Illinois Junior Academy of Science - Yearbook (Urbana, IL)

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the plates was decreased with each exposure and the results analyzed. As the number of photons striking the film de- creased, there seemed to be some irregularity in the pat- terns. This conclusion was not decisive because of the dif- ficulty in reading the films and detecting the faint inter- ference patterns. UHF Oscillators I MICHAEL MARENTIC An oscillator is a voltage amplifier with feedback from the plate, output, to the grid, input-. The prefix UHF, ultra high frequency, is the frequency range from 3 x 10' through 3 x 10' cycles per second. In my project I used only single triode tube oscillator circuits, the Hartly and the parallel line oscillator. My hypotheses were that wiring techniques should have a profound effect on the oscillators, as well as different circuits and tubes. The suppositions were sup- ported by my work. Frequency measurement was at first a serious problem. All the methods I used were ways of meas- uring the placement of standing waves in a parallel line transmission line. The method that worked best was to move a shorting bar along the line and notice the dips in voltage as indicated by a meter connected through an amp- lifier to the ends of the transmission line. The highest fre- quency that I was able to obtain was 760 megacycles, a wavelength of 40 centimeters, using an acorn tube in a parallel line circuit. The frequency of the oscillator isn't that great, but granted it is well into the UHF region of the electromagnetic! spectrum. I hope to try some other acorn tubes or lighthouse tubes in the oscillator circuit. I should get the frequency past at least 1,000 megacycles,

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The Effect of Temperature on Nerve Impulse Transmission ROBERT M. KAYE Niles North High School , Ii Ihetffpnon gggg Hmn5m,ss4QA 5 e 'W'df'1ffo... wffvf 5l ,mu amp? Dem miK 'fRfAnl sH1IIAlC'?5fUm. - V Lag poukataslgg . Inmglii , A , V ' , . - . It at T X AttimPizentiil,.asfunctWfIffHP A - - Ippmxtui I I ' .' I 'il . -L. This investigation is an attempt to relate the laws of thermodynamics to activity in biological systems. Specifically, it studies the effect of temperature on nerve impulse trans- mission and action potential. Based on the fact that the nervous system seems to regulate all body functions, it was hypothesized that the optimum temperature of these bio- chemical processes would indicate the optimum temperature of the organism as a whole. If this is the case, then behavior could be linked to environmental conditions. Apparatus was designed and constructed to test the reliability of the hypothesis. Frog sciatic nerves were elec- trically stimulated and observed with an oscilloscope. It was found that increases in temperature between 5.0 C and 25.5 C resulted in changes of the above factors according to Qi... Beyond 25.5 C transmission rate and action potential decreased. In analysis of transmission rate and action po- tential, both were found to have the same temperature of greatest activity. This optimum temperature was 25.5 C. Although the data shows the influence of thermody- namics as checked by QW, it cannot be soundly concluded that these are the prime factors in nerve transmission. Further, it cannot be safely deduced that these factors, as affected by temperature, are the significant variables in poikilother- mal behavior. Other research suggest the importance of absolute threshold. Further investigation must be done. months. My conclusion is that there are many differences between frogs and toads which are never seen or known by the average person. Frogs and Toads: What is The Difference? DAVID B. DUNN The purpose of this exhibit is to study and describe the principal characteristics of frogs and toads and to learn the differences between them. Outside assistance I received was help and counsel from my teacher, Mrs. Foard and typing by my parents. I read and studied resource materials listed in biblio- graphy. Accumulated and labeled preserved specimens. Col- lected and cared for live specimens in captivity for several months. My conclusion is that there are many differences between frogs and toads which are never seen or known by the average person. s, I I 1 DAVID MOLNNR n Pm-pose: The purpose of my experimentation is to in- vestigate and mathematically analyze some of the variables inyolved in the evaporation of ethyl alcohol. I am primarily concerned with temperature change and heat loss caused by the evaporation. Procedure: Sixty grams of ethyl alcohol is placed in a thermos bottle filler, a thermometer is inserted, and the whole apparatus is set upon a scale. A small fan is used to blow the vapors away, thereby speeding the evaporation, and a timer is used to keep track of the time since evapora- tion began. The alcohol is allowed to evaporate freely and the temperature and time are noted after every half gram of alcohol evaporates. The alcohol starts at room tempera- ture in each case. In the second phase of the project I at- tempt to reproduce the literature value for the latent heat of vaporization for ethyl alcohol by adding enough energy, electrically, to keep the temperature constant throughout evaporation. Results: The results are best summarized in the data tables which appear in the body of the report. Interpretation: My interpretation consisted primarily of an analysis of the data which resulted in four original equa- tions: 13 T 2 21.1 110-0-079 ml 23 T-6.8 I 15.5 C10-3-2810-401 35 c + 210 2 44.9 L0-344 41 c Z 235 tm-0.659 0-432 where T is the temperature in C., m is the total weight lost, t is the time in seconds since evaporation began, and c is the total number of calories lost. My problem has two parts. My first part is to learn what weather conditions affect the entry of box turtles into the ground for hibernation. The second part of my problem concerns whether their downward movement through the ground is related to weather conditions. I recorded the dates that the box turtles entered the ground in 1964 and 1965. In 1965 I also kept regular meas- urements of the box turtles downward movement. Then I got weather data on air temperatures, ground temperatures, precipitation and cloud cover and compared these with my turtle data. When I compared the data to the weather data I found