38 resultados para Topic hotness evaluation

em Helda - Digital Repository of University of Helsinki


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Financing trade between economic agents located in different countries is affected by many types of risks, resulting from incomplete information about the debtor, the problems of enforcing international contracts, or the prevalence of political and financial crises. Trade is important for economic development and the availability of trade finance is essential, especially for developing countries. Relatively few studies treat the topic of political risk, particularly in the context of international lending. This thesis explores new ground to identify links between political risk and international debt defaults. The core hypothesis of the study is that the default probability of debt increases with increasing political risk in the country of the borrower. The thesis consists of three essays that support the hypothesis from different angles of the credit evaluation process. The first essay takes the point of view of an international lender assessing the credit risk of a public borrower. The second investigates creditworthiness assessment of companies. The obtained results are substantiated in the third essay that deals with an extensive political risk survey among finance professionals in developing countries. The financial instruments of core interest are export credit guaranteed debt initiated between the Export Credit Agency of Finland and buyers in 145 countries between 1975 and 2006. Default events of the foreign credit counterparts are conditioned on country-specific macroeconomic variables, corporate-specific accounting information as well as political risk indicators from various international sources. Essay 1 examines debt issued to government controlled institutions and conditions public default events on traditional macroeconomic fundamentals, in addition to selected political and institutional risk factors. Confirming previous research, the study finds country indebtedness and the GDP growth rate to be significant indicators of public default. Further, it is shown that public defaults respond to various political risk factors. However, the impact of the risk varies between countries at different stages of economic development. Essay 2 proceeds by investigating political risk factors as conveivable drivers of corporate default and uses traditional accounting variables together with new political risk indicators in the credit evaluation of private debtors. The study finds links between corporate default and leverage, as well as between corporate default and the general investment climate and measeures of conflict in the debtor country. Essay 3 concludes the thesis by offering survey evidence on the impact of political risk on debt default, as perceived and experienced by 103 finance professionals in 38 developing countries. Taken together, the results of the thesis suggest that various forms of political risk are associated with international debt defaults and continue to pose great concerns for both international creditors and borrowers in developing countries. The study provides new insights on the importance of variable selection in country risk analysis, and shows how political risk is actually perceived and experienced in the riskier, often lower income countries of the global economy.

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In the future the number of the disabled drivers requiring a special evaluation of their driving ability will increase due to the ageing population, as well as the progress of adaptive technology. This places pressure on the development of the driving evaluation system. Despite quite intensive research there is still no consensus concerning what is the factual situation in a driver evaluation (methodology), which measures should be included in an evaluation (methods), and how an evaluation has to be carried out (practise). In order to find answers to these questions we carried out empirical studies, and simultaneously elaborated upon a conceptual model for driving and a driving evaluation. The findings of empirical studies can be condensed into the following points: 1) A driving ability defined by the on-road driving test is associated with different laboratory measures depending on the study groups. Faults in the laboratory tests predicted faults in the on-road driving test in the novice group, whereas slowness in the laboratory predicted driving faults in the experienced drivers group. 2) The Parkinson study clearly showed that even an experienced clinician cannot reliably accomplish an evaluation of a disabled person’s driving ability without collaboration with other specialists. 3) The main finding of the stroke study was that the use of a multidisciplinary team as a source of information harmonises the specialists’ evaluations. 4) The patient studies demonstrated that the disabled persons themselves, as well as their spouses, are as a rule not reliable evaluators. 5) From the safety point of view, perceptible operations with the control devices are not crucial, but correct mental actions which the driver carries out with the help of the control devices are of greatest importance. 6) Personality factors including higher-order needs and motives, attitudes and a degree of self-awareness, particularly a sense of illness, are decisive when evaluating a disabled person’s driving ability. Personality is also the main source of resources concerning compensations for lower-order physical deficiencies and restrictions. From work with the conceptual model we drew the following methodological conclusions: First, the driver has to be considered as a holistic subject of the activity, as a multilevel hierarchically organised system of an organism, a temperament, an individuality, and a personality where the personality is the leading subsystem from the standpoint of safety. Second, driving as a human form of a sociopractical activity, is also a hierarchically organised dynamic system. Third, in an evaluation of driving ability it is a question of matching these two hierarchically organised structures: a subject of an activity and a proper activity. Fourth, an evaluation has to be person centred but not disease-, function- or method centred. On the basis of our study a multidisciplinary team (practitioner, driving school teacher, psychologist, occupational therapist) is recommended for use in demanding driver evaluations. Primary in a driver’s evaluations is a coherent conceptual model while concrete methods of evaluations may vary. However, the on-road test must always be performed if possible.

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This study examined the fundamental question of what really matters when selecting a new employee. The study focused on tacit knowledge used by personnel recruiters when interviewing employees. Knowledge was defined as the best view available, which helps one not to act haphazardly. Tacit knowledge was also defined as a positive concept, and it was seen as a part of personnel recruiters` improving proficiency. The research topic was chosen based on the observed increase in the amount of employment interviews and their importance in society. As recruiting is becoming a more distinct profession, it was reasonable to approach the topic from an educational point of view. The following research problems guided the examination of the phenomenon: 1) Where does the interviewer seek tacit knowledge from during the employment interview? 2) How is tacit knowledge achieved during the employment interview? 3) How does the interviewer defend the significance of the tacit knowledge gained as knowledge that has influence on the selection decision? The research data was collected by interviewing six personnel recruiters who conduct and evaluate employment interviews as part of their work responsibilities. The interview themes were linked to some recently made selection decision in each organization and the preceding employment interview with the selected candidate. In order to conceptualize tacit knowledge, reflective consideration of the interview event was used in the study. The lettered research data was analyzed inductively. As a result of the study, the objects of tacit knowledge in the context of an employment interview culminated into three areas: the applicant s verbal communication, the applicant s non-verbal communication and the interaction between interview participants. Observations directed toward those objects were shown to be intentional and three schemes were found behind them: experiences from previous interviews, applicant s application papers and the aptitude for the work responsibilities. The question of gaining knowledge was answered with the concept of procedural knowledge. Personnel recruiters were found to have four different, but interconnected ways to encounter knowledge during an employment interview: understanding, evaluative, revealing, and approving knowing. In order to explain the importance given to tacit knowledge, it was examined in connection with the most prevalent practices in the personnel selection industry. The significance of knowledge as the kind of knowledge that has an impact on the decision was supported by references to collective opinion (other people agree with it), circumstance (interview s short duration), or using some instrument (structured interview). The study revealed new aspects of employment selection process through examining tacit knowledge. The characteristics of the inductive analysis of the research data may also be utilized, when applicable, in tacit knowledge research within other contexts.

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Positron emission tomography (PET) is an imaging technique in which radioactive positron-emitting tracers are used to study biochemical and physiological functions in humans and in animal experiments. The use of PET imaging has increased rapidly in recent years, as have special requirements in the fields of neurology and oncology for the development of syntheses for new, more specific and selective radiotracers. Synthesis development and automation are necessary when high amounts of radioactivity are needed for multiple PET studies. In addition, preclinical studies using experimental animal models are necessary for evaluating the suitability of new PET tracers for humans. For purification and analysing the labelled end-product, an effective radioanalytical method combined with an optimal radioactivity detection technique is of great importance. In this study, a fluorine-18 labelling synthesis method for two tracers was developed and optimized, and the usefulness of these tracers for possible prospective human studies was evaluated. N-(3-[18F]fluoropropyl)-2β-carbomethoxy-3β-(4-fluorophenyl)nortropane ([18F]β-CFT-FP) is a candidate PET tracer for the dopamine transporter (DAT), and 1H-1-(3-[18F]fluoro-2-hydroxypropyl)-2-nitroimidazole ([18F]FMISO) is a well-known hypoxia marker for hypoxic but viable cells in tumours. The methodological aim of this thesis was to evaluate the status of thin-layer chromatography (TLC) combined with proper radioactivity detection measurement systems as a radioanalytical method. Three different detection methods of radioactivity were compared: radioactivity scanning, film autoradiography, and digital photostimulated luminescence (PSL) autoradiography. The fluorine-18 labelling synthesis for [18F]β-CFT-FP was developed and carbon-11 labelled [11C]β-CFT-FP was used to study the specificity of β-CFT-FP for the DAT sites in human post-mortem brain slices. These in vitro studies showed that β-CFT-FP binds to the caudate-putamen, an area rich of DAT. The synthesis of fluorine-18 labelled [18F]FMISO was optimized, and the tracer was prepared using an automated system with good and reproducible yields. In preclinical studies, the action of the radiation sensitizer estramustine phosphate on the radiation treatment and uptake of [18F]FMISO was evaluated, with results of great importance for later human studies. The methodological part of this thesis showed that radioTLC is the method of choice when combined with an appropriate radioactivity detection technique. Digital PSL autoradiography proved to be the most appropriate when compared to the radioactivity scanning and film autoradiography methods. The very high sensitivity, good resolution, and wide dynamic range of digital PSL autoradiography are its advantages in detection of β-emitting radiolabelled substances.

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Topic detection and tracking (TDT) is an area of information retrieval research the focus of which revolves around news events. The problems TDT deals with relate to segmenting news text into cohesive stories, detecting something new, previously unreported, tracking the development of a previously reported event, and grouping together news that discuss the same event. The performance of the traditional information retrieval techniques based on full-text similarity has remained inadequate for online production systems. It has been difficult to make the distinction between same and similar events. In this work, we explore ways of representing and comparing news documents in order to detect new events and track their development. First, however, we put forward a conceptual analysis of the notions of topic and event. The purpose is to clarify the terminology and align it with the process of news-making and the tradition of story-telling. Second, we present a framework for document similarity that is based on semantic classes, i.e., groups of words with similar meaning. We adopt people, organizations, and locations as semantic classes in addition to general terms. As each semantic class can be assigned its own similarity measure, document similarity can make use of ontologies, e.g., geographical taxonomies. The documents are compared class-wise, and the outcome is a weighted combination of class-wise similarities. Third, we incorporate temporal information into document similarity. We formalize the natural language temporal expressions occurring in the text, and use them to anchor the rest of the terms onto the time-line. Upon comparing documents for event-based similarity, we look not only at matching terms, but also how near their anchors are on the time-line. Fourth, we experiment with an adaptive variant of the semantic class similarity system. The news reflect changes in the real world, and in order to keep up, the system has to change its behavior based on the contents of the news stream. We put forward two strategies for rebuilding the topic representations and report experiment results. We run experiments with three annotated TDT corpora. The use of semantic classes increased the effectiveness of topic tracking by 10-30\% depending on the experimental setup. The gain in spotting new events remained lower, around 3-4\%. The anchoring the text to a time-line based on the temporal expressions gave a further 10\% increase the effectiveness of topic tracking. The gains in detecting new events, again, remained smaller. The adaptive systems did not improve the tracking results.

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During the last 10-15 years interest in mouse behavioural analysis has evolved considerably. The driving force is development in molecular biological techniques that allow manipulation of the mouse genome by changing the expression of genes. Therefore, with some limitations it is possible to study how genes participate in regulation of physiological functions and to create models explaining genetic contribution to various pathological conditions. The first aim of our study was to establish a framework for behavioural phenotyping of genetically modified mice. We established comprehensive battery of tests for the initial screening of mutant mice. These included tests for exploratory and locomotor activity, emotional behaviour, sensory functions, and cognitive performance. Our interest was in the behavioural patterns of common background strains used for genetic manipulations in mice. Additionally we studied the behavioural effect of sex differences, test history, and individual housing. Our findings highlight the importance of careful consideration of genetic background for analysis of mutant mice. It was evident that some backgrounds may mask or modify the behavioural phenotype of mutants and thereby lead to false positive or negative findings. Moreover, there is no universal strain that is equally suitable for all tests, and using different backgrounds allows one to address possible phenotype modifying factors. We discovered that previous experience affected performance in several tasks. The most sensitive traits were the exploratory and emotional behaviour, as well as motor and nociceptive functions. Therefore, it may be essential to repeat some of the tests in naïve animals for assuring the phenotype. Social isolation for a long time period had strong effects on exploratory behaviour, but also on learning and memory. All experiments revealed significant interactions between strain and environmental factors (test history or housing condition) indicating genotype-dependent effects of environmental manipulations. Several mutant line analyses utilize this information. For example, we studied mice overexpressing as well as those lacking extracellular matrix protein heparin-binding growth-associated molecule (HB-GAM), and mice lacking N-syndecan (a receptor for HB-GAM). All mutant mice appeared to be fertile and healthy, without any apparent neurological or sensory defects. The lack of HB-GAM and N-syndecan, however, significantly reduced the learning capacity of the mice. On the other hand, overexpression of HB-GAM resulted in facilitated learning. Moreover, HB-GAM knockout mice displayed higher anxiety-like behaviour, whereas anxiety was reduced in HB-GAM overexpressing mice. Changes in hippocampal plasticity accompanied the behavioural phenotypes. We conclude that HB-GAM and N-syndecan are involved in the modulation of synaptic plasticity in hippocampus and play a role in regulation of anxiety- and learning-related behaviour.

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High quality of platelet analytics requires specialized knowledge and skills. It was applied to analyze platelet activation and aggregation responses in a prospective controlled study of patients with Finnish type of amyloidosis. The 20 patients with AGel amyloidosis displayed a delayed and more profound platelet shape change than healthy siblings and healthy volunteers, which may be related to altered fragmentation of mutated gelsolin during platelet activation. Alterations in platelet shape change have not been reported in association with platelet disorders. In the rare Bernard-Soulier syndrome with Asn45Ser mutation of glycoprotein (GP) IX, the diagnostic defect in the expression of GPIb-IX-V complex was characterized in seven Finnish patients, also an internationally exceptionally large patient series. When measuring thrombopoietin in serial samples of amniotic fluid and cord blood of 15 pregnant women with confirmed or suspected fetal alloimmune thrombocytopenia, the lower limit of detection could be extended. The results approved that thrombopoietin is present already in amniotic fluid. The application of various non-invasive means for diagnosing thrombocytopenia (TP) revealed that techniques for estimating the proportion of young, i.e. large platelets, such as direct measurement of reticulated platelets and the mean platelet size, would be useful for evaluating platelet kinetics in a given patient. Due to different kinetics between thrombopoietin and increase of young platelets in circulation, these measurements may have most predictive value when measured from simultaneous samples. Platelet autoantibodies were present not only in isolated autoimmune TP but also in patients without TP where disappearance of platelets might be compensated by increased production. The autoantibodies may also persist after TP has been cured. Simultaneous demonstration of increased young platelets (or increased mean platelet volume) in peripheral blood and the presence of platelet associated IgG specificities to major glycoproteins (GPIb-IX and GPIIb-IIIa) may be considered diagnostic for autoimmune TP. Measurement of a soluble marker as a sign of thrombin activation and proceeding deterioration of platelet components was applied to analyze the alterations under several stress factors (storage, transportation and lack of continuous shaking under controlled conditions) of platelet products. The GPV measured as a soluble factor in platelet storage medium showed good correlation with an array of other measurements commonly applied in characterization of stored platelets. The benefits of measuring soluble analyte in a quantitative assay were evident.

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For optimal treatment planning, a thorough assessment of the metastatic status of mucosal squamous cell carcinoma of the head and neck (HNSCC) is required. Current imaging methods do not allow the recognition of all patients with metastatic disease. Therefore, elective treatment of the cervical lymph nodes is usually given to patients in whom the risk of subclinical metastasis is estimated to exceed 15-20%. The objective of this study was to improve the pre-treatment evaluation of patients diagnosed with HNSCC. Particularly, we aimed at improving the identification of patients who will benefit from elective neck treatment. Computed tomography (CT) of the chest and abdomen was performed prospectively for 100 patients diagnosed with HNSCC. The findings were analysed to clarify the indications for this examination in this patient group. CT of the chest influenced the treatment approach in 3% of patients, while CT of the abdomen did not reveal any significant findings. Our results suggest that CT of the chest and abdomen is not indicated routinely for patients with newly diagnosed HNSCC but can be considered in selected cases. Retrospective analysis of 80 patients treated for early stage squamous cell carcinoma of the oral tongue was performed to investigate the potential benefits of elective neck treatment and to examine whether histopathological features of the primary tumour could be used in the prediction of occult metastases, local recurrence, or/and poor survival. Patients who had received elective neck treatment had significantly fewer cervical recurrences during the follow-up when compared to those who only had close observation of the cervical lymph nodes. Elective neck treatment did not result in survival benefit, however. Of the histopathological parameters examined, depth of infiltration and pT-category (representing tumour diameter) predicted occult cervical metastasis, but only the pT-category predicted local recurrence. Depth of infiltration can be used in the identification of at risk patients but no clear cut-off value separating high-risk and low-risk patients was found. None of the histopathological parameters examined predicted survival. Sentinel lymph node (SLN) biopsy was studied as a means of diagnosing patients with subclinical cervical metastases. SLN biopsy was applied to 46 patients who underwent elective neck dissection for oral squamous cell carcinoma. In addition, SLN biopsy was applied to 13 patients with small oral cavity tumours who were not intended to undergo elective neck dissection because of low risk of occult metastasis. The sensitivity of SLN biopsy for finding subclinical cervical metastases was found to be 67%, when SLN status was compared to the metastatic status of the rest of the neck dissection specimen. Of the patients not planned to have elective neck dissection, SLN biopsy revealed cervical metastasis in 15% of the patients. Our results suggest that SLN biopsy can not yet entirely replace elective neck dissection in the treatment of oral cancer, but it seems beneficial for patients with low risk of metastasis who are not intended for elective neck treatment according to current treatment protocols.