36 research outputs found
Study of the antioxidant, anti-inflammatory and anti-diabetic effects of extracts from Cotinus coggygria in models with experimental animals and cell cultures // Проучване на антиоксидантното,противовъзпалително и противодиабетно действие на екстракти от Cotinus coggygria в експериментални модели с опитни животни и клетъчни култури
No full text[EN] The aim of the dissertation is to study the antioxidant, anti-inflammatory and anti-diabetic properties of Cotinus coggygria by: (1) Determination of the phytochemical composition and the antioxidant activity of the extracts from leaves and wood; (2) Evaluation of the toxicity of the extracts on cell cultures and experimental animals; (3) Determination of biological activity of the extracts in models of oxidative stress and inflammation. In order to resolve the aim, following tasks are performed: (1) Separation, identification and quantification of major polyphenols in extracts of leaves and wood of sumac tree by high performance liquid chromatography (HPLC); (2)Fractionation and purification of the extracts by high-performance countercurrent chromatography (HPCCC); (3) Measurements of the concentration of total polyphenols and determination of in vitro antioxidant activity of the extracts of C. coggygria; (4) MTT cytotoxicity assay of extracts of C. coggygria on cell cultures: 3T3-L1 (murine preadipocytes) and J774A.1 (murine macrophages);5)treatment of male Wistar rats with three aqueous extract from the leaves and aqueous-ethanolic extract of wood in a model of subchronic toxicity (30 days); (6) Study of in vivo antioxidant properties of the extracts from sumac tree in models of indomethacin-induced gastric ulcerogenesis and acetaminophen-induced hepatotoxicity in rats; (7) Evaluation of anti-inflammatory activities of the extracts of the sumac tree in a model of carrageenan-induced inflammation of the hind paw in rats; (8) Examination of antidiabetic potential of Cotinus coggygria by analyzing the expression of genes for adiponectin and PPARγ in murine 3T3-L1 preadipocytes.[BG] Дисертационният труд има за цел да се изследват антиоксидантните, противовъзпалителни и противодиабетни свойства на смрадликата (Cotinus coggygria) чрез: (1)Определяне на фитохимичния състав и антиоксидантната активност на екстракти от листа и дървесина; (2) Оценка на токсичността на екстрактите върху клетъчни култури и експериментални животни; (3) Установяване на биологичната активност на екстрактите в модели на оксидативен стрес и възпаление. В изпълнение на поставената цел е направен опит да бъдат разрешени следните задачи: (1) Разделяне, идентифициране и количествено измерване на главните полифеноли в извлеци от листа и дървесина на смрадлика чрез високоефективна течна хроматография (HPLC); (2) Фракциониране и пречистване на извлеците чрез високоефективна противоточна хроматография (HPCCC); (3) Измерване концентрацията на тотални полифеноли и определяне на in vitro антиоксидантната активност на извлеците от C. coggygria; (4) Провеждане на MTT тест за цитотоксичност на извлеци от C. coggygria върху клетъчни култури: 3Т3-L1 (миши преадипоцити) и J774A.1 (миши макрофаги); (5) Третиране на мъжки Wistar плъхове с три водни извлека от листа и водно-етанолен извлек от дървесина на смрадлика в модел на субхронична токсичност (30 дни); (6) Проучване на in vivo антиоксидантните свойства на извлеците от смрадлика в модели на индометацин-индуцирана стомашна улцерогенеза и парацетамол-индуцирана хепатотоксичност при плъхове; (7) Оценка на противовъзпалителните свойства на извлеците от смрадлика в модел на карагенан-индуцирано възпаление на задната лапа при плъхове; (8) Изследване на противодиабетния потенциал на смрадликата чрез анализ на експресията на гени за адипонектин и PPARγ при 3Т3-L1 миши преадипоцити
Paleoclimate changes and ecosystem responses of the Bulgarian Black Sea zone during the last 26000 years
No full textMulti-proxy analysis (spore-pollen, dinoflagellate cysts, other non-pollen palynomorphs (NPPs), radiocarbon dating and lithology) was performed on marine sediments from three new cores retrieved during the two cruise expeditions on board the Research Vessel “Akademik” in 2009 and 2011. The Varna transect comprises three cores extending from the outer shelf, continental slope and deep-water zone. The record spans the last 26000 years (all ages obtained in this study are given in calendar years BP (cal. yrs BP)). The pollen record reveals the spreading of steppe vegetation dominated by Artemisia and Chenopodiaceae, suggesting cold and dry environments during the Late Pleniglacial – Oldest Dryas (25903–15612 cal. yrs BP). Stands of Pinus and Quercus reflect warming/humidity increase during the melting pulses (19.2–14.5 cal. ka BP) and the Late Glacial interstadials Bølling and Allerød. The Younger Dryas (13257–11788 cal. yrs BP) coldest and driest environments are clearly demonstrated by the maximum relative abundance of Artemisia and Chenopodiaceae. During the Early Holocene (Preboreal and Boreal chronozones, 11788–8004 cal. yrs BP), Quercus appeared as a pioneer species and, along with other temperate deciduous arboreal taxa, formed open deciduous forests as a response to the increased temperature. The rapid expansion of these taxa indicates that they survived in Glacial refugia in the coastal mountains. During the Atlantic chronozone (8004–5483 cal. yrs BP), optimal climate conditions (high humidity and increased mean annual temperatures) stimulated the establishment of species-rich mixed temperate deciduous forests. During the Subboreal chronozone (5483–2837 cal. yrs BP), Carpinus betulus and Fagus expanded simultaneously and became more important components of mixed oak forests and probably also formed separate communities. During the Subatlantic chronozone (2837 cal. yrs BP to pre-industrial time), climate-driven changes (an increase of humidity and a cooling of the climate) appear to be the main drivers of the specific vegetation succession expressed by increased abundance of Alnus, Fraxinus excelsior and Salix along with lianas, suggesting formation of flooded riparian forests (so called ‘Longoz’) lining the river valleys along the Black Sea coast. The first indicators of farming and other human activities have been recorded since 7074 cal. yrs BP. The dinoflagellate cyst (dinocyst) assemblages have been analysed to assess the changes in the Black Sea environment over the last 26000 years in terms of fluctuation in paleoproduction and surface water conditions related to changes in climate, freshwater input and Mediterranean water intrusion. Two major dinocyst assemblages were distinguished: one dominated by stenohaline freshwater/brackish-water species and a successive one dominated by euryhaline marine species. The changes in the composition of the assemblages occurred at 7668 cal. yrs BP. The abrupt decrease of stenohaline freshwater/brackish-water species Pyxidinopsis psilata and Spiniferites cruciformis was followed upwards by a gradual increase in euryhaline marine species, such as Lingulodinium machaerophorum, Spiniferites belerius, S. bentorii and acritarch Cymatiosphaera globulosa. The first occurrence of euryhaline marine species took place synchronously with the onset of sapropel deposition. Modern marine conditions were established after 6417 cal yrs BP when an abundance of Mediterranean-related species, such as Operculodinium centrocarpum and Spiniferites mirabilis, along with other heterotrophic species, occurred. After the stable cold and dry environment during the Last Glacial Maximum, the phytoplankton record of core AKAD 11-17 shows that Pediastrum boryanum var. boryanum has a cyclical abundance associated with the deposition of four red-brown clay layers between 19.2 and 14.5 cal. ka BP. This event is associated with the major melting phase of European Ice drained by the Danube and Dnieper Rivers in response to climate warming observed after the end of the Last Glacial Maximum. During the Early Holocene, P. psilata, characterised by a preference to warmer temperatures, demonstrates its ecological optimum for growth concerning SST reaching maximum relative abundance of 94% between 11072 and 8638 cal. yrs BP. This maximum was interrupted by an abrupt significant short-term decrease in the relative abundance of P. psilata centred between 8500 and 8300 cal. yrs BP reflecting cold conditions similar to those of Younger Dryas. This finding, also confirmed by the rapid significant decrease of arboreal pollen, particularly of Quercus in the same studied core, is considered a regional expression of the well-known ‘8.2 ka cold event’ which is commonly linked to a meltwater-related perturbation of the Atlantic Meridional Overturning Circulation (AMOC) and associated collapse of oceanic northward heat transport. Our fossil pollen and dinocyst data confirm that the high amplitude temperature anomaly associated with ‘the 8.2 ka cold event’ may have also occurred in south-eastern Europe, at lower latitudes of the western Black Sea coastal area, most probably due to atmospheric transition and/or river discharge
52. Western Black Sea continental slope: continuous Late Pleniglacial to Subatlantic palaeovegetation record
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Multimedia Data Management � Characteristics
No full textData management lies at the heart of a multimedia information system. The spatial, temporal, storage, retrieval, integration and presentation requirements of multimedia data differ significantly from those for the traditional data. Hence, the goal of the multimedia data management system is to allow efficient storage, manipulation usin
The determinants of ethnic minority party formation and success in Europe
Full text linkWhy do some ethnic minority groups in Europe form political parties of their own in order to obtain political representation, whereas others choose to work within the confines of established, mainstream political parties? Further, why do some ethnic minority parties (EMPs) achieve electoral success, whereas others fail?
In addressing these questions, I incorporate insights from history and social psychology to develop an original theory of EMP emergence and success. I argue that an ethnic minority group’s historical background influences its political engagement strategies through sociopsychological processes. I propose that native groups (those that inhabited the territory of the modern-day state in which they reside prior to that state’s establishment) and groups with historical experiences of autonomous self-rule are more likely to form ethnic minority parties, and that EMPs formed by such groups are more likely to enjoy electoral success. I argue that groups possessing one or both of these characteristics are more likely to exhibit the traits of positive distinctiveness and shared grievances, contributing to the development of a salient collective political identity. Ultimately, groups that perceive themselves as native to their state and that have enjoyed autonomy are more likely to feel entitled to the unique form of representation provided by an ethnic minority party, and more likely to generate sufficient electoral support to sustain such a party. In contrast, groups lacking these traits are likely to either have non-politicized identities or to approach the political process from an individual, rather than collective, perspective. This makes them more prone to seek participation in established, mainstream political parties. In addition to this original theory, I consider existing theories regarding the role of the political opportunity structure and the role of international organizations such as the European Union.
I test my predictions with a mixed-methods approach combining a large-N, cross-national quantitative analysis with a detailed case study focusing on Bulgaria. The quantitative portion of my analysis uses an original dataset of European elections in the period 1990-2012. I test my predictions regarding the determinants of EMP entry and success using generalized linear mixed models, finding substantial support for the influence of the two historical variables. For the qualitative case study, I performed a month of field research, conducting semi-structured elite interviews with leading Bulgarian political figures with expertise in the country’s ethnic politics. I sought to determine why the country’s Turkish minority has produced one of the most successful ethnic parties in Europe, whereas the country’s Roma population remains without a notable political party. The case study confirms many of the findings of the quantitative analysis and allows a deeper exploration into the complex causal mechanisms behind EMP emergence and success.Item withdrawn by Laura Spradlin ([email protected]) on 2014-07-09T14:11:51Z
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How a feedback system enhances vendor reputation, mitigates product complexity and facilitates online purchase decision-making : insights from B2C transaction logs.
Full text linkDespite the growing population of Internet customers, purchasing online can still be a confusing and overwhelming activity. Perceived risk plays a crucial role in online buying decisions. The mechanism of online customer feedback has been identified to improve trust and to reduce risk in online marketplaces. Feedback from previous customers greatly builds online vendor reputation and establishes trust, which positively influence the intent to purchase. This study aims to find out how a feedback system enhances vendor reputation and can thereby be used to mitigate product complexity and facilitate online purchasing decisions in the B2C environment. The cooperation with a feedback company creates an experimental setting that allows a relationship between positive feedback, conversion rate, arbitrations and feedback submissions to be inferred. The access to real feedback and transaction data allows the investigation of actual risk perception and the need for risk evaluation. This study considers both the user’s and the vendor’s interaction with the feedback system.
Nelson’s (1970) product classification is used to divide product categories into different levels of product complexity. The study follows a positivist quantitative approach and applies deductive strategies and procedures to address the research objective. The author presents a number of hypotheses and has analysed data from 400 online stores that have implemented a feedback system. Transaction and feedback data were drawn from a feedback company database and have been analysed using linear regression and partial correlation.
The results of this research indicate that product complexity has an inevitable influence upon an online buying process. The greater the transaction value (average price) and the functional/technical complexity of the product (product complexity), the more the presence of feedback grows in importance. However, the aspect of trust, that emerged due to of the percentage of positive feedback by past customers, only influences sales of highly complex products, which means that product category matters with regard to the trust transference theory. The findings identified different risk types which corraborate the theory that risk is multi-faceted. Finally this study provides valuable insights about the vendor's strategic work with a feedback system.
The conclusions provide suggestions for online vendors as to how they can use online feedback systems as tools for dealing with the shortcomings associated with electronic commerce. It is important for vendors of complex products to invest in their reputation and to establish trust on the basis of feedback that is as positive as possible. By better understanding the relationships among positive reputation profiles and certain risk types (financial risk, product risk, physical risk, time risk), vendors may be able to take more appropriate actions in their efforts to make shopping online a less risky experience and motivate certain behaviour, such as purchasing. It is recommended that the vendor carries out proper complaint management in the form of arbitration procedures on negative feedback. A feedback system gives online vendors the advantage of protecting themselves against the negative opinions spread on the World Wide Web. The process of arbitrations enables vendors to show competence and has the ability to turn dissatified customers into satisfied customers. In order to enhance the online reputation, organisations should offer workshops on the efficacy of working with a feedback system and how to conduct arbitrations properly
Author Correction: The IDEAL framework for surgical robotics: development, comparative evaluation and long-term monitoring
No full textIn the version of the article initially published, three authors were missing from The IDEAL Robotics Colloquium. Art Sedrakyan (Weill Cornell Medical College, New York, NY, USA), Joel Horowitz (Maimonides Medical Center, New York, NY, USA) and Arsenio Paez (Centre de Recherche de l’Institut Universitaire de Gériatrie de Montréal (CRIUGM), Montreal, Quebec, Canada) have all been added in the HTML and PDF versions of the article.</p
