Showing papers by "University of Groningen published in 1980"
TL;DR: In this paper, the parent adjusts its effort in relation to prevailing environmental conditions in order to maximize the output of young in its lifetime, rather than measurable in terms of adult survival and recruitment of young.
Abstract: 1. Energetics of reproduction in birds is reviewed with the question in mind how the parent adjusts its effort in relation to prevailing environmental conditions in order to maximize the output of young in its lifetime. Emphasis is on proximate controls, rather than ultimate factors measurable in terms of adult survival and recruitment of young. 2. The decision to breed or not to breed is clearly related to body condition of the female, presumably because of the implications this has for survival. 3. Laying date and clutch size are likewise under the influence of female condition and can hence be modified by experiments involving supplementary feeding. Natural variation in these features may often be related to territory quality. 4. How the bird decides whether or not to commence a second brood is not clear, but in the Great Tit the habitat-related difference in incidence of second broods is functionally understandable when survival probabilities of birds at different times are considered. 5. A distinction is made between a "capital" and "income" model for translatting rates of change of female body condition into appropriate decisions on laying date and clutch size and experiments are suggested that discriminate between the two. 6. Lack's view that brood size is in an evolutionary sense adjusted in order to balance food requirement and foraging capacity of the parents is accepted, and growth rates in nidicolous birds are analysed to ascertain if a finer adjustment exists superimposed on the integer steps of brood adjustment. Critical for this analysis are groups of birds where broods of one are common, since only in these circumstances is growth adjustment the only strategy open to the parents. In common with other animals, growth rate is related to mature body size but within a category of adult weight clear examples can be found for retardation of growth rate in pelecaniform and charadriiform species with singleton broods. 7. Since daily energy requirement is related to nestling size and growth rate, retardation of growth is explicable as a strategy only in terms of reducing the daily commitment of the parents, not reducing the total cost of producing a nestling. 8. An additional economy in growth is to reduce the contribution of fat to the nestling body. 9. Implied in Lack's view of brood size is a limitation of parental foraging capacity, and the last section of the paper is devoted to exploration of the proximate factors delimiting what Royama terms the optimal working capacity of parents feeding young. Observations of parent starlings confronted with manipulated brood size suggest a limit on the time that can be devoted to energetically extravagant flight activity, rather than a shortage of absolute time. Beyond the limit to which stressed parents can be made to fly, body weight declines. 10. Preliminary data on energy metabolized daily by parents confronted with large broods conforms to the simplified view that parental effort on a sustained basis equates to energy mobilization equivalent to 4 B.M.R. units and it is suggested that this level of energy expenditure represents a proximal decision substrate for determining the optimal working capacity of the parent. 11. The paper ends with a plea for more research on the proximate controls of avian reproduction, and calls attention to the central importance of the protein bank to parental body condition.
2,070 citations
TL;DR: It was found that the alpha rhythms of the LGN influenced only moderately the coherence between cortical alpha rhythms whereas that of the pulvinar had much more influence, at least in relation to some cortical areas.
425 citations
TL;DR: In this paper, a study has been made of the general crystallization behavior of poly(L-lactic acid), PLLA, and is intended to be the basis for further work on fibre formation processes.
393 citations
TL;DR: In this article, a set of classical variables associated with the interacting-boson model is defined and the classical equilibrium ''shapes'' corresponding to the three limits of the BOS model are analyzed and the nature of the ''shape'' phase transitions between them is studied.
Abstract: A set of classical variables associated with the interacting-boson model is defined. It is shown that these variables can be put in one-to-one correspondence with Bohr's liquid-drop variables. The classical equilibrium ''shapes'' corresponding to the three limits of the interacting-boson model are analyzed and the nature of the ''shape'' phase transitions between them is studied.
382 citations
TL;DR: Several ill-related lines of inquiry deal with problems of "risk" and "perceived risk" as discussed by the authors, such as "voluntariness of exposure", "controllability of consequences", and "catastrophality".
314 citations
TL;DR: It is argued that the unique cheek tooth structure allows lagomorphs to apply various combinations of crushing, shearing and grinding forces to their food and remain generalized and adapted to different niches.
Abstract: Jaw muscle activity and mandibular movements were studied in the domestic rabbit by quantitative electromyography and cineradiography. Mandibular movement profile and occlusal interaction depend on the consistency of the food masticated. Minimal vertical and maximal transverse jaw excursions combined with initial edge-to-edge apposition of cheek tooth ridges, followed by an oblique antero-medial shearing movement of the lower teeth into intercuspation characterize hay mastication. This movement is followed by a purely transverse grinding stroke guided by the interlocked ridges and valleys of the teeth. In carrot mastication a vertical, crushing movement predominates. In laboratory pellets, the movement profile is intermediate; occlusal movement is usually confined to a transverse grinding stroke. During chewing jaw closure and deflection toward the working side are caused by simultaneous action of balancing side superficial masseter and medial pterygoid and working side deep masseter and temporalis. The lingually directed power stroke is produced by working side superficial masseter and medial pterygoid and balancing side deep masseter and temporalis. Firing levels are higher on the working than on the balancing side and decrease from hay to pellets to carrot. Transverse muscle force components, generated mainly by the pterygoids also decrease in the series hay-pellets-carrot. The ratio between forces on working and balancing sides allows the balancing side joint to act as a fulcrum; the working side joint remains unloaded. During biting joints are loaded symmetrically. The unique cheek tooth structure allows lagomorphs to apply various combinations of crushing, shearing and grinding forces to their food. By combining strong protractive and transverse muscular forces they can adjust bite force direction. It is argued that this versatility enables them to utilize a wide variety of vegetable matter as food and remain generalized and adapted to different niches.
292 citations
TL;DR: In this article, a number of copper sulfides and selenides were studied using X-ray photoelectron spectroscopy, and it was found that the copper in all the compounds is monovalent, while the average oxidation state of the chalcogen varies from − 3 2 in Cu3Se2, to − 1 in CuS and CuSe and to built− 1 2 in CoS2 and CoSe2.
Abstract: A number of copper sulphides and selenides were studied using X-ray photoelectron spectroscopy. It was found that the copper in all the compounds is monovalent, while the average oxidation state of the chalcogen varies from —2 in Cu2S and Cu2Se, to − 3 2 in Cu3Se2, to −1 in CuS and CuSe and to built− 1 2 in CuS2 and CuSe2. The deficit of electrons relative to a closed-shell configuration is delocalized (holes in the S(3p) or Se(4p) valence band), leading to p-type metallic conduction. This is also found for the ternary compounds KCu4S3, CuV2S4 and TlCu2Se2. S2− and S− coexist in KCu4S3; the new compounds TlCu4S3 and KCu4Se3 are isostructural with KCu4S3.
267 citations
TL;DR: Small sets of clinical features were identified that, when combined, yield high quality predictions of long term outcome that allows bedside predictions in individual patients and provides a tool for comparing the severity of injury between series of patients.
Abstract: In this study small sets of clinical features were identified that, when combined, yield high quality predictions of long term outcome. The study is based on a series of 305 consecutive head-injured Dutch patients, all of whom had been in coma for at least 6 hours. The overall social outcome was assessed after 6 months using the Glasgow outcome scale. Predictions of outcome were made by assigning probabilities to each possible outcome category. The prognostically most promising features recorded during the early post-traumatic course were identified, and powerful combinations of prognostic features were selected on admission and 1, 3, 7, 14, and 28 days after the start of coma by an appropriate statistical method. At each time point, optimal prediction required sets of only three to five features, typically including age in decades, depth and duration of coma as assessed by the Glasgow coma scale, pupil reactivity to light, and spontaneous and reflex eye movements. The method described allows bedside predictions in individual patients and provides a tool for comparing the severity of injury between series of patients.
254 citations
TL;DR: A mathematical model based on an assumed linear relationship between the forces exerted by a muscle and its integrated electromyogram is presented for calculating muscle forces and joint forces acting on the human mandible during static bite situations, finding that forces in all muscles are dependent on the location of the bite force, most clearly demonstrated in the temporal muscles.
243 citations
TL;DR: In this article, the photoelectron spectra of the synthetic compounds FeS2, CoS2 and CoSe2, and a natural crystal of MnS2 with pyrite structure are reported.
243 citations
TL;DR: It is concluded that SDD is a promising and widely applicable method of infection prevention that decreases the need for treatment in a ‘protected environment’.
TL;DR: The behavior involved consists of a large repertoire of separate elements, which may differ widely from species to species as discussed by the authors, and two aspects of these elements will be stressed here: Two aspects of as discussed by the authors
TL;DR: This chapter briefly reports on authors, as yet unpublished, experiments in adult male rats conducted on relationships between hormone levels and agonistic behavior; and hormonal and behavioral changes after agonistic experience.
Abstract: Publisher Summary Most studies of the hormonal correlates of agonistic behavior in adult animals have been performed in mice, and only a few in rats. This chapter briefly reports on authors, as yet unpublished, experiments in adult male rats. Two themes were investigated: (a) relationships between hormone levels and agonistic behavior; and (b) hormonal and behavioral changes after agonistic experience. The experimental animals were Tryon Maze Dull S-3 rats, which show a high level of aggressive behavior, as do wild rats. Twenty behavioral elements of the experimental rats were registered, either during tests in which a male stimulus rat (WEzob strain) was placed into the home cage of the experimental rat, or in a cage that was strange to both rats. During certain behavioral tests, blood samples for hormone assays were taken by means of an indwelling jugular vein cannula, according to Steffens.
TL;DR: In this article, the collective quadrupole states of the Xe, Ba and Ce isotopes were calculated in the framework of the proton-neutron interacting boson model.
TL;DR: Afferents of the lateral (LH) and ventromedial (VMH) hypothalamic nuclei were studied with the horseradish peroxidase method to investigate relations between these two centers presumed to be involved in the regulation of food intake, indicating that LH and VMH do not maintain direct interconnections.
TL;DR: If the knowledge about strength or dominance of the other individuals is perfect, the “Threat-right” strategy turns out to be most successful under a wide variety of conditions, but if that knowledge is not perfect, other strategies can yield better results.
TL;DR: Org NC 45 appears to be approximately as potent as pancuronium, but has a more rapid onset of action, considerably shorter duration of action and faster recovery rate than Pancuronium and represents a potentially valuable addition to the armamentarium of clinically useful muscle relaxants.
Abstract: The neuromuscular blocking effects of the new monoquaternary analogue of pancuronium, Org NC 45, have been investigated in anaesthetized patients. In different doses administered as a single i.v. bolus or as an initial bolus followed by several small maintenance doses or by a continuous infusion, Org NC 45 appears to be approximately as potent as pancuronium, but has a more rapid onset of action, considerably shorter duration of action and faster recovery rate than pancuronium. It showed no cumulative effects even after 10 maintenance doses were injected in succession. Doses of 0.08 mg kg−1 provided ideal intubatmg conditions in 90–95 8. Infusions of Org NC 45 provided much smoother control of neuromuscular blockade than did pancuronium. No cardiovascular side-effects were noted even at the greatest dose (0.12 mg kg−1)used. Org NC 45 has clear advantages over pancuronium and represents a potentially valuable addition to the armamentarium of clinically useful muscle relaxants.
TL;DR: Investigation in the yeasts Hansenula polymorpha and Kloeckera sp.
Abstract: The regulation of the synthesis of four dissimilatory enzymes involved in methanol metabolism, namely alcohol oxidase, formaldehyde dehydrogenase, formate dehydrogenase and catalase was investigated in the yeasts Hansenula polymorpha and Kloeckera sp. 2201. Enzyme profiles in cell-free extracts of the two organisms grown under glucose limitation at various dilution rates, suggested that the synthesis of these enzymes is controlled by derepression — represion rather than by induction — repression. Except for alcohol oxidase, the extent to which catabolite repression of the catabolic enzymes was relieved at low dilution rates was similar in both organisms. In Hansenula polymorpha the level of alcohol oxidase in the cells gradually increased with decreasing dilution rate, whilst in Kloeckera sp. 2201 derepression of alcohol oxidase synthesis was only observed at dilution rates below 0.10 h−1 and occurred to a much smaller extent than in Hansenula polymorpha.
TL;DR: It could be shown that obstetrical conditions such as acidemia, preterm birth and intrauterine growth retardation have a stronger relationship to neurological morbidity when the accompanying obstetrical optimality is lower.
TL;DR: It is presented that the direct depressing effect of ammonium chloride on nitrogen fixation by Azotobacter vinelandii is due to inhibition of the electron transport system to nitrogenase, and its significance as a regulator for the rapid ‘switch off/switch on’ of nitrogenase activity is discussed.
Abstract: 1
Evidence is presented that the direct depressing effect of ammonium chloride on nitrogen fixation by Azotobacter vinelandii is due to inhibition of the electron transport system to nitrogenase. Furthermore, we were able to confirm the observation [Houwaard, F. (1979) Appl. Environ. Microbiol. in the press] that ammonium chloride has no short-term effect on nitrogen fixation by isolated bacteroids of Rhizobium leguminosarum.
2
By means of the flow dialysis technique it could be demonstrated that in A. vinelandii ammonium is taken up as a cation in response to the ΔΨ and that uptake of ammonium specifically inhibits the flow of reducing equivalents to nitrogenase by lowering the ΔΨ across the cytoplasmic membrane. In A. vinelandii, like in bacteroids, the generation of reducing equivalents at a potential low enough to reduce nitrogenase was found to be extremely sensitive towards changes in ΔΨ. At ΔΨ values less than 80 mV, interior negative, no such reducing equivalents are generated, while at a ΔΨ value of 110 mV nitrogenase is supplied optimally with reducing equivalents. The nature of the ammonium transport system in A. vinelandii and its significance as a regulator for the rapid ‘switch off/switch on’ of nitrogenase activity is discussed.
3
Bacteroids of R. leguminosarum did not accumulate ammonium and no effect of ammonium on ΔΨ was observed. On the contrary, it could be demonstrated that bacteroids excrete ammonium in response to the ΔpH.
Journal Article•
TL;DR: In this article, a consecutive series of 30 hospitalized cervical injury patients, 18 proved to have widening of the prevertebral soft tissue space due to hematoma, almost exclusively manifested at C1-C4 and proved to be closely related to fractures of anterior elements of the spine.
Abstract: In a consecutive series of 30 hospitalized cervical injury patients, 18 proved to have widening of the prevertebral soft tissue space due to hematoma. The upper limit of normal width in 50 noninjury patients was used as a reference. Hematoma almost exclusively manifested at C1-C4 and proved to be closely related to fractures of anterior elements of the spine. Relatively small hematomas were encountered in odontoid fractures and compression fractures of vertebral bodies; relatively large hematoma in disruptive hyperextension injury. Large hematomas are explained by extensive anterior ligamentous damage with rupture of larger blood vessels. As a rule, most hematomas disappeared within 2 weeks after the injury.
TL;DR: In this paper, the results of calculations performed for Ru and Pd isotopes (Z = 44,46; 54 ≦ N ≦ 78) within the framework of the IBA-2 were presented.
TL;DR: The observation indicates that the emersion time of the mudflat and hence its exposure to full daylight is an important factor in the development of the spring bloom, and dispersal of diatom cells into the sediment is probably responsible for the decreased photosynthetic rates and, consequently, for the low doubling rates of sediment-inhabiting diatoms.
Abstract: Cultures of four benthic diatom species (Navicula salinarum, Amphiprora cf, paludosa, N. arenaria, Gyrosigma spenceni) were kept at the surface of a mudflat in order to measure division rates. During incubations in the period of December to June the mean temperature was the predominant factor regulating cell division rate. Immersion of the mudflat with very turbid tidal water was an important factor only at a low-level mudflat station during winter and early spring. Strong temperature fluctuations during incubations, with periods of frost in winter and periods of insolation during hot summer weather, did not interrupt growth of the cultures. Hence high temperatures and high irradiance values are unlikely to be the direct cause of the summer minimum in population density that is frequently observed in the estuary. After the winter minimum the increase in population density was measured at three levels of the mudflat. At the high-level station the density increased in January at still very low temperatures, whereas at the mid- and low-level stations this increase started in March. This observation indicates that the emersion time of the mudflat and hence its exposure to full daylight is an important factor in the development of the spring bloom. The density of the diatom populations in the 0.5 cm top layer of the sediment increased only at a very low rate (with maximum rates of ca. 0.1 doublings d-l). Low photosynthetic rates of natural diatom populations in the sediment core are the cause of these low doubling rates of natural populations on the mudflat. Dispersal of diatom cells into the sediment is probably responsible for the decreased photosynthetic rates and, consequently, for the low doubling rates of sediment-inhabiting diatoms.
TL;DR: In this paper, the Coulomb correlation energy was used to calculate the Auger spectrum for an initially filled simple-cubic tight-binding $s$ band, and the results were compared to various approximate Auger line shapes.
Abstract: A calculation of the Auger spectrum for an initially filled simple-cubic tight-binding $s$ band is presented. The spectra are obtained for various values of the Coulomb correlation energy as compared to the one-electron bandwidth. The results are compared to various approximate Auger line shapes. The Auger line shape is found to be strongly dependent on the Coulomb interaction between the two holes in the final state and deviate strongly from the self-convolution of the density of states even for small Coulomb interactions.
TL;DR: In this article, it was shown that the three dynamical symmetries that occur in IBA correspond to the anharmonic vibrator, the axially symmetric rigid rotor and the gamma unstable rotor, respectively.
TL;DR: In this article, a new formalism is proposed for incorporating solvent effects into the quantum mechanical description of molecular electronic states, which does not lead to a non-linear effective hamiltonian, while both the solvent and solute interactions are treated self-consistently.
Abstract: A new formalism is proposed for incorporating solvent effects into the quantum mechanical description of molecular electronic states. In contrast to existing methods, it does not lead to a non-linear effective hamiltonian, while both the solvent/solvent and the solute/solvent interactions are treated self-consistently. It also accounts more accurately for the solute's electrical field than the usual dipole approximation. Although formally treated on the Hartree-Fock level, the method incorporates dispersion interactions between solute and solvent.
TL;DR: The results bear out the hypothesis that post-concussional sequelae start off on an organic basis (PTA) and that persistent sequelae after minor head injuries are also caused by psychogenic, and especially by iatrogenic factors.
TL;DR: An adaptation of the d-ribulose-1,5-bisphosphate carboxylase (RuBPCase) activity to changing CO2 concentrations in the growth medium in the chemostat was observed in the obligate chemolithotroph Thiobacillus neapolitanus.
Abstract: An adaptation of the d-ribulose-1,5-bisphosphate carboxylase (RuBPCase) activity to changing CO2 concentrations in the growth medium in the chemostat was observed in the obligate chemolithotroph Thiobacillus neapolitanus. RuBPCase activity has been separated in a soluble and particulate fraction. The activity of the particulate fraction appeared to be associated with the carboxysomes.
TL;DR: In this article, data reduction schemes for time differential perturbed angular correlation measurements are evaluated in terms of their relative effectiveness in eliminating irrelevant variables, including single counter efficiencies and spectrum time shifts; and their effectiveness in putting data in a form that can easily be fitted by theoretical correlation functions.
Abstract: Data reduction schemes currently used for time differential perturbed angular correlation measurements are evaluated in terms of (i) their relative effectiveness in eliminating irrelevant variables, including single counter efficiencies and spectrum time shifts; and (ii) their effectiveness in putting data in a form that can easily be fitted by theoretical correlation functions. It is pointed out that erroneous conclusions may be derived from improperly reduced data, but that properly analyzed experiments performed at four angles allow a good determination of both the time-dependent and time-independent parts of the correlation function. Correction of data for accidentals, source self-absorption and spectrum livetime differences are discussed.