Single Harmonic-based Narrowband Magnetic Particle Imaging

Visualization of the in vivo spatial distribution of superparamagnetic iron oxide nanoparticles (SPIONs) is crucial to biomedicine. Magnetic particle imaging (MPI) is one of the most promising approaches for direct measurements of the SPION distribution. In this paper, we systematically investigate a single-harmonic-based narrowband MPI approach. Herein, only the 3rd harmonic at 15 kHz of the SPION signal induced in an excitation magnetic field of 5 kHz is measured via a narrowband detection system for imaging during scanning a field-free-point in a field of view. Experiments on spot and line phantoms are performed to evaluate the spatial distribution by the assessment of the full width at half maximum and modulation transfer function at different excitation magnetic fields from 4 to 10 mT. Experimental results demonstrate that reconstructed images have a spatial resolution of 1.6 and 1.5 mm for a gradient field of 2.2 T/m and 4.4 T/m in x- and z-direction, respectively, at an excitation magnetic field of 4 mT. In terms of line gap, two lines with a gap of 0.5 mm are resolved. With increasing the excitation magnetic field to 10 mT, the spatial resolution gets worse to 2.4 and 2.0 mm in x- and z-direction, respectively. Moreover, the custom-built MPI scanner allows a limit of detection of 53 microgram (Fe)/mL (500 ng Fe weight) using perimag SPIONs. In addition, the excellent performance is demonstrated by imaging experiments on an "emg" logo phantom. We believe that the proposed narrowband MPI approach is a promising approach for SPION imaging

Cross-sectional view of factors associated with back pain

Objective: To examine the factors associated with back pain within a working population. Methods: A cross-sectional survey of employees using a self-administered questionnaire and physical fitness tests. This study assessed 10,321 participants (6,251 male and 4,070 female) of two nationwide companies throughout Switzerland between 1996 and 1998. The participation rate was 41%. Results: Of the participants, 4,945 (48%) suffered mild back pain and 696 (7%) suffered severe back pain. Reported "stress” was associated with back pain of any intensity. Abdominal muscle strength was inversely associated with severe back pain, while physical activity was non-linearly associated with severe back pain. Smoking was directly associated with any intensity of back pain. The variables gender, obesity, strength of the abdominal musculature and frequency of physical activity were insignificant for back pain of any intensity in multivariate analyses. Conclusion: Our results confirm the association of back pain with physical and behavioural factors. The non-linear relationship between physical activity and back pain may need further examination. Performing any kind of sport three to four times a week appears optima

Methods of the National Check Bus Project

Summary: Objectives: Prevention at the worksite is considered increasingly important. This paper describes the methods used in a nationwide prevention campaign performed at a large Swiss bank and a Swiss industrial company. The aim of this project was to encourage general health awareness among company employees. We also aimed to provide the companies with general health analyses of their staff as a basis for future health promotion. Furthermore, new screening methods were evaluated in the field of research. Methods: Participation in the programme was voluntary and free of charge. The programme targeted all 25243 employees of the two companies in all regions of Switzerland. A mobile unit was available on site. The programme included a written health questionnaire and medical examinations (e.g., blood pressure, blood tests, ultrasound of the common carotid artery, osteodensitometry, examinations of the eye, etc). Analysis of individual test results, information brochures, and a telephone information service were also provided. Based on the data of the individuals, the "health status” of the employees of the two companies was analysed. The companies did not have access to the data of the individuals. The programme ran from August 1996 to August 1998. Results: With a total of 10 321 persons taking part in the project, the participation rate was 41%. For the different examinations offered, patterns of participation were identifiable that varied with age, hierarchical status within the concern, body mass index, and number of physical complaints of the employee. Some of the variables showed the same trend for different tests, while others showed opposite trends. Conclusions: Participation in worksite health promotion programmes is dependent on a complex system of individual and structural variables that need to be considered when planning worksite health promotion programmes. Consideration of specific target population characteristics, including motivations and incentives as well as structural constraints is likely to improve participation rates in worksite health promotion programmes among employee

The Magmatic to Hydrothermal Evolution of the Intrusive Mont Saint-Hilaire Complex: Insights into the Late-stage Evolution of Peralkaline Rocks

The Cretaceous Mont Saint-Hilaire complex (Quebec, Canada) comprises three major rock units that were emplaced in the following sequence: (I) gabbros; (II) diorites; (III) diverse partly agpaitic foid syenites. The major element compositions of the rock-forming minerals, age-corrected Nd and oxygen isotope data for mineral separates and trace element data of Fe-Mg silicates from the various lithologies imply a common source for all units. The distribution of the rare earth elements in clinopyroxene from the gabbros indicates an ocean island basalt type composition for the parental magma. Gabbros record temperatures of 1200 to 800°C, variable silica activities between 0·7 and 0·3, and fO2 values between −0·5 and +0·7 (log ΔFMQ, where FMQ is fayalite-magnetite-quartz). The diorites crystallized under uniform aSiO2 (aSiO2 = 0·4-0·5) and more reduced fO2 conditions (log ΔFMQ ~ −1) between ~1100 and ~800°C. Phase equilibria in various foid syenites indicate that silica activities decrease from 0·6-0·3 at ~1000°C to <0·3 at ~550°C. Release of an aqueous fluid during the transition to the hydrothermal stage caused aSiO2 to drop to very low values, which results from reduced SiO2 solubilities in aqueous fluids compared with silicate melts. During the hydrothermal stage, high water activities stabilized zeolite-group minerals. Fluid inclusions record a complex post-magmatic history, which includes trapping of an aqueous fluid that unmixed from the restitic foid syenitic magma. Cogenetic aqueous and carbonic fluid inclusions reflect heterogeneous trapping of coexisting immiscible external fluids in the latest evolutionary stage. The O and C isotope characteristics of fluid-inclusion hosted CO2 and late-stage carbonates imply that the surrounding limestones were the source of the external fluids. The mineral-rich syenitic rocks at Mont Saint-Hilaire evolved as follows: first, alkalis, high field strength and large ion lithophile elements were pre-enriched in the (late) magmatic and subsequent hydrothermal stages; second, percolation of external fluids in equilibrium with the carbonate host-rocks and mixing processes with internal fluids as well as fluid-rock interaction governed dissolution of pre-existing minerals, element transport and precipitation of mineral assemblages determined by locally variable parameters. It is this hydrothermal interplay between internal and external fluids that is responsible for the mineral wealth found at Mont Saint-Hilair

Health technology assessment in Switzerland

OBJECTIVES AND METHODS: To review Switzerland's mixed public and private healthcare system with regard to health technology assessment (HTA). RESULTS: In the past, remarkable work in HTA was done. Accomplishments include the following: (i) Switzerland became an early member of the International Network of Agencies for Health Technology Assessment. (ii) HTA has its legal bases in terms of effectiveness, appropriateness, and efficiency. (iii) The federal law allows the introduction of new technologies for a limited time for evaluation. (iv) A Swiss Network for Health Technology Assessment was established. In 2004, federal HTA activities moved from the Swiss Federal Office "of Social Security" to the one for "Public Health." The Office mainly mandates, manages, and coordinates evaluations attached to its prevention and intervention sections in the fields of AIDS, illegal drugs, and legal drugs. CONCLUSIONS: Because of the absence of a governmental institution assessing and reporting on new health technologies, private and for profit organizations became more important for the decision-making processes. In a regulated market, the implications may be crucial for the public health