scholarly journals Studies on the biological action of light

1925 ◽  
Vol 98 (688) ◽  
pp. 171-187 ◽  
Keyword(s):  
Radiant Energy ◽  
Biological Action ◽  
Small Animals ◽  
Respiration Chamber ◽  
General Metabolism ◽  
Carbon Arc ◽  
Animal Metabolism ◽  
Quartz Beaker ◽  
Effect Of Light ◽  
Approximate Measurement

Section I.—The Effect of Light on the Metabolic Rate of Small Animals. Introduction .—Whereas plant life is directly dependent on the supply of radiant energy from the sun or an artificial source of light, animals may lead perfectly healthy lives in complete darkness. Early observations by K. A. Hasselbalch on the total metabolic changes in experimental animals, and by A. Durig and his co-workers on the respiratory exchange in man, seemed to show that light was without action on animal metabolism. Recently, however, the therapeutic application of sunlight at Alton and Leysin (1) and the radiations of the large carbon arc in the hospitals of our large towns have yielded results which suggest a stimulant action on general metabolism. Measurements by Leonard Hill and A. C. Campbell (2), however, show that the open-air conditions were mainly responsible at the former resorts. The present investigation of the gaseous metabolism of small animals supplies an approximate measurement of the total metabolism during exposure to artificial radiations. Method .—The rat was the species chosen as it could be comfortably confined in a small quartz beaker used as a respiration chamber. The latter was fitted up in a manner somewhat similar to the arrangement in the Haldane-Pembrey respiration apparatus.

scholarly journals Dynamic aspects of oxygen consumption and carbon dioxide production in swine

1997 ◽  
Vol 78 (3) ◽  
pp. 397-410 ◽  
Author(s):  
J. Van Milgen ◽  
J. Noblet ◽  
S. Dubois ◽  
J.-F. Bernier
Keyword(s):  
Differential Equations ◽  
Heat Production ◽  
Carbon Dioxide Production ◽  
Measurement Range ◽  
Open Circuit ◽  
Growing Pigs ◽  
Model Parameters ◽  
Respiration Chamber ◽  
Gas Exchanges ◽  
Animal Metabolism

A model is proposed that allows study of the short-term dynamics of gas exchanges (and heat production) in large open-circuit respiration chambers. The model describes changes in [O2] and [CO2] in the respiration chamber by a series of differential equations based on animal metabolism and physical characteristics of gas exchange. The model structure was similar for O2 and CO2, although model parameters differed. A constant level of O2 consumption (and CO2 production) was assumed for resting animals which was different for fed and fasted animals. The adaptation from a fed to a fasting state was described as a first-order process. Physical activity (standing or sitting) was recorded and was included in the model as a constant. Thermic effect of feed comprised the O2 consumption and CO2 production related to several relatively rapidly occurring processes after ingestion of a meal (e.g. ingestion, digestion or absorption). In the model, these processes were pooled into a single phenomenon. Model parameters were obtained statistically by comparing model predictions (based on the numerically integrated differential equations) with the observed [O2] and [CO2]. The model was evaluated by studying gas exchanges in growing pigs that were fasted for 31 h and re-fed a single meal thereafter. The model fitted the data well over the 47 h measurement range. Traditional methods in which heat production is calculated suffer from noisy data when the interval between observations becomes too short. The proposed method circumvents this by modelling the observed concentration of gases in the respiration chamber rather than the calculated heat production.

Effect of Light on Alteration of Nutritional Value and Flavor of Milk: A Review1

1980 ◽  
Vol 43 (4) ◽  
pp. 314-320 ◽  
Author(s):  
R. L. BRADLEY
Keyword(s):  
Nutritional Value ◽  
Radiant Energy ◽  
Flavor Stability ◽  
Fluorescent Light ◽  
Partial Loss ◽  
Plastic Bags ◽  
Exposure Interval ◽  
Flavor Development ◽  
Protective Packaging ◽  
Effect Of Light

Milk in glass, polycarbonate, high density polyethylene, blow-molded polyethylene, plastic bags and paperboard containers, when exposed to fluorescent light or sunlight, will develop a characteristic off-flavor described synonomously by many researchers as activated, sunlight or oxidized flavor. The extent of flavor development is related to the exposure interval, strength of the light and amount of milk surface exposed. Paperboard containers. particularly those with large printed areas of dark ink or foil in the laminate, offer the best protecton to milk, while the remaining containers offered limited protection at best. Characteristic flavor is produced prinicipally by conversion of methionine to methional. Partial loss of vitamins B2 and C and some amino acids parallel development of light-induced off-flavor. Loss of other constituents is minimal. Many researchers offered suggestions to improve the flavor stability of milk held in display cases illuminated with fluorescent lights. Among these are changes to more protective packaging, reduction of radiant energy to 538 lux, use of gold or “bug light” types of fluorescent lights and more dark ink areas on exposed parts of paperboard cartons (gables and main display panels). Perhaps grocers should bag all containers of milk to afford adequate protection from sunlight between points of refrigeration.

Effect of light intensity on the ultrastructure of the filamentous cyanobacterium, Anabaena variabilis

1988 ◽  
Vol 46 ◽  
pp. 300-301
Author(s):  
C. S. Bricker ◽  
S. R. Barnum ◽  
B. Huang ◽  
J. G. Jaworskl
Keyword(s):  
Fatty Acid ◽  
Light Intensity ◽  
Acid Content ◽  
Fatty Acid Content ◽  
Anabaena Variabilis ◽  
Chloroplast Envelope ◽  
Major Constituent ◽  
Filamentous Cyanobacterium ◽  
Photosynthetic Membrane ◽  
Effect Of Light

Cyanobacteria are Gram negative prokaryotes that are capable of oxygenic photosynthesis. Although there are many similarities between eukaryotes and cyanobacteria in electron transfer and phosphorylation during photosynthesis, there are two features of the photosynthetic apparatus in cyanobacteria which distinguishes them from plants. Cyanobacteria contain phycobiliproteins organized in phycobilisomes on the surface of photosynthetic membrane. Another difference is in the organization of the photosynthetic membranes. Instead of stacked thylakolds within a chloroplast envelope membrane, as seen In eukaryotes, IntracytopIasmlc membranes generally are arranged in three to six concentric layers. Environmental factors such as temperature, nutrition and light fluency can significantly affect the physiology and morphology of cells. The effect of light Intensity shifts on the ultrastructure of Internal membrane in Anabaena variabilis grown under controlled environmental conditions was examined. Since a major constituent of cyanobacterial thylakolds are lipids, the fatty acid content also was measured and correlated with uItrastructural changes. The regulation of fatty acid synthesis in cyanobacteria ultimately can be studied if the fatty acid content can be manipulated.

Electron-diffraction studies of amorphous carbon thin films

1993 ◽  
Vol 51 ◽  
pp. 1100-1101
Author(s):  
David A. Muller
Keyword(s):  
Thin Films ◽  
Electron Diffraction ◽  
Amorphous Carbon ◽  
Glassy Carbon ◽  
Spherical Structure ◽  
Local Ordering ◽  
Carbon Arc ◽  
Similar Appearance ◽  
Carbon Thin Films ◽  
Large Spherical

The sp2 rich amorphous carbons have a wide variety of microstructures ranging from flat sheetlike structures such as glassy carbon to highly curved materials having similar local ordering to the fullerenes. These differences are most apparent in the region of the graphite (0002) reflection of the energy filtered diffracted intensity obtained from these materials (Fig. 1). All these materials consist mainly of threefold coordinated atoms. This accounts for their similar appearance above 0.8 Å-1. The fullerene curves (b,c) show a string of peaks at distance scales corresponding to the packing of the large spherical and oblate molecules. The beam damaged C60 (c) shows an evolution to the sp2 amorphous carbons as the spherical structure is destroyed although the (220) reflection in fee fcc at 0.2 Å-1 does not disappear completely. This 0.2 Å-1 peak is present in the 1960 data of Kakinoki et. al. who grew films in a carbon arc under conditions similar to those needed to form fullerene rich soots.

Small animals levitated by sound

Nature ◽  
2006 ◽  
Author(s):  
Philip Ball
Keyword(s):  
Small Animals
Sign in / Sign up

Export Citation Format

Share Document