Ontogenija usnog aparata salmo faroides and salmo macedonicus gajenih u mrestilištu tokom ranih faza razvitka

Continuing losses of natural production from over harvesting, habitat degradation and disappearance of spawning habitat due to hydroelectric development, irrigation, logging and transportation are increasingly showing the importance of hatchery operations in many countries. Few years ago, the Republic of Macedonia started with captive breeding programs for salmons. This program involves capturing wild fish of species as Salmo faroides and Salmo macedonicus from their native habitats and subsequent culturing the offspring from captive broodstocks which are then stocked into ancestral streams at the juvenile stage. From a practical point of view, the importance of study on how a developing larva copes with the changing functional demands during ontogeny, especially when being reared under artificial conditions, is obvious. Understanding how the locomotor and feeding apparatus is formed during early ontogeny can assist in improving the success of artificial propagation in terms of effective production of high quality juveniles. This would especially be valuable when offspring would be re-introduced into the river ecosystem. On the other hand knowledge on the ontogeny of fishes, especially for the early development of the skeletal system, provides information that can also be useful for solving some taxonomic problems and unravel phylogenetic relationships. For example, it is well known that morphological variation is commonly observed in salmonids. These fishes often form reproductively isolated populations across a diversity of environments and exhibit high levels of phenotypic variation. The final form of a phenotype and its life history are determined during early ontogeny. To better understand the relationship between morphology and ecology studies on the effect on environmentally induced variation in early life stage development within a single species, or study differences in the effect of a single environment in closely related species. Among the Salmo species that are present in the Balkan Peninsula, there is a high level of phenotypic variability, where also phenotypic plasticity is problematic for demarcate species boundaries between previously defined salmon species. Molecular data have confirmed the existence of previously defined species but several nominal species and populations of Balkan trout still remain unresolved. Still, understanding patterns of phenotypic variation that underlies molecular affinities remains essential. Within this context, we analysed the ontogeny of the skeletal system in Salmo faroides and Salmo macedonicus, two species of a still uncertain taxonomic status, reared under controlled condition. We wanted to test to what degree ontogeny of these closely related species is similar. In this study we focus on the early development of the feeding apparatus, from hatching till beginning of the exogenous feedin

Thermal mass impact on energy performance of a low, medium and heavy mass building in Belgrade

Heavy mass materials used in building structures and architecture can significantly affect building energy performance and occupant comfort. The purpose of this study was to investigate if thermal mass can improve the internal environment of a building, resulting in lower energy requirements from the mechanical systems. The study was focused on passive building energy performance and compared annual space heating and cooling energy requirements for an office building in Belgrade with several different applications of thermal mass. A three-dimensional building model was generated to represent a typical office building. Building shape, orientation, glazing to wall ratio, envelope insulation thickness, and indoor design conditions were held constant while location and thickness of building mass (concrete) was varied between cases in a series of energy simulations. The results were compared and discussed in terms of the building space heating and cooling energy and demand affected by thermal mass. The simulation results indicated that with addition of thermal mass to the building envelope and structure: 100% of all simulated cases experienced reduced annual space heating energy requirements, 67% of all simulated cases experienced reduced annual space cooling energy requirements, 83% of all simulated cases experienced reduced peak space heating demand and 50% of all simulated cases experienced reduced peak space cooling demand. The study demonstrated that there exists a potential for reducing space heating and cooling energy requirements with heavy mass construction in the analyzed climate region (Belgrade, Serbia)

Experimental and Analytical Research of the Heat Transfer Process in the Package of Perforated Plates

The need for compact heat exchangers has led to the development of many types of surfaces that enhance the rate of heat transfer, among them the perforated plate heat exchangers, also known as matrix heat exchangers. The perforated plate heat exchangers consist of a series of perforated plates that are separated by a series of spacers. The present study investigates the heat transfer characteristics of the package of perforated plates. Perforated plates were 2 mm thick, with holes with 2 mm in diameter and porosity of 25.6%. The package of one, two, and three perforated plates was set in the channel of the experimental chamber at which entrance was a thrust fan with the ability to control the flow rate. The fluid flow rates, the temperatures of the fluids at the inlet and outlet of the chamber and the temperature of the air between the plates, were measured at the pre-defined locations in the package and the experimental chamber. Based on the measurements, heat transfer coefficients for the individual plates, as well as for the packages of perforated plates were determined. In further research, an iterative analytical procedure for investigation of the heat transfer process and the overall heat transfer coefficient for the package of perforated plates were developed. Based on these analytical and experimental results, conclusions were drawn about the heat transfer in a package of perforated plates.17th Symposium of the Society-of-Thermal-Engineers-of-Serbia (SIMTERM), Oct 20-23, 2015, Sokobanja, Serbi

A Two-stage Flow-based Intrusion Detection Model ForNext-generation Networks

The next-generation network provides state-of-the-art access-independent services over converged mobile and fixed networks. Security in the converged network environment is a major challenge. Traditional packet and protocol-based intrusion detection techniques cannot be used in next-generation networks due to slow throughput, low accuracy and their inability to inspect encrypted payload. An alternative solution for protection of next-generation networks is to use network flow records for detection of malicious activity in the network traffic. The network flow records are independent of access networks and user applications. In this paper, we propose a two-stage flow-based intrusion detection system for next-generation networks. The first stage uses an enhanced unsupervised one-class support vector machine which separates malicious flows from normal network traffic. The second stage uses a self-organizing map which automatically groups malicious flows into different alert clusters. We validated the proposed approach on two flow-based datasets and obtained promising results

Disparity Changes in 370 Ma Devonian Fossils: The Signature of Ecological Dynamics?

Early periods in Earth's history have seen a progressive increase in complexity of the ecosystems, but also dramatic crises decimating the biosphere. Such patterns are usually considered as large-scale changes among supra-specific groups, including morphological novelties, radiation, and extinctions. Nevertheless, in the same time, each species evolved by the way of micro-evolutionary processes, extended over millions of years into the evolution of lineages. How these two evolutionary scales interacted is a challenging issue because this requires bridging a gap between scales of observation and processes. The present study aims at transferring a typical macro-evolutionary approach, namely disparity analysis, to the study of fine-scale evolutionary variations in order to decipher what processes actually drove the dynamics of diversity at a micro-evolutionary level. The Late Frasnian to Late Famennian period was selected because it is punctuated by two major macro-evolutionary crises, as well as a progressive diversification of marine ecosystem. Disparity was estimated through this period on conodonts, tooth-like fossil remains of small eel-like predators that were part of the nektonic fauna. The study was focused on the emblematic genus of the period, Palmatolepis. Strikingly, both crises affected an already impoverished Palmatolepis disparity, increasing risks of random extinction. The major disparity signal rather emerged as a cycle of increase and decrease in disparity during the inter-crises period. The diversification shortly followed the first crisis and might correspond to an opportunistic occupation of empty ecological niche. The subsequent oriented shrinking in the morphospace occupation suggests that the ecological space available to Palmatolepis decreased through time, due to a combination of factors: deteriorating climate, expansion of competitors and predators. Disparity changes of Palmatolepis thus reflect changes in the structure of the ecological space itself, which was prone to evolve during this ancient period where modern ecosystems were progressively shaped