Showing papers by "University of Oregon published in 1969"

Introduction to Statistical Analysis

Abstract: Introduction to statistical analysis , Introduction to statistical analysis , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی

Perceptual recognition as a function of meaningfulness of stimulus material

Abstract: The present study evaluates a class of models of human information processing made popular by Broadbent. A brief tachistoscopic display of one or two single letters, four-letter common words, or four-letter nonwords was immediately followed by a masking field along with two single-letter response alternatives chosen so as to minimize informational differences among the tasks. Giving 5s response alternatives before the stimulus display as well as after it caused an impairment of performance. Performance on single words was clearly better than performance on single letters. The data suggest that the first stages of information processing are done in parallel, but scanning of the resultant highly processed information is done serially.

Antitrinitrophenyl (TNP) Plaque Assay. Primary Response of Balb/c Mice to Soluble and Particulate Immunogen

Abstract: SummaryA technique was developed for the detection of individual cells producing anti-TNP antibody by the hemolytic plaque technique. Conjugation of TNP directly to the erythrocyte surface by use of TNBS resulted in a stable reagent that permitted a study of the antihapten response to TNP-KLH. It was possible to induce a primary anti-TNP response with soluble TNP-KLH but the response was greater when the immunogen was made particulate by coating it onto bentonite. Both primary and secondary responding cells (those brought out by antiglobulin serum) were inhibited by TNP-BSA added to the plating medium but at an equivalent concentration of hapten only the secondary cells were completely inhibited. This was interpreted to indicate the higher binding affinity of secondary antibody.Author's note. As we were in process of submitting this manuscript, we became aware of an abstract which indicated that responses of similar magnitude to those reported here with TNP could be obtained in Balb/c mice to DNP using a ...

Piezo-Optical Birefringence Modulators: New Use for a Long-Known Effect

Abstract: A general description is given of a long-neglected use for the piezo-optic or photoelastic effect (stress-induced birefringence). An acoustic vibration, such as a fundamental extensional mode in a bar or long thin plate, is set up in a block of isotropic transparent material, such as glass or fused silica; the vibration is sustained by a transducer. The resulting modulated birefringence can be used in a variety of ways, notably to produce a beam of alternately left- and right-circularly polarized light for circular-dichroism measurements. Strains of the order 10−5 are required, considerably below the breakage point for most materials. Because advantage is taken of the high Q of the vibrational modes, typically 103 to 104, very small transducer power is needed, usually less than 1 W. The literally enormous useful angular aperture, of the order 50° total cone angle, makes the device far superior to Pockels or Kerr cells for many applications. Reference is made to current practical realizations and to present and future uses of the device.

The determination of perceived tridimensional orientation by minimum criteria

Abstract: The hypothesis investigated is that the perceived tridimensional orientation of an object is determined, in monocular vision, by tendencies to make the perceived object as simple as possible. Line drawings seen as “boxes” were viewed by Os who judged the slant fangle with frontal plane) of various edges. For every such edge, there is a determinate hypothetical slant consistent with perfect homogeneity of values on one or more of three variables (angle, length, and slope) Perceived slant was highly predictable from hypothetical slant, though always with some regression to the frontal plane. Results add support to aPragnanz or minimum-principle theory of space perception.

Formation of spindle fibers, kinetochore orientation, and behavior of the nuclear envelope during mitosis in endosperm

Abstract: The formation of kinetochore (chromosomal) and continuous fibers, and the behavior of the nuclear envelope (NE) was described in studies combining light and electron microscopy. Microtubules (MTs) “push” and “pull” the NE which becomes progressively weaker before breaking. It breaks to a certain extent due to mechanical pressure. Clear zone MTs penetrate into the nuclear area as dense bundles and form continuous fibers. These MTs also attach to some kinetochores during this process. Some kinetochore fibers seem to be formed by the kinetochores themselves which are also responsible for further development and changes of kinetochore fibers. Formation of kinetochore fibers is asynchronous for different chromosomes and even for two sister kinetochores. Often temporary “faulty” connections between different kinetochores or the polar regions are formed which usually break in later stages. This results in movements of chromosomes toward the poles and across the spindle during prometaphase. The NE, whose fine structure has been described, breaks into small pieces which often persist to the next mitosis. Old pieces of NE are utilized in the formation of new NE at telophase. Several problems concerning the mechanism of chromosome movements, visibility of the NE, etc., have also been discussed.

On Defining Areas of Voter Choice: Professor Tullock on Stable Voting

Abstract: I. Degree of voter agreement, 478. — II. The conditions of noncircular voting, 481. — III. Size of the decision set, 482. — IV. Democratic processes, 485. — V. Conclusions, 486. — Mathematical note, 487.

Formal Power Series

Abstract: (1969). Formal Power Series. The American Mathematical Monthly: Vol. 76, No. 8, pp. 871-889.

Neuronal Network Triggering a Fixed Action Pattern

Abstract: Bursts of impulses in groups of brain cells of the nudibranch Tritonia trigger prolonged swimming that is identical to the natural escape response. The cells in which the activity occurs form two bilaterally symmetrical groups of at least 30 cells in each pleural ganglion. These neurons are interconnected by pathways that have a low electrical resistance, both within a ganglion and across the brain. Together they form a network that determinies whether a swimming escape response will occur or not by filtering out weak neural activity yet responding with a burst of impulses to intensive specific input to either group.

The neural control of swimmeret beating in the lobster.

Abstract: 1. The neural basis of swimmeret beating in the lobster Homarus americanus was studied by recording the cyclic motor output to the swimmeret muscles of intact, unrestrained specimens. 2. The force produced by each swimmeret is regulated by changes in the number of impulses within single motoneurones during each movement cycle, and by changes in the number of motoneurones which discharge during each cycle. Both of these parameters increase with the frequency of swimmeret beating. 3. The burst duration of single swimmeret motoneurones is independent of the frequency of swimmeret beating. The duration of the total electrical activity of each muscle nevertheless increases with the cycle duration, owing to changes in the relative timing of the activities of the motoneurones which innervate the muscle. By this method the forces produced by each muscle are presumably distributed evenly throughout cycles of variable duration. 4. As the frequency of swimmeret beating increases, the movement response progressively lags behind the motor nerve activity. At high frequencies of beating powerstroke motoneurones fire during the returnstroke of the preceding movement cycle because of this phase change, thereby actively braking the swimmeret. 5. Tilting the lobster to one side changes the direction of the powerstroke of each swimmeret on the side tilted upward. This change is achieved by an increase in the activity of muscles which rotate the appendage outward on its long axis, by an increase in the activity of a muscle which directs the powerstroke out toward the side, and by a decrease in the activity of a muscle which directs the powerstroke to the rear. The latter decrease is accomplished through the use of a peripheral inhibitor axon. 6. Under some conditions individual swimmeret motoneurones discharge in continuous trains rather than in bursts. This tonic activity is characterized by the occurrence of a disproportionate number of impulse pairs and triplets, a pattern to which the swimmeret muscles may be especially sensitive. 7. During swimmeret beating, all of the swimmeret motoneurones discharge in cyclic bursts. The temporal structure of the bursts suggests that the underlying excitatory input oscillates sinusoidally with time at the same frequency as that of swimmeret beating.

Polaritons at Surfaces

Abstract: We calculate the reflectivity of light incident upon the exposed face of a semi-infinite crystal, using the point-dipole model. This requires an accurate solution for the polariton modes near the crystal surface. The variation of the Lorentz local field, caused by the surface, is included in the calculations. The boundary conditions for the polariton modes are derived rigorously. This represents the first rigorous microscopic solution of polariton modes near ideal surfaces.

Psychobiology of Sexual Behavior in the Guinea Pig

Abstract: Publisher Summary This chapter discusses the psychobiology of the sexual behavior in the guinea pig. When a female guinea pig is placed with a male, he begins to follow and circle her almost immediately, usually sniffing at the anogenital region. This behavior is called “nuzzling.” Within a few seconds he may mount her, usually posteriorly, but often elsewhere. Frequently, the mounting is accompanied by pelvic thrusts without intromission, but more commonly it is followed by intromission with or without pelvic thrusts. The duration of the pelvic thrusts varies, depending partly on the male and partly on the responsiveness of the female. Following ejaculation, both animals roll back on their haunches and lick the genitalia. The male can be seen to drag his butt along the floor of the cage somewhat like a dog infested with intestinal worms does. Unless the female with which copulation has occurred is replaced by another female ejaculation usually marks the end of any strong interest in the female. A behavior that is displayed by many males is a “nondirected hyper-excitability.” The frequency of this behavior is increased following castration of sexually experienced adult males and its frequency is much greater in intact males reared alone in which the organization of normal patterns has not been perfected.

The mechanics and neural control of the prey capture strike in the mantid shrimps Squilla and Hemisquilla

Abstract: 1. The prey capture strike of Squilla and Hemisquilla has been studied by high speed motion picture photography and by electromyography from the limb muscles of the unrestrained animal. 2. The strike consists of a rapid unfolding of the dactyl, propus and carpus about the merus of the raptorial, 2nd thoracic limb. The prey may be struck by the folded propus-dactyl joint, pierced by the extended dactyl or grasped between the open propus and dactyl. 3. Contact is made with the prey in 4–8 ms, when the animal is underwater, at which time the propus is moving about the merus at an angular velocity of 20,000°·s−1 or at a linear velocity of 10 m·s−1. 4. Acceleration is applied to the limb in less than 1.5 ms and an energy requirement of 1.25×105 ergs is necessary for the strike. This could not be produced by a single muscle twitch. 5. Electrophysiology and experiments in which the strike has been simulated have shown that the strike is produced by the co-contraction of flexor and extensor muscles in the merus operating a ‘click’ joint. The flexor muscles begin to contract first, often 1 s before the strike so pulling a sclerite over a stop on the ventral wall of the merus. This gives them a 900∶1 mechanical advantage over the extensor muscles and allows the extensor muscles to contract almost isometrically and time to reach tetanic tension. The flexor muscles relax just prior to the strike so that the sclerite then snaps over its stop on the merus allowing the stored energy of the extensor muscles to be delivered suddenly.

Centrally Generated Nerve Impulse Sequences determining Swimming Behaviour in Tritonia

Abstract: AN act of behaviour is caused by correlated sequences of motor nerve impulses. These can be determined by pro-prioceptive input (reflexes), by strictly centrally generated programmes, or by a combination of the two. Much earlier work, particularly that on vertebrates1–3, supported the view that continuing sensory input exclusively determines output patterns. This view was not readily compatible with several observations made by ethologists, for example on “fixed action patterns” released by “sign stimuli”, and a search was begun for centrally generated neural patterns. Experimental evidence suggesting such programmes is being found, particularly in invertebrates which have relatively simple nervous systems4–7.

Growth rates and longevity of some gastropod mollusks on the coral reef at Heron Island

Abstract: Information on growth, gained from individually marked animals, is provided for at least one species of each of the families Trochidae, Neritidae, Strombidae, Cypraeidae, Thaisidae, Fasciolariidae, Vasidae and Conidae. Except in the cowries and strombs, which have determinate growth, shell growth is adequately described by a von Bertalanffy curve only to a certain point. Beyond this, growth continues slowly and at a rate that is independent of size. Size frequency distributions are characteristically negatively skew, mainly because early growth is fast relative to the total life span. Longevities seem to indicate that turnover rates are comparable to those of Prosobranch mollusks from colder seas.