The paper presents the results of research on innovation activities of manufacturing firms in Serbia. In order to answer the question how innovation takes place in one transition country, key influencing factors were ...The paper presents the results of research on innovation activities of manufacturing firms in Serbia. In order to answer the question how innovation takes place in one transition country, key influencing factors were identify （i.e., firm＇s size, age, ownership, industry sector, personnel qualifications and experience）. Based on the analysis of a sample comprising 73 firms, the study tried to highlight certain innovation barriers, which may have a negative impact on the total efficiency of economic performance, and growth and development of manufacturing firms in Serbia. Comparing overall innovation activities of Serbian firms to the other transition countries, it can be concluded that majority of the fhnns had innovation performances below the level EU-27. This study draws out the potential contributions to existing literature of managing innovation in Serbia.展开更多
Large-amplitude X-ray variation is a special feature of AGN, reflecting possible extreme change in the central engine or the ab- sorption along the line of sight. Till now there are only a few relevant studies on indi...Large-amplitude X-ray variation is a special feature of AGN, reflecting possible extreme change in the central engine or the ab- sorption along the line of sight. Till now there are only a few relevant studies on individual sources or rather small samples. In this work we aim to perform a systematic study of AGNs with strong soft X-ray variations at timescale of 〉 10 years. To build the sample, we compare the soft X-ray fluxes of AGNs measured in ROSAT All-Sky Survey （RASS） during 1990-1991 with those measured by XMM-Newton during 2000-2009. This investigation bings forth to a sample of 13 AGNs, which appeared bright in RASS era, and went into low states （flux dropped by a factor of 〉 10） when they were caught by XMM-Newton. Most of the 13 sources are type I Seyfert galaxies. 5 of them are noticed to have strong X-ray vai＇iation for the first time. We study the nature of their variations through performing XMM-Newton spectral analyses and by collecting reports from the existing literature. We find the sample could be divided into three categories according to the possible causes of the strong X-ray variations. The variations in MRK 0478 and 1H 0419-557 are consistent with strong light-bending effect, i.e., the observed X-ray flux drops significantly as the X-ray emitting corona gets much closer to the central black hole. The variations in ESO 140-G043 and NGC 7158 are caused by absorption changes along the line of sight. For one special case MRK 0335, the variation can be explained by either light-bending or absorption variation. In the rest 8 sources （- 60%）, the strong soft X-ray variations are likely to exist due to intrinsic changes in the activities of the corona, although in some of them without high quality X-ray spectra we are unable to rule out alternative models. This sample provides good targets for future monitoring campaigns with more extensive studies.展开更多
文摘The paper presents the results of research on innovation activities of manufacturing firms in Serbia. In order to answer the question how innovation takes place in one transition country, key influencing factors were identify （i.e., firm＇s size, age, ownership, industry sector, personnel qualifications and experience）. Based on the analysis of a sample comprising 73 firms, the study tried to highlight certain innovation barriers, which may have a negative impact on the total efficiency of economic performance, and growth and development of manufacturing firms in Serbia. Comparing overall innovation activities of Serbian firms to the other transition countries, it can be concluded that majority of the fhnns had innovation performances below the level EU-27. This study draws out the potential contributions to existing literature of managing innovation in Serbia.
基金supported by the National Natural Science Foundation of China(Grant No.11233002)the Strategic Priority Research Program "The Emergence of Cosmological Structures" of the Chinese Academy of Sciences(Grant No.XDB09000000)support from Chinese Top-notch Young Talents Program
文摘Large-amplitude X-ray variation is a special feature of AGN, reflecting possible extreme change in the central engine or the ab- sorption along the line of sight. Till now there are only a few relevant studies on individual sources or rather small samples. In this work we aim to perform a systematic study of AGNs with strong soft X-ray variations at timescale of 〉 10 years. To build the sample, we compare the soft X-ray fluxes of AGNs measured in ROSAT All-Sky Survey （RASS） during 1990-1991 with those measured by XMM-Newton during 2000-2009. This investigation bings forth to a sample of 13 AGNs, which appeared bright in RASS era, and went into low states （flux dropped by a factor of 〉 10） when they were caught by XMM-Newton. Most of the 13 sources are type I Seyfert galaxies. 5 of them are noticed to have strong X-ray vai＇iation for the first time. We study the nature of their variations through performing XMM-Newton spectral analyses and by collecting reports from the existing literature. We find the sample could be divided into three categories according to the possible causes of the strong X-ray variations. The variations in MRK 0478 and 1H 0419-557 are consistent with strong light-bending effect, i.e., the observed X-ray flux drops significantly as the X-ray emitting corona gets much closer to the central black hole. The variations in ESO 140-G043 and NGC 7158 are caused by absorption changes along the line of sight. For one special case MRK 0335, the variation can be explained by either light-bending or absorption variation. In the rest 8 sources （- 60%）, the strong soft X-ray variations are likely to exist due to intrinsic changes in the activities of the corona, although in some of them without high quality X-ray spectra we are unable to rule out alternative models. This sample provides good targets for future monitoring campaigns with more extensive studies.
