Attraction of Aedes aegypti (L.): responses to human arms, carbon dioxide, and air currents in a new type of olfactometer

1969 ◽  
Vol 58 (3) ◽  
pp. 629-642 ◽  
Author(s):  
M. S. Mayer ◽  
J. D. James
Keyword(s):  
Carbon Dioxide ◽  
Aedes Aegypti ◽  
Large Scale ◽  
Host Location ◽  
Direct Method ◽  
Behavioural Effects ◽  
Infra Red ◽  
New Type ◽  
Red Radiation ◽  
A Current

A new type of olfactometer was designed to study the responses of mosquitos to various stimuli. Hosts could be displayed downwind as well as upwind from the mosquitos, and two hosts could be displayed simultaneously, one upwind from the other. Responses to radiations, if any, and to odours could be measured.Mosquitos were not attracted downwind to an arm displayed within 61 cm., even when they were stimulated by CO2 (under an incident illumination of about 10 foot-candles). About half the mosquitos showed a positive anemotactic response (i.e., they left the end downwind compartment in which they were released) in a current of room air, which undoubtedly contained human emanations. Only 15 per cent, responded to filtered air. Carbon dioxide caused no increase in response to filtered air but increased the number responding to room air (76 per cent, left the end down-wind compartment). Equal numbers of mosquitos responded to an arm displayed upwind in room air and in filtered air, i.e., about 83 per cent, left the end compartment. Carbon dioxide caused no increase in the number of mosquitos responding to an arm but increased the number responding to attenuated emanations from an arm. A repellent (deet) eliminated most of the response to an arm; the addition of carbon dioxide increased upwind flight to the treated arm, but many of the mosquitos flew past it. Carbon dioxide therefore appears to have a synergistic action with arm odours in the attraction of females of Aedes aegypti (L.). However, this conclusion does not exclude other behavioural effects of carbon dioxide demonstrated by other investigators.Eesponses to arms in this new type of olfactometer were nearly identical to those obtained in another type previously used in a large-scale study. The testing confirmed earlier reports that mosquitos do not fly far in the same direction as wind-current and that host location was not possible through positive anemotaxis in the absence of light. Mosquitos were not attracted to a source of infra-red radiation.The new direct method of comparing the attractiveness of different subjects demonstrated that mosquitos would leave the vicinity of one arm and migrate further upwind to another that was more attractive. Water and acetone rinses of human arms reduced attraction; acetone appeared to be a better solvent for the attractant substance than water.

Model of a folded polypeptide chain

1950 ◽  
Vol 137 (886) ◽  
pp. 79-79
Keyword(s):  
Amino Acid ◽  
Polypeptide Chain ◽  
Molecular Model ◽  
Polymer Chains ◽  
Side Chains ◽  
Amino Acid Residues ◽  
Infra Red ◽  
New Type ◽  
Folded Proteins ◽  
Red Radiation

The models on view in the ante-room show a way of folding a polypeptide chain which is consistent with some observations we have recently made with polarized infra-red radiation (Ambrose & Hanby 1949; Ambrose, Elliott & Temple 1949). The α -folded proteins, keratin, myosin and tropomyosin, have been found when oriented to show greater absorption of the N-H frequency when the electric vector of the absorbed radiation is in the direction of the fibre axis, hence the N-H bond must be preferentially oriented in this direction. A study of models has suggested that the only likely folding of the polypeptide chain consistent with this fact involves a seven-membered ring containing two amino-acid residues; the ring is completed by hydrogen bonds: A new type of atomic model which has been developed in our laboratories has been used. The scale is 0·8 in. to the Angstrom unit. The valency links, while allowing free rotation about single co-valent bonds, also allow some distortion of the bond angles when strains occur but are strong enough to allow long polymer chains to be built. The molecular model exhibited shows twenty-four amino-acid residues, with side chains on one side of the back-bone, representative of those occurring in myosin; the side chains on the other side have been removed for clearness and their positions indicated by single carbon atoms.

scholarly journals The estimation of small quantities of carbon dioxide in air by the absorption of infra-red radiation

1940 ◽  
Vol 129 (857) ◽  
pp. 468-474 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Absorption Band ◽  
Water Vapour ◽  
Preliminary Treatment ◽  
Transmitted Radiation ◽  
Infra Red ◽  
Red Radiation

This paper describes an investigation of the possibility of measuring small amounts of carbon dioxide in air by the absorption of infra-red radiation. It is shown that the method is simple, trustworthy and accurate, and is very sensitive for small amounts of carbon dioxide, of the order of that present in ordinary air. The principle is applied in a form superior to any hitherto used, in that the whole of the transmitted radiation is measured instead of merely the radiation at the maximum of a particular absorption band. This makes a spectrometer unnecessary, eliminates the disturbing effect of variation of temperature, and allows much less sensitive detecting apparatus to be used. The only preliminary treatment necessary is the removal of water vapour from the air under examination.

Smallseed Dodder (Cuscuta planiflora) Phototropism toward Far-red When in White Light

Weed Science ◽  
1996 ◽  
Vol 44 (2) ◽  
pp. 233-240 ◽  
Author(s):  
Gregory L. Orr ◽  
Mustapha A. Haidar ◽  
Deborah A. Orr
Keyword(s):  
Blue Light ◽  
Potassium Iodide ◽  
White Light ◽  
Host Location ◽  
Red Light ◽  
Infra Red ◽  
Red Radiation

White light-grown seedlings of smallseed dodder were (a) provided with unilateral far-red (700 to 800 nm) at photon irradiances ranging from 20 to 110 μmol m−2s−1against a background of cool white light (400 to 700 nm) from above at 77 μmol m−2s−1, or (b) transferred to darkness and provided with unilateral white light at 20 μmol m−2s−1, unilateral blue light (400 to 500 nm) at 10 μmol m−2s−1, unilateral red light (600 to 700 nm) at 10 μmol m−2s−1, unilateral far-red at 50 μmol m−2s−1, or (c) in experiments utilizing bilateral irradiations, provided with unilateral far-red perpendicular to unilateral white light. Positive phototropic curvature was induced by unilateral white light and by unilateral blue light in otherwise darkness and by unilateral far-red in a background of cool white light. Seedling vines were also phototropic toward unilateral far-red when provided with unilateral white light perpendicular to unilateral far-red. Phototropism to unilateral white light was inhibited in seedlings treated with 200 μM norflurazon and 50 mM potassium iodide. Norflurazon- and potassium iodide-treated seedlings remained phototropic toward unilateral far-red when provided with unilateral white light perpendicular to unilateral far-red. Seedling vines were not phototropic to unilateral red or to unilateral far-red in otherwise darkness, and seedlings in cool white light were neither skototropic (i.e., tropic toward unilateral darkness) nor tropic to or from infra-red (radiation with wavelengths greater than 900 nm). Phototropism toward regions of lowered red:far-red may aid smallseed dodder in chlorophyllous host location and attachment.

Ultra-violet and infra-red investigations on muscle

1950 ◽  
Vol 137 (886) ◽  
pp. 80-87 ◽  
Keyword(s):  
Absorption Spectrum ◽  
Visible Region ◽  
Ultra Violet ◽  
Muscle Fibres ◽  
Absorption Bands ◽  
Important Region ◽  
Infra Red ◽  
New Type ◽  
Single Fibres ◽  
Red Radiation

Infra-red absorption spectroscopy of muscle has already been carried out, using the Burch reflecting microscope (Barer, Cole & Thompson 1949: Barer, Thompson & Williams unpublished). There are considerable difficulties involved in this type of work. In the first place it is rather doubtful whether such measurements will ever be possible on living muscle owing to the presence of water, which possesses intense absorption bands in some of the most useful regions of the infra-red spectrum. It may be possible to overcome this difficulty to some extent by using heavy water which has a different absorption spectrum. It is in principle possible to obtain information similar to that given by infra-red spectroscopy, even in the presence of water, by means of Raman spectroscopy, but the technical difficulties involved, particularly fight scattering by colloids, would seem to preclude this method of attack so far as muscle is concerned. Our infra-red measurements have hitherto been confined to dried material. The results indicate that there is little prospect of working with whole muscles, as even single isolated striated fibres of the frog, rabbit and crab were usually too thick. However, it was possible to obtain good spectra in the chemically important region from 3 to 14/ µ on exceptionally thin single fibres or on artificially compressed fibres. An attempt was made to detect dichroism by means of polarized infra-red radiation, but to our surprise none was observed throughout the 3 to 14 µ range, even though the material used showed strong birefringence in the visible region. Hr Stocken and I have recently examined certain molecular models of muscle, in the fight of the work of Ambrose, Elliott & Temple (1949) on myosin, and it now appears possible that infra-red dichroism of muscle might be expected to manifest itself only under rather special conditions. We hope to put these theoretical deductions to experimental test. As regards measurements on muscle in the ultra-violet region, the position is much more promising. It is quite possible to determine the absorption spectrum of the A or I band in living single fibres. The entire spectrum from about 230 m µ in the ultra-violet to over 600 m µ , in the visible can be recorded simultaneously, using the reflecting microscope. This technique can also be used with polarized ultra-violet fight, in order to detect variation of dichroism in crystals at different wave-lengths (Barer, Jope & Perutz unpublished), and I intend to apply it to the study of dichroism in muscle fibres. Another new possibility is the observation of birefringence, as well as dichroism, in the ultra-violet. I have recently carried out experiments with a view to developing a new type of ultra-violet polarizer and it should now be possible to use the reflecting microscope as an ultra-violet polarizing microscope.

Studies of the Responses of the Female Aëdes Mosquito. Part III. The Response of Aëdes aegypti (L.) to a Warm Body and its Radiation

1951 ◽  
Vol 42 (3) ◽  
pp. 535-541 ◽  
Author(s):  
D. G. Peterson ◽  
A. W. A. Brown
Keyword(s):  
Aedes Aegypti ◽  
Surface Temperature ◽  
Yellow Fever ◽  
Convective Heat ◽  
Positive Response ◽  
Radiant Heat ◽  
Aedes Mosquito ◽  
Infra Red ◽  
Almost All ◽  
Red Radiation

1. A warm object is more attractive to the female yellow-fever mosquito than a cooler object, such that the numbers touching a ball warmed to 100° or 110°F. were twice as great as those touching a ball 20°F. cooler. This attractiveness was reversed when the temperature of the warmer ball reached 120°F.2. This response is eliminated by the insertion of an air-tight window of thallium bromoiodide, despite the fact that it allows almost all of the radiation to filter through. It is therefore concluded that heat convection, which is eliminated by the air-tight window, is the factor which makes a warm object attractive to the mosquito.3. The several faces of a warm cube, differing in their radiant emissivity but identical as to surface temperature, exhibited attractancies to Aëdes which were not significantly different one from another (except in the case of black enamel, which will be explained in a later paper). These results may be interpreted to indicate that radiation plays no part in the attraction of the mosquitos to the warm face.4. It is concluded that the failure of Parker (1948) to obtain a positive response of Aëdes mosquitos to a warm dry object was due to the fact that his apparatus allowed only the radiant heat but not the convective heat to reach the insects.5 Since the response of Aëdes aegypti to heat is eliminated by a window transparent to infra-red radiation, the theory of olfaction proposed by Beck and Miles (1947) evidently has no application to this species of mosquito.

Is economic inequality a universal evil?

2019 ◽  
pp. 91-106 ◽  
Author(s):  
Rostislav I. Kapeliushnikov
Keyword(s):  
Quantitative Data ◽  
Large Scale ◽  
Economic Inequality ◽  
The State ◽  
Fair Play ◽  
Left Wing ◽  
Ordinary People ◽  
The Public ◽  
Discursive Power ◽  
A Current

Using published estimates of inequality for two countries (Russia and USA) the paper demonstrates that inequality measuring still remains in the state of “statistical cacophony”. Under this condition, it seems at least untimely to pass categorical normative judgments and offer radical political advice for governments. Moreover, the mere practice to draw normative conclusions from quantitative data is ethically invalid since ordinary people (non-intellectuals) tend to evaluate wealth and incomes as admissible or inadmissible not on the basis of their size but basing on whether they were obtained under observance or violations of the rules of “fair play”. The paper concludes that a current large-scale ideological campaign of “struggle against inequality” has been unleashed by left-wing intellectuals in order to strengthen even more their discursive power over the public.

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