Showing papers by "Utrecht University published in 1987"
Book•
01 Jan 1987
TL;DR: This book discusses iterative projection methods for solving Eigenproblems, and some of the techniques used to solve these problems came from the literature on Hermitian Eigenvalue.
Abstract: List of symbols and acronyms List of iterative algorithm templates List of direct algorithms List of figures List of tables 1: Introduction 2: A brief tour of Eigenproblems 3: An introduction to iterative projection methods 4: Hermitian Eigenvalue problems 5: Generalized Hermitian Eigenvalue problems 6: Singular Value Decomposition 7: Non-Hermitian Eigenvalue problems 8: Generalized Non-Hermitian Eigenvalue problems 9: Nonlinear Eigenvalue problems 10: Common issues 11: Preconditioning techniques Appendix: of things not treated Bibliography Index .
1,418 citations
TL;DR: Two types of corticosteroid receptors can be distinguished in rat brain and the CR has its predominant localization in neurons of the septo-hippocampal complex and has a ten-fold higher affinity for CORT than that of the GR, which mediates a tonic influence exerted with stringent specificity by CORT on hippocampus-associated functions.
615 citations
TL;DR: The scattering process of two pointlike particles at CM energies in the order of Planck units or beyond, is very well calculable using known laws of physics, because graviton exchange dominates over all other interaction processes.
508 citations
TL;DR: In this paper, the authors studied the bosonization of chiral fermion theories on arbitrary compact Riemann surfaces and obtained explicit expressions for a class of determinants relevant to string theory.
422 citations
TL;DR: In this paper, the authors give a complete proof that d = 11 supergravity compactified on S 7 admits a consistent truncation to its zero-mass sector and the resulting theory is shown to coincide with gauged N = 8 supergravity to all orders.
411 citations
TL;DR: The main subject of this overview is the current understanding of the mammalian toxicity of the organotin compounds, namely neurotoxicity, hepatoxicity, immunotoxicity, and cutaneous toxicity.
360 citations
TL;DR: In this article, the authors presented the first ammonia emission survey with spatially detailed information, where sources of atmospheric ammonia include livestock wastes, fertilizers, and some industrial activities in 26 European and 1 Asian countries.
335 citations
TL;DR: In this article, the conditions for residual supersymmetry in compactified ten-dimensional supergravity theories are investigated, including the effect of a non-constant warp factor, based on on-shell transformation laws which implies that certain linear combinations of classical field equations must be satisfied.
335 citations
TL;DR: In this paper, the superstring multiloop amplitudes in terms of theta functions were constructed using BRST-invariance and it was shown that these poles have no physical effect for on-shell amplitudes, and that the partition functions is given by a total derivative on moduli space.
330 citations
TL;DR: Curvilinear relations were obtained between leaf nitrogen and photosynthetic rate on both an instantaneous and a daily basis and the predicted optimum leaf nitrogen content for each level in the canopy was close to the actual nitrogen distribution as found through sampling.
Abstract: Photosynthetic capacity was measured on detached leaves sampled in a canopy of Solidago altissima L. Non-rectangular hyperbola fitted the light response curve of photosynthesis and significant correlations were observed between leaf nitrogen per unit area and four parameters which characterize the light-response curve. Using regressions of the parameters on leaf nitrogen, a model of leaf photosynthesis was constructed which gave the relationships between leaf nitrogen, photon flux density (PFD) and photosynthesis. Curvilinear relations were obtained between leaf nitrogen and photosynthetic rate on both an instantaneous and a daily basis. Nitrogen use efficiency (NUE, photosynthesis per unit leaf nitrogen) was calculated against leaf nitrogen under varying PFDs. The optimum nitrogen content per unit leaf area that maximizes NUE shifted to higher values with increasing PFD. Field measurements of PFD showed high positive correlations between the distribution of leaf nitrogen in the canopy and relative PFD. The predicted optimum leaf nitrogen content for each level in the canopy, to achieve maximized NUE during a clear day, was close to the actual nitrogen distribution as found through sampling.
311 citations
TL;DR: In this article, the distribution of benthic foraminifera in bottom sediments from the Adriatic Sea has been studied in 285 grab samples, and four main biofacial units have been recognized; these can all be characterized by the predominance of one or more of the eight clusters of BFA taxa which result from an R-mode cluster analysis.
TL;DR: This paper examined the production of /b, d, g/ and /p, t, k/ in the initial position of English and Spanish words by two groups of native Spanish adults and native Spanish 9-10 year-olds who began learning English as a second language (L2) by the age of 5-6 years.
TL;DR: In this article, a seismic survey was carried out on a tidal flat in the Netherlands in order to determine shear-wave velocities in sediments by means of higher-mode Rayleigh waves.
Abstract: A seismic survey was carried out on a tidal flat in the SW-Netherlands in order to determine shear-wave velocities in sediments by means of higher-mode Rayleigh waves. The dispersion properties of these Rayleigh waves were measured in the 2-D amplitude spectrum–or f, k-spectrum–and resulted in phase velocities for six different modes as a function of frequency (5–30 Hz). These observed phase velocities were inverted for a nine-layer model for the shear-wave velocity to a depth of 50 m.
TL;DR: It is argued that the impact of nutrients by air pollution, especially of nitrogen, causes the increasing dominance of Brachypodium and management strategies are needed in order to prevent degradation of the species diversity in chalk grasslands.
TL;DR: In this article, the Eu3+ ion occupies two different crystallographic sites in (Y1−xEux)2O3 and (Gd1−exEux), with site symmetry S6 and C2.
TL;DR: The results showed the subjects were aware of acoustic differences distinguishing Dutch and English /t/ and that the procedures were effective in creating differing language sets, and speculated that the language set effect was small because subjects used their English /T/ category to identify stops in both sets.
TL;DR: It is suggested that, in the spike oligomer, these α-helices form a complex coiled-coil, resembling the supersecondary structures in two other elongated membrane proteins, the haemagglutinin of influenza virus and the variable surface glycoprotein of trypanosomes.
TL;DR: The phase diagram of a system of hard parallel spherocylinders with length-to-width ratios L/D between 0 and ∞ is investigated by Monte Carlo simulation, finding a stable smectic phase formed at densities well below the thermodynamic melting point.
Abstract: The phase diagram of a system of hard parallel spherocylinders with length-to-width ratios L/D between 0 and ∞ is investigated by Monte Carlo simulation. In addition to a low-density nematic phase and a high-density crystalline phase, two phases with partial translational order are observed, viz., a smectic phase and a columnar phase. By computing the absolute free energy of all phases, their range of stability and coexistence points are determined. For L/D ratios exceeding 0.5, a stable smectic phase is formed at densities well below the thermodynamic melting point. The nematic-to-smectic transition appears to be continuous. A columnar phase is only observed for L/D>3 at densities intermediate between the smectic and crystalline phases. The smectic-to-columnar transition is first order for L/D≤5. In the limit L/D→∞ this transition becomes continuous.
TL;DR: In this article, the authors compared the results obtained by the CO- and the dithionite (DT)-difference methods for total cytochrome P-450 in four laboratories.
Abstract: Assay conditions in determining total cytochrome P-450 in four laboratories were compared. Although the determination was derived from the original Omura and Sato method in each laboratory, the four standard protocols differed slightly, resulting in considerable differences in the results. Since the cytochrome P-450 content is usually expressed per mg protein, the protein assay conditions were evaluated as well. Furthermore, we compared the cytochrome P-450 values obtained by the CO- and the dithionite (DT)-difference methods. The effect of a number of variables in the assay was investigated. The influence of the storage temperature of the microsomes was ascertained as well as effects of the gassing time with CO and the time between addition of dithionite, CO-gassing and the recording of the difference spectra. After evaluating these variables a standard operation procedure was established. Using this procedure the interlaboratory coefficient of variation for total cytochrome P-450 was 4.8%, a value which was comparable to the intralaboratory coefficients of variation. The final results also show that the millimolar extinction coefficient for the DT-difference method is higher than for the CO-difference method.
TL;DR: The technique of Neutralization Reionization Mass Spectrometry (NRMS) is performed in the diluted gas phase, a medium where intermolecular interactions are entirely absent as discussed by the authors.
Abstract: The diluted gas phase within a mass spectrometer is ideally suited for performing collision experiments of fast moving ions with thermalized target atoms. One important reaction which can be brought about with a given cation is its selective reduction, i. e. its neutralization. This allows the synthesis in tailored experiments of a variety of unusual chemical species, which because of intermolecular processes cannot be prepared or studied in solution or in a matrix. Among the molecules which have been generated in this way are hypervalent species (Rydberg radicals) like H, van der Waals complexes like He2, mono- or disubstituted acetylene derivatives XCCY (X H, Y OH, NH2; X Y OH, NH2), and elusive compounds like carbonic acid (H2CO3) or carbamic acid (NH2CO2H). Collision experiments can also be used advantageously for the structural analysis of the neutral molecule N generated in unimolecular dissociation reactions of the type m m+N. The dissociation of ionized aniline for example yields, besides C5H cations, neutral isocyanic acid, HNC, and not cyanic acid, HCN. The technique of Neutralization Reionization Mass Spectrometry (NRMS) is performed in the diluted gas phase, a medium where intermolecular interactions are entirely absent. The method may therefore increasingly be applied to the study of molecular species whose reactivity precludes their characterization in matrices. Molecules in specific excited states and fragments of organometallic compounds with unsaturated valencies are two examples of systems which could fruitfully be studied.
TL;DR: To investigate the effect of GH status on abundance of Sm-C/IGF-I and IGF-II mRNAs in rat brain, a second experiment was performed that differed from the first in that hypophysectomized rats were given an injection of hGH into the lateral ventricle (intracerebroventricular injection).
Abstract: The GH dependence of somatomedin-C/insulin-like growth factor I (Sm-C/IGF-I) and insulin like growth factor II (IGF-II) mRNAs was investigated by Northern blot hybridizations of polyadenylated RNAs from liver, pancreas, and brain of normal rats, untreated hypophysectomized rats, and hypophysectomized rats 4 h or 8 h after an ip injection of human GH (hGH). Using a 32P-labeled human Sm-C/IGF-I cDNA as probe, four Sm-C/IGF-I mRNAs of 7.5, 4.7, 1.7, and 1.2 kilobases (kb) were detected in rat liver and pancreas but were not detectable in brain. In both liver and pancreas, the abundance of these Sm-C/IGF-I mRNAs was 8- to 10-fold lower in hypophysectomized rats than in normal rats. Within 4 h after injection of hGH into hypophysectomized animals, the abundance of liver and pancreatic Sm-C/IGF-I mRNAs was restored to normal. A human IGF-II cDNA was used as a probe for rat IGF-II mRNAs which were found to be very low in abundance in rat liver and showed no evidence of regulation by GH status. In pancreas, IGF-II mRNA abundance was below the detection limit of the hybridization procedures. The brain contained two IGF-II mRNAs of 4.7 and 3.9 kb that were 5-fold lower in abundance in hypophysectomized rats than in normal rats. These brain IGF-II mRNAs were not, however, restored to normal abundance at 4 or 8 h after ip hGH injection into hypophysectomized animals. To investigate further, the effect of GH status on abundance of Sm-C/IGF-I and IGF-II mRNAs in rat brain, a second experiment was performed that differed from the first in that hypophysectomized rats were given an injection of hGH into the lateral ventricle (intracerebroventricular injection) and a rat Sm-C/IGF-I genomic probe was used to analyze Sm-C/IGF-I mRNAs. In this experiment, a 7.5 kb Sm-C/IGF-I mRNA was detected in brain polyadenylated RNAs. The abundance of the 7.5 kb mRNA was 4-fold lower in hypophysectomized rats than in normal rats and was increased to 80% of normal within 4 h after icv administration of hGH to hypophysectomized animals. As in the first experiment, the abundance of the 4.7 and 3.9 kb brain IGF-II mRNAs was lower than normal in hypophysectomized rats. Brain IGF-II mRNAs were increased to 50% of normal in hypophysectomized rats given an icv injection of hGH but within 8 h after the injection rather than at 4 h as with Sm-C/IGF-I mRNAs.
TL;DR: During the last 20 years this replacement of Erica-dominant communities by monocultures of Molinia has been observed in almost all wet heathlands in The Netherlands along with a strong increase in nitrogen availability.
Abstract: The term relative nutrient requirement is introduced in order to measure and to compare the nutrient losses from different perennial plant populations and the amount of nutrient that they need to absorb to compensate these losses. The relative nutrient requirement (L) is defined as the amount of the growth-limiting nutrient that must be taken up to maintain or replace each unit of biomass during a given time interval (e.g., mgN g-1 biomass year-1). It is derived that in a plant community with two competing perennial plant populations, species1 will become dominant if the relative competition coefficient k 12 (sensu De Wit 1960) exceeds the ratio between the relative nutrient requirements of the two species (L 1/L 2), whereas species 2 will become dominant, if k 12 is below this critical ratio. The above-ground litter production was measured inwet heathland communities dominated by Erica tetralix or by Molinia caeruleain order to estimate N and P losses from theaboveground biomass and to calculate the relative N and P requirements of these species. Molinia lost during one year 63% and 34%, respectively, of the amount of N and P present in the above-ground biomass at the end of the growing season. These losses were in Erica 27% and 31%, respectively. The relative N requirements of the two species show the same difference: 7.5 and 2.6 mg N g-1 yr-1, respectively, in Molinia and in Erica. Also the relative P requirement of Molinia is higher as well as that of Erica (0.18 versus 0.08 mg P g-1 yr-1). The relative competition coefficient of Molinia with respect to Erica (k me ) is equal to unity under unfertilized conditions but increases with increasing nutrient supply. Under nutrient-poor conditions k me is below the critical ratio of the relative nutrient requirements of the two species (L m /L e =2.9 or 2.3), so that Erica will be the dominant species. After an increase in nutrient availability k me increases and exceeds this critical limit which results in Molinia replacing Erica. During the last 20 years this replacement of Erica-dominant communities by monocultures of Molinia has been observed in almost all wet heathlands in The Netherlands along with a strong increase in nitrogen availability.
TL;DR: Amino acid sequence comparison of the A59 and 1HM E2 proteins showed extensive homology and revealed a stretch of 89 amino acids in the 90B region ofThe A59 E2 protein that is absent in JHM.
TL;DR: In this paper, an integrale fonctionnelle associee is defined: If(x,v)≡∫f(r,x,(t), v(t)μdt)
Abstract: Soit (T, #7B-F, μ) un espace fini de mesure nonatomique (X, II-II) un espace de Banach non separable, et V, I•I) un espace de Banach reflexif separable dont V' est le dual. Soit f:TxXxV→(−∞, −∞] une fonction #7B-F∞#7B-B(X×V) mesurable. On etudie l'integrale fonctionnelle associee I f :L X 1 × L V 1 →[−∞, +∞] definie par If(x,v)≡∫f(r,x,(t), v(t)μdt
TL;DR: In this paper, a critical study is made of the mathematics needed to describe the current response towards a potential step perturbation of an electrode at which phase formation takes place by the process of nucleation and diffusion-controlled hemispherical growth.
TL;DR: In this article, the authors report a new automated method for studying the temporal and spatial aspects of mass movement activity, which uses filtering techniques and statistical time series analysis for tree growth and tree form analysis.
Abstract: Tree growth and inclination on sloping land is affected by mass movement. Suitable analysis of tree growth and tree form can therefore provide considerable information on mass movement activity.
This paper reports a new, automated method for studying the temporal and spatial aspects of mass movement activity. Ringwidth data from only a few cores per tree are required. The method uses filtering techniques and statistical time series analysis.
Preliminary results for two landslides in the Barcelonnette area of the French Alps show a relative stability of movement activity over the last hundred years (no trend) and short periodicity (six to seven year periods) of mass movement activity.
The advantages of the method (over other, mostly visual, methods) are its clearness, flexibility, repeatability and rapidity. However, further testing is needed to examine its reliability.
TL;DR: Using two distinct IGF‐II cDNAs isolated from a human adult liver and a human hepatoma cDNA library, respectively, it is established that the human IGF‐ II gene contains at least 7 exons.
TL;DR: The experience supports the idea that zinc sulphate is a good choice for the treatment of Wilson's disease: the drug is effective, safe and cheap.
TL;DR: neutralization of PM SG shortly after the preovulatory LH peak suppresses adverse effects of PMSG on final follicular maturation, leading to an almost 2-fold increase of the ovulation rate.
Abstract: Normally cyclic heifers received 2500 i.u. PMSG i.m. at Day 10 of the oestrous cycle and 15 mg prostaglandin (PG) i.m. 48 h later. From 30 h after PG the LH concentration in the peripheral blood was estimated every hour using a rapid RIA method which allowed the LH concentration to be known within 4 h. Monoclonal antibody against PMSG was injected in the jugular vein of 29 heifers at 4.8 h after the maximum of the preovulatory LH peak; 28 heifers were not treated with anti-PMSG (controls). Peripheral blood concentrations of PMSG, LH, progesterone and oestradiol were compared. Ovaries were collected by ovariectomy at fixed times, 22-30 h after the LH peak, and numbers were counted of small (2-10 mm), large (greater than 10 mm) and ovulated follicles, and of follicles with a stigma. In anti-PMSG-treated cows, the PMSG concentration fell sharply to non-detectable levels within 2 h of the treatment, indicating that PMSG was neutralized in these cows at the onset of final follicular maturation. In all cows, the concentration of oestradiol showed a significant decrease at about 8 h after the LH peak. After anti-PMSG treatment ovulations took place from 24 until 30 h after the LH peak, whereas in control cows follicles had already ovulated at or before 22 h and ovulations continued until 30 h. At 30 h 90% of the follicles had ovulated in anti-PMSG-treated cows vs 72% in the controls, resulting in 15 and 8 ovulations per cow respectively (P less than 0.05). Also, administration of monoclonal antibody against PMSG synchronized final follicular maturation and shortened the period of multiple ovulations. In conclusion, neutralization of PMSG shortly after the preovulatory LH peak suppresses adverse effects of PMSG on final follicular maturation, leading to an almost 2-fold increase of the ovulation rate.