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Sewage sludge constitutes a source of valuable biogenic raw materials, but it is a carrier of many pathogenic microorganisms and viruses. Subjected to an effective sanitization by means of the process of composting, it is suitable to use in agriculture as fertilizers. The aim of this study was to observe the survival rate of Suid Herpesvirus under the influence of the temperature alone (water bath) as well as in sewage sludge subjected to the process of composting (pile). The samples were taken at different time intervals, and the virus titres were determined. The viruses survived considerably longer under laboratory conditions: at 30°C as long as 21 days, at 40°C - 93 hours, and at 50°C - less than an hour. In the compost pile, in spite of the lack of the thermophylic phase, the total survival time of the viruses ranged from 34 to 44.5 hours, which indicates the vast importance of other physicochemical factors, apart from the temperature, contributing to virus inactivation.
The aim of the present paper was to evaluate the survival rate of Listeria monocytogenes in meat processing industry sewage, depending on the pH under laboratory conditions. In the present experiment we determined the time of survival of listeria bacilli in three kinds of sewage: crude, alkalized and acidified. The present research shows that Listeria monocytogenes survived longest in crude sewage where, as calculated with the use of regression analysis, theoretical time of survival was defined as 38 days, while in the alkalized sewage and acidified sewage the time was 33 and 25 days, respectively. Besides, the present experiment also investigated the potential of listeria bacilli survival in sewage under strongly acidic and alkaline conditions.
Survival and hazard functions supply suitable information concerning changes in the population dynamics, especially in the case of species that are not subjected to artificial selection. One of such species is David’s deer (Elaphurus davidianus Milne-Edwards, 1866) that underwent a dramatic reduction in the population size in the first years of the XX century, but has been subsequently restored from 18 individuals.Population dynamics changes were studied on 1221 David’s deers kept in zoological gardens in the years 1947-2001. Survival and hazard functions were constructed for all individuals according to sex, and separately for those which died in the first year of life, i.e. 14.5% males and 8% females.The hazard function showed similar values for individuals of both sexes in the year 6, 10, 15, 17 and 18 of life. For all males the medians for mortality (hazard function) appeared similar to those for all females. Similar pattern was shown for yearlings. However, between day 40 and 323 shapes of these functions were quite different. Generally, the life span in females was found longer than in males.
The estimation of demographic rates is important for conservation and management of species. However, with the exception of an estimate for adult survival by Humphrey and Cope in 1977, there are no estimates of any demographic rates for the endangered Indiana myotis (Myotis sodalis). Their estimate is based on techniques that have been replaced by newer, more flexible, and less biased techniques. Therefore, we reanalyzed a subset of the data first analyzed by Humphrey and Cope using a Cormack-Jolly-Seber model. Two models [φ(year)p(year) and φ(year)p(sex*year)] are equally parsimonious, so we used model averaging to estimate apparent survival. We used this estimate to calculate the average cumulative survival each year after banding for four un-aged cohorts. Our estimate suggests that apparent survival is considerably higher than estimated by Humphrey and Cope the first year after banding and lower the second year after banding. Subsequent to the first two years after banding, our estimates are similar, but slightly lower than those reported by Humphrey and Cope. These results, while useful, cannot be taken as true survival rates for Indiana myotis because of limitations in the data and we suggest this estimate be used appropriately when making management decisions. We discuss limitations in this type of data and make suggestions for experimental design of future studies to collect data more appropriate for estimation of demographic rates in bats.
This paper presents the results of studies on the influence of clear-cut site management on survival rate of 3-year-old Scots pine saplings, conducted in the Forest District Bierzwnik in September 2011. Statistical analysis showed, that only the soil cultivation method significantly influences the survival rate on the studied Scots pine plantation. No statistically significant influence of cutting residues management or combined methods of residues management and various variants of soil cultivation was found.
The number of ground-nesting bird species in meadows, one of the most vulnerable habitats in the ornithological reserve of Vrana Lake Nature Park has decreased in recent decades. Nest survival rates were investigated in meadows and reed beds using nest predation experiments in late March and in May 2005. Predators damaged 18% of the 50 artificial nests placed in the pasture meadow habitat in March and 22% in May. Daily survival rate of nests were found to be similar in March (97%) and May (96%). In May, 64% of 25 nests located in the reed bed were discovered by the predators, with the daily survival rate of nests (90%) being significantly lower than that of nests in the nearby meadow. The results suggest that the reasons for the decreasing number of nesting bird species may be – instead of the pronounced presence and activity of predators in the area – the shrinkage of meadow area, the lack of buffer zone, the proximity of agricultural lands, and disturbance caused by intensive grazing.
Survival rates of Campylobacter jejuni ATCC 33 291, Campylobacter jejuni PZH 38 and Campylobacter coli ATCC 43 478 in leg quarters (ca 330g) of chicken broilers after microwave heating (480 and 760 Watt) for 2, 4, 6, 8 and 10 minutes were determined. Heating the meat in a microwave oven (Moulinex, type Dialog cook) at 480 Watts caused a gradual decrease in the number of cells of the studied bacterial strains to total inactivation after 8 – 10 minutes of heating. Increasing the heating power to 760 Watts led to a decreased microwave heating time of 6 – 8 minutes for inactivation of all the cells of the studied C. jejuni/coli strains. These findings clearly indicate the dependence of effectiveness of inactivation of the bacteria studied on microwave heating power, heating duration and bacterial strain.
The purpose of this work was to quantify the impact of spontaneous and X-radiation-induced chromosome rearrangements on survival rate of androgenetic rainbow trout (Oncorhynchus mykiss). Various doses of X irradiation (50, 150, 250, 350 Gy) were used for inactivation of nuclear DNA in oocytes. After the irradiation, eggs were inseminated with normal sperm from 4 males derived from a strain characterized by Robertsonian rearrangements and length polymorphism of the Y chromosome. The haploid zygotes were exposed to a high hydrostatic pressure (7000 psi) to duplicate the paternal DNA. Neither Robertsonian chromosome polymorphism nor the Y chromosome morphology impaired the viability of the androgenetic embryos and alevins. Moreover, survival of eyed embryos of the androgenetic rainbow trout increased significantly with increasing doses of oocyte X irradiation. After 6 months of rearing, only specimens from the 250 and 350 Gy variants survived. The number of fingerlings with remnants of the maternal genome in the forms of chromosome fragments was higher in the 250 Gy group. Intraindividual variation of chromosome fragment number was observed, and some individuals exhibited haploid/diploid mosaicism and body malformations. Individuals irradiated with less than 250 Gy died, presumably because of the conflict between intact paternally derived chromosomes and the residues of maternal genome in the form of chromosome fragments.
This work presents the survival rate of the Lactobacillus rhamnosus and Lactobacillus plantarum bacteria in a changing pH medium inhibiting their growth. The bacteria were kept in pH ranging from 2 – 6, which is a pH of pickled vegetables or stomach. The growth of the bacteria was measured with the use of the method of inoculation onto Petrie’s plates and nephelometric method. The longest survival rate of the bacteria was noticed in the pH ranging from 4 – 6. Moreover, the growth of the bacteria is correlated with the absorbance level measured with a nephelometric method. The results of the experiments upheld the presumption saying that the Loctobacillus plantarum bacteria are able to survive in man’s stomach the time they spend there together with the food.
Escherichia coli suspension was introduced into meat and bone carriers of different sizes and a number of the bacteria was analysed at suitable time intervals. The cycles analysed were characterised by a slightly different distribution of temperature, but it was sufficient to inactivate the rods in all types of the carriers. The quickest elimination rate of E. coli (0.1-0.14 log/h) was noted in the cycle in which the temperature ranged from 50 to 60°C. In the other cycles, with lower temperatures generated, the decrease in the bacteria's numbers was 0.03-0.04 log/h. However, the inactivation of the introduced pathogens occurred in both cycles. When properly conducted, a process of composting wastes guarantees retaining environmental safety.
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