A Search for Near-Infrared Emission From the Halo of NGC 5907 at Radii of 10 kpc to 30 kpc

We present a search for near-infrared (3.5-5 micron) emission from baryonic dark matter in the form of low-mass stars and/or brown dwarfs in the halo of the nearby edge-on spiral galaxy NGC 5907. The observations were made using a 256 by 256 InSb array with a pixel scale of 17" at the focus of a liquid-helium-cooled telescope carried above the Earth's atmosphere by a sounding rocket. In contrast to previous experiments which have detected a halo around NGC 5907 in the V, R, I, J and K bands at galactic radii 6kpc < r < 10kpc, our search finds no evidence for emission from a halo at 10kpc < r < 30kpc. Assuming a halo mass density scaling as r^(-2), which is consistent with the flat rotation curves that are observed out to radii of 32kpc, the lower limit of the mass-to-light ratio at 3.5-5 microns for the halo of NGC 5907 is 250 (2 sigma) in solar units. This is comparable to the lower limit we have found previously for NGC 4565 (Uemizu et al. 1998). Based on recent models, our non-detection implies that hydrogen- burning stars contribute < 15% of the mass of the dark halo of NGC 5907. Our results are consistent with the previous detection of extended emission at r < 10kpc if the latter is caused by a stellar population that has been ejected from the disk because of tidal interactions. We conclude that the dark halo of NGC 5907, which is evident from rotation curves that extend far beyond 10kpc, is not comprised of hydrogen burning stars.Comment: 12 pages, LateX, plus 6 ps figures. Accepted by ApJ. minor changes, added references, corrected typo

HR managers views and practices in SME's regarding return to work of sick listed employees

Background Little is known about the return to work (RTW) policies implemented in small and medium size enterprises (SME) which have limited resources to define and apply such policies. This study aimed at assessing the existing return to work practices in SME’s and exploring their view regarding the help they could receive from their occupational health service. Methods HR managers of 46 SME’s (23 in Flanders, 23 in Wallonia) employing 100 to 200 employees were contacted for an interview. The manager was asked to fill in a written questionnaire and to comment his/her answers in an open discussion with the researcher. The questionnaire involved three parts: 1°) describing existing rules or procedures when returning to work after sick leave, 2) assessing the manager knowledge of the RTW legal regulations within the occupational health care system, 3) assessing the occupational health physician (OP) involvement in RTW and the enterprise expectations for the future. Results Participation to the survey was accepted in 38 SME’s. In slightly more than half of them a sick leave related policy has been defined. While almost all SME’s have a well-defined procedure for the RTW examination by the OP, only 22 (out of 38) have defined procedures for maintaining a contact with the worker during the sick leave period, only 17 are informing their employees about the possibility to meet the OP during that period, and only 6 are systematically organising a worker-supervisor meeting when the worker comes back at work. Knowledge about RTW regulations is rather poor: 10 managers wrongly think that the OP may check the sick leave medical validity; only 14 managers know that the employer must inform the OP about any sick leave longer than 4 weeks; less than half of the managers have a good knowledge of the pre-return to work visit. Various expectations have been put forward as regard the role of the OH service: knowledge transfer about the regulations, coaching of the supervisors, training managers in carrying RTW talks with the worker, suggesting procedures, etc. Conclusions The lack of knowledge about RTW regulations underlines the need for information campaigns focused on the employers. The participating RH managers are awaiting a more proactive role from their OH service

Metabolic engineering and dynamic modelling of E. coli for the production of chemicals from renewable resources

Industrial biotechnology uses biological systems for the production of useful chemical substances. This technology has developed into a main contributor to the so-called green or sustainable chemistry, in which renewable resources such as sugars or vegetable oils are converted by micro-organisms into a wide variety of chemical substances. One of the key technologies for industrial biotechnology is metabolic engineering. By this technique, micro-organisms can be improved to produce metabolites with a better yield. By extending their metabolism with novel synthetic pathways, they can even be programmed to produce new metabolites that these organisms do not naturally synthesize. In light of these trends the MEMORE project was founded, to create novel insights in industrial biotechnology and more specifically in the field of metabolic engineering. This project is a multidisciplinary project involving 4 laboratories from Belgium and The Netherlands. About 20 researchers with expertise spanning from genetics over microbial physiology to metabolic modelling and analytics collaborate in this project to develop a dynamic metabolic model of the central metabolism of micro-organisms. With this approach it aims to replace the more commonly used ‘trial and error’ approach for optimization of industrial production processes with the more rational metabolic modelling approach. The constructed dynamic metabolic model simulates “in-silico” envisaged pathway modifications or pathway extensions and predicts its effects. The use of this model allows also for a better understanding of the metabolic flux in micro-organisms and the optimisation of fermentation conditions, particularly of fed batch fermentations. After having developed the methodology and the metabolic model of the central metabolism of E. coli, this will be put to the test by designing an E. coli strain that overproduces succinate