| 1. |
- Zhao, Jingcheng
(författare)
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Bloody big data : ensuring the health of blood donors and transfused patients with health registers
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Blood transfusion is widely considered a pillar of modern medicine and is one of the most common medical interventions. A transfusion intimately links two persons and their health through the altruism of blood donors. In turn, this has necessitated the development of rigorous safety measures for both donors and recipients. Hemovigilance is the systematic surveillance of adverse events in the entire blood supply chain, stretching from blood donation to transfusion and follow-up care. Although transfusion safety has dramatically improved in recent decades, especially in regard to transfusion-transmitted infections, there are still evidence gaps for many aspects of blood donation and transfusion safety. This thesis explores several aspects of current controversies in both blood donation and transfusion safety and proposes a ‘big-data’ approach to hemovigilance with the use of data from electronic healthcare records and health registers, and provides a data-driven method for calculating longitudinal transfusion costs. In Study I, we constructed a new nationwide research database that encompasses all electronically recorded blood donations, transfusions, blood donors, transfused patients, and persons with a blood typing result in Sweden. The database is the Swedish portion of the third iteration of the Scandinavian Donations and Transfusions (SCANDAT3-S) database and contains data spanning from 1968 to 2018 for more than 8 million persons, over 21 million transfusion records, and over 300 million laboratory results. This database is one of the largest and most comprehensive research databases for blood donation and transfusion research and served as the main data source for the other studies in this thesis. In Study II, we followed up on studies that have observed CD4+ T-cell counts below 200 cells/μl, a level typically indicating AIDS, among frequent platelet donors. This is believed to be caused by frequent leukocyte depletion through the use of widely-used instruments equipped with so-called Leukoreduction System (LRS) chambers. However, it is unknown if this leads to clinically relevant immunosuppression. We conducted a nationwide cohort study of 74,408 platelet and plasmapheresis donors between 1996 and 2017 and observed an increased, donation frequency-dependent hazard ratio (HR) for both immunosuppression-related and common bacterial infections. For a subcohort, we replicated an association between donation frequency and low CD4+ T-cell counts. Together, these findings suggest that frequent platelet donation utilizing the LRS chamber is associated with both T-cell lymphopenia and an increased risk of infections. In Study III, we aimed to investigate possible transfusion-transmission of cerebral amyloid angiopathy (CAA). CAA is an amyloid-β pathology that co-occurs with Alzheimer’s disease in 80% of cases and is a common cause of multiple spontaneous intracerebral hemorrhages (ICH). Previous studies have demonstrated human-to-human transmission of CAA through peripheral injection of contaminated cadaveric pituitary hormone, but it is unknown if it is transmissible by blood transfusions. Because CAA is rarely diagnosed routinely and would not be frequently registered in health registers, we instead studied possible transfusion-transmission of spontaneous ICH suggestive of CAA. In a binational cohort study of 1,089,370 red-cell recipients between 1970 and 2017, patients that received blood from a donor that subsequently developed multiple spontaneous ICH were associated with an increased hazard ratio for developing spontaneous ICH themselves. This was observed independently in both the Swedish (HR, 2.73; 95% confidence interval [CI], 1.72 to 4.35) and Danish cohort (HR, 2.32; 95% CI, 1.04 to 5.19), after adjusting for known confounders. This association was not observed for ischemic stroke, which is associated with many of the same risk factors as spontaneous ICH but not with CAA. These findings support possible transfusion-transmission of CAA, but other explanations should not be rejected without further mechanistic studies. In Study IV, we assessed if blood donor sex and parity affected the survival of adult patients transfused with red-cells. Antibodies produced during pregnancy in blood donors have been associated with transfusion-related acute lung injury in recipients and led to the use of predominantly male donor plasma, in some regions also platelets. However, data on red-cell transfusions have been contradictory. Some, but not all, observational studies have found increased mortality among recipients of female donors, parous donors, and sex-mismatched transfusions. We conducted a nationwide study of 368,778 adult patients transfused with red-cells between 2010 and 2018. We demonstrated that donor sex and parity were distributed as-if randomized and constituted a natural experiment. However, female blood donors had lower hemoglobin counts and their units were less efficacious, creating a phenomenon known as treatment-confounder feedback that causes bias in standard regression models. Using inverse probability weighting to mitigate bias due to treatment-confounder feedback, we exploited the natural experiment to emulate a randomized controlled trial. We found no difference in 2-year overall survival comparing transfusions from female to male donor red-cells only (-0.1%; 95% CI, -1.3 to 1.1%) and parous female to male donor red-cells only (0.3%; 95% CI, -0.6 to 1.2%), nor in any subgroup defined by patient sex and age. Comparatively lower hemoglobin counts among female donors is a previously unrecognized source of bias and may help explain the diverging results from previous studies. In Study V, we calculated longitudinal transfusion costs for patients with myelodysplastic syndromes (MDS) stratified by disease severity defined using the Revised International Prognostic Scoring System (IPSS-R). Transfusion costs included the acquisition cost of blood products, labor costs for nurses, cost for consumables, and costs for laboratory testing. We constructed algorithms to calculate cost based on incident data on blood transfusions and laboratory testing. These algorithms accounted for whether transfusions were administered in an inpatient or outpatient setting, that the first transfusion requires longer administration time than subsequent transfusions, needs for cross-matching, and high patient mortality. In 2018 US dollars, transfusion costs after 4 years ranged from $8805 (95% CI, $6482 to $11,625) in the very low IPSS-R category to $80,106 (95% CI, $61,460 to $95,792) in the very high IPSS-R category.
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| 2. |
- Zhao, Jinli, et al.
(författare)
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Cloud-Edge Collaboration-Based Local Voltage Control for DGs With Privacy Preservation
- 2023
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Ingår i: IEEE Transactions on Industrial Informatics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1551-3203 .- 1941-0050. ; 19:1, s. 98-108
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Tidskriftsartikel (refereegranskat)abstract
- The increased distributed generators (DGs) have exacerbated voltage violations in active distribution networks (ADNs). Local reactive power control of DG inverters can realize a fast response to frequent voltage fluctuations. However, commonly used model-based voltage control depends upon accurate network parameters and entire ADN data, which may cause the sensitive information leakage of ADN and DG behaviors in practical operation. In this article, a cloud-edge collaboration-based local voltage control strategy for DGs is proposed with privacy preservation. First, a local voltage control framework is established based on cloud-edge collaboration, in which a surrogate model is built based on the graph convolutional neural networks to estimate the ADN voltages. By transferring the surrogate model, the edge side can obtain the exact voltage estimation in the local curve tuning process without the authority of the whole ADN data, preserving the network parameters of ADN. Then, the interarea coordination based on federated learning is proposed to realize the parameter updating of DG control curves, which can achieve better voltage control performance. By updating surrogate submodels based on private data distributed across multiple edge devices, federated learning can effectively preserve DG behaviors. Finally, the effectiveness and adaptability of the proposed control strategy are validated using the modified IEEE 33-node system. The proposed local DG control strategy can effectively cope with voltage problems and enhance the adaptability to variations in practical operation states while considering privacy preservation.
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| 3. |
- Zhao, Jing, et al.
(författare)
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Detecting Adverse Drug Events Using Concept Hierarchies of Clinical Codes
- 2014
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Ingår i: 2014 IEEE International Conference on Healthcare Informatics. - : IEEE Computer Society. - 9781479957019 ; , s. 285-293
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Konferensbidrag (refereegranskat)abstract
- Electronic health records (EHRs) provide a potentially valuable source of information for pharmacovigilance. However, adverse drug events (ADEs), which can be encoded in EHRs with specific diagnosis codes, are heavily under-reported. To provide more accurate estimates for drug safety surveillance, machine learning systems that are able to detect ADEs could be used to identify and suggest missing ADE-specific diagnosis codes. A fundamental consideration when building such systems is how to represent the EHR data to allow for accurate predictive modeling. In this study, two types of clinical code are used to represent drugs and diagnoses: the Anatomical Therapeutic Chemical Classification System (ATC) and the International Statistical Classification of Diseases and Health Problems (ICD). More specifically, it is investigated whether their hierarchical structure can be exploited to improve predictive performance. The use of random forests with feature sets that include only the original, low-level, codes is compared to using random forests with feature sets that contain all levels in the hierarchies. An empirical investigation using thirty datasets with different ADE targets is presented, demonstrating that the predictive performance, in terms of accuracy and area under ROC curve, can be significantly improved by exploiting codes on all levels in the hierarchies, compared to using only the low-level encoding. A further analysis is presented in which two strategies are employed for adding features level-wise according to the concept hierarchies: top-down, starting with the highest abstraction levels, and bottom-up, starting with the most specific encoding. The main finding from this subsequent analysis is that predictive performance can be kept at a high level even without employing the more specific levels in the concept hierarchies.
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| 4. |
- Zhao, Jingcheng, et al.
(författare)
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Frequent platelet donation is associated with lymphopenia and risk of infections : A nationwide cohort study
- 2021
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Ingår i: Transfusion. - : John Wiley & Sons. - 0041-1132 .- 1537-2995. ; 61:2, s. 464-473
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Tidskriftsartikel (refereegranskat)abstract
- Background: Recently, plateletpheresis donations using a widely used leukoreduction system (LRS) chamber have been associated with T-cell lymphopenia. However, clinical health consequences of plateletpheresis-associated lymphopenia are still unknown.Study Design and Methods: A nationwide cohort study using the SCANDAT3-S database was conducted with all platelet- and plasmapheresis donors in Sweden between 1996 and 2017. A Cox proportional hazards model, using donations as time-dependent exposures, was used to assess the risk of infections associated with plateletpheresis donations using an LRS chamber.Results: A total of 74 408 apheresis donors were included. Among donors with the same donation frequency, plateletpheresis donors using an LRS chamber were at an increased risk of immunosuppression-related infections and common bacterial infections in a dose-dependent manner. While very frequent donors and infections were rare in absolute terms resulting in wide confidence intervals (CIs), the increased risk was significant starting at one-third or less of the allowed donation frequency in a 10-year exposure window, with hazard ratios reaching 10 or more. No plateletpheresis donors that used an LRS chamber experienced a Pneumocystis jirovecii, aspergillus, disseminated mycobacterial, or cryptococcal infection. In a subcohort (n = 42), donations with LRS were associated with low CD4+ T-cell counts (Pearson's R = -0.41; 95% CI, - 0.63 to -0.12).Conclusion: Frequent plateletpheresis donation using an LRS chamber was associated with CD4+ T-cell lymphopenia and an increased risk of infections. These findings suggest a need to monitor T-lymphocyte counts in frequent platelet donors and to conduct future investigations of long-term donor health and for regulators to consider steps to mitigate lymphodepletion in donors.
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| 5. |
- Bengtsson, Magdalena, 1967-
(författare)
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Det hotade barnet : Tre generationers spädbarns- och barnadödlighet i 1800-talets Linköping
- 1996
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study deals with the decline in infant and child mortality in Sweden during the 19th century. Around 1800 about a quarter of all children died before the age of one and 100 years later the proportion had been reduced to one tenth. The purpose of this study has been to investigate infant and child mortality in three birth cohorts, consisting of all children born in Linköping in the following periods: 1797-1810, 1840-49 and 1870-75. Mortality has been analysed with regard to age, sex, legitimacy and class. The main focus is upon certain family-specific factors, such as the survival of siblings, parental deprivation and spread of disease within the family.The results show that mortality in ages 0-4 markedly decreased from the first to the second cohort, while the situation had deteriorated in the third cohort, mainly due to an increase in epidemic diseases such as smallpox, scarlet fever and diphtheria. The improvement from cohort 1 to 2 was caused by reduced mortality in respiratory infections and sudden death. Mortality figures for those over five years of age were relatively stable throughout the cohorts. The mortality decline was earlier and more rapid in the upper middle class and was already evident in the first cohort. In the lower middle class and the working class mortality decreased from the first to the second cohort. Illegitimate infants experienced the highest mortality in all cohorts, although these children were better off if they had access to a social network, i.e. resided with grandparents or other relatives. Maternal care was important, a fact illustrated by increased mortality among infants who lost their mothers at an early age. Infants with surviving siblings showed much lower mortality than those with deceased siblings. This correlation was visible regardless of class or legitimacy.
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| 6. |
- Fu, Qilin, 1986-, et al.
(författare)
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Suppressing tool chatter with novel multi-layered nanostructures of carbon based composite coatings
- 2015
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 223, s. 292-298
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Tidskriftsartikel (refereegranskat)abstract
- Multi-layered nanostructured Cu and Cu-CNx composites synthesized by plasma-enhanced chemical vapour deposition were applied in the clamping area of a milling tool to suppress regenerative tool chatter. Scanning electron microscopy analysis showed a multi-layered nanostructure with excellent conformality, i.e. coating is not only uniform on planar surfaces but also around corners of the substrate. Cu:CuCNx nanostructured multilayers with thicknesses of approximately 0.5:1.6 mu m were obtained. With a diameter of 20 mm, the milling tool performed slotting processes at an overhang length of 120 mm. Modal analysis showed that a coating, with a thickness of approximately 300 mu m, can add sufficient damping without losing stiffness of the tool, to increase the critical stability limit by 50% or 100% depending on cutting direction.
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| 7. |
- Kajko-Mattsson, Mira Miroslawa, et al.
(författare)
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A model of predelivery problem management
- 2008
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Ingår i: IMECS 2008. - HONG KONG : INT ASSOC ENGINEERS-IAENG. - 9789889867188 ; , s. 976-981
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Konferensbidrag (refereegranskat)abstract
- Often, one connotes problem management with a postdelivery process for resolving problems within corrective maintenance. Very seldom, however, one relates it to the testing process within development, evolution and maintenance. In this paper, we propose a model of predelivery problem management. Using the model, we study the industrial status within eight companies situated in Greece. Our results show that all the organizations studied conduct a predelivery problem management process within system testing. However, only three out of eight companies perform it within central integration testing.
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| 8. |
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| 9. |
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| 10. |
- Lindberg, Fredrik, 1974, et al.
(författare)
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Observations and modelling of mosquito prevalence within urban areas – A case study from Uppsala, Sweden
- 2024
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Ingår i: Urban Ecosystems. - 1083-8155 .- 1573-1642.
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Tidskriftsartikel (refereegranskat)abstract
- Urban green–blue infrastructure (GBI) can provide important benefits to urban residents but may also affect mosquito abundance, with associated negative nuisance and infection transmission impacts. This study addresses important knowledge and quantification gaps for the relationships between mosquito prevalence and GBI features within cities. This is done for the city of Uppsala in Sweden as an urban case example, where mosquitos were captured and ambient air temperature and humidity were observed at seven different locations in the summer of 2022. A weighted multi-critera analysis (WMCA) model was developed based on relevant open data and open tools for resolving the mosquito (Culex pipiens) variations based on geographical variables, such as land cover/use, leaf area index, and building and green (vegetation) area fractions, within the city. The results show a clear relationship between mosquito prevalence and green-area fraction (of grass and trees), indicating that urban GBI extension can enhance mosquito prevalence, with possible associated negative impacts. This relationship is supported directly by data, showing significantly higher mosquito prevalence with higher ambient humidity, which in turn is related to larger green-area fraction. The developed WMCA model emerges as a promising tool, e.g., for urban development planning that needs to account for and seek relevant trade-off balances between positive and negative effects of urban GBI changes.
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