The Signal Generated by an Insect in a Spider's Web

1965 ◽  
Vol 43 (1) ◽  
pp. 185-192
Author(s):  
D. A. PARRY
Keyword(s):  
Linear Response ◽  
Wave Form ◽  
Irregular Wave ◽  
Prey Recognition ◽  
Upper Limit ◽  
Fast Transients ◽  
Sudden Release ◽  
House Spider ◽  
Rotational Oscillations ◽  
The Web

1. There is evidence that web-spinning spiders discriminate between prey and artifacts in their webs, and that the signal involved is a mechanical one. As a contribution to our understanding of the basis of this discrimination, an analysis has been made of the natural signal generated by an insect in the web of the British house spider Tegenaria atrica. 2. The signal investigated was frequency-limited to 1 kc./sec, this being the upper limit of the linear response of the specially designed transducer. 3. The signal has an irregular wave-form with most of the energy lying below 50 cyc./sec. Damped transverse and rotational oscillations of the mass of the spider in the compliance of the web have been recognized. In addition there are ‘fast transients’, most likely due to the sudden release of tension in the web by slight movements of the insect. 4. The possibility that the fast transients form the basis of prey-recognition is being investigated.

scholarly journals Foraging behaviour and the risk of predation in the black house spider, Badumna insignis (Desidae)

1999 ◽  
Vol 47 (1) ◽  
pp. 29 ◽  
Author(s):  
Robbie J. Henderson ◽  
Mark A. Elgar
Keyword(s):  
Foraging Behaviour ◽  
Foraging Efficiency ◽  
Foraging Success ◽  
Short Term ◽  
Risk Of Predation ◽  
House Spider ◽  
The Web ◽  
Model Predator

Many animals adjust their behaviour according to the presence or threat of predators. However, the foraging behaviour of sit-and-wait predators is typically thought to be inflexible to short-term changes in the environment. Here we investigate the foraging behaviour of the nocturnally active black house spider, Badumna insignis. Experiments in which different kinds of prey were introduced into the web during either the day or night indicated that the foraging success of Badumna is compromised by behaviours that reduce the risk of predation. During the day, spiders generally remain within the retreat and take longer to reach the prey, which may reduce their foraging success. In contrast, spiders sat exposed at the edge of the retreat at night, and from here could usually reach the prey before it escaped. The spiders were able to escape from a model predator more rapidly if they were at the edge of the retreat than if they were out on the web. These data suggest that the costs to Badumna of reduced fecundity through poor foraging efficiency may be outweighed by the benefits of reducing the risk of predation

scholarly journals The nature of atmospherics. VI

1939 ◽  
Vol 171 (946) ◽  
pp. 285-313 ◽  
Keyword(s):  
Time Scale ◽  
High Frequency ◽  
Potential Gradient ◽  
The Other ◽  
Wave Form ◽  
Predominant Frequency ◽  
Photographic Recording ◽  
Upper Limit ◽  
Open Time ◽  
Rapid Changes

In Paper V of this series (Watson Watt, Herd and Lutkin 1937) the results of the early photographic recording of the wave form of atmospherics have been described. It was shown that these rapid changes of the atmospheric potential gradient produced by thunderstorm discharges at quite long distances consist of two distinct oscillatory trains, one having a predominant frequency of the order of 10 kc./sec. and the other about 0.5 kc./sec. The photographic resolution attainable at the time made it impossible to analyse in detail the higher frequency oscillations, and the present paper describes the results of recording on a much more open time scale. This involved the development of a drum camera which could be operated at speeds up to 20 r.p.s. giving film speeds up to 20 m./sec. as compared with 2 m./sec. which was the upper limit attainable by the earlier methods. Two series of observations are discussed. One was made during the autumn of 1934, and consisted of records of atmospherics originating at considerable distances from the receivers. This series, which served to test the methods for improved resolution of the wave form, confirmed the nature of the high-frequency portion of that wave form and emphasized the need for similar records of the atmospherics from storms occurring near to one of the receivers. Such records were obtained in the second series made during the summer of 1936.

scholarly journals Design of Monitoring System Step Walking With MPU6050 Sensor Based Android

2017 ◽  
Vol 1 (1) ◽  
pp. 1 ◽  
Author(s):  
Diah Ayu Fitriani ◽  
Wahyu Andhyka ◽  
Diah Risqiwati
Keyword(s):  
Angular Momentum ◽  
Cardiovascular Health ◽  
Sine Wave ◽  
Wave Form ◽  
Limit Value ◽  
Upper Limit ◽  
Object Based ◽  
Angle Data ◽  
Gyroscope Sensor ◽  
Device Test

Walking is said to increase endurance, burn calories and improve cardiovascular health. To monitor the steps when walking, we need a tool that is a gyroscope sensor MPU6050. Making this tool uses a gyroscope sensor for monitoring footsteps because Gyroscope is used to measure or determine the orientation of an object based on the provisions of angular momentum. This tool has been tested by foot with a number of different steps. The device test carried out by one person testers.Data obtained from these tests resulting from the detection lower limit value and upper limit value of X axis angle data is used in data processing is the value of the X-axis is converted into a sine wave form chart. To detect footsteps, each wave has the upper value limit is 20o and the bottom value is -20o. Once the step is detected, these measures will be multiplied by the width of the foot when walking, then obtained distance

scholarly journals The effects of temperature on the web-building behaviour of the common house spider, Achaearanea tepidariorum

1997 ◽  
Vol 11 (1) ◽  
pp. 4-10 ◽  
Author(s):  
L. E. BARGHUSEN ◽  
D. L. CLAUSSEN ◽  
M. S. ANDERSON ◽  
A. J. BAILER
Keyword(s):  
The Common ◽  
Effects Of Temperature ◽  
Building Behaviour ◽  
House Spider ◽  
Web Building ◽  
Common House ◽  
The Web

scholarly journals The FRATS project: real-time searches for fast radio bursts and other fast transients with LOFAR at 135 MHz

2019 ◽  
Vol 621 ◽  
pp. A57 ◽  
Author(s):  
S. ter Veen ◽  
J. E. Enriquez ◽  
H. Falcke ◽  
J. P. Rachen ◽  
M. van den Akker ◽  
...  
Keyword(s):  
Real Time ◽  
Low Frequency ◽  
Radio Bursts ◽  
Pilot Survey ◽  
Upper Limit ◽  
Previous Decade ◽  
Fast Transients ◽  
Radio Transients ◽  
The Individual ◽  
Galactic Sources

Context. In the previous decade, two new classes of fast radio transients were detected: the Galactic, rotating radio transients (RRATs) and the extragalactic fast radio bursts (FRBs). If the detectable emission of these objects extends to lower radio frequencies, the LOw Frequency ARray (LOFAR) is ideally suited to seek and localize these transients at frequencies of 10–250 MHz. This is due to LOFAR’s sensitivity, diverse beamform capabilities, and transient buffers for the individual elements that allow post-event imaging of events, potentially at arcsecond resolution. Aims. Our aim is to identify and localize pulses at frequencies below 250 MHz and, in the case of nondetections, derive upper limits on the sky and volume rates of FRBs. Methods. A real-time search program for fast radio transients is installed on the LOFAR systems which runs commensally with other observations, and uses the wide incoherent LOFAR beam (11.25 deg2 at 150 MHz). Buffered data from hundreds of dipoles are used to reconstruct the direction and polarization information of the event, and to distinguish between celestial, terrestrial, and instrumental origins. Results. Observations were taken covering either the frequency range 119–151 MHz or in four frequency bands, each of 2 MHz in width, centered at 124, 149, 156, and 185 MHz. A first pilot survey covered a range of dispersion measures (DM) below 120 pc cm−3, focusing on Galactic sources, and resulted in an upper limit on the transient rate at LOFAR frequencies of less than 1500 events per sky per day above a fluency of 1.6 kJy ms for an 8-ms pulse. A second pilot survey covered a range of DMs below 500 pc cm−3, focusing on extragalactic sources to about 1 Gpc, and resulted in an upper limit of 1400 events per sky per day above a fluency of 6.0 kJy ms for an 8-ms pulse. Using a model for the distance-DM relationship, this equates to an upper limit of 134 events per Gpc3 per day.

A Note on the Bending Moment Induced in the Booms of a Spar at the Point of Application of a Concentrated Load

1950 ◽  
Vol 1 (4) ◽  
pp. 281-290
Author(s):  
H. F. Winny
Keyword(s):  
Shear Strain ◽  
Experimental Verification ◽  
Mathematical Theory ◽  
Bending Moment ◽  
Wave Form ◽  
Concentrated Load ◽  
Original Investigation ◽  
Wing Spar ◽  
The Web

SummaryThe effect of a concentrated load, such as occurs in a wing spar at the fuselage, is to cause a discontinuity in shear strain of the spar web, which induces a bending moment in the booms through the medium of the rivets (or bolts) which attach the booms to the web. A mathematical theory is developed which shows that this bending induced in the boom is of a damped wave form starting at the point of application of the shear, and in practice the magnitude of the stresses produced by the bending moment may be appreciable at the wing root when the boom is deep compared with the spar depth (say 20 per cent.).Further experimental verification is desirable, but a single wing test suggested the original investigation, and showed a measure of agreement with the theory.

A Rapid Procedure for the Simultaneous Estimation of the Anticonvulsant Drugs, Ethosuximide, Phenobarbitone, Phenytoin, and Carbamazepine in Serum Using High-Pressure Liquid Chromatography

1983 ◽  
Vol 20 (1) ◽  
pp. 37-40 ◽  
Author(s):  
David C Turnell ◽  
Susan C Trevor ◽  
John D H Cooper
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Linear Response ◽  
Simultaneous Estimation ◽  
Single Extraction ◽  
Rapid Procedure ◽  
Upper Limit ◽  
Drug Concentrations ◽  
Alumina Treatment

A rapid isocratic high-pressure liquid chromatography procedure for the analysis of ethosuximide, phenobarbitone, phenytoin, and carbamazepine in serum is described. The method employs a single extraction from serum; alumina treatment of this extract eliminates interference from fast-eluting compounds, allowing rapid chromatography. A linear response is obtained for drug concentrations up to three times the upper limit of the therapeutic ranges. Within-batch and between-batch precisions for the means of these ranges varied from 2·2 to 5·5% and from 3·1 to 7·5%, respectively.

Photographic Equidensitometry of High Voltage Electron Images of Thick Noncrystalline Materials

1972 ◽  
Vol 30 ◽  
pp. 594-595
Author(s):  
Keinosuke Kobayashi
Keyword(s):  
High Voltage ◽  
Linear Response ◽  
Thickness Distribution ◽  
Contour Map ◽  
Mass Thickness ◽  
Voltage Electron ◽  
High Voltage Electron ◽  
Homogeneous Particle ◽  
Photographic Emulsions ◽  
Logarithmic Relation

Equidensitometry as developed by E. Lau and W. Krug has been little used in the analysis of ordinary electron photomicrographs, yet its application to the high voltage electron images proves merits of this procedure. Proper sets (families) of equidensities as shown in the next page are able to reveal the contour map of mass thickness distribution in thick noncrystalline specimens. The change in density of the electron micrograph is directly related to the mass thickness of corresponding area in the specimen, because of the linear response of photographic emulsions to electrons and the logarithmic relation between electron opacity and mass thickness of amorphous object.This linearity is verified by equidensitometry of a spherical solid object as shown in Fig. 1a. The object is a large (1 μ) homogeneous particle of polystyrene. Fig. 1b is a composite print of three equidensities of the 1st order prepared from Fig. 1a.

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