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A population of wild Rattus rattus living in the roofs of the laboratory buildings was studied by supplying food every evening and watching the behaviour of the animals at the feeding place. Some observations were also made on caged animals. The rats were predominantly of the black rattus variety but white-bellied greys appeared now and then. In breeding tests the grey colour behaved as though determined by a single recessive gene. The study covered two periods of approximately 9 months each, separated by an interval of 3 months during which a reduced quantity of food was provided and the rat population underwent a major decline. During the two periods of richer feeding the population first increased and then stabilized at a level where the animals remained in good condition and there was no starvation. In the first 9-month period, stabilization was achieved by emigration of young adults who colonized neighbouring buildings. Towards the end of the second period, stabilization was achieved by limitation of breeding. The rats accepted a wide variety of foods, including meat, and a number of instances of predation were seen. Small vertebrates as well as insects were killed and eaten. Small pieces of food were usually eaten in situ but large bits were taken up to the nests in the roof. Such differential treatment in relation to size may be a factor of some importance in the evolution of hoarding. The rats visiting the feeding place formed a unit with a definite social structure. A single dominant male and never more than one, was always present and in certain circumstances a linear male hierarchy was formed. There were usually two or three mutually tolerant top ranking females who were subordinate to the top male but dominant to all other members of the group. Within the group attacks were directed downwards in the social scale. An attacked subordinate either fled or appeased and serious fights therefore did not develop. The most essential component of the appease. ment appeared to be a mouth to mouth contact which may be derived from the infantile pattern of 'mouth suckling'. Appeasement permitted superior rats to maintain their status without the necessity of carrying attacks on subordinates to the point where actual hurt was inflicted. A group territory round the feeding place was defended against interlopers. Both sexes took part in chasing out intruders but since males showed inhibition in attacking females, the exclusion of strange females was due principally to the activities of the home females. The point at which pursuit of an intruder stopped was regarded as the territorial boundary. This was also the limit beyond which a group member would not allow himself to be chased but it was not a prison wall. When agonistic tendencies were not aroused the animals no longer always I turned back at the boundary and foraging beyond its limits allowed them to become familiar with an area larger than the territory. Although intruders were normally driven out, it was occasionally possible for a particularly determined animal of either sex to force its way in and ultimately become a member of the group. The patterns of behaviour seen are described, particularly those concerned with hostile encounters and with mating. Scent marking with urine drip trails was not seen but adults of both sexes marked by rubbing the cheeks and ventral surface on branches. The circumstances in which tooth gnashing was heard suggest that this behaviour is not a form of threat but a response to unfamiliar auditory or visual stimuli. There was some evidence that it functioned as an alarm signal within the group. Pilo-erection and a gait or posture with the hind legs much extended ('stegosauring') are considered to function as threats. Pilo-erection occurred in situations where there was little to suggest conflict and is considered to represent a form of threat which has undergone emancipation. Various forms of displacement and ambivalent behaviour were seen. Rapid vibration of the tail occurred in thwarting situations, either during mating or when a defeated opponent suddenly vanished. There was no evidence that it acted as a signal. The common form of amicable behaviour was social grooming. Another amicable action was sitting together with the bodies in contact. Animals reared in cages remained shy and wary and even hand reared young developed the usual alarm responses to movement and noises. Females had their first litters at ages of 3 to 5 months. For first litters gestation periods were 21 to 22 days but in females that were simultaneously lactating they ranged from 23 to 29 days. Eight was the commonest litter number and ten the highest recorded. At birth the tail is very much shorter than the body but has outstripped it by the time the youngster emerges from the nest. This was found to be the result of a period of extremely rapid tail growth immediately preceding emergence. In Rattus norvegicus the peak in tail growth rate was found to be later and less striking. The difference is interpreted as related to the importance of the tail in climbing in the more arboreal R. rattus. During the second week of life an edge response (retreat from a declivity) and a clinging response made their appearance: these have the function of preventing accidental falls from a nest situated above ground level. Mouth suckling was seen only during a period of a few days towards the end of lactation. Play developed within a few days of emergence from the nest: locomotor and fighting play were the common types. Older animals occasionally joined in play with the young. In problem solving tests, first solutions were not insightful but once a solution had been found, the successful technique was at once adopted and subsequently perfected. There was no evidence of learning by imitation but the rats did learn from each other's behaviour that food could be obtained at a certain location and thus the solution of a problem by one rat accelerated its independent solution by others. The reasons for the differences between the behaviour of the free living population and the caged animals studied by other authors are discussed.
One of the earliest consequences of slicing plant storage organs such as potato tubers into thin disks is the formation of polysomes, which in potato slices is complete after 9 hours and is dependent on transcription. Fresh disks do not incorporate 32P, 3H-uridine or 14C-leucine into their ribosomes, whereas ribosomes and polysomes of aged disks use these precursors effectively. This development can be completely blocked by actinomycin D. Among the different RNAs synthesized during aging is 28S- and 16S—rRNA, 5S—RNA, tRNA, and a component sedimenting around 15—18S with a base-composition different from 16S—rRNA, 5S- and 4S—RNA and which supports peptide formation in an in vitro incorporation system.
It is suggested that this compound represents mRNA, which is not available immediately after slicing the tissue. These findings are consistent with the view of a derepression phenomenon in sliced storage tissue.
An upper limit to the electric field strength, such as that of the nonlinear electrodynamics of Born and Infeld, leads to dramatic differences in the energy eigenvalues and wave functions of atomic electrons bound to superheavy nuclei. For example, the 1s1/2 energy level joins the lower continuum at Z=215 instead of Z=174, the value obtained when Maxwell's equations are used to determine the electric field.
The morphology of green and blue feathers of the Rose-faced Lovebird (Agapomis roseicollis) is described from light-, fluorescence-, and electron microscopical findings and discussed in relation to earlier works. The description is intended to provide a basis for future comparative studies. Special attention is given to the colour-producing elements (pigments and the short-wave reflecting spongy structure ('Blaustruktur', 'cloudy medium') of specialized medullary barb cells (spongy cells, box cells)), and the findings are correlated with macro- and microspectrophotometric measurements. Green barbs differ from those of blue ba rbs in having their cortex yellow pigmented, but are further distinguished by their spongy structure which is denser (wider keratin rods and correspondingly narrower air-filled channels) than that of blue barbs. This difference corresponds to the wave-length of maximum reflectance being shifted c. 30 nm towards longer wave-lengths compared to that of blue barbs. Thus green barbs are not the same as blue barbs only with a yellow pigmented instead of an unpigmented cortex, as usually stated. Dark green hack feathers reflect approximately half as much light throughout the visible spectrum as do green belly feathers. This difference is due to variations in yellow and black pigmentation of the barbules. These variations are described quantitatively and the importance of barbules for the resulting feather colour is stressed. Variation in size and shape of barbs and barbules are discussed, principally in relation to their optical efIects and the presumed functions of the colours. The colour produced by the spongy structure cannot be explained by Tyndall (Rayleigh) scattering as is usually done. This follows from the shapes of the barb reflectance spectra which are not in agreement with the Rayleigh equation (scattering inversely proportional to lambda4). A new model for colour production is forwarded. It is based on a model of the spongy structure in which this is considered to consist of short hollow keratin cylinders (diameter 0.3-0.35 ft) with air-filled cores. Backscattering from these cylinders is considered responsible for colour production and good agreement is obtained between values of lambda max calculated from the model and those measured spectrophotometrically. The backscattering from the Individual cylinders can be regarded as an Interference phenomenon. The colour of the spongy structure thus is an interference colour. That it appears diffuse and not iridescent, as is generally the case for interference colours in feathers, is due to the presence of many hollow cylinders oriented in all directions in the spongy structure.
The aim of any Automatic Translation project is to give a mechanical procedure for finding an equivalent expression in the target language to any sentence in the source language. The aim of my linguistic translation project is to find the corresponding structures of the languages dealt with. The two main problems that have to be solved by such a project are the difference of word order between the source language and the target language and the ambiguous words of the source language for which the appropriate word in the target language has to be chosen. The first problem is of major linguistic interest: once the project has been worked out, it will give us the parallel sentence structures for the two languages in question. Since there is no complete analysis of any language that could be used for the purpose of automatic translation, we decided to build up our project sentence by sentence. The rules which are needed for translating each sentence will have to be included in the complete program anyway, and the translation may be checked and corrected immediately. The program is split up into subroutines for each word-class, so that a correction of the program in case of an unsatisfactory translation does not complicate the program unnecessarily.
The potential energy surface has been calculated by two methods which are compared with respect to spontaneous fission. In the first one essentially the sum of the single particle energies is computed as was done in a previous paper3 while in the second one the Strutinsky technique of renormalizing to a liquid drop model has been applied. Also the half-lives for electron capture are investigated together with the predictions of the half-lives for spontaneous fission and α-decay. The results support the existence of superheavy nuclei in the regions around Z = 114 and Z = 164.
The nuclear charge form factgr from the high-energy elastic electron scattering on 6Li has been calculated from the modified independent-particle shell model (IPSM) wave function. The usual harmonic oscillator type IPSM wave function has been modified by the inclusion of a nucleon-nucleon correlation function which involves extra-core nucleons only. The technique is extremely simple and provides an excellent agreement with the experimental data.