Competitive growth of blue-greens and diatoms (fragilaria) in the saidenbach reservoir, saxony

1995 ◽  
Vol 32 (4) ◽  
pp. 77-88 ◽  
Author(s):  
H. Horn ◽  
D. Uhlmann
Keyword(s):  
Turbulent Mixing ◽  
Concentration Level ◽  
Mutual Exclusion ◽  
Late Summer ◽  
Meteorological Conditions ◽  
Competitive Growth ◽  
Absolute Concentration ◽  
Resource Concentration ◽  
High Yields ◽  
Simultaneous Growth

Since 1975, different patterns of the growth of Fragilaria and Cyanobacteria in the mid or late summer have been observed in the Saidenbach Reservoir. In most of the years, there was a mutual exclusion of mass growths of these two groups. High yields of Fragilaria caused low yields of blue-greens and vice versa. In the first years, Fragilaria was always the first to achieve a mass growth, followed by the Cyanobacteria. Then, in the last years, the blue-greens were succeeded by Fragilaria. Only in some years, there was a large and simultaneous growth of both groups. It has been shown, that the supply of silicon and phosphorus immediately before controlled the pattern of succession in the midsummer period. Mostly, the Si:P ratio was the regulating factor, but there were also years in which the absolute concentration level of these two nutrients were either non-limiting high or below the minimum resource concentration necessary to compensate for the losses. In these cases, the Si:P ratio lost its controlling function. Other influencing factors are discussed, in particular the effect of turbulent mixing. The special nutrient conditions in the midsummer were not only determined by the external load but also by the Si depletion during the spring mass development of diatoms other than Fragilaria, which mostly is physically controlled. Therefore, the succession pattern in the midsummer is sensitive to the meteorological conditions to a large extent.

scholarly journals Modeling and Predicting the Simultaneous Growth of Escherichia coli O157:H7 and Ground Beef Background Microflora for Various Enrichment Protocols

2006 ◽  
Vol 72 (1) ◽  
pp. 261-268 ◽  
Author(s):  
A. Vimont ◽  
C. Vernozy-Rozand ◽  
M. P. Montet ◽  
C. Lazizzera ◽  
C. Bavai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Incubation Temperature ◽  
Basal Medium ◽  
Ground Beef ◽  
Immunomagnetic Separation ◽  
Enrichment Factors ◽  
Screening Methods ◽  
Competitive Growth ◽  
Enrichment Protocol ◽  
Simultaneous Growth

ABSTRACT The simultaneous growth of Escherichia coli O157:H7 (O157) and the ground beef background microflora (BM) was described in order to characterize the effects of enrichment factors on the growth of these organisms. The different enrichment factors studied were basal medium (Trypticase soy broth and E. coli broth), the presence of novobiocin in the broth, and the incubation temperature (37°C or 40°C). BM and O157 kinetics were simultaneously fitted by using a competitive growth model. The simple competition between the two microfloras implied that O157 growth stopped as soon as the maximal bacterial density in the BM was reached. The present study shows that the enrichment protocol factors had little impact on the simultaneous growth of BM and O157. The selective factors (i.e., bile salts and novobiocin) and the higher incubation temperature (40°C) did not inhibit BM growth, and incubation at 40°C only slightly improved O157 growth. The results also emphasize that when the level of O157 contamination in ground beef is low, the 6-h enrichment step recommended in the immunomagnetic separation protocol (ISO EN 16654) is not sufficient to detect O157 by screening methods. In this case, prior enrichment for approximately 10 h appears to be the optimal duration for enrichment. However, more experiments must be carried out with ground beef packaged in different ways in order to confirm the results obtained in the present study for non-vacuum- and non-modified-atmosphere-packed ground beef.

scholarly journals Application of the Data Mining Methods to Assess the Impact of Meteorological Conditions on the Episodes of High Concentrations of PM10 along the Polish – Czech Border

2018 ◽  
Vol 28 ◽  
pp. 01027
Author(s):  
Leszek Ośródka ◽  
Ewa Krajny ◽  
Marek Wojtylak
Keyword(s):  
Data Mining ◽  
Air Pollution ◽  
Particulate Matter ◽  
Concentration Level ◽  
Meteorological Data ◽  
Meteorological Conditions ◽  
Mining Methods ◽  
High Concentrations ◽  
The Impact ◽  
Derivatives Of

The paper presents an attempt to use selected data mining methods to determine the influence of a complex of meteorological conditions on the concentrations of PM10 (PM2.5) proffering the example of the regions of Silesia and Northern Moravia. The collection of standard meteorological data has been supplemented by increments and derivatives of measurable weather elements such as vertical pseudo-gradient of air temperature. The main objective was to develop a universal methodology for the assessment of these impacts, i.e. one that would be independent of the analysed pollution. The probability of occurrence (at a given location) of the assumed concentration level as exceeding the value of the specified distributional quintile was adopted as the discriminant of the incidence. As a result of the analyses conducted, incidences of elevated concentrations of air pollution particulate matter PM10 have been identified and the types of weather responsible for the emergence of such situations have also been determined.

Control of Weeds in an Oat (Avena sativa)—Soybean (Glycine max) Ecofarming Rotation

Weed Science ◽  
1980 ◽  
Vol 28 (1) ◽  
pp. 46-50 ◽  
Author(s):  
O. C. Burnside ◽  
G. A. Wicks ◽  
D. R. Carlson
Keyword(s):  
Glycine Max ◽  
Weed Control ◽  
Avena Sativa ◽  
Crop Production ◽  
Production Systems ◽  
Late Summer ◽  
Reduced Tillage ◽  
No Tillage ◽  
Soil Exposure ◽  
High Yields

Soybeans [Glycine max(L.) Merr.] and oats (Avena sativaL.) were grown in a rotation using reduced or no-tillage crop production systems at Lincoln, Nebraska, over a 4-yr period. Oat stubble was treated after harvest with 3.4 kg/ha of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] to reduce the growth of late summer weeds. The following spring soybeans were planted directly into the undisturbed stubble or into a seedbed prepared by tandem discing. Three seedbed preparations, two soybean cultivars, and six preemergence weed control treatments were compared. Glyphosate [N-(phosphonomethyl)glycine] applied at 0.8 kg/ha or tandem discing were equally effective in producing a weed-free seedbed. Herbicides applied preemergence on soybeans were still necessary for the reduced tillage or no-tillage production systems if weeds were to be adequately controlled in soybeans without cultivation. Differences in seed-yield occurred between cultivars only when late summer rains benefited the later maturing ‘Williams' soybeans over earlier maturing ‘Wells'. With adequate weed control, soybeans and oats can be grown in a no-tillage, crop rotation, production system in eastern Nebraska to produce high yields with a minimum of labor and soil exposure.

The yield and survival of lucerne lines in the upper south-east of South Austrialia

1971 ◽  
Vol 11 (49) ◽  
pp. 186 ◽  
Author(s):  
GJ Leach
Keyword(s):  
Dry Matter ◽  
South Australia ◽  
Late Summer ◽  
Winter Period ◽  
Poor Survival ◽  
Cool Temperate ◽  
Upper South ◽  
One Year ◽  
High Yields ◽  
B Lines

Thirty lines of lucerne from regions with Mediterranean and temperate climates were grown on a degp and infertile sandy soil in the Upper South East of South Australia. One trial (A) was cut at the frequency usually recommended for lucerne, and the other (B) was cut twice as often. Both trials were sown in spring 1965 in drills 35 cm apart, and were maintained as pure lucerne stands. The yield of dry matter of the tops was measured in Trial A between November 1966 and November 1969, and in trial B for one year from November 1966. The row cover attained by the plants was measured in each year. In trial A, yields rose to maximum values in spring and declined during the summer months to minimal values in autumn. At most harvests there mere significant differences between lines. Mediterranean lines gave good yields in the early phase of the trial, and were the most productive lines through each late summer to winter period. Lines from cool temperate regions, e.g. Rhizoma, gave low initial yields and low winter yields, but gave largest yields in spring 1968. Two Portuguese lines consistently gave high yields : they were the only lines to produce significantly more total dry matter than Hunter River over three years. All lines adequately survived a very dry year (1967), and most plant losses occurred in the final year of the trial. In 1969, six Mediterranean lines showed poor survival, each had less than 50 per cent row cover. Dry matter yields were smaller in trial B. Lines from cool temperate regions maintained 80 per cent row cover throughout and gave the largest yields. Three Mediterranean lines were eliminated after two years of frequent cutting, and the row cover of five other lines was reduced to less than 50 per cent.

Behavioural responses of 6-month-old beef calves prevented from suckling: influence of dam's milk yield

2010 ◽  
Vol 50 (10) ◽  
pp. 909 ◽  
Author(s):  
M. J. Hötzel ◽  
R. Ungerfeld ◽  
G. Quintans
Keyword(s):  
Milk Production ◽  
Milk Yield ◽  
Social Contact ◽  
Late Summer ◽  
Behavioural Response ◽  
Lactation Period ◽  
Beef Calves ◽  
Behavioural Responses ◽  
Instantaneous Sampling ◽  
High Yields

The objective of the present experiment was to compare the behavioural response of calves reared by cows of different milk yields to the prevention of suckling with the aid of nose-flaps that allowed the maintenance of social contact with the dam. Twenty Hereford or Hereford × Angus crossbred primiparous cows from a single herd remained with their calves suckling until the beginning of the experiment, in late summer–early autumn. Milk production was determined monthly during the lactation period and the pairs were selected according to the cows’ milk production, for higher or lower milk yield (HMY and LMY, respectively). On Day 0, suckling was prevented by placing a nose-flap anti-suckling device on each calf for 11 days. Calf behaviour was recorded from Day –3 to Day 5, using instantaneous sampling of individual animals in each group, and the calves were weighed monthly since birth, and on Days –8 and 11. Bodyweight profiles for HMY and LMY calves were similar until Day –8; from then on, up to Day 11, HMY calves lost weigh, whereas LMY calves gained weight. Suckling frequency before nose-flaps were fitted was similar for HMY and LMY calves. There was no relationship between the cow’s milk yield and the changes observed in behaviour. Apart from playing, all behaviours were affected by prevention of suckling. The distance between the calves and the dam, and the frequency of grazing and rumination, decreased after nose-flaps were placed, whereas vocalisations, suckling attempts, walking and standing increased. In conclusion, the behavioural responses to prevention of suckling did not differ between the 6-month-old calves reared by cows with high yields and those with low milk yields. The behavioural response of calves that were prevented from suckling but were kept with the dams indicates that the cessation of suckling contributes to the weaning distress of 6-month-old beef calves.

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Bulk standards for low-temperature biological x-ray microanalysis

1984 ◽  
Vol 42 ◽  
pp. 282-283
Author(s):  
P. Echlin ◽  
M. McKoon ◽  
E.S. Taylor ◽  
C.E. Thomas ◽  
K.L. Maloney ◽  
...  
Keyword(s):  
Phase Separation ◽  
Low Temperature ◽  
Analytical Method ◽  
Salt Solutions ◽  
Absolute Concentration ◽  
Cooling Process ◽  
X Ray ◽  
The Absolute ◽  
Analytical Procedures ◽  
Electrical Conductors

Although sections of frozen salt solutions have been used as standards for x-ray microanalysis, such solutions are less useful when analysed in the bulk form. They are poor thermal and electrical conductors and severe phase separation occurs during the cooling process. Following a suggestion by Whitecross et al we have made up a series of salt solutions containing a small amount of graphite to improve the sample conductivity. In addition, we have incorporated a polymer to ensure the formation of microcrystalline ice and a consequent homogenity of salt dispersion within the frozen matrix. The mixtures have been used to standardize the analytical procedures applied to frozen hydrated bulk specimens based on the peak/background analytical method and to measure the absolute concentration of elements in developing roots.

The use of transmission and analytical electron microscopy in studying reactions and phase transformations in thin film

1993 ◽  
Vol 51 ◽  
pp. 842-843
Author(s):  
K. Barmak
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Transformations ◽  
Analytical Electron Microscopy ◽  
Ex Situ ◽  
Multilayer Thin Films ◽  
Absolute Concentration ◽  
Analytical Electron ◽  
Deposition Step

Generally, processing of thin films involves several annealing steps in addition to the deposition step. During the annealing steps, diffusion, transformations and reactions take place. In this paper, examples of the use of TEM and AEM for ex situ and in situ studies of reactions and phase transformations in thin films will be presented.The ex situ studies were carried out on Nb/Al multilayer thin films annealed to different stages of reaction. Figure 1 shows a multilayer with dNb = 383 and dAl = 117 nm annealed at 750°C for 4 hours. As can be seen in the micrograph, there are four phases, Nb/Nb3-xAl/Nb2-xAl/NbAl3, present in the film at this stage of the reaction. The composition of each of the four regions marked 1-4 was obtained by EDX analysis. The absolute concentration in each region could not be determined due to the lack of thickness and geometry parameters that were required to make the necessary absorption and fluorescence corrections.

Case Exercise: Toxic Exposure-Related Illness: Causation, Diagnosis, and Permanent Impairment

2007 ◽  
Vol 12 (2) ◽  
pp. 4-8
Author(s):  
Frederick Fung
Keyword(s):  
Concentration Level ◽  
Treatment Plan ◽  
Toxic Exposure ◽  
Dose Response Relationship ◽  
Specialty Board ◽  
History Of ◽  
Subjective Complaints ◽  
Based Medicine ◽  
Illness Causation ◽  
Rule Out

Abstract A diagnosis of toxic-related injury/illness requires a consideration of the illness related to the toxic exposure, including diagnosis, causation, and permanent impairment; these are best performed by a physician who is certified by a specialty board certified by the American Board of Preventive Medicine. The patient must have a history of symptoms consistent with the exposure and disease at issue. In order to diagnose the presence of a specific disease, the examiner must find subjective complaints that are consistent with the objective findings, and both the subjective complaints and objective findings must be consistent with the disease that is postulated. Exposure to a specific potentially causative agent at a defined concentration level must be documented and must be sufficient to induce a particular pathology in order to establish a diagnosis. Differential diagnoses must be entertained in order to rule out other potential causes, including psychological etiology. Furthermore, the identified exposure at the defined concentration level must be capable of causing the diagnosis being postulated before the examiner can conclude that there has been a cause-and-effect relationship between the exposure and the disease (dose-response relationship). The evaluator's opinion should make biological and epidemiological sense. The treatment plan and prognosis should be consistent with evidence-based medicine, and the rating of impairment must be based on objective findings in involved systems.

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