scholarly journals THE EFFECT OF UNILATERAL ULTRAVIOLET LIGHT ON THE DEVELOPMENT OF THE FUCUS EGG

1941 ◽  
Vol 24 (3) ◽  
pp. 263-278 ◽  
Author(s):  
D. M. Whitaker
Keyword(s):  
Ultraviolet Light ◽  
Wave Length ◽  
Single Layer ◽  
The Other ◽  
Maximum Response ◽  
Strong Response ◽  
Wide Range ◽  
The Difference ◽  
Adequate Dosage ◽  
Rhizoid Formation

1. When Fucus eggs which have been fertilized for a sufficient length of time are irradiated unilaterally with monochromatic ultraviolet light (λ2804 Å) of adequate dosage, 97–100 per cent form rhizoids on the halves of the eggs away from the source of radiation (see Figs. 1 and 2). 2. The responsiveness of the eggs increases gradually after fertilization and does not reach a maximum until about 7 hours at 15°C. (see Fig. 3). The first rhizoids begin to form in a population at about 12 hours after fertilization. The responsiveness remains maximal until at least 11 hours after fertilization. 3. It is suggested that the low responsiveness of a population of eggs at an earlier period is due to recovery from the effects of irradiation before the rhizoids begin to form. 4. The response of eggs to λ2804 Å is proportional, over a wide range, to the logarithm of the dosage (see Fig. 1). Dosage was regulated by the duration of exposure during the period of maximum response. 5. High dosages of λ2804 Å, of the order of 10,000 ergs per mm.2, cause the rhizoids to form fairly precisely away from the source of radiation (see Fig. 2). Twice this dosage inhibits rhizoid formation altogether without causing cytolysis. 6. Other wave-lengths which have also been shown to be effective are: 3660, 3130, 2654, 2537, 2482, and 2345 Å. Only exploratory measurements have been made to test the effectiveness of these wave-lengths, but they show that much greater energy is necessary to obtain a strong response with λ3130 and 3660 Å, especially the latter. The wave-lengths shorter than 2804 Å, on the other hand, show the same order of effectiveness as λ2804 Å. Some may be more effective. 7. A beam of λ2804 Å which is incident on a single layer of Fucus eggs is completely extinguished at 2, 3, 6, or 6½ hours after fertilization. About 85 per cent of a beam of λ3660 Å is extinguished. The wave-length 3660 Å is thus not so completely absorbed as λ2804 Å, but the difference in proportion absorbed by the egg is not nearly so great as the difference in effectiveness.

scholarly journals Natural Science and Supernatural Thought Experiments

Religions ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 389
Author(s):  
James Robert Brown
Keyword(s):  
Natural Science ◽  
Thought Experiment ◽  
Thought Experiments ◽  
The Other ◽  
Space And Time ◽  
Wide Range ◽  
The Difference ◽  
Theological Thought

Religious notions have long played a role in epistemology. Theological thought experiments, in particular, have been effective in a wide range of situations in the sciences. Some of these are merely picturesque, others have been heuristically important, and still others, as I will argue, have played a role that could be called essential. I will illustrate the difference between heuristic and essential with two examples. One of these stems from the Newton–Leibniz debate over the nature of space and time; the other is a thought experiment of my own constructed with the aim of making a case for a more liberal view of evidence in mathematics.

scholarly journals I. A wave-length comparator for standards of length: An instrument for fine measurement in wave-lengths of light. - With an appendix on the use of wave-length rulings as defining lines on standards of length

1911 ◽  
Vol 210 (459-470) ◽  
pp. 1-34
Keyword(s):  
Wave Length ◽  
The Other ◽  
Single Spectrum ◽  
Interference Band ◽  
Half Wave ◽  
Autocollimation Method ◽  
New Apparatus ◽  
Reference Spot ◽  
The Difference ◽  
Reflecting Surfaces

The following is a brief account of a new apparatus for fine measurement in wavelengths of light, designed primarily as a comparator for the measurement in wavelengths of the difference between a standard of length, either a line or an end measure bar—the Imperial Standard Yard, for instance—and any duplicate or similar bar proposed to be employed as a derived standard. The instrument is also, however, the most perfect instrument yet devised for measurement in wavelengths in general, and performs its functions so admirably as to render it highly desirable that a description should now be published concerning it. It has been constructed to the designs and under the supervision of the author for the Standards Department of the Board of Trade, and this account of it is communicated to the Royal Society with the permission of the President of the Board of Trade. The principle underlying the instrument is that of the author’s interferometer, which has also proved so successful in its application, in the interference dilatometer, to the determination of the thermal expansion of small bodies by the Fizeau method, and in the elasmometer, to the measurement of the elastic bending of a small plate or bar under a given weight applied at the centre. The essence of the interferometer is that homogeneous light, of a definite wave-length, corresponding to a single spectrum line—isolated with the aid of a constant-deviation prism from the spectrum derived from a cadmium or hydrogen Geissler tube, or a mercury lamp—is directed by an autocollimation method, ensuring identity of path of the incident and reflected rays, normally upon two absolutely plane surfaces, arranged close to each other, and nearly, but not absolutely, parallel; the two reflected rays give rise, by their interference, to rectilinear dark interference bands on a brilliantly illuminated background in the colour corresponding to the selected wave-length. In the instrument now described, one of these two reflecting surfaces concerned in the production of the interference bands is carried by, and moves absolutely with, one of the two microscopes employed to focus the fiducial marks, or "defining lines", determinative of the length of the standard, the other surface being absolutely fixed. The movement of either of the surfaces with respect to the other causes the interference bands to move, and the extent of the movement of the surface is equal to half the wave-length of the light employed for every interference band that moves past a reference mark carried by the fixed surface. The movement of the microscope parallel to itself and to the length of the standard bar is thus measured by counting the number of bands and the initial and final fractions of a band which are observed to pass the reference spot during the movement, and multiplying that number by the half wave-length of the light radiation used in the production of the bands. It is only necessary, therefore, in order to compare the lengths of two bars, (1) to place the bar of known length, say, the Imperial Standard Yard, under the two microscopes so that the two defining lines are adjusted in each case between the pair of parallel spider-lines carried by each of the micrometer eye-pieces; (2) to replace the standard by the copy to be tested, so that the defining line near one end is similarly adjusted under the corresponding microscope, then, if the other defining mark is not also automatically adjusted under the second microscope which carries the interferometer glass surface, as it should be if it is an exact copy, (3) to traverse that microscope until it is so adjusted, and (4) to observe and count the number of interference bands which move past the reference spot during the process. The product of this number into the half wave-length of the light used to produce the bands thus obviously affords the difference between the two lengths included between the defining marks on the two bars.

Analysis of chromosome movement in crane fly spermatocytes by ultraviolet microbeam irradiation of individual chromosomal spindle fibres. I. General results

1981 ◽  
Vol 59 (9) ◽  
pp. 770-776 ◽  
Author(s):  
Peggy J. Sillers ◽  
Arthur Forer
Keyword(s):  
Ultraviolet Light ◽  
Monochromatic Light ◽  
The Other ◽  
Spindle Fibre ◽  
Chromosome Movement ◽  
Opposite Pole ◽  
Other Hand ◽  
Ultraviolet Microbeam ◽  
The Difference ◽  
Spindle Fibres

Single chromosomal spindle fibres in anaphase Nephrotoma ferruginea (crane fly) spermatocytes were irradiated with monochromatic ultraviolet light focussed to a 4-μm spot by means of an ultraviolet microbeam apparatus. The movement of the half-bivalent associated with the irradiated spindle fibre was either unaffected or the half-bivalent stopped moving; i.e., the effect was all-or-none. When the half-bivalent associated with the irradiated spindle fibre did stop moving, the partner half-bivalent moving towards the opposite pole (i.e., the half-bivalent with which the first half-bivalent was previously paired) also stopped moving: all other half-bivalents moved normally. In over 90% of the 69 cases the movements of the two half-bivalents were only temporarily blocked; when movement resumed both half-bivalents resumed movement at the same time, after stoppage times ranging from 2 min to more than 15 min. In a few cases the half-bivalents never resumed poleward motion.When half-bivalents that had stopped movement finally resumed movement they often did not reach the poles; i.e., they "lagged" and remained separate from the other chromosomes. This result occurred only in spermatocytes of N. ferruginea. In spermatocytes of N. suturalis or N. abbreviata, on the other hand, the stopped half-bivalents did not lag but always reached the poles.Half-bivalent pairs that stopped moving in N. ferruginea spermatocytes did so for shorter times than did those previously reported (after irradiation of chromosomal spindle fibres) in N. suturalis spermatocytes. We suggest that the difference is due to our use of monochromatic ultraviolet light as opposed to the previous use of heterochromatic ultraviolet light. We assume that different wavelengths of monochromatic light produce different effects, that any given monochromatic irradiation produces only one effect (albeit different effects at different wavelengths), but that heterochromatic irradiations can produce multiple effects.Irradiation of the interzone (between separating half-bivalents) had no effect on the chromosome-to-pole movements of the half-bivalents. Therefore the stoppage of movement of half-bivalent pairs is specific for irradiation of chromosomal spindle fibres. On the other hand, irradiation of the interzone often blocked pole-to-pole elongation.

Study On The Effect Of Ddavp On Factor VIII- Related Properties In Hemophilia And VWD

1981 ◽  
Author(s):  
N Ciavarella ◽  
S Solinas ◽  
D Pilolli ◽  
P Ranieri ◽  
D Corrao ◽  
...  
Keyword(s):  
Factor Viii ◽  
Electrophoretic Mobility ◽  
Hemophilia A ◽  
The Other ◽  
Strong Response ◽  
The Difference ◽  
Classic Form ◽  
O 19

Twenty-one patients affected by mild and moderate Hemophilia A as well as 9 patients with the classic form of vonWillebrand’s disease (vWD) were given a total of 58 infusions of DDAVP. Concerning Hemophilia a three fold mean raise ( x = 3.0, sem O. 19; range of ratios post/preinfusion 1.35 - 5.55) of factor VIII : C levels was observed after the infusion of 0.3 μg/Kg b.w. A mean raise of 3.44 ( sem 0.48, range 2.20 - 6.7) after the infusion of 0.4/ug/Kg was found. The difference between the two regimens is not statistically significant (p < 0.5). As to the vWD 18 infusions were given. In 6 patients the changes of factor VI1I: C, VIIIR: Ag and VIII: vWF were roughly consensual ( ratios post/preinfusion ranging from 2.2 to 4.0 for VIII: C; from 1.8 to 3.5 for VIHR:Ag and from 3.1 to 6.2 for VIII: vWF). In the remaining 3 patients a very strong response of VIII : C ( ratios post/preinfusion 12.0, 15.1 and 6.5) was observed. Also the other properties related to factor VIII underwent to relevant increase. In one of these patients a modified electrophoretic mobility of factor VIII was found; the other two (father and doughter) had a normal factor VIII mobility after stimulation with DDAVP.

STEADY STATE POLAR SENSITIVITY CURVES

Geophysics ◽  
1939 ◽  
Vol 4 (1) ◽  
pp. 33-52 ◽  
Author(s):  
C. H. Johnson
Keyword(s):  
Steady State ◽  
Wave Length ◽  
Maximum Response ◽  
Seismic Exploration ◽  
Time Of Arrival ◽  
Relative Response ◽  
Specific Direction ◽  
Sensitivity Curves ◽  
The Difference ◽  
The Waves

The resultant amplitude, “A,” of the combined outputs of a group of geophones is derived as a function of the difference in time of arrival, ΔT, at extreme geophones in the group—the number of geophones and the period of the waves being parameters. “A” plotted as a function of ΔT is shown to have principal and secondary maxima whose amplitudes, separation, and sharpness are discussed. The relative response of the geophone group to waves from every direction is considered and illustrated by polar sensitivity curves. The changes in the polar sensitivity curves effected by changes in the number of geophones, the geophone spread, or the wave length, are considered. The effect of introducing artificially controlled time differences between geophone outputs, so as to vary the direction of maximum response (so‐called variable compounding) as is done in the Rieber Sonograph, is considered. By this means the resultant response of the group of geophones can be focused, so as to emphasize waves arriving from any specific direction. While the results are strictly applicable only to the case of steady state, sinusoidal waves, they may apply qualitatively to all the waves encountered in seismic exploration. The versatility of variable compounding is pointed out.

scholarly journals Resonance Between Pulsation Modes Due to Tidal Perturbation

1992 ◽  
Vol 151 ◽  
pp. 289-292
Author(s):  
Z. Kolláth ◽  
J. Nuspl
Keyword(s):  
Parametric Excitation ◽  
Orbital Motion ◽  
Variable Stars ◽  
The Other ◽  
Amplitude Equations ◽  
Stellar Pulsation ◽  
Orbital Frequency ◽  
Wide Range ◽  
Tidal Perturbation ◽  
The Difference

The effect of tidal perturbation to stellar pulsation is a relatively underdeveloped problem in the theory of variable stars. We derive amplitude equations describing the resonances between pulsational modes and orbital motion taking into consideration the rotation of stars as well. In the case of δ Scuti stars the two-mode-tidal resonance was found to be the most powerful effect. If the difference between frequencies of excited and damped mode is close to the orbital frequency, parametric excitation of the damped mode may occur, while the other mode loses energy. We discuss this effect for a wide range of parameters.

Mind and body in early modern philosophy

2018 ◽  
Author(s):  
Stewart Duncan
Keyword(s):  
Immanuel Kant ◽  
Gottfried Wilhelm Leibniz ◽  
The Body ◽  
The Other ◽  
Nicolas Malebranche ◽  
Wide Range ◽  
Mind And Body ◽  
The Difference ◽  
The Mind ◽  
Human Brains

European philosophers of the seventeenth and eighteenth centuries proposed a wide range of views about the nature of the mind and its relation to the body. René Descartes (1596–1650) argued that there are two distinct parts to human beings, mind and body, which are substances of radically different kinds, and either of which could exist without the other – although, in fact, in living humans, they are always connected together. He argued for this dualism in several works, including his Meditations on First Philosophy (Descartes [1641] 1984). Elsewhere, in his Discourse on the Method (Descartes [1637] 1985), he argued – based on empirical observation of the difference between humans and other animals – that reason is unique to humans. Indeed, Descartes thought that, because non-human animals do not have an incorporeal mind, they do not even really have sensations. Though Descartes’s views have been very influential, they attracted critics from the outset. For example, Thomas Hobbes (1588–1679) argued against Descartes that the thinking mind is corporeal, Pierre Gassendi (1592–1655) objected to Descartes’s method of investigating the mind, and Princess Elisabeth of Bohemia (1618–80) objected to his explanation – or lack of explanation – of how the incorporeal mind and the corporeal body are related to one another. Questions about that relationship continued to divide philosophers in the generation after Descartes. In different ways, occasionalists such as Nicolas Malebranche (1638–1715) and the anti-occasionalist Gottfried Wilhelm Leibniz (1646–1716) both denied that distinct created substances (such as the Cartesian mind and body) could really have a causal influence on each other. Benedict Spinoza (1632–77) denied this too, in his own way, while also arguing for a claim that sounds like a form of materialism: that mind and body are the very same thing ‘expressed in two ways’ (Spinoza [1677] 1988: II, prop. 7, scholium). Other philosophers, such as Hobbes, were more straightforwardly materialists, arguing that the structure and movements of various corporeal systems gave rise to thought. Margaret Cavendish (1623–73), meanwhile, was a materialist who argued that matter itself was fundamentally and irreducibly thinking. Hobbesian materialism seeks to explain the mind in terms of the body. Idealism, on the other hand, seeks to explain the body in terms of the mind. This is the view that what there are, fundamentally, are incorporeal thinking things and their states (such as thoughts, ideas and perceptions). Material stuff somehow depends on these more basic things. Leibniz proposed this view at some points, as did George Berkeley (1685–1753). Descartes’s views about animals’ lack of minds also continued to attract attention. A wide range of philosophers thought he must have gone wrong here. This debate has complex connections to others. For example, if you believe that animals can think, but you also believe that thought requires an incorporeal soul, what should you say about animals’ incorporeal souls? What happens to them when an animal dies and their body decays? Dualist, anti-materialist views were sometimes connected to the notion of simplicity. The idea was that the soul was a simple, indivisible thing, unlike corporeal things such as human brains. Various philosophers thought that they could prove that the soul had to be simple and thus that it could not be corporeal. Leibniz (again), Christian Wolff (1679–1754) and Immanuel Kant (1724–1804) discussed such issues.

to increase simultaneously the manifestness of a wide range of assumptions, so that her intention concerning each of these assumptions is weakly manifest, then each of them is weakly communicated. An example would be sniffing ecstatically and osten-sively at the fresh seaside air. There is, of course, a continuum of cases in between. In the case of strong communication, the communicator can have fairly precise expectations about some of the thoughts that the audience will actually entertain. With weaker forms of communication, the communicator can merely expect to steer the thoughts of the audience in a certain direction. Often, in human interaction, weak communication is found sufficient or even preferable to the stronger forms. Non-verbal communication tends to be relatively weak. One of the advantages of verbal communication is that it gives rise to the strongest possible form of com-munication; it enables the hearer to pin down the speaker’s intentions about the explicit content of her utterance to a single, strongly manifest candidate, with no alternative worth considering at all. On the other hand, what is implicit in ver-bal communication is generally weakly communicated: the hearer can often fulfil part of the speaker’s informative intention by forming any of several roughly similar but not identical assumptions. Because all communication has been seen as strong communication, descriptions of non-verbal communication have been marred by spurious attributions of ‘meaning’; in the case of verbal communication, the difference between explicit content and implicit import has been seen as a differ-ence not in what gets communicated but merely in the means by which it is com-municated, and the vagueness of implicatures and non-literal forms of expression has been idealised away. Our account of informative intentions in terms of man-ifestness of assumptions corrects these distortions without introducing either ad hoc machinery or vagueness of description.

2005 ◽  
pp. 164-164
Keyword(s):  
Ad Hoc ◽  
Verbal Communication ◽  
Human Interaction ◽  
The Other ◽  
Other Hand ◽  
Wide Range ◽  
Explicit Content ◽  
The Difference

A unified description of two-layer flow over topography

1984 ◽  
Vol 146 ◽  
pp. 127-167 ◽  
Author(s):  
Peter G. Baines
Keyword(s):  
Multiple Equilibria ◽  
Single Layer ◽  
Nonlinear Effects ◽  
Wave Dispersion ◽  
Interfacial Stress ◽  
The Other ◽  
Two Dimensional ◽  
Wide Range ◽  
Flow Over Topography ◽  
Layer Flow

Observations of the flow of a two-layer fluid resulting from the motion of a towed streamlined two-dimensional obstacle are described in some detail. The experiments were designed to further our understanding of the factors governing the nature and magnitude of upstream disturbances in the general flow of stratified fluid over two-dimensional topography, and predictions for arbitrary two-dimensional flows are made from the results of these experiments. In particular, the relationship between uniformly stratified flow and single-layer flow over topography is suggested. Most of the observed features of interest in these experiments are nonlinear in character. Relatively complete descriptions of the observed flows are presented over a wide range of parameter values, and the phenomena observed include upstream undular and turbulent bores, bores with zero energy loss, ‘rarefactions’ (in which the interface height changes monotonically over a transition region of continuously increasing length), and downstream hydraulic drops and jumps. Their properties are shown to be broadly consistent with predictions from a two-layer hydrostatic model based on continuity and momentum considerations, which employs jump criteria and rarefaction equations where appropriate. Bores occur because of nonlinear steepening when the layer containing the obstacle is thinner than the other, and rarefactions occur when this layer thickness is comparable with or greater than that of the other layer. The speed and amplitude of the upstream bores are governed by nonlinear effects, but their character is determined by a balance between nonlinear steepening, wave dispersion and interfacial friction when the bore is non-turbulent.Experimental evidence is presented for two types of hysteresis or ‘multiple equilibria’ - situations where two different flow states may exist for the same external steady conditions. In the first of these hysteresis types, the upstream flow may be supercritical or consist of an upstream bore state. It is analogous to the type anticipated for single-layer flow by Baines & Davies (1980) and described numerically by Pratt (1983), but it is only found experimentally for part of the expected parameter range, apparently because of interfacial stress effects. The second hysteresis type is new, and involves the presence or absence of a downstream hydraulic drop and following jump.

Comparative Effects of High-Tech Visual Scene Displays and Low-Tech Isolated Picture Symbols on Engagement From Students With Multiple Disabilities

2019 ◽  
Vol 50 (4) ◽  
pp. 693-702 ◽  
Author(s):  
Christine Holyfield ◽  
Sydney Brooks ◽  
Allison Schluterman
Keyword(s):  
Language Learning ◽  
Augmentative And Alternative Communication ◽  
Visual Analysis ◽  
Multiple Disabilities ◽  
Visual Scene ◽  
Future Research ◽  
High Tech ◽  
Single Subject ◽  
Wide Range ◽  
The Difference

Purpose Augmentative and alternative communication (AAC) is an intervention approach that can promote communication and language in children with multiple disabilities who are beginning communicators. While a wide range of AAC technologies are available, little is known about the comparative effects of specific technology options. Given that engagement can be low for beginning communicators with multiple disabilities, the current study provides initial information about the comparative effects of 2 AAC technology options—high-tech visual scene displays (VSDs) and low-tech isolated picture symbols—on engagement. Method Three elementary-age beginning communicators with multiple disabilities participated. The study used a single-subject, alternating treatment design with each technology serving as a condition. Participants interacted with their school speech-language pathologists using each of the 2 technologies across 5 sessions in a block randomized order. Results According to visual analysis and nonoverlap of all pairs calculations, all 3 participants demonstrated more engagement with the high-tech VSDs than the low-tech isolated picture symbols as measured by their seconds of gaze toward each technology option. Despite the difference in engagement observed, there was no clear difference across the 2 conditions in engagement toward the communication partner or use of the AAC. Conclusions Clinicians can consider measuring engagement when evaluating AAC technology options for children with multiple disabilities and should consider evaluating high-tech VSDs as 1 technology option for them. Future research must explore the extent to which differences in engagement to particular AAC technologies result in differences in communication and language learning over time as might be expected.

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