Seasonal variation

Temperature and/or humidity to be maintained Allowable seasonal variations Permissible control tolerance... 

Time of Dosing. The time of day, or day of the year, may influence the toxic response. These changes reflect diurnal and seasonal variations in biochemical and physiological profiles, which may influence toxicity through a variety of mechanisms. 

Unesterified tocopherols are found in a variety of foods however, concentration and isomer distribution of tocopherols vary gready with source. Typically, meat, fish, and dairy contain <40 mg/100 g of total tocopherols. Almost all (>75%) of this is a-tocopherol for most sources in this group. The variation in the content of meat and dairy products can be related to the content of the food ingested by the animal. A strong seasonal variation can also be observed. Vegetable oils contain significant levels of y-, P-, and 5-tocopherol, along with a-tocopherol (Table 3). 

Example A commercial item is sold in a retail outlet as a unit product. In the past, sales have averaged 10 units per month with no seasonal variation. The retail outlet must order replacement items 2 months in advance. If the outlet starts the next 2-month period with 25 items on hand, what is the probabihty that it wih stock out before the end of the second month ... 

Fig. 4-3. Seasonal variation of suspended particulate matter concentration. Composite of 20 nonurban sites. United States. Source Pirtas, R., and Levin, H. ]. Air PoUut. Control Assoc. 21(6), 329-333, 1971.

Average airport visibilities over the eastern half of the United States have been determined over a period of approximately 25 years (1948-1974) (6). Although seasonal variations occur, the long-term trend has been decreased visual air quality over the time period. 

Finally, fuel availability must be considered. If future reserves are unknown, or seasonal variations are expected, dual fuel capability must be considered. 

Between various wood species great differences can occur in pH as well as in the buffer capacity. Even within the same wood species, differences might occur due to seasonal variations, portion of the wood substance under investigation, pH of the soil, age of the tree, time span after cutting, drying and processing parameters. 

Seasonal variations of the wood quality in the panel board industry... 

The experience of the particleboard industry on the influence of seasonal variations of the wood quality has been reported. Problems occur especially using wood which has been harvested in the wintertime and which goes into board production immediately. 

Adjust for seasonal variations. Reverse osmosis operation is influenced by water temperature, and the anion exchange resis must be kept below 60 C. 

After determination of the seasonal variation in alkaloidal content of the leaves, stems and roots of belladonna and the production of evidence that there is a considerable movement of alkaloid upwards from root to leaves and a small transport in the opposite direction, Cromwell found that of a laige number of amines injected, with or without glucose, into... 

These applications avoid the major obstacles for using biomass for electricity generation fluctuation in the supply, and the type of biomass available. Seasonal variations and differing quality of feedstock are the biggest barriers to more widespread use. This is especially true for biomass wastes. 

Variability of Seawater Vertical sections through seawater showing the distribution of temperature, salinity, and oxygen for the Pacific Ocean and Western Atlantic Ocean are shown in Figures 21.3 and 21.4. The global variability of natural seawater and its effects on corrosion have been reviewed in particular with respect to seasonal variation of temperature, salinity, oxygen and pH in the Pacific surface water. Data is also given on... 

Seasonal variations are associated not only directly with the elevation of the sun, but also with changes of surface currents depending on the prevailing winds. The annual variation is generally quite small in the tropics and greatest in the temperate zones, where it may amount to about 10° C. 

Atmospheric exposure trials, carried out in Cambridge, established the fact that when rusty specimens were painted in the summer, their condition, after some years exposure, was very much better than that of similar specimens painted in the winter It was found that steel weathered in Cambridge carried spots of ferrous sulphate, deeply imbedded in the rust, and that the quantity of ferrous sulphate/unit area was very much greater in the winter than in the summer this seasonal variation was attributed to the increased sulphur dioxide pollution of the atmosphere in the winter, caused by the combustion of coal in open grates. It was concluded that there was a causal relationship between the quantity of ferrous sulphate and the effective life of the paint. It was suggested that these soluble deposits of ferrous sulphate short-circuit the resistance of the paint film and, since paint films are very permeable to water and oxygen, the ferrous sulphate will become oxidised and hydrolysed with the production of voluminous rust, which will rupture the film at numerous points, thus giving rise to the characteristic type of failure seen on painted rusty surfaces. 

Where IX designs are being considered, a one-off sample is simply not appropriate. Real analyses over a period of time are required, and seasonal variations should be properly understood in order to provide a realistic design. 

The oxygen atom produced in this step can react with oxygen molecules to produce more ozone, and so the ozone concentration in the stratosphere normally remains constant, with seasonal variations. Because the decomposition of ozone... 

Trends Seasonal variations Basic statistics Correlation... 

Lehman PW, Boyer G, Satchwell M, Waller S (2008) The influence of environmental conditions on the seasonal variation of Microcystis cell density and microcystins concentration in San Erancisco Estuary. Hydrobiologia 600 187-204... 

Inputs from WWTP effluents can also affect the hydrologic and nutrient concentration regimes of recipient streams at different temporal scales. Daily variations of these parameters may be exacerbated in streams below the WWTP input by the diel patterns of the effluent discharge associated with plant operation [46]. In contrast, at the annual scale, seasonal variations of physical and chemical parameters upstream of the WWTP may be dampened by the constant input of additional water and nutrients from the WWTP. At its extreme, naturally intermittent or ephemeral streams may turn into permanent streams downstream of WWTPs [28, 30]. In these effluent-dominated streams, the relative contribution of WWTP inputs may vary widely on an annual basis, as shown by the 3-100% range measured in a Mediterranean stream [47]. Finally, WWTP inputs also cause shifts in the relative availability of N and P as well as in the relative importance of reduced and oxidized forms of N in the stream [30, 47]. The magnitude of these shifts depends on the level of wastewater treatment (i.e., primary, secondary, or tertiary treatment), the type of WWTP infrastructure (e.g., activated sludge reactor. 

Vieno NM, Tuhkanen T, Kronberg L (2005) Seasonal variation in the occurrence of pharmaceuticals in effluents from a sewage treatment plant and in the recipient water. Environ Sci Technol 39 8220-8226... 

Schwarez 1997 Kohn et al. 1997) report zoned variation within certain teeth which correlates with seasonal variation in rainfall 8 0. Intratooth variation reached almost 3%o in some teeth from east Turkana (Kohn et al. 1997). While this isotopic variation reflects important climate information regarding seasonal variation in rainfall, this topic is not pursued here and the interested reader is directed to the literature cited above. 

Kirsanow K., Makarewicz, C., Tuross, N. (2008). Stable oxygen (8i 0) and hydrogen (8D) isotopes in ovicaprid dentinal collagen record seasonal variation. Journal of Archaeological Science Vol. 35, No. 12, pp. 3159-3167. 

A problem with this model is that very early values and recent values have an equal contribution to the precision of the forecast. The random walk model provides a good forecast of trend but is less efficient with cyclical and seasonal variations. 

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