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Search Results: 1 - 10 of 633 matches for " Nikola Pernar "
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The Impact of Technical and Biological Measures on Soil and Erosion Dynamics in the Research Site of Abrami
Nikola Pernar,Danko Holjevi?,Darko Bak?i?,Josip Petra?
Croatian Journal of Forest Engineering , 2011,
Abstract: Soil erosion is one of the most devastating soil degradation processes. In temperate climate regions, soil erosion rarely assumes excessive proportions. In the management of forest soil, the potential erosion threat drastically increases with an increase in climate aridity. Water erosion is particularly favored by parent materials of low water permeability and by soils derived from such materials. In theMediterranean and sub-Mediterranean area of Croatia, these are primarily flysch, marl and Werfen schists. These materials show good physical weathering properties, thus providing a rich source of erosion material.As a rule, the soil formed from such parentmaterial is of silty-clayey to clayey texture, and has a relatively low infiltration capacity. The soil unprotected by vegetation (burned sites) manifests particularly devastating forms of water-induced erosion. In the past 50 years, flysch terrains of Istria have been subjected to a series of technical, biological and biological- technical treatments aimed at preventing water erosion and recovering the eroded soils. An experimental (research) site was set up in Abrami near Buzet for the purpose of monitoring erosion processes and rehabilitation effects of different biological-technical and biological methods of eroded area recovery. The effects of the treatments on soil properties in the research site are in the form of progressive pedogenetic processes. Asynergy of the effects of recovery methods and different natural conditions (relief, vegetation) in the experimental site is particularly well reflected in erosion indicators, such as the production of erosion sediment (erosion production), and to a lesser extent, the surface flow index. For this reason, research in this work focuses primarily on soil properties and erosion production dynamics. From the geological-lithological aspect, the research site of Abrami is made up of Eocene flysch composed of alternate layers of light grey marl and dark lime sandstone, i.e. thinner or thicker interbeds of sandy limestone. The climate is sub-Mediterranean. The mean annual temperature is 12 °C and the mean annual precipitation is 975 mm. The natural potential vegetation in the localities is represented by the community of hop hornbeam and autumn moor grass. Established in 1956 on the slope exposed to highly pronounced erosion processes, the research site has an area of 23.46 ha.Aseries of technical and biological erosion recovery measures had been undertaken in the site by 1963 for the purpose of investigating their applicability in practice. Technical activitie
Pedophysiographic Features and Heavy Metal Content (Pb, Zn, Cd and Cu) in Spruce Forests of Northern Velebit and tirova a
Darko Bak?i?,Ivan Perkovi?,Nikola Pernar,Joso Vukeli?
Croatian Journal of Forest Engineering , 2011,
Abstract: The largest and the most coherent complexes of natural spruce stands in Croatia are currently distributed in the altimontane and subalpine vegetation belt of Velebit over an area of 3165 ha and altitudes ranging from 1100 to almost 1600 m.Past phytocoenological research into spruce forests in northern Velebit distinguishes three different associations: frost valleys of tirova a and Apati anska Duliba support the altimontane spruce forest with bastard agrimony (Aremonio-Piceetum Horvat 1938), shallower sink holes and slopes descending from the surrounding tops contain the altimontane-subalpine spruce forest with Laserpitium krapfii (Laserpitio krapfii-Piceetum Vukeli et al. 2010), while rocky tops, hips, karrens and ridges feature the subalpine spruce forest with small-reed (Calamagrostio variae-Piceetum Bertovi 1975). These associations are distributed as azonal, microclimatically and edaphically conditioned associations, of which spruce forest with bastard agrimony occurs in the belt of Dinaric beech-fir forest (Omphalodo-Fagetum) while the two others grow in a higher belt of subalpine beech forest with buttercup (Ranunculo platanifoliae-Fagetum). Their mutual differences result from ecological factors which are decisive for their occurrence and distribution. Of these, the edaphic relationships which we explored in this work draw particular interest.Composite samples were taken from the top layer up to 5 cm deep (13 composite samples composed of 9 individual samples each), pedological profiles were opened (11 profiles), and soil samples were taken by pedogenetic horizons within pedological research in three spruce communities: altimontane spruce forest with bastard agrimony (Aremonio-Piceetum), altimontane-subalpine spruce forest with Laserpitium krapfii (Laserpitio krapfii-Piceetum), and subalpine spruce forest with small-reed (Calamagrostio-Piceetum) in the area of northern Velebit and tirova a. Composite samples, taken from the top soil layer up to 5 cm deep, consisted of 9 samples, each taken at a distance of 1 m in a cross pattern.Soil samples were analyzed by means of the following laboratory methods: determination of pH values (HRN ISO 10390:2005), determination of CaCO3 content (HRN ISO 10693:2004), determination of organic and total carbon and nitrogen with dry combustion (HRN ISO 10694:2004, HRN ISO 13878:2004), determination of concentrations of Pb, Zn, Cu and Cd (HRN ISO 11466:2004), and determination of the granulometric soil composition (HRN ISO 11277:2004). Descriptive statistics were made for all the samples by the investigated phyto
Growth of Pedunculate Oak Seedlings under Soil Contamination by Mineral and Biodegradable Oils
Milan Or?ani?,Dubravko Horvat,Nikola Pernar,Marijan ?u?njar
Croatian Journal of Forest Engineering , 2008,
Abstract: The purpose of this study is to research the effects of different concentrations of mineral and biodegradable oils for chainsaws on seedling growth of pedunculate oak (Quercus robur L.) during two-year vegetation period. The paper also examines the influence of the above mentioned oils and their concentrations on the development of the seedling root system at the end of the second vegetation. Tests were carried out in forest nurseries on seven 1 m2 plots. Three plots were treated, after the planting of the pedunculate oak acorns, with biodegradable oil in the concentrations of 0.1 L/m2, 0.2 L/m2, and 0.5 L/m2. The other three plots were treated with mineral oil of the same concentrations. The control plot received only seed sowing. The analysis of the root system of the two-year-old seedlings of pedunculate oak was carried out with WinRHIZO ProLA 2400 software. The SAS and Statistica 7 program packages were used for the statistic data processing and for determination of statistically significant differences among variables. Results showed that the lower oil concentration the larger root lengths. The lowest heights of the two-year-old pedunculate oak seedlings were measured from the test plots treated with mineral oil and the highest on those from the plots treated with bio-oil, although the heights of seedlings from the control plots were very close to heights of those treated with bio-oil.
The Effectiveness of the Functional Magnetic Stimulation Therapy in Treating Sciatica Syndrome  [PDF]
Tamara Radakovi?, Nikola Radakovi?
Open Journal of Therapy and Rehabilitation (OJTR) , 2015, DOI: 10.4236/ojtr.2015.33009
Abstract: Introduction: Degenerative or traumatic causes are most common in generating sciatica syndrome, which is normally treated with well-known physical therapy methods. A relatively new way of treating sciatica problems is so-called functional magnetic stimulation (FMS), whose principle is based on electromagnetic field inducing electrical field inside the body. Electrical field triggers action potential of nerve cells and that way stimulates peripheral motor nerve system. Aim: Aim of this study is to measure and estimate the effectiveness of implementing therapy with functional magnetic stimulation in regular physical treatment of sciatica syndrome. Materials and Methods: 28 male patients aged between 30 and 55 with back problem were recruited on an outpatient basis. FMS therapy was performed with TESLA Stym? device (Iskra Medical d.o.o., Slovenia) treating lumbosacral region equally on both sides of the spine. Physical examination was performed to evaluate tree parameters: the mobility of the lumbar spine in flexion and extension, together with the straight leg raise test (Lasegue sign). We estimated patients’ progress, comparing angle values of mobility from the first examination day with other examination days. Results: In FMS treated group of patients, lumbosacral flexion, extension and Lasegue test angle were significantly higher compared to day 0 on the first physical examination day (day 3) (p < 0.05). In control group such increase of a measured angle was not noticed until a second physical examination day (day 5) or a third physical examination day (day 8) (p < 0.05). Discussion: Results in this study showed that applying FMS therapy along with other standard physical therapy methods rapidly increased effectiveness of the treatment of sciatica syndrome (lat. ischialgia). It suggests that functional magnetic therapy could be suggested as a regular physical therapy method in treating this kind of pain syndromes.
Pricing the Cost of Cybercrime—A Financial Protection Approach  [PDF]
Thomas Poufinas, Nikolaοs Vordonis
iBusiness (IB) , 2018, DOI: 10.4236/ib.2018.103008
Abstract: Infrastructures, businesses, end-users and services offered in the digitally integrated environment are exposed to a wide range of risks such as denial of service, hacking, phishing, ransomware, viruses, etc. Consequently, along with their physical life, individuals and organizations have to secure their digital life as well. Digital threats may have a major economic impact both on the individuals and the society, through the direct loss of income and/or property or even an indirect reduction of the individuals’ contribution back to the society and the state. The purpose of this paper is to study the effect of cyber-attacks to the economy, to price the associated cost and to recommend possible measures that internet service providers (ISPs) and policy makers can apply in order to mitigate these risks. In order to achieve that, we employ insurance (actuarial) pricing techniques to calculate the cost of cyber-attacks for an individual and for the economy of a country in total. We are therefore at the same time in place to recommend insurance coverage solutions that can assist in protecting the entity of interest from cyber risks. This resembles to the calculation of a risk premium, as the premium is calculated taking into account only the probability of occurrence of a cyber-attack and the interest rate and not any other loadings. In this context, we mimic the pricing of a policy that provides coverage for the cyber-attack, as well as the calculation of the amount that has to be set aside in order to compensate for the one-off economic loss suffered by the individual, as a result of its occurrence. Here lies our contribution to the scientific research in the field of cyber security insurance, as we employ insurance-based actuarial techniques in order to quantify the relevant loss.
Features of Spatial Snag Distribution in a Beech-Fir Forest
Renata Pernar,Ante Seletkovi?,Mario An?i?,Jelena Su?i?
Croatian Journal of Forest Engineering , 2011,
Abstract: With the participation of about 65% in the total growing stock of conifers, silver fir is the most important and the best represented conifer species in Croatia. The increasing share of sanitary felling in the annual felling plans demands that special attention be paid to the health status of fir forests and the quantity of unplanned felling. This is the reason why dieback of silver fir in beech-fir forests in the Dinaric Alps is an acute and topical management-ecological problem. In the past 10 years, the share of total unplanned felling in the overall annual felling for fir has amounted to 57%. Such a high share of unplanned yield (mainly snags) has had a negative effect on sustainable forest management. Determining the spatial distribution of damaged trees and snags, as well as their monitoring is one of the priorities of sustainable management. Hence, it is of utmost importance to detect less healthy stands and apply timely measures for the purpose of maintaining their vitality and productivity at an optimal level. Due to the seriously disturbed stand stability caused by forced canopy opening, which in turn affects the health condition and natural regeneration of the stand, it is necessary not only to detect snags but also determine the causes of dieback. According to the results of past research, increased tree dieback is associated with the impact of different site and stand characteristics (altitude, exposition, slope, soil, structure, etc.), as well as abiotic and biotic factors (fir needle moth, mistletoe); however, the real causes are yet to be discovered. It is difficult to make efficient snag inventories with standard field methods. For large areas, a remote sensing method (the application of CIR aerial photographs) is much more practical, more cost effective and more reliable. All research activities so far have proved that, in terms of accuracy, this method is equal to field working methods, while in terms of speed and objectivity it is far more efficient. Snag inventories by means of CIR aerial photography interpretation and GIS enable efficient enumeration (detection) and spatial distribution (mapping) of snags. The proposed method is highly important not only for the detection and monitoring of the occurrence, distribution and direction of dieback progress, but also for the detection of possible dieback causes, on the basis of which experts will prescribe adequate measures and treatments. The objective of CIR aerial photography interpretation is to determine the current situation and acquire an objective picture of forest condition (data
Assessment of Stand Structural Elements on the Basis of Spectral Reflectance Values of an IKONOS Satellite Image
Ante Seletkovi?,Renata Pernar,Mario An?i?,Jelena Su?i?
Croatian Journal of Forest Engineering , 2011,
Abstract: Rapid technological advances in the second part of the 20th century have brought about immense changes in data collection methods, especially in developed countries. In addition to standard terrestric data collection methods, forest data are increasingly being collected with remote sensing methods. The application of remote sensing reduces the amount of field work and offers the possibility of saving time and money.Satellite remote sensing is a very efficient method, while satellite images are a useful means for the surveillance and study of forest vegetation. Remote sensing is based on the prediction of the relationship between spectral reflectance and the observed variable. To interpret this kind of relationship, it is important to know the reflective characteristics of the target object (spectral features of vegetation, leaf, etc.), the size of area presentation (spatial resolution), and other factors such as topography, sun height, slope and orientation between the surveyed area and the survey sensor. A detailed and high quality analysis of satellite imagery, recognition and selection of certain data is highly dependent on image resolution, and especially on spatial resolution.Acquiring information on forests from satellite photographs of high spatial resolution has been the subject of a large number of research activities. One of the approaches involves classification based on pixel value, or regression analyses in which spectral records are used to predict classes or continuous variables of stand structure.The basic objective of this work is to explore the relationship between spectral reflectance recorded in the IKONOS satellite image of high spatial resolution and any individual stand parameter, as well as regression models for the evaluation of stand parameters.The main material for this work was provided by the IKONOS satellite image of high spatial resolution for the Spa va basin area. The survey was conducted on 18 October 2006. An IKONOS satellite image of the Spa va basin with an area of 132 km2 was delivered in 5 spectral channels: PAN (1x1m), and 4 MS Bundle. In the area of Vinkovci Forest Administration, within the management units encompassed by satellite surveying (MU Vrbanjske ume, Kragujna, Slavir and Oto ke ume), field measurements were conducted in management classes of pedunculate oak and narrow-leaved ash through all age classes (2nd to 7th age class), for the purpose of subsequent comparison of interpretations and assessments of structural elements. Based on field measurements and Management Plan data, a database with compartm
Wastewater Treatment After Improved Scourings of Raw Wool
Dosen-Sver, D.,Pernar, E.,Bujevic, I.
Kemija u Industriji , 2007,
Abstract: Textile industry processes need high amounts of water for wet treatment of textiles. Therefore, high amounts of wastewater also appear containing different inorganic and organic substances depending on the used materials and processes. Raw wool is contaminated with wool wax, suint, skin flakes, dirt, sand, vegetable matter, urine and various microorganisms. The methods for raw wool scouring and cleaning today often in use are: scouring in the suint, scouring with soaps or tenside in alkaline, extraction by organic solvents and freezing. The different methods for wastewater purification after scouring in use are: settling/floculation, biological treatment, adsorptionand catalytic oxidation. In this work, wastewater treatments after improved raw wool scouring with enzymes and EDTA have been investigated. Isothermal adsorption on zeolite A, active carbon and a natural and H+ type of bentonite for removal of the obtained wastewater impurities was used. The results were determined by means of different physical-chemical test methods.
On certain sufficient conditions for starlikeness
Nikola Tuneski
International Journal of Mathematics and Mathematical Sciences , 2000, DOI: 10.1155/s0161171200003574
Abstract: We consider certain properties of f(z)f″(z)/f′2(z) as asufficient condition for starlikeness.
A study of the distribution of phylogenetically conserved blocks within clusters of mammalian homeobox genes
Stojanovic, Nikola;
Genetics and Molecular Biology , 2009, DOI: 10.1590/S1415-47572009000300034
Abstract: genome sequencing efforts of the last decade have produced a large amount of data, which has enabled whole-genome comparative analyses in order to locate potentially functional elements and study the overall patterns of phylogenetic conservation. in this paper we present a statistically based method for the characterization of these patterns in mammalian dna sequences. we have applied this approach to the study of exceptionally well conserved homeobox gene clusters (hox), based on an alignment of six species, and we have constructed a map of hox cataloguing the conserved fragments, along with their locations in relation to the genes and other landmarks, sometimes showing unexpected layouts.
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