Energy production and use in Dutch agriculture

Energy relationschips in the agriculture of one of the most densely populated areas of the world, the Nether lands, are described. The Netherlands appear selfsupporting in food energy. However, if one takes account of energy consumption in horticulture, the direct and indirect fossil energy cost exceeds the food energy produced in agriculture. An input-output analysis to estimate the indirect energy is applied on Japanese data. It appears that in Japanese agriculture for every unit energy used directly, two units are used indirectly. Energy relationships are different for the main agricultural sectors. In the primary production sector more energy is produced than consumed (9 : 1), while in the secondary production sector and in the horticulture the oppositie holds (1 : 7). The energy input of the secondary production sector, however, is mainly of plant origin. Energy balances of an arable farm at present and around 1800 are given to show in more detail in which way food energy is and was produced. Possible ways to diminish the fossil energy input of the modern farm are discussed

New Supersymmetric Solutions in N=2 Matter Coupled AdS_3 Supergravities

We construct new 1/2 supersymmetric solutions in D=3, N=2, matter coupled, U(1) gauged supergravities and study some of their properties. We do this by employing a quite general supersymmetry breaking condition, from which we also redrive some of the already known solutions. Among the new solutions, we have an explicit non-topological soliton for the non-compact sigma model, a locally flat solution for the compact sigma model and a string-like solution for both types of sigma models. The last one is smooth for the compact scalar manifold.Comment: 1+21 pages, 2 figures, LaTeX2e, JHEP style; v2: added one reference + made minor changes and added a few comments to clarify the presentatio

Kind, kinderen en jeugd

Niet UB, maar tijdelijk ter bevordering van de PDF bestanden in het Leids Repositorium

Obituary: Dr. Marie-Jose Walenkamp (1966-2021)

Developmen

Should skeletal maturation be manipulated for extra height gain?

Skeletal maturation can be delayed by reducing the exposure to estrogens, either by halting pubertal development through administering a GnRH analogue (GnRHa), or by blocking the conversion of androgens to estrogens through an aromatase inhibitor (AI). These agents have been investigated in children with growth disorders (off-label), either alone or in combination with recombinant human growth hormone (rhGH). GnRHa is effective in attaining a normal adult height (AH) in the treatment of children with central precocious puberty, but its effect in short children with normal timing of puberty is equivocal. If rhGH-treated children with growth hormone deficiency or those who were born small-for-gestational age are still short at pubertal onset, co-treatment with a GnRHa for 2-3 years increases AH. A similar effect was seen by adding rhGH to GnRHa treatment of children with central precocious puberty with a poor AH prediction and by adding rhGH plus GnRHa to children with congenital adrenal hyperplasia with a poor predicted adult height on conventional treatment with gluco- and mineralocorticoids. In girls with idiopathic short stature and relatively early puberty, rhGH plus GnRHa increases AH. Administration of letrozole to boys with constitutional delay of growth puberty may increase AH, and rhGH plus anastrozole may increase AH in boys with growth hormone deficiency or idiopathic short stature, but the lack of data on attained AH and potential selective loss- of-follow-up in several studies precludes firm conclusions. GnRHas appear to have a good overall safety profile, while for aromatase inhibitors conflicting data have been reported.Developmen

Leven, werken en geloven in zeevarende gemeenschappen : Schiedam, Maassluis en Ter Heijde in de zeventiende eeuw

In veel dorpen en steden in de zeventiende-eeuwse Republiek der Zeven Verenigde Nederlanden werd het leven bepaald door het ritme van de zeevaart. Een groot gedeelte van de mannelijke beroepsbevolking was in deze gemeenschappen bijna voortdurend afwezig. Tot nog toe is binnen de Nederlandse maritieme geschiedenis weinig aandacht besteed aan zeevarende gemeenschappen. Dit proefschrift geeft een gedetailleerd beeld van het leven in zeventiende-eeuws Schiedam, Maassluis en Ter Heijde. Historica Annette de Wit analyseert aan de hand van een grote diversiteit aan bronnenmateriaal op welke wijze de economische afhankelijkheid van de zeevaart het dagelijks bestaan beïnvloedde. Geanalyseerd wordt hoe (de dominantie van) de zeevaart invloed had op het werk dat mannen en vrouwen deden, op het huishouden en het gezin, op de sociale verhoudingen binnen de samenleving en op het godsdienstig leven van de inwoners van de drie gemeenschappen. Samenvattend kan gesteld worden dat de zeevaart invloed had op vrijwel alle aspecten van het dagelijks bestaan in Schiedam, Maassluis en Ter Heijde. In de havenstad Schiedam werd deze invloed aan het einde van de zeventiende eeuw minder als gevolg van het groeiende belang van de brandewijnindustrie. Anders was dat in de occupational communities Maassluis en Ter Heijde, waar de zeevaart bepalend bleef voor het leven van de inwoners van het dorp. De visserij bepaalde hier niet alleen de sociale en economische verhoudingen, maar was ook verweven met cultuur en geloof.LEI Universiteit LeidenColonial and Global Histor

Negative Energy in String Theory and Cosmic Censorship Violation

We find asymptotically anti de Sitter solutions in N=8 supergravity which have negative total energy. This is possible since the boundary conditions required for the positive energy theorem are stronger than those required for finite mass (and allowed by string theory). But stability of the anti de Sitter vacuum is still ensured by the positivity of a modified energy, which includes an extra surface term. Some of the negative energy solutions describe classical evolution of nonsingular initial data to naked singularities. Since there is an open set of such solutions, cosmic censorship is violated generically in supergravity. Using the dual field theory description, we argue that these naked singularities will be resolved in the full string theory.Comment: 23 pages, 2 figures, v2: argument for forming naked singularities clarified, references adde