28,317 research outputs found
Productie en kostprijs van pootvis (WP 4)
De cyclus van een marktwaardige consumptievis binnen de aquacultuur bestaat uit twee fases. De hatcheryfase, waar ouderdieren tot paaien worden gebracht en de nakomelingen tot pootvis worden gekweekt. En de doorgroeifase waar de pootvis wordt opgegroeid tot consumptievis. De prijs van deze consumptievis wordt mede bepaald door de kosten van de in eerste instantie ingekochte of voorgekweekte pootvis wat vaak een significant aandeel heeft in de kostprijsopbouw. De kostprijs van pootvis is opgebouwd uit verschillende soorten kosten. Alle factoren die van invloed zijn op de kweek van pootvis zijn in twee kostenposten te verdelen: lopende kosten en vaste kosten. Al deze kosten worden bepaald door biologische en technische invloeden vanuit het proces (mortaliteit, groeisnelheid, temperatuur etc.). Van een aantal vissoorten (zeebaars, Afrikaanse meerval) is de kostprijs en de kostprijsopbouw van pootvis bekend. Bij noorzee tong (Solea solea) is dit nog niet in kaart gebracht. Eerste pogingen gaan terug op berekeningen in de jaren 200 en 2001. Maar deze zijn niet publiek. Het is dus noodzakelijk om de kostprijs van tong pootvis te berekenen, om de haalbaarheid van tong kweek te onderbouwen
A Study of the Accuracy of Mass-Radius Relationships for Silicate-Rich and Ice-Rich Planets up to 100 Earth Masses
A mass-radius relationship is proposed for solid planets and solid cores
ranging from 1 to 100 Earth-mass planets. It relies on the assumption that
solid spheres are composed of iron and silicates, around which a variable
amount of water is added. The M-R law has been set up assuming that the
planetary composition is similar to the averaged composition for silicates and
iron obtained from the major elements ratio of 94 stars hosting exoplanets.
Except on Earth for which a tremendous amount of data is available, the
composition of silicate mantles and metallic cores cannot be constrained.
Similarly, thermal profiles are poorly known. In this work, the effect of
compositional parameters and thermal profiles on radii estimates is quantified.
It will be demonstrated that uncertainties related to composition and
temperature are of second order compared to the effect of the water amount. The
Super-Earths family includes four classes of planets: iron-rich, silicate-rich,
water-rich, or with a thick atmosphere. For a given mass, the planetary radius
increases significantly from the ironrich to the atmospheric-rich planet. Even
if some overlaps are likely, M-R measurements could be accurate enough to
ascertain the discovery of an earth-like planet .The present work describes how
the amount of water can be assessed from M-R measurements. Such an estimate
depends on several assumptions including i) the accuracy of the internal
structure model and ii) the accuracy of mass and radius measurements. It is
shown that if the mass and the radius are perfectly known, the standard
deviation on the amount of water is about 4.5 %. This value increases rapidly
with the radius uncertainty but does not strongly depend on the mass
uncertainty.Comment: In press in The Astrophysical Journa
Huge quadratic magneto-optical Kerr effect and magnetization reversal in the CoFeSi Heusler compound
CoFeSi(100) films with L2 structure deposited onto MgO(100) were
studied exploiting both longitudinal (LMOKE) and quadratic (QMOKE)
magneto-optical Kerr effect. The films exhibit a huge QMOKE signal with a
maximum contribution of up to 30 mdeg, which is the largest QMOKE signal in
reflection that has been measured thus far. This large value is a fingerprint
of an exceptionally large spin-orbit coupling of second or higher order. The
CoFeSi(100) films exhibit a rather large coercivity of 350 and 70 Oe for
film thicknesses of 22 and 98 nm, respectively. Despite the fact that the films
are epitaxial, they do not provide an angular dependence of the anisotropy and
the remanence in excess of 1% and 2%, respectively
The VLT-FLAMES Tarantula Survey
We present a number of notable results from the VLT-FLAMES Tarantula Survey
(VFTS), an ESO Large Program during which we obtained multi-epoch
medium-resolution optical spectroscopy of a very large sample of over 800
massive stars in the 30 Doradus region of the Large Magellanic Cloud (LMC).
This unprecedented data-set has enabled us to address some key questions
regarding atmospheres and winds, as well as the evolution of (very) massive
stars. Here we focus on O-type runaways, the width of the main sequence, and
the mass-loss rates for (very) massive stars. We also provide indications for
the presence of a top-heavy initial mass function (IMF) in 30 Dor.Comment: 7 Figures, 8 pages. Invited talk: IAUS 329: "The Lives and
Death-Throes of Massive Stars
Iterated Binomial Sums and their Associated Iterated Integrals
We consider finite iterated generalized harmonic sums weighted by the
binomial in numerators and denominators. A large class of these
functions emerges in the calculation of massive Feynman diagrams with local
operator insertions starting at 3-loop order in the coupling constant and
extends the classes of the nested harmonic, generalized harmonic and cyclotomic
sums. The binomially weighted sums are associated by the Mellin transform to
iterated integrals over square-root valued alphabets. The values of the sums
for and the iterated integrals at lead to new
constants, extending the set of special numbers given by the multiple zeta
values, the cyclotomic zeta values and special constants which emerge in the
limit of generalized harmonic sums. We develop
algorithms to obtain the Mellin representations of these sums in a systematic
way. They are of importance for the derivation of the asymptotic expansion of
these sums and their analytic continuation to . The
associated convolution relations are derived for real parameters and can
therefore be used in a wider context, as e.g. for multi-scale processes. We
also derive algorithms to transform iterated integrals over root-valued
alphabets into binomial sums. Using generating functions we study a few aspects
of infinite (inverse) binomial sums.Comment: 62 pages Latex, 1 style fil
GaBoDS: The Garching-Bonn Deep Survey - III. Lyman-Break Galaxies in the Chandra Deep Field South
We present first results of our search for high-redshift galaxies in deep CCD
mosaic images. As a pilot study for a larger survey, very deep images of the
Chandra Deep Field South (CDFS), taken withWFI@MPG/ESO2.2m, are used to select
large samples of 1070 U-band and 565 B-band dropouts with the Lyman-break
method. The data of these Lyman-break galaxies are made public as an electronic
table. These objects are good candidates for galaxies at z~3 and z~4 which is
supported by their photometric redshifts. The distributions of apparent
magnitudes and the clustering properties of the two populations are analysed,
and they show good agreement to earlier studies. We see no evolution in the
comoving clustering scale length from z~3 to z~4. The techniques presented here
will be applied to a much larger sample of U-dropouts from the whole survey in
near future.Comment: 11 pages, 11 figures, replaced with version accepted by A&A. Minor
changes and tabular appendix with LBG catalogues. Version with full
resolution figures available at
http://www.astro.uni-bonn.de/~hendrik/2544.pd
The Bs -> Ds pi and Bs -> Ds K selections
The decay channels Bs->Dspi and Bs->DsK will be used to extract the physics parameters , and . Simulation studies based on Monte Carlo samples produced in 2004 and 2005 show that a total of 140k Bs->Dspi and 6.2k Bs->DsK events are expected to be triggered, reconstructed and selected in of data ( of data taking at a luminosity of 2\times 10^{32}\unit{cm^{-2}s^{-1}}). The combinatorial background-over-signal ratio originating from inclusive bb events is expected to be B/S < 0.18~\at~90\%$~CL
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