Browse

You are looking at 91 - 100 of 91,141 items for

Open access

Jae Hee Noh, Gwang Hee Jo, Deok Won Lim, Jin Hyuk Lee, Sun Yong Lee and Sang Jeong Lee

Abstract

Research on precise positioning is being actively carried out to provide accurate position information for land transportation. The most significant problem when performing precise positioning in urban canyon is the degradation of performance due to the lack of visible satellites. Prior to open service of BDS, most of the studies on positioning were focused on using GPS/GLONASS integrated navigation system. Since BDS began open service, studies using GPS/BDS have been actively performed in the Asia-Pacific region as it became possible to acquire enough available BDS satellites. The average number of visible satellites in Korea is 9 for GPS and 14 for BDS. In this paper, we analyze the availability of precise positioning using BDS in urban canyon. To do this, we simulate the urban canyon environment by applying the mask to the azimuth and the elevation. We analyze the positioning accuracy using two simulation scenarios. From the results, it is shown that the accuracy of precise positioning in the case where the satellites in the east-west direction are blocked is lowered than that in the case where the satellites in the south-north direction are blocked for the same elevation mask angle. This result comes from the fact that the PDOP increases when the satellites are blocked in the east-west direction. Also, it can be confirmed that the GPS/BDS integrated positioning is available for the high mask angle while the GPS-only positioning is not possible continuously.

Open access

Georgi Kunev and Rossen Tzonev

Abstract

The study presents new data on the habitat dominated by the species complex of Genista lydia/G. rumelica in Bulgaria. It is based on 129 phytocoenological relevés and provides information on the chorology, ecology and floristic structure of these communities. This habitat type occupies substrates composed by different volcanic rocks. The floristic structure is very rich in species. The phytogeographical relationships with the East Mediterranean region are considerable, which is proved by the high occurrence of floristic elements with Mediterranean or sub-Mediterranean origin. The plant life-forms analysis demonstrates that the therophytes, geophytes and chamephytes prevail in their floristic structure, which is also typical for the shrub communities in this region. During the field study this vegetation type has been mapped and its total area of occupancy has been calculated. For a first time it is proposed this habitat to be divided into three habitat sub-types due to the established differences in the environmental factors. Some recommendations have been proposed on the conservation management and also complements on the habitat‘s descriptions in EUNIS habitat classification.

Open access

Alexandra Maria Rașcu, Marina Ruxandra Oțelea and Călin Giurcăneanu

Abstract

Modern medicine has increasingly directed its interest towards discovering the etiology of occupational dermatitis, but unfortunately it is not completely elucidated. As with other occupational diseases, the presence of the exposure and the temporal relation between the exposure and the appearance of the characteristic signs is a defining element, but obtaining the information on the etiological factors is not always easy, therefore the attention must be directed to a systematic collection of these data. Clinical diagnosis is not sufficient, so additional paraclinical tests are needed for a complete diagnosis. Currently, more and more emphasis is being placed on experimental studies targeting the discovery of molecular or genetic markers that complement the idea of individual susceptibility in the appearance of contact dermatitis. As frequent as it is difficult to diagnose, occupational dermatitis is still a public health problem.

Open access

Oskar Mężyk, Michał Doligalski and Ryszard Rybski

Abstract

In the work a method of latency measurement in software defined radio (SDR) is proposed and validated. The test setup uses customer grade GNSS modules as reference time sources and enables relative delay calculation between signals received directly and those bypassed through SDR platform. The method is hardware agnostic in a sense, that it does not involve any custom software or hardware modifications. Tests that compare reported carrier-to-noise ratio and positioning errors were performed to prove functionality of such system. Additionally, authors measured several gnuradio blocks with respect to their impact on total latency introduced into signal path. All tests were performed on a bladeRF low-cost RF front-end. Minimum observed latency for the signal was below 10 ms.

Open access

Viktor Onyshchenko

Abstract

The article aims to 1) describe the distribution of non-native species of vascular plants (only kenophytes, i. e. naturalized species introduced after the 15th century) in different types of forests and different biogeographical regions of Ukraine; 2) compare proportions of kenophytes in forests of different areas; 3) detect statistically significant changes in the occurrence of kenophytes over the last 80 years. The material consists of 2701 relevés sampled in 1990–2018. They were taken from Ukrainian phytocoenological publications and databases. In Ukraine, as in other European countries, the highest proportion of kenophytes (percentage of species number per relevé) is in floodplain forests (up to 9.1% in willow and poplar forests). The lowest proportion is characteristic for bog woods (0%) and most types of mountain forests. Among biogeographical regions, the highest values were found in the flatland areas of the Steppic region and the forest-steppe part of the Continental region. The most frequent species are Impatiens parviflora (predominantly in broadleaved woods, absent in relevés from the steppic biogeoregion) and Erigeron canadensis (pine woods on sand). Comparison with 1466 older relevés sampled in 1950–1989 allows us to make a conclusion that the proportion of kenophytes increased at least in one habitat type (oak-hornbeam forests).

Open access

Csaba Albert Tóth, Balázs Deák, István Nyilas, László Bertalan, Orsolya Valkó and Tibor József Novák

Abstract

Prehistoric mounds of the Great Hungarian Plain often function as refuges for relic loess steppe vegetation and their associated fauna. The Zsolca mounds are a typical example of kurgans acting as refuges, and even though they are surrounded by agricultural land, they harbour a species rich loess grassland with an area of 0.8 ha. With a detailed field survey of their geomorphology, soil, flora and fauna, we describe the most relevant attributes of the mounds regarding their maintenance as valuable grassland habitats. We recorded 104 vascular plant species, including seven species that are protected in Hungary and two species (Echium russicum and Pulsatilla grandis) listed in the IUCN Red List and the Habitats Directive. The negative effect of the surrounding cropland was detectable in a three-metre wide zone next to the mound edge, where the naturalness of the vegetation was lower, and the frequency of weeds, ruderal species and crop plants was higher than in the central zone. The ancient man-made mounds harboured dry and warm habitats on the southern slope, while the northern slopes had higher biodiversity, due to the balanced water supplies. Both microhabitats had different assemblages of ground-dwelling invertebrates.

Open access

Victor Meșina and Grigore Friptuleac

Abstract

We present the particularities of the morbidity with temporary labor incapacity (TLI) of the employees of confection factories during the years 2011 - 2017. We placed emphasis on the risk factors affecting the health of the employees. It is an established fact that the main risk factors are unfavorable microclimate, vibration, dust, noise, and others. Morbidity with TLI according to frequency index (IFc) has practically a constant character. The highest level of IFc was registered in 2013, reaching 93.3 cases per 100 workers, while the severity index being oscillatory in nature constituted 1311.2 days in 100 workers in the same year. Both indices have shown a growth trend towards the end of 2017. The average duration of a case remained at the same level of 13-14 days. There were also particularities of morbidity based on gender, profession, etc. The data obtained can be the basis for the elaboration of the prophylaxis measures.

Open access

Anatoliy Khapugin

Abstract

Paper presents a systematic global review of Acer negundo, Fraxinus pennsylvanica, Ailanthus altissima, Robinia pseudoacacia invasions focusing on the Scopus and Web of Science databases. We examined the data on papers, study areas, habitat studied, topic discussed. We hypothesized that these species were studied evenly throughout their invaded ranges and, as such, indexed by international databases. We asked whether four selected species are presented evenly in publications related to their invaded ranges, and whether both selected databases cover well a content of these papers. We found 48 papers for A. negundo, 14 – for F. pennsylvanica, 83 – for A. altissima, 96 – for R. pseudoacacia. A high percentage of the studies were conducted in Central Europe and USA (for A. altissima), while Eastern Europe, Russia, Western United States were poorly represented. Most studies were conducted in forests, and focused on impacts or distribution of aliens in invaded range, and their control and management. We encountered habitat types invaded by trees, factors influencing tree invasions, consequences of invaders’ impact on ecosystems, counteracting measures. We concluded that the use only Web of Science and Scopus is not sufficient to obtain the complete data about the invasion biology.

Open access

Agripina Rașcu, Paraschiva Postolache, Doina Carmen Mazilu and Marina Ruxandra Oțelea

Abstract

Understanding the factors influencing the rationing of nursing care is crucial for any quality control intervention in healthcare services. Occupational factors such as workload, night shifts, management style and organization of work have a potential influence. There are few studies specifically designed to evaluate these factors in relation with nurses’ work. In this study, we investigate several occupational factors influencing the quality of work in a sample of hospital nurses in order to identify the most important influencers of stress at work. The article describes the conceptual framework of the study, the population, the methods and the expected results. We also present a brief review of recent studies related to occupational risk factors and the perceived quality of care provided by Romanian nurse population.