scholarly journals Relative humidity, temperature, substrate type, and height of terrestrial lichens in a tropical paramo

2019 ◽  
Vol 67 (1) ◽  
Author(s):  
Julián Monge-Nájera
Keyword(s):  
Costa Rica ◽  
Relative Humidity ◽  
Substrate Temperature ◽  
Substrate Type ◽  
Main Determinant ◽  
Buena Vista ◽  
Terricolous Lichens ◽  
Different Shapes ◽  
Atmospheric Factors

Lichens are traditionally divided into types such as "crustose", "foliose" and "fruticose", with different shapes and heights. Substrate, temperature and water are thought to affect lichen height, but there are few studies regarding tropical paramo lichens. Along 2015 I measured those variables in the terricolous lichens of the Cerro Buena Vista, paramo (Costa Rica, 9°33' N & 83°45' W). The measurements were taken inside the lichens and in the substrate under them, in 61 randomly located quadrats (50 x 50 cm). Lichens grew taller on (1) warmer ground, (2) wetter ground, (3) the moister Caribbean slope, and (4) the season with heavier rainfall, as expected. Apparently, atmospheric factors are more important than substrate in the determination of temperature, relative humidity and growth of lichens. Physiologically available water seems to be the main determinant of lichen vertical growth in the Buena Vista paramo.

scholarly journals The Role of Substrate Type, Moisture and Temperature on the Vertical Growth of Terricolous Lichens

2018 ◽  
Author(s):  
Julián Monge-Nájera
Keyword(s):  
Water Levels ◽  
Soft Ground ◽  
Substrate Type ◽  
Main Determinant ◽  
Vertical Growth ◽  
Terricolous Lichens ◽  
The Caribbean ◽  
Terricolous Lichen ◽  
Recorded Temperature

Lichens are traditionally divided into short “crustose”, intermediate “foliose” and tall “fruticose” types, a practice that hides a growth continuum. Substrate, temperature and water are thought to affect vertical growth, but such factors are difficult to measure, because, for example, the water actually available to lichens does not match rainfall patterns or even ground water levels. To reliably assess the effect of those factors, I recorded temperature, moisture, and substrate in and under individual terricolous lichen colonies in 60 fixed quadrats on April, August, October, and December of 2015 (Cerro de la Muerte, Costa Rica, 9°33′N; 83°45′W). The measurements were taken inside the colonies themselves (rather than on the general environment), covering an annual cycle of the relatively simple páramo habitat, where animals and vegetation have less impact than in lower ecosystems. The hypotheses were that lichens would grow taller on softer, warmer, and moister ground; on the Caribbean versant; and on the rainy season. Results matched the hypotheses, with one exception: lichens on soft ground were not taller than those on rock. Caribbean colonies were, on the average, 7 cm taller than those on the drier Pacific versant. Physiologically available water seems to be the main determinant of lichen vertical growth: more water means taller lichens and greater protection from climatic change for both the lichens and their microcommunities.

scholarly journals The role of substrate type, moisture and temperature on the vertical growth of terricolous lichens

2018 ◽  
Author(s):  
Julián Monge-Nájera
Keyword(s):  
Water Levels ◽  
Soft Ground ◽  
Substrate Type ◽  
Main Determinant ◽  
Vertical Growth ◽  
Terricolous Lichens ◽  
The Caribbean ◽  
Terricolous Lichen ◽  
Recorded Temperature

AbstractLichens are traditionally divided into short “crustose”, intermediate “foliose” and tall “fruticose” types, a practice that hides a growth continuum. Substrate, temperature and water are thought to affect vertical growth, but such factors are difficult to measure, because, for example, the water actually available to lichens does not match rainfall patterns or even ground water levels. To reliably assess the effect of those factors, I recorded temperature, moisture, and substrate in and under individual terricolous lichen colonies in 60 fixed quadrats on April, August, October, and December of 2015 (Cerro de la Muerte, Costa Rica, 9°33′N; 83°45′W). The measurements were taken inside the colonies themselves (rather than on the general environment), covering an annual cycle of the relatively simple páramo habitat, where animals and vegetation have less impact than in lower ecosystems. The hypotheses were that lichens would grow taller on softer, warmer, and moister ground; on the Caribbean versant; and on the rainy season. Results matched the hypotheses, with one exception: lichens on soft ground were not taller than those on rock. Caribbean colonies were, on the average, 7 cm taller than those on the drier Pacific versant. Physiologically available water seems to be the main determinant of lichen vertical growth: more water means taller lichens and greater protection from climatic change for both the lichens and their microcommunities.

Excess entropy of the systems of molecules differing in size and shape

1983 ◽  
Vol 48 (1) ◽  
pp. 192-198 ◽  
Author(s):  
Tomáš Boublík
Keyword(s):  
Equation Of State ◽  
Hard Spheres ◽  
Excess Entropy ◽  
Convex Bodies ◽  
Pure Substance ◽  
Liquid Equilibrium ◽  
Simple Rules ◽  
Different Shapes ◽  
The Mean

The excess entropy of mixing of mixtures of hard spheres and spherocylinders is determined from an equation of state of hard convex bodies. The obtained dependence of excess entropy on composition was used to find the accuracy of determining ΔSE from relations employed for the correlation and prediction of vapour-liquid equilibrium. Simple rules were proposed for establishing the mean parameter of nonsphericity for mixtures of hard bodies of different shapes allowing to describe the P-V-T behaviour of solutions in terms of the equation of state fo pure substance. The determination of ΔSE by means of these rules is discussed.

Research on a Generating Method of Spiral Flutes of Hourglass Worm Gear Hob

2017 ◽  
Author(s):  
Yang Jie ◽  
Li Haitao ◽  
Rui Chengjie ◽  
Wei Wenjun ◽  
Dong Xuezhu
Keyword(s):  
Mathematical Model ◽  
Manufacturing System ◽  
Worm Gear ◽  
Virtual Manufacturing ◽  
Transmission Ratio ◽  
Method Of Determination ◽  
Generating Method ◽  
Multiple Threads ◽  
Different Shapes

All of the cutting edges on an hourglass worm gear hob have different shapes and spiral angles. If the spiral angles are small, straight flutes are usually adopted. But for the hob with multiple threads, the absolute values of the negative rake angles at one side of the cutting teeth will greatly affect the cutting performance of the hob if straight flutes are still used. Therefore, spiral flutes are usually adopted to solve the problem. However, no method of determination of the spiral flute of the hourglass worm gear hob has been put forward till now. Based on the curved surface generating theory and the hourglass worm forming principle, a generating method for the spiral flute of the planar double enveloping worm gear hob is put forward in this paper. A mathematical model is built to generate the spiral flute. The rake angles of all cutting teeth of the hob are calculated. The laws of the rake angles of the cutting teeth of four hobs with different threads from one to four threads are analyzed when straight flutes and spiral flutes are adopted respectively. The laws between the value of the negative rake angles of the hob with four threads and the milling transmission ratio are studied. The most appropriate milling transmission ratio for generating the spiral flute is obtained. The machining of the spiral flutes is simulated by a virtual manufacturing system and the results verify the correctness of the method.

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