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H Schuhmacher

Publications and source records attributed to H Schuhmacher.

At least 19 recordsLinked to original sources
PubMed2006

Evaluation of individual monitoring in mixed neutron/photon fields: mid-term results from the EVIDOS project.

EVIDOS is an EC sponsored project that aims at an evaluation and improvement of radiation protection dosimetry in mixed neutron/photon fields. This is performed through spectrometric and dosimetric investigations during different measurement campaigns in representative workplaces of the nuclear industry. The performance of routine and, in particular, novel personal dosemeters and survey instruments is tested in selected workplace fields. Reference values for the dose equivalent quantities, H(*)(10) and H(p)(10) and the effective dose E, are determined using different spectrometers that provide the energy distribution of the neutron fluence and using newly developed devices that determine the energy and directional distribution of the neutron fluence. The EVIDOS project has passed the mid-term, and three measurement campaigns have been performed. This paper will give an overview and some new results from the third campaign that was held in Mol (Belgium), around the research reactor VENUS and in the MOX producing plant of Belgonucléaire.

Equipment Design↗
PubMed2006

Electronic neutron personal dosemeters: their performance in mixed radiation fields in nuclear power plants.

This work describes spectral distributions of neutrons obtained as function of energy and direction at four workplace fields at the Krümmel reactor in Germany. Values of personal dose equivalent H(p)(10) and effective dose E are determined for different directions of a person's orientation in these fields and readings of personal neutron dosemeters--especially electronic dosemeters--are discussed with respect to H(p)(10) and E.

Dose-Response Relationship, Radiation↗
PubMed2006

[Subdural empyema in children: therapeutic strategy. Five cases].

We report a series of five subdural empyema (SDE) in children and young adults treated in the same neurosurgical department. These five cases were reviewed retrospectively. There were four boys and one girl, aged from three months to 18 years at time of diagnosis (median age: 7 years). SDE following intracranial surgery were excluded from the study. All patients were treated surgically (burr hole evacuation or craniotomy, repeated in some cases), followed by intravenous antibiotic therapy (mean time: 52 days) adapted to the micro-organism. Only the two patients treated by large craniotomy at first had a single surgical procedure. Involved micro-organisms are as follow: Streptococcus intermedius (n=2), Streptococcus pneumoniae (n=1), Escherichia coli (n=1), absence of any identified micro-organism (n=1). The five patients are alive (median follow-up: 22 month) without any sequelae. We advocate an aggressive surgical treatment of SDE in children with a large bone flap to allow the surgeon to remove pus and membranes as much as possible, even in the interhemispheric fissure, followed by intravenous appropriate antibiotherapy and eradication of the source of infection. Even this "aggressive" treatment may sometimes not avoid re-operation. A careful follow-up is mandatory, because of the high risk of recurrence.

Adolescent↗
PubMed2005

[Infectious complications and misuse of high-dose buprenorphine].

BACKGROUND: High-dose buprenorphine (HDB) treatment began in France in 1996 according to relatively unrestricted prescription rules. Continued heroin injection by patients on HDB maintenance treatment and even HDB injection remain underestimated and may lead to a variety of infectious diseases. OBJECTIVES: Description of infectious complications occurring in patients receiving HDB maintenance treatment. METHODS: Retrospective study of drug addicts receiving HDB maintenance treatment, injecting (or highly suspected of injecting) it, and hospitalized for infections (other than HIV or viral hepatitis) in the department of infectious and tropical diseases in Nancy University Hospital. Data collection covered 1998 through 2003. RESULTS: We identified 21 case reports, 9 concerning infectious endocarditis, 8 cutaneous abscesses, 2 osteoarticular infections, 1 meningitis and 1 Candida retinitis. The sex-ratio was of 1 woman for 2 men, and the patients' mean age was 29.8 years. Globally 13 patients had systemic infections. Nine patients admitted having injected HDB (and no other drugs) (including the case of Candida retinitis), while in the other 12 cases, the patients continued injecting heroin as well. The role of misused HDB was strongly suspected in those 12 infections, but was not clearly confirmed. All patients recovered from the infections. The long-term psychosocial outcome remains unknown. CONCLUSION: The cases analyzed illustrate the dual reality that HDB is often ineffective as a maintenance treatment, since some patients continue to inject heroin, and that its misuse can have infectious consequences. The results of HDB maintenance treatment substitution are mixed. The individual benefit/risk ratio must be improved. Networking is crucial, notably between physician and pharmacist, and the monitoring system must be reinforced.

Abscess↗
PubMed2004

Quasi-monoenergetic neutron reference fields in the energy range from thermal to 200 MeV.

Well-characterised neutron fields are a prerequisite for the investigation of neutron detectors. Partly in collaboration with external partners, the PTB neutron metrology group makes available for other users neutron reference fields covering the full energy range from thermal to 200 MeV. The specification of the neutron fluence in these beams is traceable to primary standard cross sections.

Algorithms↗
PubMed2004

Neutron calibration facilities.

Reliable measurement of neutron radiation is a difficult task due to the large energy range of neutrons, their complex and energy-dependent interaction mechanisms with matter and, consequently, the imperfect response characteristics of most instruments. Therefore, Calibration procedures and calibration facilities play an important role. Different types of calibration fields have been developed and made available at several institutions. The primary reference quantity used for the calibration of neutron measuring devices--area monitors, personal dosemeters, spectrometers, etc.--is the neutron fluence. This quantity is determined by appropriate experimental methods whereas dosimetric quantities are derived by applying recommended fluence-to-dose conversion coefficients. This paper summarises the basic principles underlying neutron production, the metrology employed to characterise the radiation fields and the calibration procedures employed. Examples of calibration facilities will be given, which enable routine calibrations, investigations of energy dependence and application-specific calibrations.

Calibration↗
PubMed2004

Individual neutron monitoring in workplaces with mixed neutron/photon radiation.

EVIDOS ('evaluation of individual dosimetry in mixed neutron and photon radiation fields') is an European Commission (EC)-sponsored project that aims at a significant improvement of radiation protection dosimetry in mixed neutron/photon fields via spectrometric and dosimetric investigations in representative workplaces of the nuclear industry. In particular, new spectrometry methods are developed that provide the energy and direction distribution of the neutron fluence from which the reference dosimetric quantities are derived and compared to the readings of dosemeters. The final results of the project will be a comprehensive set of spectrometric and dosimetric data for the workplaces and an analysis of the performance of dosemeters, including novel electronic dosemeters. This paper gives an overview of the project and focuses on the results from measurements performed in calibration fields with broad energy distributions (simulated workplace fields) and on the first results from workplaces in the nuclear industry, inside a boiling water reactor and around a spent fuel transport cask.

Artifacts↗
PubMed2004

High dose vancomycin for osteomyelitis: continuous vs. intermittent infusion.

OBJECTIVES: To compare the efficacy, ease of use and safety of intermittent vancomycin infusion (IVI) and continuous vancomycin infusion (CVI) in high-dose therapy of osteomyelitis. METHODS: Forty-four patients with an osteomyelitis requiring vancomycin for more than 4 weeks were prospectively included, 21 receiving IVI and 23, CVI. The target serum concentration of vancomycin was 20-25 mg/L. Pharmacokinetics, adverse effects, and clinical efficacy were recorded. RESULTS: The mean daily vancomycin dosing was the same in the two groups, but the serum vancomycin concentrations (trough or plateau) were lower in the IVI group than the CVI group (21.7 +/- 9.3 and 26.0 +/- 6.1 mg/L, respectively; P < 0.0001). The target concentrations were achieved quicker with CVI, and daily dosing was changed more frequently in the IVI group. After reaching the target, variability of vancomycin serum concentration (trough or plateau concentrations) was higher in the IVI group than in CVI group (standard deviation 7.9 mg/L vs. 5.6 mg/L, respectively; P = 0.001). CVI did not show clinical superiority, but adverse drug effects were more frequent in the IVI group as compared with the CVI group, 9 (42.9%) and 2 (8.7%), respectively (P = 0.03). Survival multiple regression using Cox's proportional hazard model showed that IVI (RR = 5.9, P = 0.03) and osteomyelitis of the foot (RR = 5.2, P = 0.01) were the only factors associated with adverse drug reactions leading to treatment termination. CONCLUSIONS: CVI is practical and effective, and may be a good alternative for patients requiring prolonged treatment with high vancomycin serum levels.

Anti-Bacterial Agents↗
PubMed2002

Experimental tools for track structure investigations: new approaches for dosimetry and microdosimetry.

In recent years, several new methods have been developed for track structure investigations. They use macroscopic gas volumes to transfer the results to microscopic dimensions and are based on either the cluster counting principle or on optical methods for full track analysis. The first type of method allows cluster size distributions in nanometre dimensions to be measured. The second type reveals the full topology of the ionisation pattern of tracks or track segments within a volume of a few micrometres with a spatial resolution down to 5 nm. The basic principles of these instruments and their main features are summarised and a selection of results obtained to date are shown.

Cluster Analysis↗
PubMed2001

Tolerability of postexposure prophylaxis with zidovudine, lamivudine, and nelfinavir for human immunodeficiency virus infection.

Tolerability of the combination of zidovudine, lamivudine, and nelfinavir used as postexposure prophylaxis (PEP) for HIV infection was prospectively evaluated among 185 patients at 11 hospitals in eastern France. After exclusion of the 106 persons who discontinued PEP either because the source patient subsequently tested HIV seronegative or because the injury was reassessed as resulting in a low risk for transmission of HIV, 67 (85%) of the patients who received such PEP experienced adverse effects, which led to withdrawal of nelfinavir in 28 (35%) of these patients.

Anti-HIV Agents↗
PubMed2001

[Post-traumatic dissection of the abdominal aorta].

Dissections due to deceleration trauma are rarely limited to the infradiaphragmal aorta (only 2-3%) and are usually lethal. Here we report the unusual course of an abdominal aortic dissection with aneurysmatic enlargement of the false lumen. Based on diagnostic imaging, a therapeutic stent application was planned in order to close the entry and to prevent rupture. During the intervention sondation of the false lumen revealed that the left renal artery had a reentry. Due to the complexity of the entry-reentry situation of the left renal artery the intervention was not possible, and the patient had to undergo vascular surgery.

Abdominal Injuries↗
PubMed2001

Development of personal neutron dosemeters at the PTB and first measurements in the space station MIR.

A passive neutron dosemeter with thermoluminescence and etched-track detectors was used in the space station MIR in 1995 and 1997 and during some shuttle flights to MIR. High neutron doses of about 200 microSv d-1 were measured with track detectors, while the contribution of protons to the track density was estimated to be small. An active personal dosemeter based on silicon diodes providing a direct readout, improved sensitivity and spectrometric properties is proposed for additional monitoring. Firstly, measurements with a prototype were performed in the stray radiation fields of the CERN-EU Reference Radiation Facility. When mounted on a phantom at different positions, both the passive and the active dosemeter provide the directional distribution of neutrons via an unfolding procedure. This can be helpful for a better understanding of the complex radiation field in space and for comparisons with calculations.

Calibration↗
PubMed2000

Prospective validation of a diagnosis model as an aid to therapeutic decision-making in acute meningitis.

The aim of this study was to validate a diagnosis model that provides pABM, the probability of bacterial versus viral meningitis, based on four parameters collected at the time of first lumbar tap: cerebrospinal fluid protein level, cerebrospinal fluid polymorphonuclear cell count, blood glucose level, and leucocyte count. The model was evaluated prospectively as an aid to therapeutic decision-making in 109 consecutive patients with acute meningitis and negative cerebrospinal fluid Gram stain. In each case pABM was computed before a therapeutic decision and three diagnoses were established successively: (i) clinical evaluation, i.e. before pABM computation (bacterial meningitis, viral meningitis, or meningitis of undetermined origin); (ii) computation of pABM (viral meningitis if pABM< 0.1, bacterial meningitis otherwise); and (iii) determination of definitive diagnosis (bacterial meningitis: positive cerebrospinal fluid culture; viral meningitis: negative cerebrospinal fluid culture, no other aetiology and no treatment; meningitis of undetermined origin: cases fitting neither of the first two diagnoses). The computed diagnosis was viral meningitis in 78 of the 80 cases diagnosed definitively as viral meningitis, and bacterial meningitis in four of the five cases diagnosed definitively as bacterial meningitis. Negative and positive predictive values and accuracy of the model were 98.7%, 66.7%, and 96.5%, respectively. The clinical diagnosis was undetermined in 22 cases, 15 of which were diagnosed definitively as viral cases; in all of these 15 cases, the computed diagnosis was viral meningitis, leading the physician to refrain from starting antibiotics in all of them. The results confirm that the model evaluated is reliable and aids in the identification of patients in whom antibiotics can be safely avoided.

Acute Disease↗
PubMed1999

[Seroprevalence of Central European tick-borne encephalitis in the Lorraine region].

BACKGROUND: Central European encephalitis, caused by the tick-borne encephalitis virus (TBEV), is exceptional in France. Most cases have been described in Alsace. As 2 cases of tick-borne encephalitis were diagnosed in the Nancy region, a seroepidemiological survey was conducted in the Lorraine region (Meurthe & Moselle, Moselle, Vosges, Meuse) in 1996. METHODS: The survey was proposed to approximately 1,000 persons attending preventive medicine clinics. The subjects were asked to fill out a self-administered questionnaire on factors related to tick bite exposure and underwent TBEV serology tests. RESULTS: 1,777 subjects participated in the survey. Half of them lived in rural areas, 91% had occasional or regular contact with the forest environment and 21% had experienced tick bites. TBEV serology (IgG) was positive in 19 subjects (1.6%; 95% CI: 0.9%-2.3%); 9 sera were positive on Western blot (0.76). No IgM positive serum was found. Seroprevalence was higher in subjects with a past history of tick bites compared with the others (2.9% vs 1.3%, p = 0.074). CONCLUSION: The low seroprevalence of TBEV in this survey is not in favor of widespread tick-bite encephalitis virus in the Lorraine general population.

Encephalitis, Tick-Borne↗
PubMed1999

Nuclear data for radiotherapy: presentation of a new ICRU report and IAEA initiatives.

An ICRU report entitled "Nuclear Data for Neutron and Proton Radiotherapy and for Radiation Protection" is in preparation. The present paper presents an overview of this report, along with examples of some of the results obtained for evaluated nuclear cross sections and kerma coefficients. These cross sections are evaluated using a combination of measured data and the GNASH nuclear model code for elements of importance for biological, dosimetric, beam modification and shielding purposes. In the case of hydrogen both R-matrix and phase-shift scattering theories are used. In the report neutron cross sections and kerma coefficients will be presented up to 150 MeV and proton cross sections up to 250 MeV. An IAEA Consultants' Meeting was also convened to examine the "Status of Nuclear Data needed for Radiation Therapy and Existing Data Development Activities in Member States". Recommendations were made regarding future endeavours.

Models, Theoretical↗