Half Of Field Research Articles

Dianion triplet of 9,9′-bianthranyl

The formation of the dianion triplet of 9,9′-bianthranyl was observed at low temperature. The absorption spectrum of the monoanion implies that an electron is localized in one of anthranyl rings, and in the case of dianion two electrons are localized in both rings. The temperature dependence of the ESR signal at half field suggests that the triplet dianion has many configurations compared with the singlet dianion.

Spatial summation in color-receptive pathways

Spatial summation in human color vision was studied by measuring color discrimination thresholds with bipartite fields that had a varying amount of blur of the half field's dividing line. Thresholds were determined as a function of the width of the color gradient at different field sizes, with three colors and at several luminance levels. From the results the integration width in the red, and green-sensitive pathways is estimated. It is further concluded that the distribution of light-dark boundaries in the colored pattern controls spatial summation in the color-receptive channels of the visual system.

Paramagnetic resonance of Fe 2+ in KMgF 3

An isotropic paramagnetic resonance of Fe 2+in KMgF 3 has been observed at low temperature. From the relatively sharp resonances associated with the double quantum transition and with the half field line it is deduced that the g-value is 3.36 instead of the value of 3.53 predicted by second order crystal field theory. The difference is attributed to a combination of the dynamic Jahn-Teller effect and the effect of covalency both of which reduce the orbital contribution to the g-value.

Superiority of right visual half-fields in right-handers for recall of digits presented at varying rates

Right-handers exhibit a consistent superiority of the right visual half-field for recall of digits; this superiority may reflect the more direct connections between the right visual half field and the speech areas of the left hemisphere. Seven digits were presented in each trial, with four digits at the point of fixation and three in either the left or right visual half-field. The first six digits were presented in pairs, with one digit at fixation and one in the half-field, followed by one additional digit at fixation. The greatest asymmetry occured at the faster presentation rates and for right-handers without family history of sinistrality.

The Half Field Line of Tetrakis(Dimethtlglyoximato)Dicopper(II) in Glasses

Abstract We have reported recently the finding1 of triplet state EPR spectra in glasses of tetrakis(dimethylglyoximato)dicopper(II) in ethyl alcohol (a.) at 77°K. Now we wish to report the resolution of the half field band (HMIN) and the observation of metal and ligand nuclear hyperfine structure on this band. In previous studies of half field lines, the metal nuclear hyperfine has been sufficiently2,3,4 clear to interpret only in a few cases and the ligand nuclear hyperfine has never been observed before.

Changes in pattern-evoked responses in man associated with the vertical and horizontal meridians of the visual field.

1. Averaged responses have been recorded from an array of ten scalp electrodes over the occipital cortex in man to the reversal of a black-and-white checkerboard pattern, presented in different octants of the visual field.2. In all subjects a prominent wave was seen, with a peak latency of about 100 msec, which showed consistent and systematic changes with variation in the position of the stimulus in the visual field.3. With stimulation of the octants next to the vertical meridian, this component was of large amplitude, while with stimulation of the octants next to the horizontal meridian, it was small and inconspicuous.4. With upper field octants, the peak at 100 msec was surface-negative, while with lower field octants it was reversed in polarity.5. The occipital response was largest 5 or 7.5 cm above the inion, and the amplitude recorded 3 cm lateral to the mid line was larger over the hemisphere contralateral to the half field being stimulated than ipsilaterally.6. These findings are discussed in relation to the underlying anatomy of the visual cortex, and it is concluded that these responses are likely to arise mainly from extra-striate areas.

Vocalization possibly initiated by the minor hemisphere.

NEUROLOGICAL evidence has favoured the view that language is a function of only one of the cerebral hemispheres, usually the left hemisphere in right handed people. This aspect of cerebral dominance has been studied in experiments in which it was possible to examine each hemisphere separately for its ability to comprehend language1–2. The subjects in these experiments were patients who had undergone forebrain commissurotomy during therapy for epilepsy3. After such surgery the inter-hemispheric transfer of highly structured visual information is abolished and each hemisphere is restricted to that gained through its primary projection pathways. These subjects were unable to give verbal reports of words presented tachistoscopically in the left visual half field—that is, when the relevant input was to the minor hemisphere. Objects corresponding to the words could be retrieved by touch with the left hand, however, so the minor hemisphere was capable of some measure of comprehension. It was suggested that the lateral specialization lies more in expressive function than in comprehension. After removal of the dominant left hemisphere, a patient has been reported4 to be able to comprehend simple instructions. He could also articulate words and simple phrases. This case may be an exception to the observation that the minor hemisphere is incapable of initiating speech, but, alternatively, the minor hemisphere may be prevented from doing so normally by the influence of the major. If so, speech could perhaps be elicited from the minor hemisphere of the commissurotomy patients in certain conditions. We have used long exposures in the left visual field to take advantage of the effects of temporal summation, while visual input to the major hemisphere is minimized.

Fluorescence and Phosphorescence in Various Proteins (Excited States in Proteins and Tissues)

AbstractAt least four different excited states were observed in various proteins under uv excitation; one with a band peaking at wavelengths around 410 nm and one band which peaks at around 370 nm. The former is ascribed to CO bonds since a very similar band appears in many highly purified materials not containing aromatic rings but only CO or peptide bonds; such as polyglutamic acid, cyclohexanone, acetamide and some sugars, for instance. This band is observed in many proteins and can also be excited with 365 nm. The 370 nm band appears preferentially in proteins of globular structure and is excited only in a relatively narrow excitation band around 310 nm.The blue is always accompanied, in proteins as well as in the above‐mentioned non‐aromatic compounds, by a short‐living (∼0.5 sec decay time at 77°K) phosphorescence, with slightly larger wavelength than the fluorescence. There is further a long‐living phosphorescence band (decay time several seconds at 77°K) also in the blue. Its decay time is strongly dependent upon the environment. It is observed in many globular proteins and in non‐protein CO containing materials, but not in fibrous proteins such as collagen, as yet. Its decay time is particularly long in globular proteins such as in eggwhites. In cyclohexanone‐Me‐pentan solutions the lifetime of this band is long, in EPA glass it is much shorter. The species from which the longtime phosphorescence originates could be picked up as EPR signals by the half field strength method.For all materials investigated (proteins, tyrosin, cyclohexanone) the g‐values are the same, but they depend on the environment, indicating a strong interaction with the surroundings. In Me‐pentan solutions the g‐value is smaller than in the solid material. Prolonged irradiation reduces the concentration of these excited species. Because of the various decay times and their dependence on the environment, many proteins do not exhibit a decay composed of one or two exponentials, but display a more complicated decay.

Apparent individual differences in channel capacity

Two experiments are described which suggest that human subjects can respond independently to stimuli presented in opposite half fields. Individual differences in the ability to achieve such independent responses are related to personality variables and it is suggested that subjects who are able to process two stimuli achieve this by inhibiting the interhemisphere transfer of some part of the central organizing processes involved.

NEURAL LIMITATIONS OF VISUAL EXCITABILITY. VII. NONHOMONYMOUS RETROCHIASMAL INTERACTION.

Visual excitability changes were obtained from two trained observers by measuring threshold with a brief test flash of light at varying temporal intervals from the onset of a longer, supraliminal conditioning flash. The test target was either a 1°20' or a 5°20' solid disc, and was exposed to the right eye at 6°40' along the horizontal meridian in the temporal half field. The conditioning target was a 6°40' disc containing central masks of various angular subtenses, and was so placed in the left eye that the resulting annuli surrounded the test target in the binocularly fused field of view. For all conditions, threshold rose when test preceded conditioning flash in time, reaching a maximum at about o-msec interval between onsets. As the test flash was progressively delayed in time, thresholds fell to an asymptote, returning to resting level after termination of the conditioning flash. The smaller the mask diameter in the center of the conditioning target, i.e., the tighter the fit around the binocularly fused test target, the greater the maximum rise in threshold in the other eye. With small test targets, greater threshold changes were produced by conditioning targets with small masks than by those without a mask (solid targets). Observations on a third observer indicate that similar findings obtain when conditioning stimuli are equated for total luminous flux. These data indicate that retrochiasmal interaction is greater at target borders, and are compatible with recent unit studies on the cortical receptor field.

Paramagnetic Resonance of Divalent Iron in Calcium Oxide

Paramagnetic resonance of divalent iron in single crystals of CaO has been observed at 4.2° and 2°K. The features of the resonance spectrum are: (1) a broad line at g≃3.30; (2) a narrow resonance superimposed upon the broad line at g=3.298±0.002; (3) an asymmetric line at half field with a high-field cutoff at g≃6.58. At 4.2°K the double quantum transition exhibits an anisotropic behavior with microwave power and orientation. There is evidence of tetragonal distortions about the Fe2+ ion which coincide with the cubic crystal axes. These distortions cannot be ascribed with any degree of certainty to Jahn—Teller splitting.

Equality of Velocity of Gamma-Rays of Opposite Circular Polarization in a Transverse Magnetic Field

Results are reported from an investigation of the influence of the magnetic field on the propagation of light. The Mossbauer effect was used in a study on the equality of velocity of gamma rays of opposite circular polarization in a transverse magnetic field. The source, about 80 mc of cobalt- 57 diffused into the iron foil and giving the Mossbauer radiation of 14.3 Kev, and the pure natural iron absorber were placed in front of the two opposite melanex windows on the cyclotron vacuum chamber in which a pressure of 10/sup -5/ mm mercury was maintained through the experiment. The absorber was followed by a PX 130 xenon-filled proportional counter, the output of which was fed into a single-channel pulse height analyzer selecting the 14.3Kev gamma -ray peak. The scaler input was gated with a crystal controlled timing circuit, accurate to better than one part in 10,000. In the course of the experiment, the half-field absorber transmission was compared with the full-field transmission in frequent alternation and the corresponding counting rates, hereafter called HF and FF, recorded. Both HF/FF ratios deviate from unity and there is an increase of absorption at full field. The increase is not due to themore » effect of the magnetic field on the counter. This effect is due to the fact that, although at half field the absorber material reaches a high degree of magnetization, the complete saturation is not yet attained. Thus, there is an increase in absorption when the polarizing and analyzing field changes from its half field value of 1,250 oersteds to the full field value of 2,500 oersteds, when the material has reached the magnetic saturation. (C.H.)« less

Transfer between the hands of a mirror-image tactile shape discrimination.

A SHAPE like that of the figure C is seen as a C in both the right and left halves of the visual field by adults. It is not seen as a C in, say, the right and as a C in the left half field. One may ask whether such an identity of the perceived shape in the two half fields is given by the structural organization of the sensory system, or whether it is the result of some learning process. To answer this question would require subjects without experience of shape and object discriminations, and yet able to perform such discriminations. Monkeys were selected as experimental subjects, and tactile discriminations were used in order to minimize the effect of previous experience with shape discriminations. In brief, the animals were trained to discriminate by touch with the left hand between the solid shapes C and C. they were afterwards tested for their preference between the same two shapes with the right hand.

EXPERIMENTAL STUDIES OF THE EFFECT OF WIND ON PLANT GROWTH AND ANATOMY

From results (Whitehead, I957) showing that wind has the effect of reducing water balance in the leaves it was considered that the anatomical and morphological changes described in the previous two papers were probably related to a reduction of relative turgidity in the leaves. This arises because the rate of water lost from the leaves is greater than the rate of water transported from the roots. It would be expected that rather similar conditions of disturbed water balance could be produced under lower transpiration conditions if the uptake of water by the roots were restricted by reducing the moisture content of the soil. Experiments were therefore carried out to see whether, under conditions of increasing soil moisture tensions, morphological and anatomical changes comparable to those arising in response to wind treatment might be produced. Seeds of Helianthus annuus var. Pole Star were planted in beakers as previously described and were selected for uniformity of size at the first leaf stage leaving one plant per beaker. In four lots of five beakers the sand was adjusted to field capacity, half field capacity, one-quarter field capacity and one-eighth field capacity respectively. The surface of the beakers was covered by a polythene disc and the drainage hole plugged to reduce evaporation. The beakers were weighed and were kept at the initial weight throughout the experiment by the twice-daily addition of the appropriate weight of water. The plants were kept in the greenhouse under similar conditions to those described in the previous papers. After 38 days of growth all the soils were brought up to field capacity, sealed to prevent undue evaporation and the beakers placed in the wind tunnel in a wind of 40 miles/hour. This wind speed is beyond the limits of tolerance for this species and the leaves eventually become desiccated despite the roots being in conditions of optimum moisture. The desiccation may be observed by a colour change to a darker green/black shade. Experience has shown that there is no recovery of plants when this colour change has occurred over half the area of the lower leaves (at this point the youngest leaves have completely changed colour). This point is termed the 'death' point in this experiment. The times were taken at which 'death' occurred for all the plants and these are shown graphically in Fig. i. It will be seen that 'death' occurred relatively quickly in the plants grown at field capacity and at one-half of field capacity. The plants grown at one-quarter of field capacity took about three times as long an exposure to the wind to reach the same stage. Whilst for 'death' to occur to the plants grown at one-eighth field capacity it was necessary to give nearly ten times as long an exposure as that fatal to the plants grown at field capacity.

Fast refractive infrared optical systems

Aplanatic-concentric surfaces afford a means of assuring excellent axial definition at quite large relative apertures with high index refractive material. In one particular form of objective reported, a diffraction-limited axial image at f/0.7 is obtained, and definition equivalent to a minimum circle of confusion diameter of 1.5 mrad in a five inch f/1.0 lens over a 7.5° half field on a curved image surface is obtained. In another form with flat field, essentially the same performance is secured, but at a sacrifice in compactness.

Relativity and quantum theory

It is shown that Einstein’s generalized theory of gravitation as modified by the author contains integral and half integral spin fields. A constant of the dimension of a length plays a basic role in distinguishing between Boson and Fermion type fields.

The science and practice of entomology.

Entomology in Great Britain remained for long enough the care of amateurs. A long line of distinguished naturalists whose chief interest lay with the insects runs through the nineteenth century. There was A. H. Haworth (1767–1833), a lawyer by profession, the founder of the first entomological societies in this country; there was William Kirby (1759–1850), Fellow of Gonville and Caius College and rector of Barham in the county of Suffolk for fifty-eight years, who, with William Spence (1783–1860), produced the standard work on insects that was to hold the field for half a century. There was George Newport (1803–54), physician and surgeon, who published a remarkable series of papers on the anatomy and physiology of insects. There was the lawyer’s clerk and engraver John Curtis (1791–1862) and Miss Ormerod (1828–1901) who, in the second half of the century laid the foundations of agricultural entomology in Britain. There was Sir John Lubbock (Lord Avebury) (1834–1913), worthy of remembrance indeed, for it was he who sponsored the Early Closing Act and gave us our bank holidays. As a relaxation from a most active public life, Lubbock laid the groundwork of our knowledge of the sensory physiology of the Hymenoptera; it was Lubbock who proved that bees distinguish colours and can be trained to associate particular colours with the presence of food; that the vision of ants extends into the ultra-violet; and who suggested, far ahead of his time, that ants find their way home by remembering the direction of the sun.