scholarly journals Quantifying Oxygen Management and Temperature and Light Dependencies of Nitrogen Fixation by Crocosphaera watsonii

mSphere ◽  
2019 ◽  
Vol 4 (6) ◽  
Author(s):  
Keisuke Inomura ◽  
Curtis Deutsch ◽  
Samuel T. Wilson ◽  
Takako Masuda ◽  
Evelyn Lawrenz ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
Low Temperature ◽  
Mechanistic Model ◽  
Global Scale ◽  
Physical Factors ◽  
Laboratory Studies ◽  
N Budget ◽  
Low Latitude ◽  
Chemical Factors ◽  
Physiological Explanation

Crocosphaera is one of the major N2-fixing microorganisms in the open ocean. On a global scale, the process of N2 fixation is important in balancing the N budget, but the factors governing the rate of N2 fixation remain poorly resolved. Here, we combine a mechanistic model and both previous and present laboratory studies of Crocosphaera to quantify how chemical factors such as C, N, Fe, and O2 and physical factors such as temperature and light affect N2 fixation. Our study shows that Crocosphaera combines multiple mechanisms to reduce intracellular O2 to protect the O2-sensitive N2-fixing enzyme. Our model, however, indicates that these protections are insufficient at low temperature due to reduced respiration and the rate of N2 fixation becomes severely limited. This provides a physiological explanation for why the geographic distribution of Crocosphaera is confined to the warm low-latitude ocean.

Further Studies upon Chemical Factors Affecting the Breeding of Anopheles in Trinidad

1934 ◽  
Vol 25 (4) ◽  
pp. 491-494 ◽  
Author(s):  
P. A. Buxton
Keyword(s):  
Analytical Study ◽  
Chemical Constituents ◽  
Physical Factors ◽  
Factors Affecting ◽  
Early Stages ◽  
Freshwater Biology ◽  
Chemical Technique ◽  
Chemical Factors ◽  
Physical And Chemical

During the last decade, entomologists have made progress in understanding the environment in which certain insects live; in particular, we begin to understand the effect of certain physical and chemical factors, which make up a part of the environment. With this gain in knowledge, it is sometimes possible to forecast outbreaks of insects and of diseases conveyed by them, and one can sometimes say that a particular alteration of the environment will result in loss or gain. But so far as mosquitos are concerned, one must admit that though much work has been devoted to the analytical study of the water in which the early stages are passed, the results are disappointing. A consideration of the published work suggests several reasons for this. Investigation into the ecology of the mosquito has had a vogue, and much of it has been done by workers who were isolated and whose knowledge of chemical technique and freshwater biology was limited. Apart from that, the inherent difficulties are great, for the worker must hunt for the limiting chemical and physical factors among a host of others which are doubtless unimportant, and there are few clues to indicate which of the chemical constituents of the water affects the mosquito. The data are therefore voluminous and it is difficult to reduce them to order and present them so that they can be readily understood.

How to detect occupational diseases associated with the exposure to chemical factors

2020 ◽  
pp. 26-35
Author(s):  
Sergey Babanov
Keyword(s):  
Urinary Tract ◽  
Occupational Diseases ◽  
Educational Institution ◽  
Physical Nature ◽  
Federal State ◽  
Physical Factors ◽  
Ministry Of Health ◽  
Production Factors ◽  
Chemical Factors ◽  
Medical University

Diseases of the kidneys and urinary tract, primarily of toxic and chemical etiology, constitute a large proportion of occupational diseases. Various production factors of both chemical and physical nature can cause the development of nephropathies. Sergey Babanov, Doctor of Medicine, Professor, Head of the Department of occupational diseases and clinical pharmacology at the Federal State-Funded Educational Institution of Higher Education Samara State Medical University of the Ministry of Health of the Russian Federation, chief freelance specialist in occupational pathology at the Ministry of Health of the Samara region, speaks about occupational diseases of the kidneys and urinary tract associated with the exposure to chemical and physical factors.

Effect of Blood Viscosity on Thrombosis Potential Near a Step Wall Transition

2009 ◽  
Author(s):  
Scott C. Corbett ◽  
Amin Ajdari ◽  
Ahmet U. Coskun ◽  
Hamid N.-Hashemi
Keyword(s):  
Blood Flow ◽  
Vessel Wall ◽  
Coagulation Factors ◽  
Artificial Organs ◽  
Physical Factors ◽  
Local Geometry ◽  
Induce Platelet Aggregation ◽  
Shear Rates ◽  
Chemical Factors ◽  
Low Shear

Thrombosis and hemolysis are two problems encountered when processing blood in artificial organs. Physical factors of blood flow alone can influence the interaction of proteins and cells with the vessel wall, induce platelet aggregation and influence coagulation factors responsible for the formation of thrombus, even in the absence of chemical factors in the blood. These physical factors are related to the magnitude of the shear rate/stress, the duration of the applied force and the local geometry. Specifically, high blood shear rates (or stress) lead to damage (hemolysis, platelet activation), while low shear rates lead to stagnation and thrombosis [1].

Keanekaragaman dan Kelimpahan Semut sebagai Predator Hama Tanaman Padi di Lahan Sawah Organik dan Anorganik Kecamatan Karanganom Kabupaten Klaten

2018 ◽  
Vol 19 (2) ◽  
pp. 125 ◽  
Author(s):  
Siska Lesiana Adhi ◽  
Mochamad Hadi ◽  
Udi Tarwotjo
Keyword(s):  
Insect Pests ◽  
Organic Matter Content ◽  
Rice Fields ◽  
Physical Factors ◽  
Sugar Solution ◽  
Soil Arthropods ◽  
Solenopsis Geminata ◽  
Organic Rice ◽  
High Soil ◽  
Chemical Factors

Ants potentially as predators that become natural enemies of insect pests in rice fields with paddy cultivation. This study aims to know the diversity and abundance of ants, the role of ants, the population of ants, and the influence of physical and chemical factors in organic and inorganic rice fields. The ants were collected using pit fall trap method with insect bait, fish meat, and sugar solution. The results showed that the number of species and the number of individuals in organic rice fields was higher (429 individuals, 11 species) than inorganic rice fields (193 individuals, 10 species). In general, the index of diversity in organic rice fields was higher (ranging from 0.73 to 1.65) compared to inorganic rice fields (ranging from 0 to 1.28). The index of evenness in organic rice fields ranged from 0.63 to 0.99 (evenly distributed), whereas in inorganic rice fields ranged from 0 to 0.99 (uneven until evenly distributed). The dominant ants in organic rice fields were Camponotus sp, Solenopsis geminata, Anoplolepis gracilipes, and Paratrechina longicornis, whereas in the inorganic rice fields were Tapinoma sp, Solenopsis geminata, and Camponotus sp. The index of similarity between organic and inorganic rice fields showed a high and very high degree of similarity based on the type of feed. Physical factors of high soil and air humidity environment, high soil and air temperature increased the diversity and abundance of ants in the rice fields ecosystem. Factors soil pH in accordance with the growth of soil Arthropods were neutral or slightly acidic. Chemical factors of organic matter content, Nitrogen (N), the content of C organic, and a high P total content increased the diversity and abundance of ants. Keywords: diversity and abundance, ants, organic and inorganic rice fields

scholarly journals A new mechanistic framework to predict OCS fluxes from soils

2016 ◽  
Vol 13 (8) ◽  
pp. 2221-2240 ◽  
Author(s):  
Jérôme Ogée ◽  
Joana Sauze ◽  
Jürgen Kesselmeier ◽  
Bernard Genty ◽  
Heidi Van Diest ◽  
...  
Keyword(s):  
Large Scale ◽  
Soil Microorganisms ◽  
Soil Moisture Content ◽  
Mechanistic Model ◽  
Carbonyl Sulfide ◽  
Reaction Diffusion ◽  
Global Scale ◽  
First Order ◽  
Uptake Rates ◽  
Hydrolysis Of

Abstract. Estimates of photosynthetic and respiratory fluxes at large scales are needed to improve our predictions of the current and future global CO2 cycle. Carbonyl sulfide (OCS) is the most abundant sulfur gas in the atmosphere and has been proposed as a new tracer of photosynthetic gross primary productivity (GPP), as the uptake of OCS from the atmosphere is dominated by the activity of carbonic anhydrase (CA), an enzyme abundant in leaves that also catalyses CO2 hydration during photosynthesis. However soils also exchange OCS with the atmosphere, which complicates the retrieval of GPP from atmospheric budgets. Indeed soils can take up large amounts of OCS from the atmosphere as soil microorganisms also contain CA, and OCS emissions from soils have been reported in agricultural fields or anoxic soils. To date no mechanistic framework exists to describe this exchange of OCS between soils and the atmosphere, but empirical results, once upscaled to the global scale, indicate that OCS consumption by soils dominates OCS emission and its contribution to the atmospheric budget is large, at about one third of the OCS uptake by vegetation, also with a large uncertainty. Here, we propose a new mechanistic model of the exchange of OCS between soils and the atmosphere that builds on our knowledge of soil CA activity from CO2 oxygen isotopes. In this model the OCS soil budget is described by a first-order reaction–diffusion–production equation, assuming that the hydrolysis of OCS by CA is total and irreversible. Using this model we are able to explain the observed presence of an optimum temperature for soil OCS uptake and show how this optimum can shift to cooler temperatures in the presence of soil OCS emission. Our model can also explain the observed optimum with soil moisture content previously described in the literature as a result of diffusional constraints on OCS hydrolysis. These diffusional constraints are also responsible for the response of OCS uptake to soil weight and depth observed previously. In order to simulate the exact OCS uptake rates and patterns observed on several soils collected from a range of biomes, different CA activities had to be invoked in each soil type, coherent with expected physiological levels of CA in soil microbes and with CA activities derived from CO2 isotope exchange measurements, given the differences in affinity of CA for both trace gases. Our model can be used to help upscale laboratory measurements to the plot or the region. Several suggestions are given for future experiments in order to test the model further and allow a better constraint on the large-scale OCS fluxes from both oxic and anoxic soils.

AYMA: Mechanistic Probabilistic System To Evaluate Flexible Pavement Performance

1998 ◽  
Vol 1629 (1) ◽  
pp. 137-148 ◽  
Author(s):  
Manuel Ayres ◽  
Matthew W. Witczak
Keyword(s):  
Low Temperature ◽  
Mechanistic Model ◽  
Permanent Deformation ◽  
Probabilistic Approach ◽  
Fatigue Cracking ◽  
Flexible Pavement ◽  
Analysis And Design ◽  
Mechanistic Approach ◽  
Low Temperature Cracking ◽  
User Friendly

A new rational mechanistic model for analysis and design of flexible pavement systems has been developed. Furthermore, a fundamental probabilistic approach was incorporated into this system to account for the uncertainty of material and environmental conditions. The system was integrated in a user-friendly Windows program with a variety of user-selected options that include widely used models and those recently developed in the Strategic Highway Research Program project. Three basic types of distress can be investigated separately or all together, including fatigue cracking, permanent deformation, and low-temperature cracking. The mechanistic approach makes use of the JULEA layered elastic analysis program to obtain pavement response. The system provides optional deterministic and probabilistic solutions, accounts for aging and temperature effects over the asphalt materials, variable interface friction, multiple wheel loads, and user-selected locations for analysis. Tabular and graphical results provide expected distress values for each month as well as their variability, probability of failure, and assessment of the overall reliability of the pavement relative to each type of distress for a user-selected failure criterion. Only the load-associated module of AYMA is presented; a separate work describes the low-temperature cracking analysis.

scholarly journals Effects of season, altitude and daylength on floral initiation of two contrasting genotypes of Trifolium repens L.

1986 ◽  
Vol 106 (1) ◽  
pp. 149-154 ◽  
Author(s):  
F. Von Sury ◽  
J. Nösberger
Keyword(s):  
Low Temperature ◽  
Seed Production ◽  
Floral Initiation ◽  
Cool Season ◽  
Production Potential ◽  
Low Latitude ◽  
Specific Effects ◽  
Trifolium Repens L ◽  
Growth Chambers ◽  
Main Factors

SUMMARYThe effects of season and altitude on floral initiation of two Trifolium repena L. cultivars, Haifa and California Ladino, were tested in the area of Ayacucho, Peru (2730 m, 13° S), with regard to their seed production potential. Specific effects of daylength at a constant temperature (20 °C) were examined in growth chambers.In Ayacucho, the proportion of inflorescence-bearing nodes was found to be lowest between December and June (Haifa 10–20%, Ladino 0–10%) and highest in August (Haifa 30%) and September–October (Ladino 15%). Late in the cool season, floral initiation of Ladino, but not that of Haifa, increased strongly at a high altitude (3250 m). In growth chambers, Haifa initiated few inflorescences and Ladino none in a 10 h daylength. In 16 h, the floral initiation of Haifa was very limited but Ladino formed many inflorescences. Floral initiation of Haifa was most pronounced and lasted longest after a daylength shift from 10 to 13 h.It is concluded that seasonal and altitudinal variations in low temperature were the main factors influencing floral initiation in the region of Ayacucho. Haifa is considered to be an intermediate-day plant, suited for seed production in the region because of its marked and early flowering. Ladino was classified as a quantitative longday plant, unsuitable for seed production at this low latitude because of its retarded floral response to low temperature.

scholarly journals Laboratory Studies of Planetary Molecules and Ices: The Case of IO

1992 ◽  
Vol 150 ◽  
pp. 435-436
Author(s):  
F. Salama ◽  
S. A. Sandford ◽  
L. J. Allamandola
Keyword(s):  
Low Temperature ◽  
Observational Data ◽  
Laboratory Studies

The techniques of low temperature spectroscopy are applied here to analyze infrared observational data of Io in the 2.0-5.0 μm range. The presence of solid H2S and traces of H2O in the SO2-dominant surface ices are derived from this analysis and it is suggested that CO2 clusters may as well be present near the surface of Io.

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