Onderzoek naar de ammoniak- en geuremissie van stallen LI : beddenstal voor gespeende biggen = Adapted house for weaned piglets

Ammonia emission from animal husbandry has to be reduced in the Netherlands by 70% in the year 2005, compared with the emission level in 1980. Moreover, recently adapted odour legislation requires measurements of the odour emissions of the main conventional and new housing systems. Research was carried out into the emission of ammonia and odour from a house for weaned piglets with boxes. The research was carried out during a spring and summer period

Forecasting the Varibility of Stock Index Returns with Stochastic Volatility Models and Implied Volatility

In this paper we compare the predictive abilility of Stochastic Volatility (SV) models to that of volatility forecasts implied by option prices. We develop an SV model with implied volatility as an exogeneous variable in the variance equation which facilitates the use of statistical tests for nested models# we refer to this model as the SVX model. The SVX model is then extended to a volatility model with persistence adjustment term and this we call the SVX+ model. This class of SV models can be estimated by quasi maximum likelihood methods but the main emphasis will be on methods for exact maximum likelihood using Monte Carlo importance sampling methods. The performance of the models is evaluated, both within sample and out-of-sample, for daily returns on the Standard & Poor's 100 index. Similar studies have been undertaken with GARCH models where findings were initially mixed but recent research has indicated that implied volatility provides superior forecasts. We find that implied volati..

Fijnstofemissie uit stallen: vleesvarkens = Dust emission from animal houses: growing and finishing pigs

In this study emissions of fine dust (PM10 and PM2.5) from houses for growing-finishing pigs were determined. In addition, emissions of ammonia, greenhouse gases and odour were determined

U-drawing of Fortiform 1050 third generation steels. Numerical and experimental results

Elasto–plastic behavior of the third generation Fortiform 1050 steel has been analysed using cyclic tension–compression tests. At the same time, the pseudo elastic modulus evolution with plastic strain was analysed using cyclic loading and unloading tests. From the experiments, it was found that the cyclic behavior of the steel is strongly kinematic and elastic modulus decrease with plastic strain is relevant for numerical modelling. In order to numerically analyse a U-Drawing process, strip drawing tests have been carried out at different contact pressures and Filzek model has been used to fit the experimental data and implement a pressure dependent friction law in Autoform software. Finally, numerical predictions of springback have been compared with the experimentally ones obtained using a sensorized UDrawing tooling. Different material and contact models have been examined and most influencing parameters have been identified to model the forming of these new steels

Identification of regeneration-associated genes after central and peripheral nerve injury in the adult rat

Background: It is well known that neurons of the peripheral nervous system have the capacity to regenerate a severed axon leading to functional recovery, whereas neurons of the central nervous system do not regenerate successfully after injury. The underlying molecular programs initiated by axotomized peripheral and central nervous system neurons are not yet fully understood.Results: To gain insight into the molecular mechanisms underlying the process of regeneration in the nervous system, differential display polymerase chain reaction has been used to identify differentially expressed genes following axotomy of peripheral and central nerve fibers. For this purpose, axotomy induced changes of regenerating facial nucleus neurons, and non-regenerating red nucleus and Clarke's nucleus neurons have been analyzed in an intra-animal side-to-side comparison. One hundred and thirty five gene fragments have been isolated, of which 69 correspond to known genes encoding for a number of different functional classes of proteins such as transcription factors, signaling molecules, homeobox-genes, receptors and proteins involved in metabolism. Sixty gene fragments correspond to genomic mouse sequences without known function. In situ-hybridization has been used to confirm differential expression and to analyze the cellular localization of these gene fragments. Twenty one genes (similar to 15%) have been demonstrated to be differentially expressed.Conclusions: The detailed analysis of differentially expressed genes in different lesion paradigms provides new insights into the molecular mechanisms underlying the process of regeneration and may lead to the identification of genes which play key roles in functional repair of central nervous tissues

Strip tracking measurement and control in hot strip rolling

It is well known that poor strip tracking can lead to reducedproduct quality but also to mill delays. The resultingcosts for internal rejects, customer complaints and yieldlosses have historically been significant. Moreover, the severityof these issues increases dramatically when stripsbecome wider, thinner and harder. Ultimately the rollingprocess becomes completely unstable. Hence, to reducecost of poor quality for the current product mix as well asto enable product development it is vital that strip trackingis improved.Most strip tracking issues arise at the head or the tail ofthe strip. In the rougher mill the main issue is head camber,a shape defect of the bar where the head is curved. Aclear example of this shape is shown in Fig 1. Large headcamber of the transfer bar may result in further problemsdownstream in the finishing mill and should ideally thus beprevented.Another notorious problem closely related to strip trackingis tail pinching in the finishing mill. This is a phenomenonwhere the tail of the strip suddenly moves sideward’s andgets damaged right after it has left the previous stand. AnPoor strip tracking is one of the notorious problems threatening process stability in a hot strip mill. Theseissues often lead to tail pinching and in the worst cases even to cobbles. The main pillars of the strategy setout to tackle these issues for the Hot Strip Mills in IJmuiden are rougher mill camber control and finishing millstrip steering and tail control. For such applications, a camera based measurement system has been developedin-house that is simple, cost-effective and yet both accurate and robust. Moreover, as we show in this paper,the system has proven its merits both as a finishing mill interstand centerline deviation measurement aswell as a rougher mill camber measurement. In the latter application the measurement data can be used forautomatic levelling in the rougher mill. The results of production tests presented in this paper demonstrate thatthe camber measurement in combination with a basic rougher mill tilt set-up model is sufficient to reduce thetransfer bar camber significantly

Preferences for colorectal cancer screening strategies: a discrete choice experiment

Background:Guidelines underline the role of individual preferences in the selection of a screening test, as insufficient evidence is available to recommend one screening test over another. We conducted a study to determine the preferences of individuals and to predict uptake for colorectal cancer (CRC) screening programmes using various screening tests. Methods:A discrete choice experiment (DCE) questionnaire was distributed among naive subjects, yet to be screened, and previously screened subjects, aged 50-75 years. Subjects were asked to choose between scenarios on the basis of faecal occult blood test (FOBT), flexible sigmoidoscopy (FS), total colonoscopy (TC) with various test-specific screening intervals and mortality reductions, and no screening (opt-out). Results:In total, 489 out of 1498 (33%) screening-naïve subjects (52% male; mean age±s.d. 61±7 years) and 545 out of 769 (71%) previously screened subjects (52% male; mean age±s.d. 61±6 years) returned the questionnaire. The type of screening test, screening interval, and risk reduction of CRC-related mortality influenced subjects' preferences (all P<0.05). Screening-naive and previously screened subjects equally preferred 5-yearly FS and 10-yearly TC (P=0.24; P=0.11), but favoured both strategies to annual FOBT screening (all P-values <0.001) if, based on the literature, realistic risk reduction of CRC-related mortality was applied. Screening-naive and previously screened subjects were willing to undergo a 10-yearly TC instead of a 5-yearly FS to obtain an additional risk reduction of CRC-related mortality of 45% (P<0.001). Conclusion:These data provide insight into the extent by which interval and risk reduction of CRC-related mortality affect preferences for CRC screening tests. Assuming realistic test characteristics, subjects in the target population preferred endoscopic screening over FOBT screening, partly, due to the more favourable risk reduction of CRC-related mortality by endoscopy screening. Increasing the knowledge of potential screenees regarding risk reduction by different screening strategies is, therefore, warranted to prevent unrealistic expectations and to optimise informed choice.British Journal of Cancer advance online publication, 2 March 2010; doi:10.1038/sj.bjc.6605566 www.bjcancer.com