We consider the downlink of an orthogonal frequency division multiplexing (OFDM) based cell that accommodates calls from different service-classes with different resource requirements. We assume that calls arrive in the cell according to a quasi-random process, i.e., calls are generated by a finite number of sources. To calculate the most important performance metrics in this OFDM-based cell, i.e., congestion probabilities and resource utilization, we model it as a multirate loss model, show that the steady-state probabilities have a product form solution (PFS) and propose recursive formulas which reduce the complexity of the calculations. In addition, we study the bandwidth reservation (BR) policy which can be used in order to reserve subcarriers in favor of calls with high subcarrier requirements. The existence of the BR policy destroys the PFS of the steady-state probabilities. However, it is shown that there are recursive formulas for the determination of the various performance measures. The accuracy of the proposed formulas is verified via simulation and found to be satisfactory.
The concept of creation of the geoportal “Environmental Safety of Ukrainian-Polish Transboundary Territories” has been developed. General principles and methodological approaches of spatiotemporal geographically distributed thematic data integration were substantiated. The geoinformation system, which is based on results of monitoring researches of objects of the nature reserve fund in the biosphere reserve “Roztochya”, is considered. The geoinformation monitoring technologies ensure ecological safety management. The proposed geoportal determines directions of information technology implementation for transboundary monitoring of ecosystems in the euroregions.
Changes in body mass and body reserves of Little Auks (Alle alle) were studied throughout the breeding season. Body mass loss after chick hatching was analyzed with respect to two hypotheses: (1) mass loss reflects the stress of reproduction, (2) mass loss is adaptive by reducing power consumption during flight. Body mass of both males and females increased during incubation, dropped abruptly after hatching, and remained stable until the end of the chick-rearing period. These changes were largely due to change in mass of fat reserves. Body mass, fat, and protein reserves, when corrected for body size, did not differ between sexes at the end of incubation. Female size-corrected body mass at that time was correlated with peak body mass of chicks. The estimated energy savings for flight due to the decline in adult body mass after chick hatching were small compared with the total energy expenditure of adults feedings chicks, which did not support hypothesis (2). The contribution to chick feeding was not equal; the ratio of females to males caught with food for chicks was 1.8. Size-corrected body mass during chick-rearing was lower in females, proportional to their higher chick feeding effort compared with males. Females, in contrast to males, lost protein reserves during chick-rearing. Digestive tract mass of adults increased by half throughout the breeding period. These findings supported elements of hypothesis (1). Despite high energy expenditure rates, both sexes had about 10 g of fat reserves at the end of chick feeding. Body mass of both sexes was constant during the greater part of the chick-feeding period. It was suggested therefore that mass loss is regulated with respect to lower fat reserves required during chick-rearing.
The paper presents the impact of the reformed EU ETS (Emission Trading Scheme – ETS in
the European Union) on the currently operating market for trading in CO2 emission allowances.
The new Directive introduced a number of changes aimed at tightening the climate policy, which
the Polish energy sector based mainly on hard coal may mean an increase in the costs of electricity
production, and thus an increase in the cost of the entire economy.
The main goal of the changes is to achieve one of the objectives the European Union has set for itself,
i.e. the reduction of CO2 emissions by 40% until the year 2030. These assumptions are the result of
joint arrangements of the EU countries under the Paris Agreement on climate change adopted in 2015.
The Directive introduces a new market stability reserve mechanism (MSR) which, according to its
assumptions, is designed to ensure a demand and supply balance of the ETS. Bearing the balance in
mind, it means the reduction of excess allowances, which, although their number is decreasing, it is
decreasing to slowly according to EU legislators, still oscillating around 2 billion EUA.
The paper also draws attention to the rigorous assumptions adopted in the new Directive, aimed at
increasing the price of CO2, that is the costs in electricity production. Due to manually-controlled
prices, are we doomed to high CO2 prices and therefore the prices of electricity? What are its estimated
maximum levels? Will the new assumptions encourage the Member States to switch to lowcarbon
technologies? Can they weaken the economies of countries that are currently based mainly
on coal energy sources, and strengthen countries where green energy is developed?
Pedunculate and sessile oaks (Quercus robur L.; Q. petraea [Matt] Liebl.) often coexist in mixed forest stands.
However, species-specific investigations and forest management actions in such populations require reliable
methods of identification of the species status of individuals. We investigated genetic diversity and species differentiation
of adult and naturally established seedling cohorts in a mixed forest stand composed of Q. robur and
Q. petraea, located in the Jamy Nature Reserve in north-central Poland. Using nineteen nuclear microsatellite
loci and a model-based clustering approach as a tool for species delineation, we efficiently identified 105 and
60 adults, as well as 191 and 456 seedlings of pedunculate and sessile oaks, respectively. While the adult trees
of both species were randomly distributed throughout the sample plot, the seedlings demonstrated significant
spatial clustering, which was particularly evident for Q. petraea. The two oak species exhibited similar levels of
genetic diversity in adult and offspring cohorts. Inbreeding was found to be low and significant only at the stage of
seedlings. The estimates of effective population size were higher for Q. robur than Q. petraea, despite the overall
greater reproductive success of the later one. There was a significant level of differentiation between the studied
oak species, as measured by Fst coefficient (0.084 – adults; 0.099 – seedlings). The results on genetic diversity and
species differentiation obtained in the studied indigenous near-natural stand of Q. robur and Q. petraea could be
considered as a reference for other population genetic studies of oaks.
Genetic diversity is often considered a major determinant of long term population persistence and its potential to adapt to variable environmental conditions. The ability of populations to maintain their genetic diversity across generations seems to be a major prerequisite for their sustainability, which is particularly important for keystone forest tree species. However, little is known about genetic consequences of demographic alterations occurring during natural processes of ecological succession involving changes in the species composition. Using microsatellites, we investigated genetic diversity of adult and offspring generations in beech (Fagus sylvatica L.) and oak (Quercus robur L.) populations coexisting in a naturally established old-growth forest stand, showing some symptoms of ongoing ecological succession from oak- to beech- dominated forest. In general, adult generations of both species exhibited high levels of genetic diversity (0.657 for beech; 0.821 for oak), which, however, depended on the sets of selected genetic markers. Nevertheless, several symptoms such as differences in genetic diversity indices between generations, significant levels of inbreeding (up to 0.029) and low estimates of effective population size (48-80) confirmed the declining status of the oak population. On the other hand, the uniform distribution of genetic diversity indices across generations, low levels of inbreeding (0.004), low genetic differentiation among adults and offspring and, most importantly, large estimates of effective population size (119-716), all supported beech as a successive and successful tree species in the studied forest stand.
Premises for the construction of balance equations of water reserves in the saturation zone of forest soil are presented in this paper. Changes of soil water reserves are dealt with as an effect of the atmosphere-tree stand-soil balance at the assumption of constant ground water flow and negligibly small losses for infiltration down the soil profile below saturation zone. These assumptions are met in permeable lowland forest soils, particularly in areas where the aquifer is situated on relatively shallow impermeable substratum. Then, for snow-free periods, it is possible to: 1) combine the increment of soil water reserves with precipitation above tree crowns and with plant and litter interception and 2) combine the losses of soil water reserves with plant transpiration and evaporation from the soil surface. The periods of increments and losses of soil water reserves are determined from limnigraph records of ground water table depth in piesometers. Examples are given in the paper of equations identified by long term data from 13 soil profiles localised in pine forests on Pleistocene floodplain of the Dunajec River. The data included: ground water table depth, physical properties of grounds in soil profiles, and hydro-climatic conditions. The equations combine increments and losses of water reserves in the saturation zone with rainfall and deficits of air humidity measured on a midforest meadow.