The Rate of Movement of Planaria alpina

1935 ◽  
Vol 12 (3) ◽  
pp. 271-285
Author(s):  
R. S. A. BEAUCHAMP
Keyword(s):  
Low Temperatures ◽  
Muscular Contraction ◽  
The Other ◽  
Normal Rate ◽  
Effect Of Temperature ◽  
Inhibitory Process ◽  
Natural Conditions ◽  
Anterior Border ◽  
External Stimuli ◽  
Rate Of Movement

1. The rate of movement and the length of the periods of activity of Pl. alpina are increased by raising the temperature, except at very low temperatures. 2. The normal rate of movement appears to be controlled by a balance between two nervous processes, one being excitatory, the other being inhibitory. 3. The inhibitory process is broken down at the higher temperatures before the excitatory or muscular mechanisms are damaged. 4. Starvation may lead to a slight increase in the rate of movement. 5. External stimuli affect the rate of movement. 6. The chemo-receptors are situated on the extreme anterior border of the head. 7. The effect of temperature on the normal rate of movement gives no information regarding the chemical reactions responsible for muscular contraction. 8. Pl. alpina cannot tolerate indefinitely temperatures higher than 12° C. 9. Under natural conditions Pl. alpina is never found at temperatures above 15° C

COMPARATIVE SURVIVAL AND DECOMPOSING ABILITY OF FOUR FUNGI ISOLATED FROM LEAF LITTER AT LOW TEMPERATURES

1974 ◽  
Vol 54 (3) ◽  
pp. 245-253 ◽  
Author(s):  
K. C. IVARSON
Keyword(s):  
Leaf Litter ◽  
Low Temperatures ◽  
Room Temperature ◽  
Abundant Species ◽  
Decomposition Process ◽  
The Other ◽  
Natural Conditions ◽  
Cold Temperatures ◽  
Available Energy ◽  
Cold Tolerant

The survival and decomposing ability of the four dominant fungi found in low-temperature decomposing leaf litter was studied over a 46-mo period, at temperatures ranging from 1 C to room temperature. A Rhizoctonia sp. by itself and in association with the three other fungi disappeared. When alone it brought about no decomposition. Over the temperature range a Penicillium sp. that appeared to be a member of the Penicillium terrestre series showed strong survival properties in association with the other fungi, and by itself decomposed about the same amount of litter as the natural microbial flora of the unaltered litter, indicating that under natural conditions and at temperatures above 1 C this fungus is an important colonizer and decomposer of organic matter. Mucor spinescens alone and in association survived at room temperature and 10 C, but was absent at 4 and 1 C. By itself it decomposed a small amount of litter. The most abundant species, Chrysosporium pannorum (50% of all isolates at cold temperatures), a cellulolytic fungus, was not able to survive in litter in the absence of the other fungi. In their presence, it not only survived but increased in number as temperature decreased. The facts that pH changes and litter extract did not affect its growth suggest that C. pannorum does not possess the ability to be a pioneer colonist, and it is only after associated fungi begin the initial breakdown and perhaps supply easily available energy sources or growth factors that C. pannorum is able to take part in the decomposition process and survive. Thus, as temperature decreases, there is perhaps less competition for this cold-tolerant fungus, and its role in the decomposition process increases.

Effect of temperature on the cereal aphids Metopolophium dirhodum (Wlk.), Rhopalosiphum padi (L.) and Macrosiphum avenue (F.) (Hem., Aphididae)

1974 ◽  
Vol 63 (3) ◽  
pp. 401-409 ◽  
Author(s):  
G. J. Dean
Keyword(s):  
Low Temperatures ◽  
Rhopalosiphum Padi ◽  
Survival Rates ◽  
Fourth Instar ◽  
The Other ◽  
Effect Of Temperature ◽  
Controlled Environment ◽  
Cereal Aphids ◽  
Metopolophium Dirhodum ◽  
Capacity For Increase

AbstractThe effect of temperature within the range 10–30°C on Metopolophium dirhodum (Wlk.), Rhopalosiphum padi (L.) and Macrosiphum avenae (F.) was measured in controlled environment cabinets. Development rates increased with temperature to a maximum at 20°C for Metopolophium dirhodum, 22·5°C for Macrosiphum avenae and 25°C for R. padi, decreasing thereafter to zero by 30°C when all the nymphs died. The fourth instar and pre-reproductive adult appeared to be affected at temperatures below those for the younger instars. Mortalities of immature M. avenae were similar between 10° and 25°C, but more immature Metopolophium dirhodum died at high, and R. padi at low, temperatures. Survival rates decreased with increase of temperature, and fecundity was largest at 20°C. Rates of increase became largest at 20°C for M. dirhodum and Macrosiphum avenae and at 25°C for R. padi. Above 15°C, R. padi had a 4–16 times larger capacity for increase than the other two species because it developed faster and achieved its rate of maximum fecundity sooner.

scholarly journals Temperature and Enzyme Activity

1927 ◽  
Vol 14 (3) ◽  
pp. 723-727 ◽  
Author(s):  
John R. Baker
Keyword(s):  
Enzyme Activity ◽  
Low Temperatures ◽  
The Other ◽  
Effect Of Temperature ◽  
Crystalline Style ◽  
Other Hand

The enzyme contained in the crystalline style of Pecten is destroyed more and more rapidly as temperature increases. On the other hand, it becomes more and more active if incubated at fairly low temperatures, possibly as a result of the progressive dispersion of the protein base on which it is absorbed. A graph has been calculated showing the effect of temperature on enzyme activity when both destruction and (?) dispersion are discounted.

scholarly journals The Respiration of some Planktonic copepods II. The Effect Of Temperature

1953 ◽  
Vol 31 (3) ◽  
pp. 447-460 ◽  
Author(s):  
D. T. Gauld ◽  
J. E. G. Raymont
Keyword(s):  
Respiratory Rate ◽  
The Body ◽  
The Other ◽  
Effect Of Temperature ◽  
Acartia Clausi ◽  
Temora Longicornis ◽  
Different Temperatures ◽  
Planktonic Copepods ◽  
The Difference ◽  
The Relationship

The respiratory rates of three species of planktonic copepods, Acartia clausi, Centropages hamatus and Temora longicornis, were measured at four different temperatures.The relationship between respiratory rate and temperature was found to be similar to that previously found for Calanus, although the slope of the curves differed in the different species.The observations on Centropages at 13 and 170 C. can be divided into two groups and it is suggested that the differences are due to the use of copepods from two different generations.The relationship between the respiratory rates and lengths of Acartia and Centropages agreed very well with that previously found for other species. That for Temora was rather different: the difference is probably due to the distinct difference in the shape of the body of Temora from those of the other species.The application of these measurements to estimates of the food requirements of the copepods is discussed.

scholarly journals Catalytic Conversion of n-C7 Asphaltenes and Resins II into Hydrogen Using CeO2-Based Nanocatalysts

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1301
Author(s):  
Oscar E. Medina ◽  
Jaime Gallego ◽  
Sócrates Acevedo ◽  
Masoud Riazi ◽  
Raúl Ocampo-Pérez ◽  
...  
Keyword(s):  
Hydrogen Production ◽  
Low Temperatures ◽  
Gaseous Mixture ◽  
H2 Production ◽  
The Other ◽  
Hydrogen Release ◽  
Catalytic Gasification ◽  
Three Samples ◽  
Main Decomposition ◽  
Catalytic Capacity

This study focuses on evaluating the volumetric hydrogen content in the gaseous mixture released from the steam catalytic gasification of n-C7 asphaltenes and resins II at low temperatures (<230 °C). For this purpose, four nanocatalysts were selected: CeO2, CeO2 functionalized with Ni-Pd, Fe-Pd, and Co-Pd. The catalytic capacity was measured by non-isothermal (from 100 to 600 °C) and isothermal (220 °C) thermogravimetric analyses. The samples show the main decomposition peak between 200 and 230 °C for bi-elemental nanocatalysts and 300 °C for the CeO2 support, leading to reductions up to 50% in comparison with the samples in the absence of nanoparticles. At 220 °C, the conversion of both fractions increases in the order CeO2 < Fe-Pd < Co-Pd < Ni-Pd. Hydrogen release was quantified for the isothermal tests. The hydrogen production agrees with each material’s catalytic activity for decomposing both fractions at the evaluated conditions. CeNi1Pd1 showed the highest performance among the other three samples and led to the highest hydrogen production in the effluent gas with values of ~44 vol%. When the samples were heated at higher temperatures (i.e., 230 °C), H2 production increased up to 55 vol% during catalyzed n-C7 asphaltene and resin conversion, indicating an increase of up to 70% in comparison with the non-catalyzed systems at the same temperature conditions.

Yields of mixtures of single-cross hybrid field beans (Viciafaba L.) with one of the parental inbred lines

1966 ◽  
Vol 67 (2) ◽  
pp. 235-237 ◽  
Author(s):  
D. A. Bond ◽  
J. L. Fyfe ◽  
Gillian Toynbee-Clarke
Keyword(s):  
Inbred Lines ◽  
The Other ◽  
Normal Rate ◽  
Single Cross ◽  
Parental Inbred ◽  
The Mean ◽  
Field Beans

The yields of seed from a hybrid, one of its parents and different mixtures of the hybrid and parent were compared in the case of two different hybrids. Open-pollinated controls were included in the trial, which was sown at about the normal rate for beans. With both hybrids a mixture of 11 of hybrid to 1 of parent yielded as well as the hybrid itself and mixtures of 2 of hybrid to 1 of parent yielded in both cases about 7 cwt./acro more than the mean of the open-pollinated controls. With the higher-yielding hybrid, which had less contrast in vegetative vigour between hybrid and parent, mixtures in the proportions 5:1 and 2:1 showed declining yields, but with the other hybrid they yielded as well as the pure hybrid.

scholarly journals Potential for the Postharvest Biological Control of Phthorimaea operculella (Lepidoptera, Gelechiidae) by Blattisocius tarsalis (Mesostigmata, Blattisociidae)

Agronomy ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 288
Author(s):  
Jorge Gavara ◽  
Ana Piedra-Buena ◽  
Estrella Hernandez-Suarez ◽  
Manuel Gamez ◽  
Tomas Cabello ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Storage Conditions ◽  
Control Agent ◽  
Phthorimaea Operculella ◽  
Effect Of Temperature ◽  
Potato Storage ◽  
Release Rates ◽  
Blattisocius Tarsalis ◽  
Predatory Capacity ◽  
Pest Density

Phthorimaea operculella is one of the most important pests causing damage to stored potatoes. In this work, the effect of temperature (at 10, 20 and 30 °C) on the predation of pest eggs by Blattisocius tarsalis was studied in the laboratory. In addition, the effect of three predatory release rates on two pest densities was studied under microcosm conditions. The results showed that B. tarsalis maintains its predatory capacity at low temperatures (10 °C), obtaining an efficiency of 49.66 ± 5.06% compared to the control. In turn, at 20 °C, a maximum efficacy of 78.17 ± 4.77% was achieved, very similar to that presented at 30 °C (75.57 ± 4.34%). Under microcosm conditions and at low pest density (10 eggs/container), the mortality due to the mite was 96.97 ± 3.03%, 81.82 ± 8.84%, and 84.85 ± 8.30%, respectively, for the three predatory release rates (5, 10 or 20 mites/container). At the high infestation level, the pest control ranged from 61.54 ± 9.21% to 92.31 ± 2.74%, depending on the predatory release rate. The results obtained show that B. tarsalis could be a relevant control agent against P. operculella under non-refrigerated potato storage conditions, as well as in the first stages of their storage under refrigerated conditions.

scholarly journals Effect of Temperature on the Corrosion Inhibition of Trans-4-Hydroxy-4′-Stilbazole on Mild Steel in HCl Solution

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Ayssar Nahlé ◽  
Ideisan I. Abu-Abdoun ◽  
Ibrahim Abdel-Rahman
Keyword(s):  
Weight Loss ◽  
Double Bond ◽  
Adsorption Isotherm ◽  
Mild Steel ◽  
Corrosion Inhibitor ◽  
Thermodynamic Parameters ◽  
The Other ◽  
Effect Of Temperature ◽  
Temkin Adsorption Isotherm ◽  
Hcl Solution

The inhibition and the effect of temperature and concentration of trans-4-hydroxy-4′-stilbazole on the corrosion of mild steel in 1 M HCl solution was investigated by weight loss experiments at temperatures ranging from 303 to 343 K. The studied inhibitor concentrations were between  M and  M. The percentage inhibition increased with the increase of the concentration of the inhibitor. The percentage inhibition reached about 94% at the concentration of  M and 303 K. On the other hand, the percentage inhibition decreased with the increase of temperature. Using the Temkin adsorption isotherm, the thermodynamic parameters for the adsorption of this inhibitor on the metal surface were calculated. Trans-4-hydroxy-4′-stilbazole was found to be a potential corrosion inhibitor since it contained not only nitrogen and oxygen, but also phenyl and pyridine rings that are joined together with a double bond (–C=C–) in conjugation with these rings.

scholarly journals Sex Differentiation in Amphibians: Effect of Temperature and Its Influence on Sex Reversal

2021 ◽  
pp. 1-11
Author(s):  
Adrián Ruiz-García ◽  
Álvaro S. Roco ◽  
Mónica Bullejos
Keyword(s):  
Sexual Differentiation ◽  
Sex Differentiation ◽  
Environmental Contaminants ◽  
Natural Populations ◽  
Sex Reversal ◽  
The Other ◽  
Effect Of Temperature ◽  
Amphibian Species ◽  
Expected Increase

The role of environmental factors in sexual differentiation in amphibians is not new. The effect of hormones or hormone-like compounds is widely demonstrated. However, the effect of temperature has traditionally been regarded as something anecdotal that occurs in extreme situations and not as a factor to be considered. The data currently available reveal a different situation. Sexual differentiation in some amphibian species can be altered even by small changes in temperature. On the other hand, although not proven, it is possible that temperature is related to the appearance of sex-reversed individuals in natural populations under conditions unrelated to environmental contaminants. According to this, temperature, through sex reversal (phenotypic sex opposed to genetic sex), could play an important role in the turnover of sex-determining genes and in the maintenance of homomorphic sex chromosomes in this group. Accordingly, and given the expected increase in global temperatures, growth and sexual differentiation in amphibians could easily be affected, altering the sex ratio in natural populations and posing major conservation challenges for a group in worldwide decline. It is therefore particularly urgent to understand the mechanism by which temperature affects sexual differentiation in amphibians.

Electrical interactions between the giant axons of a polychaete worm (Sabella penicillus L.)

1980 ◽  
Vol 84 (1) ◽  
pp. 119-136
Author(s):  
D. Mellon ◽  
J. E. Treherne ◽  
N. J. Lane ◽  
J. B. Harrison ◽  
C. K. Langley
Keyword(s):  
Safety Factor ◽  
Nerve Cord ◽  
Action Potentials ◽  
Divalent Cations ◽  
Muscular Contraction ◽  
The Body ◽  
The Other ◽  
Intracellular Recordings ◽  
Giant Axons ◽  
Other Hand

Intracellular recordings demonstrated a transfer of impulses between the paired giant axons of Sabella, apparently along narrow axonal processes contained within the paired commissures which link the nerve cords in each segment of the body. This transfer appears not to be achieved by chemical transmission, as has been previously supposed. This is indicated by the spread of depolarizing and hyperpolarizing voltage changes between the giant axons, the lack of effects of changes in the concentrations of external divalent cations on impulse transmission and by the effects of hyperpolarization in reducing the amplitude of the depolarizing potential which precedes the action potentials in the follower axon. The ten-to-one attenuation of electronic potentials between the giant axons argues against the possibility of an exclusively passive spread of potential along the axonal processes which link the axons. Observation of impulse traffic within the nerve cord commissures indicates, on the other hand, that transmission is achieved by conduction of action potentials along the axonal processes which link the giant axons. At least four pairs of intact commissures are necessary for inter-axonal transmission, the overall density of current injected at multiple sites on the follower axon being, it is presumed, sufficient to overcome the reduction in safety factor imposed by the geometry of the system in the region where axonal processes join the giant axons. The segmental transmission between the giant axons ensures effective synchronization of impulse traffic initiated in any region of the body and, thus, co-ordination of muscular contraction, during rapid withdrawal responses of the worm.

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