399 research outputs found

    Compact Inverses of The Multipoint Normal Diferential Operators For First Order

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    In this work, firstly all normal extensions of a multipoint minimal operator generated by linear multipoint diferential-operator expression for first order in the Hilbert space of vector functions in terms of boundary values at the endpoints of the infinitely many separated subintervals are described. Finally, a compactness properties of the inverses of such extensions has been investigated.Comment: 9 page

    Spectrum of the Direct Sum of Operators

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    In this work, a connection between some spectral properties of direct sum of operators in the direct sum of Hilbert spaces and its coordinate operators has been investigated.Comment: 10 page

    Explaining Exchange Rate Forecasts with Macroeconomic Fundamentals Using Interpretive Machine Learning

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    The complexity and ambiguity of financial and economic systems, along with frequent changes in the economic environment, have made it difficult to make precise predictions that are supported by theory-consistent explanations. Interpreting the prediction models used for forecasting important macroeconomic indicators is highly valuable for understanding relations among different factors, increasing trust towards the prediction models, and making predictions more actionable. In this study, we develop a fundamental-based model for the Canadian-U.S. dollar exchange rate within an interpretative framework. We propose a comprehensive approach using machine learning to predict the exchange rate and employ interpretability methods to accurately analyze the relationships among macroeconomic variables. Moreover, we implement an ablation study based on the output of the interpretations to improve the predictive accuracy of the models. Our empirical results show that crude oil, as Canada's main commodity export, is the leading factor that determines the exchange rate dynamics with time-varying effects. The changes in the sign and magnitude of the contributions of crude oil to the exchange rate are consistent with significant events in the commodity and energy markets and the evolution of the crude oil trend in Canada. Gold and the TSX stock index are found to be the second and third most important variables that influence the exchange rate. Accordingly, this analysis provides trustworthy and practical insights for policymakers and economists and accurate knowledge about the predictive model's decisions, which are supported by theoretical considerations

    Effect of Aging Treatment on Surface Roughness, Mechanical Properties, and Fracture Behavior of 6xxx and 7xxx Aluminum Alloys

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    The effect of aging treatment on the surface roughness and mechanical properties of AA6061 and AA7075 alloys was studied. Microhardness and tensile tests were used to investigae the mechanical properties. X-ray diffraction analysis was used to investigate the surface of the specimens. Furthermore, after tensile tests fractured surfaces were examined with scanning electron microscopy. An atomic force microscope was employed for analysis of the effect of aging treatment on surface roughness. Higher surface roughness with an increase in the volume fraction of the precipitate was revealed.Исследовано влияние процесса старения на шероховатость поверхности и механические свойства алюминиевых сплавов AA6061 и AA7075. Механические свойства исследовали при испытаниях на микротвердость и растяжение. Поверхность образцов исследовали с помощью рентгеноструктурного анализа. После испытания на растяжение поверхность разрушения исследовали методом растровой электронной микроскопии. Влияние процесса старения на шероховатость поверхности изучали с помощью атомно-силового микроскопа. Показано, что с ростом шероховатости поверхности увеличивается количество выделившихся фаз.Досліджено вплив процесу старіння на шорсткість поверхні і механічні властивості алюмінієвих сплавів АА6061 та АА7075. Механічні властивості досліджували при випробуваннях на мікротвердість і розтяг. Поверхню зразків досліджували за допомогою рентгеноструктурного аналізу. Після випробувань на розтяг поверхню руйнування досліджували методом растрової електронної мікроскопії. Вплив процесу старіння на шорсткість поверхні вивчали за допомогою атомно-силового мікроскопа. Показано, що з ростом шорсткості поверхні збільшується кількість виділених фа

    A gossypiboma (foreign body granuloma) mimicking a residual odontogenic cyst in the mandible: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Gossypiboma (foreign body granuloma) in the tooth socket as a complication of tooth removal is rare. Several cases of gossypiboma have been reported after orthopedic, abdominal, otorhinolaryngology, or plastic surgery, but there has been only one reported case after oral surgery.</p> <p>Case presentation</p> <p>A 42-year-old Caucasian German-speaking Swiss woman applied to our clinic for removal of her right mandibular first molar. Her right mandibular third molar had been removed seven years ago. Post-operatively, she complained of pain and foreign body sensation for six months in the area of the removed tooth. A panoramic radiograph of our patient showed a defined and oval radiolucent area in the socket of the right mandibular third molar evoking a residual cyst. An operation was planned to remove the cyst-like lesion. During surgery, a foreign body composed of gauze was found in the right mandibular third molar region. The histological findings were compatible with a foreign body reaction around gauze.</p> <p>Conclusion</p> <p>Retained gauze must be considered if patients complain of pain and foreign body sensation after tooth removal. The use of gauze with radio-opaque markers and extensive irrigation of the socket with saline to remove gauze fragments can avoid this mishap.</p

    Source apportionment of fine particulate matter in Houston, Texas: insights to secondary organic aerosols

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    Online and offline measurements of ambient particulate matter (PM) near the urban and industrial Houston Ship Channel in Houston, Texas, USA, during May 2015 were utilized to characterize its chemical composition and to evaluate the relative contributions of primary, secondary, biogenic, and anthropogenic sources. Aerosol mass spectrometry (AMS) on nonrefractory PM1 (PM  ≤  1&thinsp;µm) indicated major contributions from sulfate (averaging 50&thinsp;% by mass), organic aerosol (OA, 40&thinsp;%), and ammonium (14&thinsp;%). Positive matrix factorization (PMF) of AMS data categorized OA on average as 22&thinsp;% hydrocarbon-like organic aerosol (HOA), 29&thinsp;% cooking-influenced less-oxidized oxygenated organic aerosol (CI-LO-OOA), and 48&thinsp;% more-oxidized oxygenated organic aerosol (MO-OOA), with the latter two sources indicative of secondary organic aerosol (SOA). Chemical analysis of PM2.5 (PM  ≤  2.5&thinsp;µm) filter samples agreed that organic matter (35&thinsp;%) and sulfate (21&thinsp;%) were the most abundant components. Organic speciation of PM2.5 organic carbon (OC) focused on molecular markers of primary sources and SOA tracers derived from biogenic and anthropogenic volatile organic compounds (VOCs). The sources of PM2.5 OC were estimated using molecular marker-based positive matric factorization (MM-PMF) and chemical mass balance (CMB) models. MM-PMF resolved nine factors that were identified as diesel engines (11.5&thinsp;%), gasoline engines (24.3&thinsp;%), nontailpipe vehicle emissions (11.1&thinsp;%), ship emissions (2.2&thinsp;%), cooking (1.0&thinsp;%), biomass burning (BB, 10.6&thinsp;%), isoprene SOA (11.0&thinsp;%), high-NOx anthropogenic SOA (6.6&thinsp;%), and low-NOx anthropogenic SOA (21.7&thinsp;%). Using available source profiles, CMB apportioned 41&thinsp;% of OC to primary fossil sources (gasoline engines, diesel engines, and ship emissions), 5&thinsp;% to BB, 15&thinsp;% to SOA (including 7.4&thinsp;% biogenic and 7.6&thinsp;% anthropogenic), and 39&thinsp;% to other sources that were not included in the model and are expected to be secondary.This study presents the first application of in situ AMS-PMF, MM-PMF, and CMB for OC source apportionment and the integration of these methods to evaluate the relative roles of biogenic, anthropogenic, and BB-SOA. The three source apportionment models agreed that  ∼ &thinsp;50&thinsp;% of OC is associated with primary emissions from fossil fuel use, particularly motor vehicles. Differences among the models reflect their ability to resolve sources based upon the input chemical measurements, with molecular marker-based methods providing greater source specificity and resolution for minor sources. By combining results from MM-PMF and CMB, BB was estimated to contribute 11&thinsp;% of OC, with 5&thinsp;% primary emissions and 6&thinsp;% BB-SOA. SOA was dominantly anthropogenic (28&thinsp;%) rather than biogenic (11&thinsp;%) or BB-derived. The three-model approach demonstrates significant contributions of anthropogenic SOA to fine PM. More broadly, the findings and methodologies presented herein can be used to advance local and regional understanding of anthropogenic contributions to SOA.</p

    Crimean-Congo hemorrhagic fever: epidemiological trends and controversies in treatment

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    Crimean-Congo hemorrhagic fever (CCHF) virus has the widest geographic range of all tick-borne viruses and is endemic in more than 30 countries in Eurasia and Africa. Over the past decade, new foci have emerged or re-emerged in the Balkans and neighboring areas. Here we discuss the factors influencing CCHF incidence and focus on the main issue of the use of ribavirin for treating this infection. Given the dynamics of CCHF emergence in the past decade, development of new anti-viral drugs and a vaccine is urgently needed to treat and prevent this acute, life-threatening disease

    Measuring Financial Stress and Economic Sensitivity in CEE Countries

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    This report presents the methodology for the construction of the Financial Stress Index (FSI) and the Economic Sensitivity Index (ESI) and investigates the economic situation in twelve Central and East European Countries (CEECs) between 2001 and 2012. The objective of this paper is to capture key features of financial and economic vulnerability and examine the co-movement of economic turmoil and financial disturbances that strongly affected the CEECs in the last decade. Our main finding is that the FSI can be used as a leading indicator and can be used to recognize changing trends in the index. A shift in the value of the index proves that EU accession has a positive, but minor influence on financial stability in the CEECs. On the other hand, the impact of the introduction of the euro in Estonia, Slovakia and Slovenia is ambiguous. For most of the countries in our sample, in 2007, the FSI started to grow rapidly, reaching its peak around the third quarter of 2008. Consequently, financial stress remained high for a few quarters and started to fall gradually. For a number of countries, we observe higher financial stress in the latest period of our analysis, i.e. 2010-2012. However, the value of the FSI was significantly lower than three years earlier. The results show that indices might be helpful in predicting future recessions. However, forecasting properties seem to be limited at this stage of our work

    What is the recovery rate and risk of long-term consequences following a diagnosis of COVID-19?:A harmonised, global longitudinal observational study protocol

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    Introduction: Very little is known about possible clinical sequelae that may persist after resolution of acute COVID-19. A recent longitudinal cohort from Italy including 143 patients followed up after hospitalisation with COVID-19 reported that 87% had at least one ongoing symptom at 60-day follow-up. Early indications suggest that patients with COVID-19 may need even more psychological support than typical intensive care unit patients. The assessment of risk factors for longer term consequences requires a longitudinal study linked to data on pre-existing conditions and care received during the acute phase of illness. The primary aim of this study is to characterise physical and psychosocial sequelae in patients post-COVID-19 hospital discharge. Methods and analysis: This is an international open-access prospective, observational multisite study. This protocol is linked with the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) and the WHO’s Clinical Characterisation Protocol, which includes patients with suspected or confirmed COVID-19 during hospitalisation. This protocol will follow-up a subset of patients with confirmed COVID-19 using standardised surveys to measure longer term physical and psychosocial sequelae. The data will be linked with the acute phase data. Statistical analyses will be undertaken to characterise groups most likely to be affected by sequelae of COVID-19. The open-access follow-up survey can be used as a data collection tool by other follow-up studies, to facilitate data harmonisation and to identify subsets of patients for further in-depth follow-up. The outcomes of this study will inform strategies to prevent long-term consequences; inform clinical management, interventional studies, rehabilitation and public health management to reduce overall morbidity; and improve long-term outcomes of COVID-19. Ethics and dissemination: The protocol and survey are open access to enable low-resourced sites to join the study to facilitate global standardised, longitudinal data collection. Ethical approval has been given by sites in Colombia, Ghana, Italy, Norway, Russia, the UK and South Africa. New sites are welcome to join this collaborative study at any time. Sites interested in adopting the protocol as it is or in an adapted version are responsible for ensuring that local sponsorship and ethical approvals in place as appropriate. The tools are available on the ISARIC website (www.isaric.org)
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