train, were characterised by direct LD-REMPI-TOFMS of the glass fibre filter material. By combining the gas-phase and particulate results a rather comprehensive characterisation of the aromatic species present in the flue gas (i.e. aerosol--gas phase plus particulate matter) was achieved.

Mass Spectrometry↗
PubMed2004

Comprehensive on-line characterization of complex gas mixtures by quasi-simultaneous resonance-enhanced multiphoton ionization, vacuum-UV single-photon ionization, and electron impact ionization in a time-of-flight mass spectrometer: setup and instrument characterization.

This paper reports on a newly developed mobile mass spectrometer for comprehensive on-line analysis of complex gas mixtures such as ambient air or industrial process gases. Three ionization methods, namely, the resonance-enhanced multiphoton ionization (REMPI), vacuum-ultraviolet single-photon ionization (SPI), and electron impact ionization (EI) are implemented in this instrument and can be operated (quasi-) simultaneously. By means of this setup, a wide range of compounds can be analyzed due to the unique ionization selectivitiy and sensitivity profiles provided by the different ionization techniques. The mass spectrometer is designed for field application even under severe conditions. The REMPI technique is suitable for the selective and soft ionization (without fragmentation) of aromatic compounds at trace level (ppbv/pptv). The also soft but less selective SPI technique with 118-nm vacuum-ultraviolet laser pulses is used as a second laser-based ionization method. Mass spectra obtained by this technique show profiles of most organic compounds (aliphatic and aromatic species) and of some low IP inorganic substances (e.g., ammonia, nitrogen oxide) down to ppbv concentrations. In addition to the laser-based ionization techniques, EI ionization can be used for analysis of the bulk components such as water, oxygen, nitrogen, and carbon dioxide as well as for detection of inorganic minor components such as HCN or HCl from combustion flue gases at ppmv concentration levels. Each method yields specific mass spectrometric information of the sample composition. Special techniques have been developed to combine the three ionization methods in a single mass spectrometer and to allow the quasi-parallel application of all three ionization techniques.

Journal Article↗
PubMed2004

Dorsolateral dislocation of the proximal interphalangeal joint: closed reduction and early active motion or static splinting; a retrospective study.

INTRODUCTION: In a follow-up examination 50 patients who had sustained dorsal dislocations of the proximal interphalangeal (PIP) joint, the results of two conservative therapy regimens, either immobilisation or early motion, were investigated. The patients were assigned randomly. The inclusion criteria were: adult patients over the age of 18 with isolated, acute, closed dorsolateral dislocation of the PIP joint. MATERIALS AND METHODS: In group A, 25 patients were treated by closed reduction and immobilisation with a short-arm cast including both interphalangeal joints for 4 weeks. In group B, 25 patients were treated by dorsal block splinting of the PIP joint following reduction. The finger was released in extension with daily active exercise of the PIP joint. RESULTS: In group A, 9 patients showed a normal range of motion, whereas a limitation of extension of 10 deg and more was seen in 16 patients. All PIP joints were clinically stable, and 19 patients were satisfied. Two patients complained of a limitation of extension, 3 of limitation of extension and pain, and 1 of pain and swelling. In group B, only 2 of 25 patients showed a limitation of extension of 10 deg and more, whereas 23 patients showed a normal range of motion. Instability of one collateral ligament was seen in 2 cases. Palmar instability did not occur, and 18 patients were satisfied. One patient complained of instability, pain and lack of extension during hard work, 1 of pain in combination with instability, 2 of pain and 3 of swelling of the joint. CONCLUSION: Early active motion after dorsolateral dislocation of the PIP joint produces significantly superior results regarding the active range of motion and pinch power than static splinting.

Casts, Surgical↗
PubMed2004

[Computer based documentation of ultrasound data].

Usually, hospitals and private doctors are well equipped with computers. However, the documentation of ultrasound data is commonly paper-based. The paper presents a computer-based ultrasound data recording and reporting, using the ultrasound documentation software Digisono.

Cost-Benefit Analysis↗
PubMed2004

Dorsal scapholunate ligament reconstruction using a periosteal flap of the iliac crest.

INTRODUCTION: To report a new technique for scapholunate ligament reconstruction, using a periosteal flap of the iliac crest. MATERIALS AND METHODS: In 12 patients with static SL instability, a periosteal flap was harvested from the anterior portion of the iliac crest. Following repositioning of the carpals, the flap was fixed to the scaphoid and lunate between an incompletely osteotomised scale at the dorsal horn of the scaphoid and lunate. Pin fixation of the scapholunate (SL) and CL interval secured postoperative reduction for 8 weeks. A forearm plaster cast was worn for 12 weeks. RESULTS: Eleven patients, all male, were available for follow-up at an average of 29 months. The interval between trauma and surgery averaged 15 months. The preoperative SL angle measured 77 deg, CL angle was -10 deg, and SL gap amounted to 5.2 mm. At follow-up, SL angle was 59 deg, CL angle measured -2 deg, and SL gap was 2.1 mm. SL gap, SL angle, and CL angle improved significantly from preoperative to follow-up values. According to the clinical grading system of Green and O'Brian, 6 patients scored in the excellent and good category and 5 in the fair category. Using the radiologic grading system of Gickel and Millender, 9 patients scored as excellent and good, whereas the 2 poor results were due to failure of the technique. CONCLUSION: The technique enables reduction of the SL angle and SL gap in patients with static reducible scapholunate instability. The initial results are quite encouraging.

Bone Transplantation↗
PubMed2004

De novo bone formation using bovine collagen and platelet-rich plasma.

In order to regenerate critical-size bone defects, a variety of bone substitutes is used in addition to autogenous bone. The regenerative capacity of these bone substitutes is usually compared to the efficacy of autogenous bone known as the "golden standard". Different cytokines influence the regeneration process because of their morphogenic or mitogenic properties. Platelet-rich plasma (PRP), a platelet concentrate, is characterised by having a positive effect on wound healing, reducing bone graft resorption and increasing the density of bone transplants. This experiment was commenced with a view to studying the osseous defect regeneration after placing various combinations of "filler materials" in experimentally created defects in the forehead of adult pigs. Regeneration by means of grafted autogenous bone (Group 1) or a bovine collagen based medical device (Group 4) alone and combined with PRP in two concentrations (Groups 2, 3, 5 and 6) was evaluated by means of microradiography and light microscopy after 2, 4 and 12 weeks. The microradiographic and light microscopic findings showed that autogenous bone in combination with PRP (Groups 2 and 3) had a significant accelerating effect on early bone regeneration (2 weeks). This effect was not evident when PRP was added to the bovine collagen (Groups 5 and 6). When using the collagen alone, significantly higher mineralisation values were achieved after 2 and 4 weeks than when using autogenous bone alone. After a 12-week observation period, the existing differences between the healing processes in the various groups were more or less levelled out. In summary, the results of the study indicate that clinically autogenous bone, as expected, is the ideal defect filler. Combining autogenous bone with PRP did not provide significantly better results. The findings in the groups treated with bovine collagen indicate that its local application mimics the effect of autogenous bone and amplifies bone regeneration when comparing with the control defect.

Animals↗
PubMed2004

Treatment with campath-1H for relapsed chronic lymphocytic leukemia after allogeneic peripheral blood stem cell transplantation does not abrogate the development of chronic GVHD.

The graft vs. leukemia (GVL) effect is one of the most important factors of anti-tumor activity after allogeneic hematopoetic stem cell transplants (alloSCT). Its effectiveness depends mainly on the tumor biology as well as the tumor burden. Patients with a high tumor burden may not respond to GVL-effect despite otherwise sensitive biology. Campath-1H is known as an effective treatment of chronic lymphocytic leukemia (CLL). Due to its ability to induce profound immunosuppression, it has also been used as part of conditioning regimens before alloSCT. We report a patient, who received campath-1H in combination with docetaxel for treatment of chemotherapy and donor lymphocyte infusion resistant CLL after alloSCT, who developed shortly after discontinuation of treatment with campath-1H severe eosinophilia of the peripheral blood and typical clinical as well as histological signs of cutaneous chronic graft vs. host disease followed by complete clearance of CLL. The clinical course demonstrates the impact of the tumor burden on the GVL-effect, as well as the effectiveness of campath-1H in the presence chemo-resistance in a patient with CLL. Furthermore, the GVL effect was not abrogated by the use of campath-1H.

Alemtuzumab↗
PubMed2004

[Quality of routine ultrasound in twin pregnancy in a Swiss Canton].

AIMS: Optimal prenatal management of twin pregnancies requires diligent sonographical evaluation. In Switzerland the efficiency of routine ultrasound during pregnancy has recently become a point of debate. Aim of this study was to evaluate the quality of routine ultrasound of twin pregnancies in Kanton Aargau. METHOD: Standardised prospective postal interview of each practitioner caring for twin pregnancies during the time period of August 1st, 1998 to July 30th, 1999 in Kanton of Aargau. We chose the Aargau Kanton as being representative of the Swiss population in general on the basis of its average demographic and geographical condition. In addition, evaluating an entire Kanton allows the comparison of data with the official data of the Federal Statistical Office. RESULTS: 81 twin pregnancy cases were delivered during this time period. 65 interviews could be analysed which provided full information. The first sonographic diagnosis of twin pregnancy was confirmed at a mean of 11 (5 - 32) weeks gestation. All twin pregnancies were diagnosed before the onset of labour. 2/65 of the twin pregnancies remained undiagnosed until the 3rd trimester. In one of these cases the patient had refused an ultrasound examination. In 57/65 cases clear information about amnionicity, but in only 53/65 cases additional information about chorionicity was gained. CONCLUSION: All twin pregnancies were detected sonographically before delivery. Determinations of amnionicity and chorionicity were possible in 87 % and 81 %, respectively, which could be improved.

Female↗
PubMed2004

[False diagnosis in prenatal sonography - analysis of causes and formulation of conclusions for the quality management of prenatal sonographic diagnostics].

AIM: Aim of this study, carried out in a single third level gynaecological centre, was a detailed analysis of all cases with foetal anomalies not detected prior to 24th gestational week. Based on our results, we wanted to work out recommendations towards improving quality in prenatal ultrasound in Switzerland. METHODS: Retrospective survey (by means of our clinical database and a questionnaire) including all foetuses and neonates with morphological or functional anomalies which had been scanned in the Prenatal Ultrasound Unit of the University Hospital of Zurich in the year 2001. RESULTS: 50,8 % of the 185 cases were detected prior to 24 weeks, 36,2 % in the third trimester and 13 % after delivery. 26,0 % were classified as "missed, although detectable prior to 24 weeks" (group A) and 23,2 % of the cases as "not detectable prior to 24 weeks" (group B). A great majority of the missed cases were cardiac malformations and skeletal anomalies. As primary causes for the missed cases doctors mentioned unfavourable position, oligohydramnios and multiple pregnancies. Scanning at gestational stages not recommended in the screening time-table as well as not following a checklist was responsible for 20 % of all missed diagnoses, whereas ultrasound equipment was not a major problem. CONCLUSIONS: The current 11-14 weeks' and 20-23 weeks' scan in Switzerland allows, at best, a 75-80 % detection rate of congenital anomalies prior to 24 weeks. Some 20 - 25 % of abnormalities appear as late as the last trimester, the majority being urogenital malformations. Roughly one third of early detectable malformations are currently missed, heart defects and skeletal anomalies being the leading causes. The detection rate could be improved by strictly following the Swiss guidelines.

Bone and Bones↗