MINAS: een verfijnd systeem?

Op de Praktijkcentra voor de varkenshouderij Sterksel, Raalte en Rosmalen zijn de MINAS-boekhoudingen geanalyseerd op de effecten van verschillen in de voorraden voer en mest, en van afwijkingen in de bepalingen van het mineralengehalte in aangevoerd voer en afgevoerde mest. Door voorraadeffecten en onnauwkeurigheden in de bepalingen van de aan- en afvoer van mineralen is het mogelijk dat een varkenshouder heffing moet betalen, terwijl mest en dieren zijn afgevoerd volgens de regels. Om de spreiding in de MINAS-aangifte voor fosfaat en stikstof en de mogelijke heffing te bepalen werd een statistische analyse uitgevoerd voor een bedrijf met 237 zeugen en een bedrijf met 2000 vleesvarken

Chemical tools to probe the proteasome

UBL - phd migration 201

Testing Convolutional Neural Networks for finding strong gravitational lenses in KiDS

Convolutional Neural Networks (ConvNets) are one of the most promising methods for identifying strong gravitational lens candidates in survey data. We present two ConvNet lens-finders which we have trained with a dataset composed of real galaxies from the Kilo Degree Survey (KiDS) and simulated lensed sources. One ConvNet is trained with single \textit{r}-band galaxy images, hence basing the classification mostly on the morphology. While the other ConvNet is trained on \textit{g-r-i} composite images, relying mostly on colours and morphology. We have tested the ConvNet lens-finders on a sample of 21789 Luminous Red Galaxies (LRGs) selected from KiDS and we have analyzed and compared the results with our previous ConvNet lens-finder on the same sample. The new lens-finders achieve a higher accuracy and completeness in identifying gravitational lens candidates, especially the single-band ConvNet. Our analysis indicates that this is mainly due to improved simulations of the lensed sources. In particular, the single-band ConvNet can select a sample of lens candidates with $\sim40\%$ purity, retrieving 3 out of 4 of the confirmed gravitational lenses in the LRG sample. With this particular setup and limited human intervention, it will be possible to retrieve, in future surveys such as Euclid, a sample of lenses exceeding in size the total number of currently known gravitational lenses.Comment: 16 pages, 10 figures. Accepted for publication in MNRA

HST/ACS observations of shell galaxies: inner shells, shell colours and dust

AIM:Learn more about the origin of shells and dust in early type galaxies. METHOD: V-I colours of shells and underlying galaxies are derived, using HST Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in wedges and subtracted to determine shell profiles and colours. We applied Voronoi binning to our data to get smoothed colour maps of the galaxies. Comparison with N-body simulations from the literature gives more insight to the origin of the shell features. Shell positions and dust characteristics are inferred from model galaxy subtracted images. RESULT: The ACS images reveal shells well within the effective radius in some galaxies (at 1.7 kpc in the case of NGC 5982). In some cases, strong nuclear dust patches prevent detection of inner shells. Most shells have colours which are similar to the underlying galaxy. Some inner shells are redder than the galaxy. All six shell galaxies show out of dynamical equilibrium dust features, like lanes or patches, in their central regions. Our detection rate for dust in the shell ellipticals is greater than that found from HST archive data for a sample of normal early-type galaxies, at the 95% confidence level. CONCLUSIONS: The merger model describes better the shell distributions and morphologies than the interaction model. Red shell colours are most likely due to the presence of dust and/or older stellar populations. The high prevalence and out of dynamical equilibrium morphologies of the central dust features point towards external influences being responsible for visible dust features in early type shell galaxies. Inner shells are able to manifest themselves in relatively old shell systems.Comment: accepted by A&A; 36 Figures, 25 pages. A version with full resolution Figures can be found here: http://www.astro.rug.nl/~sikkema/shells.p

The counterrotating core and the black hole mass of IC1459

The E3 giant elliptical galaxy IC1459 is the prototypical galaxy with a fast counterrotating stellar core. We obtained one HST/STIS long-slit spectrum along the major axis of this galaxy and CTIO spectra along five position angles. We present self-consistent three-integral axisymmetric models of the stellar kinematics, obtained with Schwarzschild's numerical orbit superposition method. We study the dynamics of the kinematically decoupled core (KDC) in IC1459 and we find it consists of stars that are well-separated from the rest of the galaxy in phase space. The stars in the KDC counterrotate in a disk on orbits that are close to circular. We estimate that the KDC mass is ~0.5% of the total galaxy mass or ~3*10^9 Msun. We estimate the central black hole mass M_BH of IC1459 independently from both its stellar and its gaseous kinematics. Some complications probably explain why we find rather discrepant BH masses with the different methods. The stellar kinematics suggest that M_BH = (2.6 +/- 1.1)*10^9 Msun (3 sigma error). The gas kinematics suggests that M_BH ~ 3.5*10^8 Msun if the gas is assumed to rotate at the circular velocity in a thin disk. If the observed velocity dispersion of the gas is assumed to be gravitational, then M_BH could be as high as ~1.0*10^9 Msun. These different estimates bracket the value M_BH = (1.1 +/- 0.3)*10^9 Msun predicted by the M_BH-sigma relation. It will be an important goal for future studies to assess the reliability of black hole mass determinations with either technique. This is essential if one wants to interpret the correlation between the BH mass and other global galaxy parameters (e.g. velocity dispersion) and in particular the scatter in these correlations (believed to be only ~0.3 dex). [Abridged]Comment: 51 pages, LaTeX with 19 PostScript figures. Revised version, with three new figures and data tables. To appear in The Astrophysical Journal, 578, 2002 October 2

Mestverwerking varkenshouderij OrgAgro, Bouwmans te Bakel

In het kader van het onderzoeksprogramma van het Praktijkonderzoek Veehouderij 'Toepassingsmogelijkheden mestbewerking op varkenshouderijbedrijven' is onderzoek uitgevoerd aan het OrgAgro Mestverwerkingsysteem, ontwikkeld door De Heus Brokking KoudijsB.V. te Ede in samenwerking met LVN Bio Producten te Maasbracht. Met dit systeem kan varkensdrijfmest batchgewijs (duur 3-5 weken) worden omgezet in een vloeibare meststof (OrgAgro), geschikt voor toepassing in substraatteelt van glasgroente en sierteelt

Goedkope ammoniak- en geurarme systemen

Het onderzoek naar ammoniakemissie is ongeveer acht jaar oud. Het begon met het zoeken naar een speld in de mestput. Dat bleek een dure speld te zijn. Inmiddels kunnen we zeggen dat het Varkensproefbedrijf een gouden greep gedaan heeft door goedkope en eenvoudige systemen te ontwikkele

MINAS-analyse van de praktijkcentra Sterksel, Raalte en Rosmalen

Voor de praktijkcentra varkenshouderij van het Praktijkonderzoek Veehouderij isonderzocht wat het effect is van de variatie in de voorraad mineralen en detoegestane toleranties in meet- en analysemethoden op de MINAS-aangifte van1998, 1999 en 2000