Impact Of Seasonal Fluctuations Research Articles

MODERNIZATION OF THE NATURAL GAS LIQUEFACTION CYCLE AT GAS DISTRIBUTION STATIONS

The possibility of developing the liquefied natural gas (LNG) market in the Russian Federation can be realized by increasing the projects of low-tonnage LNG production. The development of LNG production projects at gas distribution stations should be a priority, since in this case it is possible to implement various production schemes: expander, throttle or cycle with a vortex pipe. To assess the efficiency of the use of low-tonnage LNG production at gas distribution stations (GDS), the dynamics of changes in maximum and minimum pressure values  in the main gas pipeline, as well as the distribution of GDS by seasonal change in pressure drop and throughput are presented. To assess the operability and applicability of the work, a design model of the natural gas liquefaction throttle cycle was built and numerical modeling of its operation was carried out at seasonal fluctuations in pressures and GDS costs, which showed a strong dependence on these fluctuations and a low degree of natural gas liquefaction. In order to further modernize the liquefaction cycles of natural gas, modeling was carried out according to the turbo expander cycle, which also showed a dependence on seasonality, but a higher degree of liquefaction of natural gas, which during modeling reached more than 8%. The final stage was the construction of a design model of the combined technology — throttling and turbo expander cycles, as well as numerical modeling, which showed the possibility of increasing the liquefaction of natural gas at GDS to 19%, but the impact of seasonal fluctuations also remains significant. Summing up, it can be said that the work has worked out options for the transition from the throttle cycle to the throttle-expander and turbo-expander, as a result of which it was concluded that the operation of each cycle is effective, due to which it is possible to expand the LNG production network at the GDS at various input pressures, flow rates and the required degree of liquefaction of natural gas.

The effects of seasonal changes on the dynamics of a fig tree's pollination

Fig trees and their pollinating wasps are mutually dependent on each other. Both partners' reproductive success is regulated by the capacity of fig wasps to enter receptive figs at an appropriate time for pollination and oviposition. Oviposition is dependent on successful female pollinator dispersal from one tree to another and although fig wasps are slow flyers and short-lived they can be carried long distances by the wind. The relative importance of local versus long-distance pollinator dispersal is unclear, as is how this may vary with season. In the highly seasonal environment of the Makana Botanical Gardens, Grahamstown, South Africa, we recorded fruiting phenologies of all the trees in a monoecious Ficus burtt-davyi Hutchinson population together with variation in the abundance of its pollinator Elisabethiella baijnathi Wiebes. By comparing captures of fig wasps flying in the air with the numbers that emerged locally, we also examined the independence of the fig tree population, which was separated from the nearest conspecifics by more than 1 km. The abundance of pollinators flying in the air and the number of fig wasps released by figs were correlated with temperature. During winter there were times when no pollinators were released locally; however, they were still caught in the traps, showing that the wasps had dispersed from elsewhere and that the population was not totally independent. These results highlight the ability of fig wasps to disperse between populations and the likely impact of seasonal fluctuations on fig tree gene flow.

A large decrease in the magnitude of seasonal fluctuations in mortality among elderly explains part of the increase in longevity in Sweden during 20th century

BackgroundMortality rates are known to depend on the seasons and, in temperate climates, rates are highest during winter. The magnitude of these seasonal fluctuations in mortality has decreased substantially in many countries during the 20th century, but the extent to which this decrease has contributed to the concurrent increase in life expectancy is not known. Here, I describe how the seasonality of all-cause mortality among people ages 60 years or more has changed in Sweden between 1860 and 1995, and investigate how this change has contributed to the increase in life expectancy observed during the same time period.MethodsYearly sex-specific birth cohorts consisting of all people born in Sweden between 1800 and 1901 who reached at least 59 years of age were obtained from a genealogical database. The mortality rates for each cohort were modeled by an exponential function of age modulated by a sinusoidal function of time of year. The potential impact of seasonal fluctuations on life expectancy was investigated by a novel decomposition of the total mortality rate into a seasonal part and a part independent of the seasons. Cohort life expectancy at age 60 was used to quantify changes in lifespan during the time period.ResultsThe magnitude of seasonal fluctuations in mortality rates decreased substantially between 1860 and 1995. For cohorts born in 1800, the risk of dying during the winter season was almost twice that of dying during summer. For cohorts born in 1900, the relative increase in winter mortality was 10%. Cohort life expectancy at age 60 increased by 4.3 years for men and 6.8 years for women, and the decrease in seasonal mortality fluctuations accounted for approximately 40% of this increase in average lifespan.ConclusionBy following a large number of extinct cohorts, it was possible to show how the decrease in seasonal fluctuations in mortality has contributed to an increase in life expectancy. The decomposition of total mortality introduced here might be useful to better understand the processes and mechanisms underlying the marked improvements in life expectancy seen over the last 150 years.

Econometric Evaluation of Micro Factors of Seasonality on Revenues, Price, Sales and Farmers Work-Occupation: Case of Apple And Tomato on the Regions of Prizren, Lushnja, and Korça

Abstract The aim of this study is to analyze the importance of effects and impact of seasonal fluctuations on income of farmers, workoccupation in farm and sales on apples activity for areas of Korça and Prizren , and in tomatos activities for areas Lushnja and Prizren. Lushnja area is one of the most popular areas of Albania on the quality of vegetable production. Seasonal effects that influence on the apples production in areas of Korça and Prizren and tomatos in areas of Lushnja and Prizren. Some seasonal effects comes as a result of weather conditions, pests and diseases, and are more expressed in those economic phenomenon such us: the volatility of price over year, to farmers income and to farmers work-occupation over a year. We also can say that the production of apples and tomatos in our country includes more intensive activities of production that require large investments. Their production cost turns out to be higher for manufacturers, but, while also enabling high levels of profit. Our estimates are based on data obtained from surveys, for 300 farmers, to make our evaluations we build some econometric models. In this paper we have used the model of seasonal indexes, where seasonal variation can be measured in terms of an index called the seasonal index. We have used these methods: seasonal indexes standard deviations, and econometric modeling. Also we have defined indicators and values of the variations coefficient. The variations coefficient is a relative indicator which expresses the ratio between to standard deviation size and arithmetic average of mass phenomenon.

The Relationship between Abnormal Growth of Inventory and Long-Term Stock Returns of Companies Listed in Tehran Stock Exchange

This study aimed to investigate the impact of seasonal fluctuations in annual and long-term inventory on stock returns of companies listed on the Stock Exchange in Tehran. A sample of 84 listed in the Tehran Stock Exchange, which their data for a period of 5 years (1388 to 1392) were the statistical analysis. Model study of research Steinker and Hoberg (2014) has been adapted where long-term stock return as the dependent variable is a function of the independent variables. The findings suggest that there is a significant relationship between annual and seasonal abnormal growth of inventory and long-term stock returns. This finding indicates that the capital market has reacted to inventory changes at different times. Based on the above results, it can be covered in the basic hypotheses accepted.

The Impact of Seasonal Fluctuations on Rat Liver Mitochondria Response to Tested Compounds— A Comparison between Autumn and Spring. New Insight into Collecting and Interpretation of Experimental Data Originating from Different Seasons

Seasonal variations play an essential role in the metabolism, behavior and activity of the laboratory animals. This study was aimed to examine whether mitochondrial function can be influenced by the seasonal changes and how large is the impact of these fluctuations on experiments with using animal models and further results interpretation. Liver mitochondria were isolated from male Wistar rats and exposed to calcium ions, PAMAM dendrimers G2.5 or their combination: (Ca2+) and dendrimer. The scientific hypothesis assumed that dendrimer G2.5 is able to limit the detrimental effect of Ca2+ ions on mitochondria function, possibly through affecting the following parameters: calcium transport, mitochondrial potential and membrane fluidity. The activity of mitochondria was monitored using fluorescent labels. The changes in calcium transport were detected using Calcium Green 5-N, the mitochondrial membrane potential and membrane fluidity were elucidated using JC-1 and DPH, respectively. The experiments were carried out during the autumn (October/November) or during the spring (May/June). The obtained data emphasize the effect of seasonal differences on liver mitochondria originating from laboratory animals and outline the importance of planning the experiments during the same seasonal period in order to receive objective and reliable results in the future. Finally, it was revealed the neutral effect of G2.5 dendrimer on mitochondria and its inability to protect mitochondria against overload of calcium ions regardless of seasonality. It was also evidenced that liver mitochondria isolated from autumn-derived animals were more sensitive to calcium and/or dendrimer exposure in comparison with mitochondria isolated from animals investigated during the spring.

Impact of Seasonal Fluctuations on the Sediment-Mercury, its Accumulation and Partitioning in Halimione portulacoides and Juncus maritimus Collected from Ria de Aveiro Coastal Lagoon (Portugal)

The availability of metals to plants is a complex function of numerous environmental factors. Many of these factors are interrelated, and vary seasonally and temporally. The current study intended to understand the influence of seasonal fluctuations and the vegetation of salt marsh plants (SMPs; Halimione portulacoides, Juncus maritimus) on sediment’s mercury (Hg) and its pH and redox potential (Eh), as well as their cumulative effect on the plant’s Hg-accumulation and Hg-partitioning potential. The area selected for the study was Laranjo Basin at Ria de Aveiro lagoon (Portugal) where a known Hg gradient was existed due to chlor-alkali plant discharge. Three sampling sites (L1, L2 and L3) were selected along a transect defined by the distance from the main Hg source. Samples were also collected from the Hg-free site (R). Irrespective of the plant vegetation, Hg in sediments gradually increased with a decreasing distance towards Hg-point source. The sediment colonised by J. maritimus showed more Hg concentration compared with H. portulacoides irrespective of the season. As a whole, J. maritimus accumulated Hg more than H. portulacoides at all the sampling sites, whereas in root, stem and leaf, the concentration was ranked as: L1 > L2 > L3 in both the plant species and was differentially influenced by seasonal changes. Moreover, root of both plants exhibited highest Hg concentration compared with stem and leaf. In addition, the leaf of H. portulacoides exhibited more Hg than leaves of J. maritimus. Bioaccumulation and translocation factors and dry weight were differentially influenced by seasonal changes. Taking together the results, the physico-chemical properties of sediment especially the sediment-Eh seems to be influnced by the type of plant vegetation and seasonal changes which in turn may have influenced the chemistry of sediments; thus, it enfluences the bioavalability of Hg and the Hg-retention capacity of both salt marsh sediments (SMSs) and SMPs (bioaccumulation factor). Moreover, SMSs vegetated by J. maritimus exhibited a stronger capacity for the retention and phytostabilization of Hg belowground (in sediments and/or roots) than those dominated by H. portulacoides. Conversely, those SMSs extensively vegetated by H. portulacoides are expected to translocate more Hg to aboveground parts, acting as a potential source of this metal to the marsh ecosystem. Therefore, J. maritimus and H. portulacoides may be used repectively for phytostabilization (in rhizosediments) and phytoextraction (by accumulation in aboveground plant tissue for subsequent plant removal).

Seasonal variation of polychlorinated biphenyl concentrations in the southern part of the Baltic Sea

The impact of seasonal fluctuations in forcing factors such as atmospheric concentration, temperature, and biological productivity on the concentration of polychlorinated biphenyls (PCBs) in the surface water of the southern part of the Baltic Sea was investigated. Water samples were collected on eight cruises over 2 years. A clear seasonal variability in dissolved PCB concentrations was observed with higher levels in summer than in winter and spring. This was attributed to changes in atmospheric concentrations and water temperature, based on measurements showing the PCB levels in the atmosphere and surface water to be close to a partitioning equilibrium. Concentrations in the suspended particulate material (SPM) fraction were also variable, and when the quotient of the organic carbon normalised concentration in SPM and the dissolved concentration was calculated (i.e., the bioaccumulation factor (BAF)), a seasonal pattern was observed which was consistent with kinetic limitations on partitioning into particles caused by plankton growth. However, seasonal variability in the partitioning properties of the SPM may also contribute to this variability.