scholarly journals Light-Dependent Eye Coupling during the Optokinetic Response of the Crab Carcinus Maenas (L.)

1985 ◽  
Vol 119 (1) ◽  
pp. 103-114
Author(s):  
H.-O. NALBACH ◽  
P. THIER ◽  
D. VARJÚ
Keyword(s):  
Horizontal Plane ◽  
Relative Phase ◽  
Carcinus Maenas ◽  
Biological Significance ◽  
The Other ◽  
Low Light ◽  
Optokinetic Response ◽  
Variable Strength ◽  
Stepwise Manner ◽  
Logarithmic Relationship

1. The movements of both distal eye stalks in the horizontal plane, elicited by optokinetic stimuli, have been recorded simultaneously. 2. A panorama was split into two separate halves and was either oscillated around the animal in a sinusoidal fashion or displaced in a stepwise manner. Both eyes could be stimulated independently. 3. The stimuli on both sides differed either (a) in the illumination, or (b) in the total amount of light impinging upon the eyes or (c) in the relative phase of the sinusoidal stimuli to either eye. 4. As the illumination decreases the optokinetic response weakens. 5. If one eye has no or only weak optokinetic input, it will be driven by the other eye. The response mediated by the contralateral optokinetic stimulus diminishes if the amount of light impinging upon the driven eye is increased. 6. There is a logarithmic relationship between the response of the driving eye and that of the driven eye. 7. The possible biological significance of these relationships is seen in the enhanced coupling at low light intensities. 8. The variable strength of coupling and possible roles of movable eyes are discussed.

scholarly journals Metabolic, Physiological, and Transcriptomics Analysis of Batch Cultures of the Green Microalga Chlamydomonas Grown on Different Acetate Concentrations

Cells ◽  
2019 ◽  
Vol 8 (11) ◽  
pp. 1367 ◽  
Author(s):  
Bogaert ◽  
Perez ◽  
Rumin ◽  
Giltay ◽  
Carone ◽  
...  
Keyword(s):  
Stationary Phase ◽  
Biomass Yield ◽  
Fatty Acid Content ◽  
Biological Significance ◽  
Exponential Phase ◽  
Low Light ◽  
Batch Mode ◽  
Batch Cultures ◽  
Green Microalga ◽  
Transcriptomics Data

Acetate can be efficiently metabolized by the green microalga Chlamydomonas reinhardtii. The regular concentration is 17 mM, although higher concentrations are reported to increase starch and fatty acid content. To understand the responses to higher acetate concentrations, Chlamydomonas cells were cultivated in batch mode in the light at 17, 31, 44, and 57 mM acetate. Metabolic analyses show that cells grown at 57 mM acetate possess increased contents of all components analyzed (starch, chlorophylls, fatty acids, and proteins), with a three-fold increased volumetric biomass yield compared to cells cultivated at 17 mM acetate at the entry of stationary phase. Physiological analyses highlight the importance of photosynthesis for the low-acetate and exponential-phase samples. The stationary phase is reached when acetate is depleted, except for the cells grown at 57 mM acetate, which still divide until ammonium exhaustion. Surprisal analysis of the transcriptomics data supports the biological significance of our experiments. This allows the establishment of a model for acetate assimilation, its transcriptional regulation and the identification of candidates for genetic engineering of this metabolic pathway. Altogether, our analyses suggest that growing at high-acetate concentrations could increase biomass productivities in low-light and CO2-limiting air-bubbled medium for biotechnology.

scholarly journals 4. On a Thermomagnetic Thermoscope

1880 ◽  
Vol 10 ◽  
pp. 538-539
Author(s):  
W. Thomson
Keyword(s):  
Magnetic Moment ◽  
Horizontal Plane ◽  
Hardened Steel ◽  
The Other ◽  
Silk Fibre ◽  
Steel Wires ◽  
The One

This thermoscope is founded on the change produced in the magnetic moment of a steel magnet by change of temperature. Several different forms suggest themselves: the one which seems best adapted to give good results is to be made as follows:—(1.) Prepare an approximately astatic system of two thin, hardened steel wires, r b, r′ b′, each 1 cm. long, one of them, r, b, hung by a single silk fibre, and the other hung bifilarly from it, by fibres about 3 cms. long, so attached that the projections of the two, on a horizontal plane, shall be inclined at an angle of about ·01 of a radian (or ·57°) to one another.

Contractile differences between muscle units in the medial rectus and lateral rectus muscles in the cat

1986 ◽  
Vol 56 (1) ◽  
pp. 50-62 ◽  
Author(s):  
M. A. Meredith ◽  
S. J. Goldberg
Keyword(s):  
Horizontal Plane ◽  
Complex Interaction ◽  
Contractile Properties ◽  
The Other ◽  
Lateral Rectus ◽  
Medial Rectus ◽  
Types Of Muscle Fibers ◽  
Horizontal Gaze ◽  
Afferent Inputs ◽  
Central Factors

Conjugate eye movements in the horizontal plane are accomplished by the coactivation of the medial rectus (MR) muscle of one orbit and the lateral rectus (LR) muscle of the other. While control of these excursions has been thought to be effected by identical inputs to these muscles, recent studies have demonstrated that MR motoneurons receive different inputs than LR motoneurons. This raises the question of whether the character of the muscles they control are different. The present study evaluated the contractile properties of MR and LR muscle units in the cat. Based on the mechanical aspects of their contractile properties, only two physiological types of muscle units were identified within the MR and LR muscles: twitch and non-twitch muscle units. Twitch muscle units represented over 90% of the units sampled in each muscle. Significant differences in the rate-related and the tension-related contractile properties were demonstrated between MR and LR twitch muscle units. MR muscle units exhibited significantly faster twitch contractions than did LR units. The rate of stimulation at which MR units exhibited fused tetany was significantly higher than for LR units, although units from both muscles demonstrated similar rates of rise of tension at fusion. The rate of rise of tension was closely correlated to tension production (twitch and tetanus) in each muscle. However, MR muscle units demonstrated significantly weaker maximum tetanic tensions and lower tetanus-to-twitch ratios than LR units. These data indicate that while similar physiological types of muscle fibers are present within the MR and LR, MR muscle units are adapted for faster rate-related properties, whereas LR units are adapted for greater tetanic tensions. These distinctions between MR and LR muscle units, coupled with differences between the afferent inputs to their respective motoneurons, suggest that the preservation of conjugacy during horizontal gaze shifts may require a complex interaction of peripheral and central factors.

Numerical Analysis of Temperature Field in Laser Cladding on Teeth Surfaces of Gear Shaft

2010 ◽  
Vol 29-32 ◽  
pp. 571-576
Author(s):  
Lie Chen ◽  
Pei Lin Xie
Keyword(s):  
Temperature Field ◽  
Laser Beam ◽  
Laser Cladding ◽  
Horizontal Plane ◽  
Laser Energy ◽  
The Other ◽  
Analysis Software ◽  
Element Analysis ◽  
Result Show ◽  
Two Sides

Temperature field of laser cladding on teeth surfaces of gear shaft was numerical simulated with finite element analysis software – ANSYS. The simulation result show that the heat caused by laser beam is concentrated inside the tooth mostly. An effect of preheating in the adjacent tooth is also brought about by injected laser energy. In order to make use of the effect of preheating and avoid the concentration of heat, all of the corresponding flanks of teeth should be cladded first and the other flanks of teeth be cladded secondly in the process of laser cladding. It is also shown that the problems of excessive melted down and collapsing of tooth-tip would be easily resulted in by the heat that concentrated in tooth-tip if the tooth-side and tooth-tip be cladded at the same time. The results of analysis and experiment show that at least two times of scanning should be executed in the process of laser cladding on teeth surfaces. At the first scanning, dimension of laser beam should be reduced properly. And the tooth-tip should not be irradiated directly by laser beam. After the first scanning, the gear should be circumrotated a certain angle. And the included angles between the two sides of tooth-tip and horizontal plane should be approximately equal. Then the second scanning could be prosecuted at the tooth-tip. Experiment results show that continuous and compact cladding coat could be gained by this craft. It is proved that this technological craft is reasonable and effective.

The Conditions under which Opposing Motion is Seen in Transparency or as Flicker

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 31-31 ◽  
Author(s):  
M M Del Viva ◽  
M C Morrone
Keyword(s):  
Feature Tracking ◽  
Relative Phase ◽  
Phase Relationship ◽  
The Other ◽  
Spatial Frequencies ◽  
Sinusoidal Gratings ◽  
Exact Degree ◽  
Harmonic Components ◽  
Over Time ◽  
Moving Pattern

We present several examples of moving stimuli comprising several harmonic components that can be perceived either as moving independently, or together as a coherent moving pattern. A simple example is two sinusoidal gratings of equal contrast and spatial frequencies moving in opposite directions that are perceived as a single grating modulated sinusoidally over time (counterphase). However, two square waves drifting in opposite directions, while being a superposition of counterphasing pairs, are perceived as two distinct patterns drifting in transparency one over the other. Intermediate situations such as pairs of counterphase gratings can be perceived alternatively as counterphases or as drifting in two directions. We show that the relative phase of the components plays a fundamental role in whether they group or become transparent. The tendency of a component to become part of a pattern is maximal when the phase relationship is 0 deg, and gradually decreases to a minimum at 90 deg. This agrees quantitatively with previous measurements on different stimuli (paper presented at Del Viva and Morrone, ARVO96), suggesting a common computational mechanism. The data were well modelled by a nonlinear model of motion analysis based on feature tracking, showing sensitivity to the exact degree of nonlinearity.

Some Effects of Temperature and Light on Floral Initiation and Development in Acacia pycnantha

1985 ◽  
Vol 12 (2) ◽  
pp. 109 ◽  
Author(s):  
M Sedgley
Keyword(s):  
Light Intensity ◽  
Floral Development ◽  
Early Stage ◽  
The Other ◽  
Floral Initiation ◽  
Ambient Conditions ◽  
Low Light ◽  
Floral Primordia ◽  
Effects Of Temperature ◽  
Normal Light

Floral initiation and development in Acacia pycnantha were studied under three environments. Two had ambient southern Australian temperatures of warm summer (mean max. 32°C, mean min. 16°C) and cool winter (mean max. 19°C, mean min. 8°C), one with full sunlight (outside) and the other with 30% light intensity (shadehouse). The other environment (glasshouse) had slightly lower than normal light intensity and a relatively constant year round temperature of mean 28°C maximum and 16°C minimum. Plants were scored for microscopic and macroscopic evidence of floral initiation and development. Floral primordia were initiated all year round under all environments. Floral development proceeded normally under ambient conditions of temperature and light, and anthesis occurred between August and October. Under low light intensity, floral development did not progress beyond a very early stage and macroscopically visible racemes were rare. Under the constant temperatures, floral development proceeded normally up to the stage of microsporogenesis and megasporogenesis. Meiosis did not occur and inflorescence buds ceased growth and were shed from the plant. Plants were transferred between the outside and glasshouse conditions in June, at around the stage of meiosis. Those transferred from outside to the glasshouse did not flower whereas some of those transferred from the glasshouse to outside flowered, but later and for a shorter period than plants maintained outside throughout. It appears that a 70% reduction in sunlight inhibits floral development at an early stage and that temperatures of approximately mean maximum 19°C and minimum 8°C are required for meiosis in Acacia pycnantha.

Identifying logical dummy activities in an activity-on-arrow network

2008 ◽  
Vol 35 (7) ◽  
pp. 739-743
Author(s):  
Kyunghwan Kim
Keyword(s):  
Construction Projects ◽  
Heuristic Method ◽  
The Other ◽  
Multiple Relationships ◽  
Critical Problem ◽  
Stepwise Manner ◽  
The Creation ◽  
One To One

The activity-on-arrow (AOA) method can be used in construction projects depending on the project condition, although it is relatively inefficient as compared to the activity-on-node (AON) method. The most critical problem of the AOA method that is yet to be resolved is the application of a logical dummy activity (dummy). This paper presents a heuristic method that can be used for systematically identifying and applying logical dummies during the creation of an AOA network based on predefined activity dependencies. The heuristic method first identifies logical dummies of one-to-one relationships, and then detects the other multiple relationships in a stepwise manner to remove the redundancies therein.

Two Egyptian Construction Tools

1993 ◽  
Vol 86 (2) ◽  
pp. 166-167
Author(s):  
John F. Lamb
Keyword(s):  
Horizontal Plane ◽  
Vertical Plane ◽  
The Other

Among the objects in the Ramses II exhibition at Fair Park in Dallas in 1989 were two tools from the tomb of Sen-nedjem, one of Ramses II's workmen. One was a level for determining the horizontal plane, the other was a plumb level for determining the vertical plane.

Some Dimensions of the Angular Acceleration Receptor Systems of Cephalopods

1984 ◽  
Vol 64 (1) ◽  
pp. 55-79 ◽  
Author(s):  
Linda Maddock ◽  
J. Z. Young
Keyword(s):  
Angular Velocity ◽  
Frequency Band ◽  
Deep Sea ◽  
Horizontal Plane ◽  
Angular Acceleration ◽  
The Body ◽  
The Other ◽  
Radius Of Curvature ◽  
Internal Radius ◽  
Neutrally Buoyant

The shapes and dimensions of the statocysts of cephalopods have been measured and compared with the semi-circular canals of vertebrates. The cavities grow much more slowly than the body as a whole, but there are knobs, anticristae, which restrict the cavity, and these grow relatively faster. This ensures that the flow of endolymph across the cupulae remains small. Where the liquid is constrained within canals the radius of curvature of the whole canal, R, is similar to that of fishes, whereas its internal radius, r, is twice as large in non-buoyant and four times as large in deep-sea buoyant cephalopods as in fishes of similar size. As in fishes the restriction is greatest in the horizontal plane, providing for operation at higher frequencies in turning about the yaw axis.The statocysts of seven species of Loligo all have similar proportions. The largest individuals of 16 genera of non-buoyant squids also have these same relative dimensions. The statocyst of Sepia is more like that of non-buoyant than of other buoyant cephalopods but yet differs significantly from that of Loligo at all sizes. On the other hand 21 genera of squids known to be neutrally buoyant are very different. Their statocysts are often larger than in the non-buoyant forms and there is less restriction of the cavity by anticristae. The greater flow of endolymph acting across the cupulae presumably provides greater sensitivity at the lower frequencies of turning of these deep-sea animals.The data suggest that the cristae of the cephalopod statocyst may operate in the frequency band where they act as angular accelerometers whereas the vertebrate semi-circular canals operate at higher frequencies as angular velocity meters.

A Portable Mechanical Insect Trap

1960 ◽  
Vol 92 (1) ◽  
pp. 48-51 ◽  
Author(s):  
C. F. Nicholls
Keyword(s):  
Electric Motor ◽  
Horizontal Plane ◽  
The Other ◽  
Central Axis ◽  
Insect Trap ◽  
Flying Insects ◽  
Conical Nets

A trap for flying insects that incorporates some of the principles described by Williams and Milne (1935) and Chamberlin and Lawson (1910) was constructed. It consists basically of two conical nets that rotate in a horizontal plane around a central axis that is driven by an electric motor through a series of pulleys. The efficiency of the trap is not affected by wind as an increased airflow through one net is balanced by a decreased airflow through the other. It is green in colour to blend with its surroundings. The trap (Fig. 1) is 5½ feet high at the centre. It has three main sections (Fig. 2): the framework, the drivillg mechanism, and the nets.

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