Showing papers by "Radboud University Nijmegen published in 1979"
TL;DR: The main emphasis in interlanguage research has shifted from a rather static error-oriented view of language learning to a dynamic view of learners' language as a constantly evolving system as mentioned in this paper.
Abstract: Current research into second-language learning has tended to ignore (or at best to treat incidentally) a linguistic phenomenon that once used to be a particular preoccupation of applied linguists, the interference error Instead, the limelight is now firmly focussed on developmental phenomena, with many studies using an approach to data gathering and analytical methodology strongly reminiscent of research into child language acquisition and language contact There have been specific attempts to establish developmental sequences in the TL, in morpheme acquisition, for instance, so as to compare first and second language learning, and not a little attention is now being paid to such sociolinguistic notions as variability, continua and simplification In other words, the main emphasis in interlanguage research has shifted from a rather static error-oriented view of language learning to a dynamic view of learners' language as a constantly evolving system The calls for longitudinal studies of interlanguage of the late sixties and early seventies have not gone unheeded, eve if the word ‘longitudinal’ is sometimes rather liberally interpreted, as in those cases where a tacit (and probably justifiable) assumption is made that studying groups of learners of varying proficiency in respect of given TL features at one and the same time is really the same as following the progress of one group over a long period
303 citations
01 Nov 1979
TL;DR: This article will first of all review the vitamin A-induced malformations in several organ systems, and will discuss their morphogenesis and the susceptible developmental stages.
Abstract: In the past decade, the toxicology of reproduction has become increasingly important. This branch of toxicology focuses on mutagenic and embryotoxic effects. The study of embryotoxicity requires an extensive knowledge of the interaction of drugs and embryonic tissues, normal and abnormal developmental processes, and the susceptible stages during prenatal development. Hypervitaminosis A is one of the most extensively studied teratogens. It produces defects in almost all organ systems. Therefore, this article will first of all review the vitamin A-induced malformations in several organ systems. Moreover, it will discuss their morphogenesis and the susceptible developmental stages. Thus, the first ten chapters will cover the following subjects: malformations of the nervous system, ocular malformations, malformations of the ear, craniofacial malformations, cleft palate, defects of the circulatory system, defects of the respiratory systems, defects of the digestive tract, urogenital defects, skeletal malformations, and abnormal postnatal development. Since in general little is known about the mechanisms involved in the induction of congenital defects, we think it is of great value to review the knowledge and experience that have been gathered by the experimental work with hypervitaminosis A. Therefore, the next chapters will discuss the following subjects: teratogenic effects in different species, minimum effective dose, interaction with other agents, influence of chemical form, solvent, and route of administration, pathophysiology of vitamin A embryotoxicity, and hypervitaminosis A and human pregnancy.
232 citations
TL;DR: The nature of the difference in skill between the preferred and non-preferred hands was investigated using a peg-board task and the more detailed analysis suggests that motor output of the nonpreferred hand is simply more variable.
Abstract: The nature of the difference in skill between the preferred and non-preferred hands was investigated using a peg-board task. The first experiment examined the effects of varying movement amplitude and target tolerance on performance. The difference between hands was found to be related to tolerance rather than movement amplitude. The second study analysed a film record of well-practised subjects, confirming the hypothesis that most of the difference between hands is due to relative slowness of the non-preferred hand in the positioning phase involving small corrective movements. Analysis of the type and number of errors further suggested that this result is not due to differences in duration of movements but to their increased frequency, implying greater accuracy of aiming with the preferred hand. Thus whilst the initial gross analysis implicated feedback processing in skill differences the more detailed analysis suggests that motor output of the nonpreferred hand is simply more variable.
225 citations
TL;DR: In this article, a one-boson-exchangepotential model is presented, which consists of local potentials due to exchanges of members of the pseudoscalar, vector, and scalar-meson nonets.
Abstract: The $\mathrm{NN}$ and $\mathrm{YN}$ results are presented from a one-boson-exchange-potential model. It consists of local potentials due to exchanges of members of the pseudoscalar, vector, and scalar-meson nonets. SU(3) relations are assumed for the axial-vector couplings of the pseudoscalar mesons, for the electric and magnetic couplings of the vector mesons, for the direct couplings of the scalar mesons, and for the hard-core radii. In the fit to $\mathrm{NN}$ the nonstrange-meson-nucleon couplings are determined. The simultaneous $\mathrm{YN}$ analysis determines the $\frac{F}{D}$ ratios and the SU(3) parameters of the scalar-meson nonet. The description of the $\mathrm{NN}$ data is good ($\frac{{\ensuremath{\chi}}^{2}}{\mathrm{data}}=2.17$), and also of the $\ensuremath{\Lambda}p$, ${\ensuremath{\Sigma}}^{+}p$, and ${\ensuremath{\Sigma}}^{\ensuremath{-}}p$ data up to the pion production threshold. Very close to the $\ensuremath{\Sigma}N$ threshold we find a $\ensuremath{\Lambda}N$ resonance, which is dominantly in the $^{3}D_{1}$ wave. The $\ensuremath{\Lambda}p$ cross section is maximal just below the ${\ensuremath{\Sigma}}^{+}n$ threshold at $E=2128.918$ MeV, in agreement with the experimental results of $\ensuremath{\Lambda}p$ final state interactions. The poles belonging to the $\ensuremath{\Lambda}p$ resonance are located on the second Riemann sheet at $E=2131.77\ifmmode\pm\else\textpm\fi{}i2.39$ MeV.
215 citations
TL;DR: The results suggest that an attachment of the replication fork to the nuclear structure occurs at sites behind but close to the branch point.
Abstract: The attachment of replicating DNA to a rapidly sedimenting nuclear structure was investigated by digestion with various nucleases. When DNA was gradually removed by DNase I, pulse label incorporated during either 1 min or during 1 hour in the presence of arabinosylcytosine, remained preferentially attached to the nuclear structure. Single strand specific digestion by nuclease S1 or staphylococcal nuclease at low concentrations caused a release of about 30% of the pulse label, without significantly affecting the attachment of randomly labelled DNA. The released material had a low sedimentation coefficient and contained most of the Okasaki fragments. The remaining pulse label was less accessible to further digestion by double strand specific nuclease activity than the bulk DNA. The results suggest that an attachment of the replication fork to the nuclear structure occurs at sites behind but close to the branch point.
191 citations
TL;DR: Filtration of AME bilaterally into the dopaminergic A10 area of the VTA induces a short-latency behavioural stimulant effect reminiscent of effects produced by stimulation of the mesolimbic DA pathway, which is antagonised by pretreatment with the opiate receptor blocker naloxone.
Abstract: THE overt behaviour of various species is affected in different ways by opiate drugs. Mice and cats show behavioural stimulation following a systemic morphine injection whereas rats and dogs generally exhibit decreased behavioural activity1–4, although in certain conditions, stimulant effects can also be seen in the latter species4,5. Tatum et al. suggested that there are several distinct sites of action of opiate drugs in brain and that the relative dominance of one system over another determines whether the stimulant or depressant effects predominate4. Indeed, direct microinjections of morphine into the ventral tegmental area (VTA) have been shown to result in facilitation of self-stimulation behaviour whereas similar injections into the periaqueductal gray matter cause only an attenuation of this behaviour6. The discovery of endogenous ligands for opiate receptors in the brain7 has focused attention on the role of these peptides in various aspects of behaviour. Their analgesic properties following intr a ventricular and intracerebral injection are well documented8. Recently, it has been reported that infusion of α-endorphin into the substantia nigra induced stereotyped behaviour9, whereas local injections into the nucleus accumbens of the long-acting synthetic enkephalin analogue, [D-Ala2]-Met5-enkephalinamide (AME), produced an increase in locomotor activity10. We now report that infusion of AME (0.03–2.0 µg) bilaterally into the dopaminergic (DA) A10 area of the VTA induces a short-latency behavioural stimulant effect reminiscent of effects produced by stimulation of the mesolimbic DA pathway11. This effect is antagonised by pretreatment with the opiate receptor blocker naloxone.
184 citations
TL;DR: The 24 carabid species investigated appeared to be polyphagous, but not equally so, and among species showing a smaller degree of polyphagy, oligophages and specialized feeders were distinguished, the latter species specializing on collembolans.
Abstract: The 24 carabid species investigated appeared to be polyphagous, but not equally so. Among species showing a smaller degree of polyphagy, oligophages and specialized feeders were distinguished, the latter species specializing on collembolans. The "phytophagous" genera Amara and Harpalus were found to behave similarly to the generalists. Cannibalism was not observed, although larvae, among which it may well occur, were not studied. Specialists are mainly confined to the Carabinae, and the literature suggests that they can also be distinguished by their morphology and behaviour, which reflect their specialization. It seems unlikely that their specialization is in response to food shortage.
148 citations
TL;DR: In this article, the synthesis and purification of β-1-alkyl glycosides have been investigated and improved so as to permit preparation of 50-100 g amounts, and some relevant properties such as melting point, optical rotation, critical micelle concentration and NMR-spectra have been determined.
135 citations
TL;DR: The intracerebral microinjection technique was used to localize sites in the brain where morphine facilitated the self-stimulation rate at hypothalamic electrode sites and a possible dopaminergic substrate for the opiate induced behavioral stimulation is discussed.
Abstract: The intracerebral microinjection technique was used to localize sites in the brain where morphine facilitated the self-stimulation rate at hypothalamic electrode sites. Bilateral injections of morphine (2 x 1 microgram) into the ventral tegmental area and substantia nigra produced the strongest enhancement at the shortest latencies. At these sites, bilateral injections of 200 ng of morphine also produced a significant enhancement whereas a dose of 50 ng was below threshold for the rate increasing effect. The enhancement by morphine was effectively antagonized by naloxone (5 mg/kg). When injected bilaterally into the same area, D-Ala2-Met5-enkephalinamide (2 x 1 microgram) also induced a strong enhancement of self-stimulation lasting for 70 minutes. A possible dopaminergic substrate for the opiate induced behavioral stimulation is discussed.
122 citations
TL;DR: Using high-accuracy roentgen stereophotogrammetry, some aspects of the three dimensional kinematics of two amputated knee joints have been studied, finding this method to be most effective, in its accuracy as well as in its flexibility aspects.
113 citations
TL;DR: Using hematoxylin-stained cross-sections of phalanges of captured and recaptured toads it is shown that in adult Bufo bufo from the Netherlands year rings are formed, and it is concluded that these year rings can be used for age determination, if the degree of resorption of initially formed year rings is known.
Abstract: Using hematoxylin-stained cross-sections of phalanges of captured and recaptured toads it is shown that in adult Bufo bufo from the Netherlands year rings are formed. It is concluded that these year rings can be used for age determination, if the degree of resorption of initially formed year rings is known.
TL;DR: The stability and homogeneity of the preparation appear to be much better than those of freshly isolated frog rod outer segments, which have been used most frequently so far for experiments on the physiology of rods outer segments.
TL;DR: In this article, the authors derived a closed expression for the orientation dependence of the long range interaction coefficients of linear molecules and then calculated the dispersion and induction multipole interaction coefficients for the systems H2-H2 and H2 He up to R -10 terms inclusive.
Abstract: We derive a closed expression for the orientation dependence of the long range interaction coefficients of Σ state linear molecules and then calculate the dispersion and induction multipole interaction coefficients for the systems H2-H2 and H2-He up to R -10 terms inclusive. The monomer states are described by SCF-LCAO wave functions with polarization functions optimized with respect to the different multipole polarizabilities. The anisotropy factors γ8 and γ10, describing the orientation dependence of the R -8 and R -10 terms, are approximately equal and much larger than γ6, due to the occurrence of the (completely anisotropic) mixed-pole terms.
TL;DR: The neon effect may occur in line patterns made up of elements of different color or brightness as discussed by the authors, and the luminance relations between the different line elements in the pattern and between these line elements and their background appear to be critical for the occurrence of the effect.
Abstract: The neon effect, i.e. an illusion of light projected onto a homogeneous lattice, may occur in line patterns made up of elements of different color or brightness. Particular luminance relations between the different line elements in the pattern and between these line elements and their background appear to be critical for the occurrence of the effect.
TL;DR: It is suggested that a combined urinary thioether and mutagenicity test may be useful in monitoring people occupationally exposed to potentially alkylating compounds, in particular to mixtures of these chemicals.
Abstract: Urinary thioether compounds, such as mercapturic acids, can be considered as nontoxic end products of potentially alkylating agents. On the other hand, urinary mutagenicity may represent the excretion of potential mutagens that have not definitively been detoxified by the organism. It is suggested that a combined urinary thioether and mutagenicity test may be useful in monitoring people occupationally exposed to potentially alkylating compounds, in particular to mixtures of these chemicals. Exposure to cigarette smoke, containing several known mutagens and carcinogens, is expected to interfere with the test results. The excretion of mutagens and thioethers was determined in urine of smokers and nonsmokers. Smokers excrete more mutagens and thioether compounds than nonsmokers. Further, it was found that the urinary mutagenicity and thioether level are significantly related to the amount of cigarettes smoked.
TL;DR: Sedimentation and electron microscopy data make the alleged non-equilibrium state within these populations questionable and the involvement of degraded chains in polymerization is postulated although it is not likely to be the only factor causing aggregation.
TL;DR: This article presents a study on Van Tuijl’s (1975) neon effect, and the efficiency of the neon interpretationrelative to that of alternative interpretations of color differences in line patterns is varied.
Abstract: This article presents a study on Van Tuijl’s (1975) neon effect. The neon effect can be described as an illusory spreading of color around the colored elements of an otherwise black line pattern. The observer has a strong impression of colored light projected onto a lattice of black lines. The hypothesis is advanced that the neon effect will only result if the structural relationships between black and colored line elements in the pattern are such that a neon interpretation is the most efficient interpretation that can be given of the pattern. The necessity of this approach to the neon phenomenon emanates from the inadequacy of alternative, more simple, explanations, such as aberrations of peripheral perceptual mechanisms or the presence in the pattern of easily definable stimulus features. To subject the hypothesis proposed above to experimental test, a precise quantification of its central concept, the efficiency of pattern interpretations, is needed. To that end, Leeuwenberg’s (1971) coding language for sequential patterns is introduced. By means of the coding language, pattern interpretations can be represented in a pattern code, the length of which is inversely proportional to the efficiency of the interpretation coded. Several possible interpretations of color differences between the elements of line patterns are discussed, and it is shown how the efficiency of each of them can be determined. Next, in two experiments, the efficiency of the neon interpretationrelative to that of alternative interpretations of color differences in line patterns is varied, by manipulating the structural relations between black and colored line elements, and the dependency of the neon effect on the relative efficiency of the neon interpretation is demonstrated. Implications of the findings are discussed.
TL;DR: A theoretical introduction to the use of Kalman filtering in analytical chemistry is based on multicomponent-analysis computations with the non-recursive least-squares estimation method as a starting point.
TL;DR: 31P-NMR measurements demonstrate that at 37 degrees C, independent of the photolytic state of the photopigment rhodopsin, the lipids in the photo-receptormembrane are almost exclusively organised in a bilayer.
TL;DR: The metabolism of pipecolic acid has been studied in three patients suffering from the cerebro-hepato-renal syndrome of Zellweger and evidence was obtained that a disturbance in the catabolic pathway was present in all patients.
Abstract: The metabolism of pipecolic acid has been studied in three patients suffering from the cerebro-hepato-renal syndrome of Zellweger. A marked pipecolic aciduria was observed in these patients and serum levels of pipecolic acid were also elevated. Fromin vivo studies evidence was obtained that a disturbance in the catabolic pathway of pipecolic acid was present in all patients. This conclusion was based on the delayed return of the serum pipecolic acid concentration to the fasting concentration after oral loading of the patients withdl-pipecolic acid. Moreover, no increase in the excretion of α-amino adipic acid was observed in the patients after loading, in contrast with the control subjects, who showed a marked increase in the excretion of this metabolite of pipecolic acid. Further evidence for the presence of a metabolic defect in the catabolism of pipecolic acid was obtained from the observation that patients excreted significantly higher amounts of pipecolic acid during the loading experiment.
TL;DR: Scanning electron microscopy showed that the maturation process is accompanied by an increase in cell size and a shortening and eventual loss of microvilli at all levels of maturation.
Abstract: SUMMARY
Cyclic AMP levels have been determined for the first time in isolated keratinocytes. Values were more reproducible than those reported using epidermal slices. Evidence is presented to show that damage to hormone receptors is minimal.
Other observations include the following:
1
Keratinocytes from psoriatic lesions showed reduced ‘resting’ levels of cyclic AMP as well as a diminished response to adrenaline.
2
Cyclic AMP levels were maximal in the basal cells, falling dramatically in fully differentiated keratinocytes.
3
The topical application of a corticosteroid (fluocinolone acetonide) did not modulate the response of adenyl cyclase to hormonal stimulation.
TL;DR: Using LCAO-SCF wave functions on the monomers and a non-empirical Unsold procedure for the second-order properties as discussed by the authors, they have calculated the (2 l ) multipole moments (up to l=6), the (l,l') multipole polarizabilities ( up to l + l' = 6) and related long-range coefficients describing the electrostatic, induction and dispersion interactions for the different azabenzene molecules.
Abstract: Using LCAO-SCF wave functions on the monomers and a non-empirical Unsold procedure for the second-order properties we have calculated the (2 l ) multipole moments (up to l=6), the (l,l') multipole polarizabilities (up to l + l' = 6) and the related long-range coefficients describing the electrostatic, induction and dispersion interactions for the different azabenzene molecules. The agreement with available experimental data is good, in particular for the dipole polarizabilities. The anisotropy of the long-range interaction potential is dominated by the electrostatic contributions, although the dispersion terms, especially the mixed-pole terms (l≠l') for even n (C8, C10), also contribute significantly; the induction energy is rather small. The π contributions to the polarizabilities and the dispersion interactions are found to be larger than earlier estimates. Moreover, it is shown by calculating the dipole polarizabilities of some (aza)naphthalenes and (aza)anthracenes, that a bond polarizability model ca...
01 Jan 1979
TL;DR: Hydroxylamine derivatization of retinals affords two reaction products in a ratio of about 3:1, and preparative high-pressure liquid chromatography allows isolation of both Products in a pure form.
TL;DR: It is concluded that the capacity to synthesize NA is developed even before the “medullary” cells have reached the cortical “anlage” and that this phenomenon might indicate the induction of PNMT by glucocorticoids secreted by the fetal cortex.
Abstract: The cellular localization of the enzymes tyrosine hydroxylase (TH), aromatic amino-acid decarboxylase (or dopa decarboxylase, DDC), dopamine beta-hydroxylase (DBH) and phenylethanolamine N-methyltransferase (PNMT) in the adrenal medulla of adult rats and rat fetuses (14th, 17th, 18th, 19th and 21st day) was examined In the prenatal stages the medullary blastema and an adjacent part of the primitive sympathetic trunk were also investigated Tissues were fixed in ice-cold 4% paraformaldehyde in 01 M phosphate buffer (pH 72) Cryostat sections (10 micron in thickness) were stained by the indirect immunofluorescence technique Rabbit antibodies to TH (isolated from human pheochromocytoma), DDC, DBH and PNMT (the latter three isolated from bovine adrenal medulla) were used Sections incubated with serum of non-immunized rabbits were used as controls In the adult adrenal medulla, two cell types can be distinguished One cell type contains only TH, DDC and DBH The other cell type contains PNMT in addition It is concluded that these cells correspond to the noradrenaline-(NA-) and adrenaline- (A-)storing cells respectively In all prenatal stages TH, DDC and DBH are found in the primitive sympathetic trunk, in the medullary blastema, and in the medullary cells which have migrated into the cortical "anlage" PNMT is observed for the first time on the 18th day Moreover, PNMT could only be demonstrated inside the adrenal gland From these observations it is concluded that the capacity to synthesize NA is developed even before the "medullary" cells have reached the cortical "anlage" On the contrary, the capacity to synthesize A seems to be acquired only after this contact is established The hypothesis is put forward that this phenomenon might indicate the induction of PNMT by glucocorticoids secreted by the fetal cortex
TL;DR: The rat was used as a model for studying the effect of tubal obstruction on the middle ear and the final result shows a near-totally obliterated middle ear cavity resembling the atelectatic middle ear in humans.
Abstract: The rat was used as a model for studying the effect of tubal obstruction on the middle ear. Animals raised under conventional conditions, SPF- and germ-free animals were used. The predominant findings were: (1) Tubal occlusion causes an effusion of serous fluid into the middle ear cavity and promotes the pathological behaviour of pathogen and non-pathogen symbionts of the middle ear cavity. (2) The germ-free animal is an excellent model for studying the isolated effect of tubal obstruction without the interference of infectious disease. (3) The middle ear reacts towards tubal obstruction by a tendency to resorb and to organize the fluid by phagocytosis and fibrosis of the cavity. Transformation of the epithelium into mucus-producing cells was observed only in those animals which developed a middle ear infection after occlusion. (4) The final result shows a near-totally obliterated middle ear cavity resembling the atelectatic middle ear in humans.
TL;DR: In the present model parameters are introduced which allow an overall description of the complex morphological and physiological structure of the nerve trunk which is a rather promising tool in studying the main properties of compound action potentials.
Abstract: A computer model for the simulation of compound nerve action potentials, based on superposition of volume conducted single nerve fibre potentials, is presented. The model assumes that the intracellular fibre potential, the fibre diameter distribution and the electrical conductivities of different tissues are known. Volume conductor fields are calculated in the spatial frequency domain. The influence of important parametrrs in the model is evaluated numerically. It is shown that it is necessary to give up the usual assumption of homogeneity and isotropy in the extracellular medium. In the present model parameters are introduced which allow an overall description of the complex morphological and physiological structure of the nerve trunk. Simulation results indicate that the model is a rather promising tool in studying the main properties of compound action potentials which up till now have not been sufficiently well understood.
TL;DR: It is concluded that hydrostatic and osmotic gradients are not comparable when they are applied to gallbladder epithelium.
Abstract: The hydraulic conductivity of rabbit gallbladder epithelium has been studied using a continuous volumetric method based on capacitance measurements. The time resolution for measuring osmotic flows is in the range of seconds. Volume flows have been induced by osmotic gradients between 0 and 100 mosmol. In this range the flow-force relation is linear and thePf value is 9.3×10−3 cm/sec. After correction for solute polarization effects, thePf value amounts to 0.05 cm/sec. The observed flow is constant between 5 sec up to 20 min after a sudden increase in the osmolarity of the mucosal solution. The wet weight of the gallbladder tissue decreases by 22% and increases by 30% during osmotic flows from serosa to mucosa and from mucosa to serosa, respectively. Volume flows induced by hydrostatic pressure gradients on the mucosal surface are linearly related to the driving forces between 0 and 40 mbar. ThePf value is 0.15 cm/sec. The volume flows are constant between 2 sec and 15 min after pressure application. The flow-force relation for pressure gradients on the serosal surface is markedly nonlinear for gradients greater than 5 mbar. Below 5 mbar thePf value is 4.5 cm/sec. From electrical measurements, e.g., resistance and streaming potentials, and from flux studies with inulin and polyethylene glycol 4000, it is concluded that hydrostatic and osmotic gradients are not comparable when they are applied to gallbladder epithelium. They induce volume flows across different pathways, e.g., osmosis predominantly across the cellular route and pressure filtration predominantly across paracellular routes.
TL;DR: Bovine rod outer segments (rods), isolated with an intact plasma membrane and a stable calcium exchange and storage capacity, contain 2-3 mol endogenous calcium/mol rhodopsin and the calcium metabolism of these organelles has been studied.