Numerical calculation of simultaneous mass transfer of two gases accompanied by complex reversible reactions

A discretization technique is described, which makes it possible to calculate numerically mass transfer behaviour between two media in which complex chemical reactions occur. To show the stability of the technique it has been applied to the industrially well-known system of simultaneous absorption or desorption of H2S and CO2 to or from an amine solution, accompanied by simultaneously occurring strongly interfering overall chemical reaction(s) of complex, non elementary kinetics. For previously published limit cases of the transfer system considered, i.e. for the single transfer of H2S or CO2 accompanied by reversible chemical reaction, a comparison has been made with analytical and approximate solutions of previous authors. The agreement is very good. In studying simultaneous transfer of H2S and CO2, on which hardly any previous work was available, special attention has been paid to the effects of the reversibility of the reactions involved. It has been shown how, under certain conditions due to reversibility occurring in the transferzone, desorption takes place though absorption would be expected on basis of the driving forces. This revealed that not only enhancement factors larger than unity but also smaller, even negative values are possible

The effects of food habits and socioeconomic status on overweight. Differences between the native Dutch and immigrants in the Netherlands

Overweight is a worldwide growing epidemic. The Netherlands is among the countries with the highest prevalence for overweight, together with the USA, UK, and Germany. This paper investigates differences in overweight between native Dutch and three immigrant groups in the Netherlands, and the effects of food habits and socioeconomic status on overweight. The results show that all immigrant groups have a higher prevalence for overweight than the Dutch, apart from Moroccans. Males are overweight more frequently than females. Takeaway food, eating out, and fresh vegetables decrease BMI, while convenience food, ready-to-eat meals, and delivery food (in some cases) increase BMI. In all groups, BMI increases with age. For Surinamese/Antilleans and Turks BMI increases with children living at home, whereas for native Dutch BMI decreases with children living at home. The national health expenditures due to overweight is 200 million to 4 billion Euro per year, which is 1 to 5 percent of the national health expenditures. The government and health insurance companies should try to prevent overweight and encourage healthy behavior.overweight, ethnicity, food habits, Food Consumption/Nutrition/Food Safety, C20, D12, I12,

The main problems of food allergic consumers concerning food labeling: an ethnographic study

It has been estimated that 58% of children and 12% of the adults in developed countries are affected by food allergy, with symptoms ranging from discomfort to fatality. At present, avoidance of problematic foods is the only effective treatment strategy. As of November 25 th , 2005 food manufacturers in the EU are obliged to list 12 potentially allergic ingredients in food. Although the label is still not always fully understood by the consumer, or they get confused by precautionary labelling practices. This paper aims to gain insights into the information preferences of food allergic consumers regarding existing food labelling and additional information delivery systems. The results of this study will facilitate the development of best practices in information provision regarding food safety in the area of food allergy. In particular the research will elicit preferences for new ICT approaches to information delivery which can be focused on the individual needs of consumers. We argue that improved information supply will contribute to the quality of life of food allergic people.Food allergy, consumers, food labelling, information needs, Consumer/Household Economics, Food Consumption/Nutrition/Food Safety,

The demand for health: differences between the native Dutch and immigrants in the Netherlands

This paper estimates the demand for health by using a health capital model for different population groups (native Dutch, Surinamese/Antillean, Moroccan, and Turkish) in the Netherlands. Also the effect of overweight on health utility is investigated. We found a decrease in the demand for health for age, overweight, and smoking, we found an increase in the demand for health for level of education and marital status. The analyses show a strong effect of gender. Being female in all groups is negatively related to health utility. Turkish and Moroccan ethnicity is negatively related to health status.demand for health, health production, ethnicity, overweight, food habits, Health Economics and Policy, C24, C25, I10, I12,

A superburst from 4U 1254-690

We report the detection with the BeppoSAX Wide Field Cameras of a superburst from 4U 1254-690. The superburst is preceded by a normal type-I X-ray burst, has a decay time that is the longest of all eight superbursts detected so far and a peak luminosity that is the lowest. Like for the other seven superbursts, the origin is a well-known type-I X-ray burster with a persistent luminosity level close to one tenth of the Eddington limit. Based on WFC data of all persistently bright X-ray bursters, the average rate of superbursts is 0.51+/-0.25 per year per persistently bright X-ray burster. Some systems may have higher superburst rates. For all superbursters, we present evidence for a pure helium layer which is burnt in an unstable as well as a stable manner.Comment: Accepted by A&A Letter

GRB060602B = Swift J1749.4-2807: an unusual transiently accreting neutron-star X-ray binary

We present an analysis of the Swift BAT and XRT data of GRB060602B, which is most likely an accreting neutron star in a binary system and not a gamma-ray burst. Our analysis shows that the BAT burst spectrum is consistent with a thermonuclear flash (type-I X-ray burst) from the surface of an accreting neutron star in a binary system. The X-ray binary nature is further confirmed by the report of a detection of a faint point source at the position of the XRT counterpart of the burst in archival XMM-Newton data approximately 6 years before the burst and in more recent XMM-Newton data obtained at the end of September 2006 (nearly 4 months after the burst). Since the source is very likely not a gamma-ray burst, we rename the source Swift J1749.4-2807, based on the Swift/BAT discovery coordinates. Using the BAT data of the type-I X-ray burst we determined that the source is at most at a distance of 6.7+-1.3 kpc. For a transiently accreting X-ray binary its soft X-ray behaviour is atypical: its 2-10 keV X-ray luminosity (as measured using the Swift/XRT data) decreased by nearly 3 orders of magnitude in about 1 day, much faster than what is usually seen for X-ray transients. If the earlier phases of the outburst also evolved this rapidly, then many similar systems might remain undiscovered because the X-rays are difficult to detect and the type-I X-ray bursts might be missed by all sky surveying instruments. This source might be part of a class of very-fast transient low-mass X-ray binary systems of which there may be a significant population in our Galaxy.Comment: Accepted for publication in MNRA

New BeppoSAX-WFC results on superbursts

Presently seven superbursters have been identified representing 10% of the total Galactic X-ray burster population. Four superbursters were discovered with the Wide Field Cameras (WFCs) on BeppoSAX and three with the All-Sky Monitor and Proportional Counter Array on RXTE. We discuss the properties of superbursters as derived from WFC observations. There are two interesting conclusions. First, the average recurrence time of superbursts among X-ray bursters that are more luminous than 10% of the Eddington limit is 1.5 yr per object. Second, superbursters systematically have higher alpha values and shorter ordinary bursts than most bursters that have not exhibited superbursts, indicating a higher level of stable thermonuclear helium burning. Theory predicts hitherto undetected superbursts from the most luminous neutron stars. We investigate the prospects for finding these in GX~17+2.Comment: Submitted in January 2004 for the Proceedings of the meeting 'X-Ray Timing 2003: Rossi and Beyond', eds. P. Kaaret, F. K. Lamb, & J. H. Swank (Melville, NY: American Institute of Physics

X-Ray Spectroscopy of the Low-Mass X-ray Binaries 2S 0918-549 and 4U1543-624: Evidence for Neon-Rich Degenerate Donors

We present high-resolution spectroscopy of the neutron-star/low-mass X-ray binaries 2S 0918-549 and 4U 1543-624 with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory and the Reflection Grating Spectrometer onboard XMM-Newton. Previous low-resolution spectra of both sources showed a broad line-like feature at 0.7 keV that was originally attributed to unresolved line emission. We recently showed that this feature could also be due to excess neutral Ne absorption, and this is confirmed by the new high-resolution Chandra spectra. The Chandra spectra are each well fit by an absorbed power-law + blackbody model with a modified Ne/O number ratio of 0.52+/-0.12 for 2S 0918-549 and 1.5+/-0.3 for 4U 1543-624, compared to the interstellar-medium value of 0.18. The XMM spectrum of 2S 0918-549 is best fit by an absorbed power-law model with a Ne/O number ratio of 0.46+/-0.03, consistent with the Chandra result. On the other hand, the XMM spectrum of 4U 1543-624 is softer and less luminous than the Chandra spectrum and has a best-fit Ne/O number ratio of 0.54+/-0.03. The difference between the measured abundances and the expected interstellar ratio, as well as the variation of the column densities of O and Ne in 4U 1543-624, supports the suggestion that there is absorption local to these binaries. We propose that the variations in the O and Ne column densities of 4U 1543-624 are caused by changes in the ionization structure of the local absorbing material. It is important to understand the effect of ionization on the measured absorption columns before the abundance of the local material can be determined. This work supports our earlier suggestion that 2S 0918-549 and 4U 1543-624 are ultracompact binaries with Ne-rich companions.Comment: 11 pages, 5 figures, major revisions including addition of XMM spectral analysis, accepted for publication in the Astrophysical Journal, vol. 59