The evolution of the stellar populations in low surface brightness galaxies

We investigate the star formation history and chemical evolution of low surface brightness (LSB) disk galaxies by modelling their observed spectro-photometric and chemical properties using a galactic chemical and photometric evolution model incorporating a detailed metallicity depen dent set of stellar input data. For a large fraction of the LSB galaxies in our sample, observed properties are best explained by models incorporating an exponentially decreasing global star formation rate (SFR) ending at a present-day gas fraction (M_{gas}/(M_{gas}+M_{stars}) = 0.5 for a galaxy age of 14 Gyr. For some galaxies small amplitude star formation bursts are required to explain the contribution of the young (5-50 Myr old) stellar population to the galaxy integrated luminosity. This suggests that star formation has proceeded in a stochastic manner. The presence of an old stellar population in many late-type LSB galaxies suggests that LSB galaxies roughly follow the same evolutionary history as HSB galaxies, except at a much lower rate. In particular, our results imply that LSB galaxies do not form late, nor have a delayed onset of star formation, but simply evolve slowly.Comment: To be published in A&

Keuzes voor de lange termijn

Op vijf beleidsterreinen hebben het CPB en het SCP een toekomstverkenning voor het kabinet gemaakt. Dit artikel geeft de hoofdlijnen van de CPB-bijdrage

A search for Low Surface Brightness galaxies in the near-infrared I. Selection of the sample

A sample of about 3,800 Low Surface Brightness (LSB) galaxies was selected using the all-sky near-infrared (J, H and K_s-band) 2MASS survey. The selected objects have a mean central surface brightness within a 5 arcsec radius around their centre fainter than 18 mag/sq.arcsec in the K_s band, making them the lowest surface brightness galaxies detected by 2MASS. A description is given of the relevant properties of the 2MASS survey and the LSB galaxy selection procedure, as well as of basic photometric properties of the selected objects. The latter properties are compared to those of other samples of galaxies, of both LSBs and `classical' high surface brightness (HSB) objects, which were selected in the optical. The 2MASS LSBs have a (B_T_c)-(K_T) colour which is on average 0.9 mag bluer than that of HSBs from the NGC. The 2MASS sample does not appear to contain a significant population of red objects.Comment: accepted for publication in Astronomy and Astrophysics on 24/2/2003; 62 page

People with Multiple Tattoos and/or Piercings Are Not at Increased Risk for HBV or HCV in The Netherlands

BACKGROUND: Although published results are inconsistent, it has been suggested that tattooing and piercing are risk factors for HBV and HCV infections. To examine whether tattooing and piercing do indeed increase the risk of infection, we conducted a study among people with multiple tattoos and/or piercings in The Netherlands who acquired their tattoos and piercings in The Netherlands and/or abroad. METHODS: Tattoo artists, piercers, and people with multiple tattoos and/or piercings were recruited at tattoo conventions, shops (N = 182), and a biannual survey at our STI-outpatient clinic (N = 252) in Amsterdam. Participants were interviewed and tested for anti-HBc and anti-HCV. Determinants of HBV and HCV infections were analysed using logistic regression analysis. RESULTS: The median number of tattoos and piercings was 5 (IQR 2-10) and 2 (IQR 2-4), respectively. Almost 40% acquired their tattoo of piercing abroad. In total, 18/434 (4.2%, 95%CI: 2.64%-6.46%) participants were anti-HBc positive and 1 was anti-HCV positive (0.2%, 95%CI: 0.01%-1.29%). Being anti-HBc positive was independently associated with older age (OR 1.68, 95%CI: 1.03-2.75 per 10 years older) and being born in an HBV-endemic country (OR 7.39, 95%CI: 2.77-19.7). Tattoo- and/or piercing-related variables, like having a tattoo or piercing in an HBV endemic country, surface percentage tattooed, number of tattoos and piercings etc., were not associated with either HBV or HCV. CONCLUSIONS: We found no evidence for an increased HBV/HCV seroprevalence among persons with multiple tattoos and/or piercings, which might be due to the introduction of hygiene guidelines for tattoo and piercing shops in combination with the low observed prevalence of HBV/HCV in the general population. Tattoos and/or piercings, therefore, should not be considered risk factors for HBV/HCV in the Dutch population. These findings imply the importance of implementation of hygiene guidelines in other countries

Making justice more accessible

From the point of view of the Citizen, Justice is not always readily accessible. Either because it is a lengthy process, potentially expensive, sometimes unclear or simply scary, people will often avoid or withdraw from a judicial process, especially in those cases that involve relatively small amounts. This results in the giving up of a basic right, with the potential loss of rightful benefits. In this paper we briefly analyze the main aspects that impair access to Justice nowadays. We then move on to look at recent technological developments in the field of Online Dispute Resolution to argue that these can, in the near future, have a significant role in improving access to Justice. Specifically, we analyze the UMCourt Conflict Resolution Framework, developed by our research team, and address the different dimensions in which such tools contribute to make Justice more accessible, namely through better access to useful information, support in decision-making or more cost-effective processes.Development Fund through the COMPETE Programme (operational programme for competitiveness) and by National Funds through the FCT - Fundação para a Ciência e a Tecnologia (Portuguese Foundation for Science and Technology) within projects FCOMP-01-0124-FEDER-028980 (PTDC/EEISII/1386/ 2012) and PEst-OE/EEI/UI0752/201

Euro-Collins Solution Versus Uw-Solution for Long-Term Liver Preservation in the Isolated Rat-Liver Perfusion Model

To compare UW-solution (UW) and Euro-Collins (EC) for long-term liver preservation we investigated the morphology and metabolic capacity of rat liver after 18 and 42-hours cold-storage in either UW or EC

Does multidisciplinary videoconferencing between a head-and-neck cancer centre and its partner hospital add value to their patient care and decision-making? A mixed-method evaluation

Objectives Given the difficulties in diagnosing and treating head-and-neck cancer, care is centralised in the Netherlands in eight head-and-neck cancer centres and six satellite regional hospitals as preferred partners. A requirement is that all patients of the partner should be discussed in a multidisciplinary team meeting (MDT) with the head-and-neck centre as part of a Dutch health policy rule. In this mixed-method study, we evaluate the value that the video-conferenced MDT adds to the MDTs in the care pathway, quantitative regarding recommendations given and qualitative in terms of benefits for the teams and the patient. Design A sequential mixed-method study. Setting One oncology centre and its partner in the Northern part of the Netherlands. Participants Head-and-neck cancer specialists presenting patient cases during video-conferenced MDT over a period of 6 months. Semistructured interviews held with six medical specialists, three from the centre and three from the partner. Primary and secondary outcome measures Percentage of cases in which recommendations were given on diagnostic and/or therapeutic plans during video-conferenced MDT. Results In eight of the 336 patient cases presented (2%), specialists offered recommendations to the collaborating team (three given from centre to partner and five from partner to centre). Recommendations mainly consisted of alternative diagnostic modalities or treatment plans for a specific patient. Interviews revealed that specialists perceive added value in discussing complex cases because the other team offered a fresh perspective by hearing the case 'as new'. The teams recognise the importance of keeping their medical viewpoints aligned, but the requirement (that the partner should discuss all patients) was seen as outdated. Conclusions The added value of the video-conferenced MDT is small considering patient care, but the specialists recognised that it is important to keep their medical viewpoints aligned and that their patients benefit from the discussions on complex cases

Cost-effectiveness of vaccination of immunocompetent older adults against herpes zoster in the Netherlands: a comparison between the adjuvanted subunit and live-attenuated vaccines.

BACKGROUND: The newly registered adjuvanted herpes zoster subunit vaccine (HZ/su) has a higher efficacy than the available live-attenuated vaccine (ZVL). National decision-makers soon need to decide whether to introduce HZ/su or to prefer HZ/su above ZVL. METHODS: Using a Markov model with a decision tree, we conducted a cost-effectiveness analysis of vaccination with HZ/su (two doses within 2 months) or zoster vaccine live (ZVL) (single dose, or single dose with a booster after 10 years) for cohorts of 50-, 60-, 70- or 80-year-olds in the Netherlands. The model was parameterized using vaccine efficacy data from randomized clinical trials and up-to-date incidence, costs and health-related quality of life data from national datasets. We used a time horizon of 15 years, and the analysis was conducted from the societal perspective. RESULTS: At a coverage of 50%, vaccination with two doses of HZ/su was estimated to prevent 4335 to 10,896 HZ cases, depending on the cohort age. In comparison, this reduction was estimated at 400-4877 for ZVL and 427-6466 for ZVL with a booster. The maximum vaccine cost per series of HZ/su to remain cost-effective to a willingness-to-pay threshold of €20,000 per quality-adjusted life year (QALY) gained ranged from €109.09 for 70-year-olds to €63.68 for 50-year-olds. The cost-effectiveness of ZVL changed considerably by age, with corresponding maximum vaccine cost per dose ranging from €51.37 for 60-year-olds to €0.73 for 80-year-olds. Adding a ZVL booster after 10 years would require a substantial reduction of the maximum cost per dose to remain cost-effective as compared to ZVL single dose. Sensitivity analyses on the vaccine cost demonstrated that there were scenarios in which vaccination with either HZ/su (two doses), ZVL single dose or ZVL + booster could be the most cost-effective strategy. CONCLUSIONS: A strategy with two doses of HZ/su was superior in reducing the burden of HZ as compared to a single dose or single dose + booster of ZVL. Both vaccines could potentially be cost-effective to a conventional Dutch willingness-to-pay threshold for preventive interventions. However, whether HZ/su or ZVL would be the most cost-effective alternative depends largely on the vaccine cost