New Experiments on Colour Vision in Bees

1939 ◽  
Vol 16 (1) ◽  
pp. 1-8
Author(s):  
MATHILDE HERTZ
Keyword(s):  
Visible Light ◽  
Visible Spectrum ◽  
Ultra Violet ◽  
White Paper ◽  
The Other ◽  
Green Paper ◽  
Violet Light ◽  
Orange Yellow ◽  
Two Peaks ◽  
Do So

Under the condition of full, normal daylight illumination a surface which reflects a fair proportion of ultra-violet, as well as the visible spectrum, is neutral or white in the vision of the bee. If the percentage of reflexion of 3600 A. is less than one-third, or about one-quarter, of the percentage of reflexion in the visible light, a degree of coloration is obtained which is sufficient to be noticed by the bees in training experiments. When both are placed under ultra-violet absorbing filters, white paper in the vision of the bee most closely resembles a blue-green paper that possesses the highest amount of reflexion at 4900 A. Bees which have been trained to visit a blue-green surface covered by a filter glass do not do so any longer, if, by removing the filter, ultra-violet light is added to the reflexion. The paper that possesses now two peaks of maximum reflexion, one at 4900 and the other at 3600 A., appears a light grey to the bee. On the other hand, when bees have been trained to visit an ultra-violet surface--white paper under a filter that absorbs the visible light completely--do not do so any longer if by lifting the filter the whole range of visible light is added to the reflexion of ultra-violet. The white paper at once becomes unattractive to the bee. There remains no doubt, that among the four qualities of colour discriminated by the bee (see Fig. 1) the first and the third on one side and the second and fourth on the other are complementary colours for this insect and presumably for many others. In the European flowers visited by bees three principal colours are now finally known: (1) that colour which is perceived if the main bulk of light reflected by the petals lies between 6500 and 4900 A. (orange-yellow for bee and man), (2) that which is perceived if the reflexion extends from 4900 to 4000 or 3500 A. (blue-violet for bee and man), and (3) that which is perceived if the reflexion extends from 6500 A., or nearer to the red end of the visible spectrum, to 4000 A. (blue-green for the bee, but white, pink, light purple, bluish or yellowish for man). Ultra-violet seems never to occur in European flowers in such a way as to make petals which are brilliantly white for man to appear equally white for the bee.

A Study of the Argentaffin (Kultschitzky) Cells in frozen-dried Tissue by Phase-Contrast Microscopy and Ultra-Violet Light

1955 ◽  
Vol s3-96 (35) ◽  
pp. 289-293
Author(s):  
A. C. CHRISTIE
Keyword(s):  
Phase Contrast ◽  
Ultra Violet ◽  
Phase Contrast Microscopy ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Greenish Yellow ◽  
Orange Yellow ◽  
Photographic Evidence ◽  
Absorption Of Light ◽  
Contrast Microscopy

1. The argentaffin cells in guinea-pig intestine have been studied by phase-contrast microscopy and in ultra-violet light. Frozen-dried tissue has been used. 2. One such cell in a section 5-7µ thick was selected and studied throughout. In an unfixed section mounted in nonane, the cytoplasm is packed with fine granules which emit a greenish-yellow fluorescence in ultra-violet light of wavelength 2,750 Å. There is also photographic evidence of absorption of light of this wavelength. 3. After formaldehyde fixation the fluorescence changes to orange-yellow and becomes much weaker. The absorption of light by the granular cytoplasmic contents is also greatly reduced. 4. There is no fluorescence and no photographic evidence of absorption of light of wavelength 2570 Å by the granular cytoplasmic contents, either before or after formaldehyde fixation. 5. The nuclear chromatin pattern in these cells is unaltered by formaldehyde fixation, and is well demonstrated in photographs taken in ultra-violet light of both the wavelengths mentioned above.

scholarly journals Visible Light as an Antimicrobial Strategy for Inactivation of Pseudomonas fluorescens and Staphylococcus epidermidis Biofilms

Antibiotics ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 171 ◽  
Author(s):  
Valeria Angarano ◽  
Cindy Smet ◽  
Simen Akkermans ◽  
Charlotte Watt ◽  
Andre Chieffi ◽  
...  
Keyword(s):  
Visible Light ◽  
Pseudomonas Fluorescens ◽  
Staphylococcus Epidermidis ◽  
Scientific Community ◽  
Visible Spectrum ◽  
Log10 Reduction ◽  
Gram Negative ◽  
Light Emitting ◽  
Inactivation Kinetic ◽  
Violet Light

The increase of antimicrobial resistance is challenging the scientific community to find solutions to eradicate bacteria, specifically biofilms. Light-Emitting Diodes (LED) represent an alternative way to tackle this problem in the presence of endogenous or exogenous photosensitizers. This work adds to a growing body of research on photodynamic inactivation using visible light against biofilms. Violet (400 nm), blue (420 nm), green (570 nm), yellow (584 nm) and red (698 nm) LEDs were used against Pseudomonas fluorescens and Staphylococcus epidermidis. Biofilms, grown on a polystyrene surface, were irradiated for 4 h. Different irradiance levels were investigated (2.5%, 25%, 50% and 100% of the maximum irradiance). Surviving cells were quantified and the inactivation kinetic parameters were estimated. Violet light could successfully inactivate P. fluorescens and S. epidermidis (up to 6.80 and 3.69 log10 reduction, respectively), while blue light was effective only against P. fluorescens (100% of maximum irradiance). Green, yellow and red irradiation neither increased nor reduced the biofilm cell density. This is the first research to test five different wavelengths (each with three intensities) in the visible spectrum against Gram-positive and Gram-negative biofilms. It provides a detailed study of the potential of visible light against biofilms of a different Gram-nature.

Movement patterns and photosensitivity of Trichonema spp. infective larvae in non-directional light

Parasitology ◽  
1971 ◽  
Vol 62 (3) ◽  
pp. 467-478 ◽  
Author(s):  
N. A. Croll
Keyword(s):  
Visible Light ◽  
Sensory Input ◽  
Ultra Violet ◽  
Movement Patterns ◽  
Light Conditions ◽  
Infective Larvae ◽  
Violet Light ◽  
Significant Difference ◽  
Flashing Light ◽  
Individual Giving

1. Trichonema spp. infective larvae once stimulated move in darkness, dim and bright visible light and ultra-violet light. There was no significant difference between the distances moved in these photic conditions.2. Movement patterns were variable but certain shapes of tracks, rates of reversal and reversing types were typical of certain light conditions.3. The rate of reversing was dependent on light conditions and was random in direction.4. Sensory adaptation was suggested in visible light, but not in ultra-violet at 366 μm.5. Movement analyses in flashing light suggested that pulsating stimuli at intervals of 100 ms or less were required for sensory input approximating to physiologically continuous stimulation.6. Larvae showed an idiosyncrasy in their tracks, repeated tracking with the same individual giving less varied tracks than with different larvae.The author is indebted to Mr J. M. Smith for his painstaking efforts in preparing the tracks and his willing and skilful assistance throughout.

scholarly journals Diet and Tuberculosis

1927 ◽  
Vol 26 (2) ◽  
pp. 204-212 ◽  
Author(s):  
Harry Schütze ◽  
S. S. Zilva
Keyword(s):  
Vitamin C ◽  
Guinea Pigs ◽  
Ultra Violet ◽  
The Other ◽  
Cod Liver Oil ◽  
Large Excess ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Fat Soluble Vitamins ◽  
Intraperitoneal Inoculation

Guinea-pigs living on a diet restricted in quantity but not deficient in vitamin C survived inoculation with T.B. but half as long as others which had received a similar diet in abundance.Sodium chaulmoograte did not inhibit the development of the omental tumour that appears in rats after intraperitoneal inoculation with tubercle bacilli.On the other hand, there was some evidence for assuming that a large excess of fat-soluble vitamins in the diet, as supplied by cod-liver oil, inhibits the formation in rats of these tuberculous tumours, but such evidence was by no means conclusive.Similar inhibition of omental infection was obtained on exposing rats to ultra-violet light.Ultra-violet irradiation or the inclusion of large amounts of cod-liver oil in the diet of the rats produced a slight but constant leucocytosis.No evidence was obtained that lack of fat soluble vitamins in their diet renders tubercle infected rats susceptible to tuberculin shock.

Aging of Stretched Rubber

1928 ◽  
Vol 1 (1) ◽  
pp. 106-112
Author(s):  
Arthur Kelly ◽  
Bert S. Taylor ◽  
Webster N. Jones
Keyword(s):  
Direct Relationship ◽  
Strain Curve ◽  
Ultra Violet ◽  
The Other ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Test Strips ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Early Stages

Abstract Sunlight aging under tension of many compounds including the following has been investigated: tire tread shoe upper, tube stocks, golf ball thread, jar rubber, solid tire, bathing cap stock, channel rubber. With some of these stocks the sunlight aging as been compared with unstretched samples by Geer oven, Bierer bomb, and ultra-violet light methods. The stretching of the test strips accelerates deterioration in sunlight, ultra-violet light, and Geer oven. Stretched samples have not yet been tested in the Bierer bomb. The rate of deterioration was not proportional to the degree of stretch in any of the stocks in the early stages of exposure. In sunlight there is a critical elongation for each stock at which the deterioration progresses more rapidly than at any other in the early stages of aging. No direct relationship was found between the results of sunlight aging and the other methods employed. Stretched strips aged in ultra-violet light were found to give softer stress-strain curves than the unaged samples, whereas sunlight aging under the same conditions stiffens the stress-strain curve.

scholarly journals Application of the Wilson chamber to the study of spark discharge

1935 ◽  
Vol 148 (864) ◽  
pp. 446-453 ◽  
Keyword(s):  
Ultra Violet ◽  
Spark Discharge ◽  
Cloud Chamber ◽  
The Other ◽  
Present Stage ◽  
Expansion Chamber ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Negative Point ◽  
Kerr Cell

The usual methods of investigating the problems related to the phenomenon of spark discharge may be classified into two kinds. The first is to measure the potential and current or their variations with respect to time, which may be called "electrical." By this means we know only the signals transmitted from the spark. The second method is optical, to which belong the photographic and spectrographic investigations as well as the method using a Kerr cell. These methods give us information on the spark itself, but they are confined to the problems accompanied with the emission of light. For observing a process of discharge that does not accompany any luminous phenomenon, the use of Professor Wilson's cloud chamber seems to be the only method suitable for the for the purpose at our present stage of knowledge. As a matter a fact, already in 1899 Wilson, using an expansion chamber of the earlier type, had investigated the formation of ion clouds by the positive and negative point discharges. Since then no communication seems to have been published on the formation of ion clouds by an electrical break-down process until recently, when the present authors and Snoddy and Bradley published independently the reports of their experiments of this subject. Several years ago one of the present authors, under the direction of Professor T. Terada, engaged, in a study concerning the form and structure of long electric sparks. He then succeeded, using a quartz-fluorite ions, in taking a photograph of the brush discharges immediately preceding the main spark. This preceding discharge is rich in ultra-violet light, and more complicated and extended in its form than the succeeding main spark, appearing as appendages to the luminous spark track. This result led him to look for the other form of discharge which cannot be photographed even with the quartz-fluorite lens. Then, on the suggestion of Professor T. Terada, he tried to take a Wilson photograph of ions produced by a spark, but did not succeed in obtaining a satisfactory one. Later on, in the course of conversation with Professor Wilson at Cambridge he was given a great deal of advice on this problem and decided to take up this subject again.

DRIED MILK POWDER: V. THE PHOTOLYSIS OF RIBOFLAVIN IN MILK POWDERS

1946 ◽  
Vol 24f (2) ◽  
pp. 123-129 ◽  
Author(s):  
W. A. Bryce
Keyword(s):  
Absorption Spectrum ◽  
Visible Light ◽  
Spectral Region ◽  
Wave Length ◽  
Milk Powder ◽  
Skim Milk ◽  
Ultra Violet ◽  
Wave Band ◽  
Violet Light ◽  
Whole Milk

Exposure of milk powders to sunlight resulted in a much greater destruction of riboflavin than did exposure to ultra-violet light in the range 3200 to 4200 Å. The rate of photolysis was greater for skim-milk powders than for whole milk powders. Increased intensities of visible light accelerated riboflavin destruction. In the spectral region of 4200 to 5600 Å the wave band causing the greatest destruction in liquid skim-milk had a principal wave-length of 4450 Å, which corresponded to a maximum in the absorption spectrum of riboflavin. The rate of photolysis of riboflavin was a function of both wave-length and intensity of the impinging energy.

Studies on embryonic determination of the harlequin-fly, Chironomus dorsalis. II. Effects of partial irradiation of the egg by ultra-violet light

Development ◽  
1964 ◽  
Vol 12 (1) ◽  
pp. 89-100
Author(s):  
Hideo Yajima
Keyword(s):  
Ultra Violet ◽  
The Other ◽  
Centrifugal Forces ◽  
Ultra Violet Light ◽  
Violet Light

In an earlier study (Yajima, 1960) of centrifugation of the egg of Chironomus dorsalis, the author obtained various types of double malformation (double cephalon and double abdomen) which are correlated with the orientation of the egg at the time of centrifugation. As a result the author proposed (1) that the embryonic character of Chironomus was determined by two formative localities; one located in the anterior end of the egg and determining the cephalic structures, and the other located in the posterior end and having a tendency toward abdominal development, (2) that the thoracic structures are determined as the result of interaction between the two localities and, finally, (3) that such localities must be carried by a substratum not moved by centrifugal forces of less than 27,000 g.

Hyperthermia Induced Polyphosphate Changes in Propionibacterium acnes as Studied by 31P NMR

1989 ◽  
Vol 44 (1-2) ◽  
pp. 45-48 ◽  
Author(s):  
B. Kjeldstad ◽  
A . Johnsson ◽  
K. M. Furuheim ◽  
A . Schie Bergan ◽  
J. Krane
Keyword(s):  
Nmr Spectra ◽  
31P Nmr ◽  
Propionibacterium Acnes ◽  
Ultra Violet ◽  
The Other ◽  
Hyperthermia Treatment ◽  
Ultra Violet Light ◽  
Violet Light ◽  
Increasing Temperature ◽  
Induced Changes

Abstract The polyphosphate component in MP NMR spectra of the Gram-positive Propionibacterium acnes increased after hyperthermia treatment. The cells were exposed to temperatures in the interval from 15 °C to 45 °C. The amount of polyphosphate increased with increasing temperature. There were no temperature induced changes in the other phosphorous components seen in the spectra with exception of a decrease in ATP for higher temperatures. The increase in polyphosphates was less than that obtained from cells irradiated by near ultra-violet light.

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