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| 14. |
- Ahlström, Björn
(författare)
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The epidemiology of risk factors and short and long-term outcome in the Swedish intensive care cohort
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dissertation presented at Uppsala University to be publicly examined on Zoom: https://uu-se.zoom.us/j/7214327760, Tuesday, 11 May 2021 at 13:00 for the degree of Licentiate of Philosophy (Faculty of Medicine). The examination will be conducted in English and Swedish. Chairman of the Examining committee: Professor Karl Michaëlsson (Medical epidemiology, Department of Surgical Sciences, Uppsala University, Uppsala) Abstract Ahlström, B. 2021. The epidemiology of risk factors and short- and long-term out-come in the Swedish intensive care cohort. 76 pp. Severe sepsis and septic shock, linked to persistent organ dysfunctions, have poor short- and long-term mortality outcomes. These conditions also adversely affect health-related quality of life. After intensive care with severe sepsis and septic shock, memory and other cognitive functions have shown deterioration. In addition, there are indications of an increased risk of dementia. Yet, whether severe sepsis and septic shock are independently linked to dementia or dementia development is linked to more general severe illness remains unclear. In the Swedish intensive care cohort we compared 16 115 one-year sepsis survivors without previous dementia to 194 219 patients (controls) admitted to intensive care for other reasons using a Cox proportional hazards model. The crude risk of dementia was increased in the severe sepsis and septic shock group. However, after adjustment for demographics, comorbidities and factors reflecting the severity of acute illness, severe sepsis and septic shock was found not to be a significant risk factor of incident dementia with a haz-ard ratio of 1.01 (95% confidence interval 0.91-1.11). Thus, we concluded that although the incidence of dementia is high after intensive care, severe sepsis or septic shock is not causative. Coronavirus disease 2019 (COVID-19) has put a tremendous strain on the healthcare system in general and intensive care, in particular, since its emergence in Wuhan, China, in late 2019. Risk factors of ICU admission and mortality from COVID-19 were reported early during the pandemic, but only as univariate variables. Under the hypothesis that there are several independent risk factors of critical COVID-19, we used statistical models to explore demographic characteristics and comorbidi-ties in the first 1 981 ICU-admitted patients with COVID-19 in Sweden. On the risk of ICU admission, we also included matched population controls in a 1:4 ratio. Hypertension, type 2 diabetes mellitus, chronic renal failure, asthma, obesity, solid organ transplant recipient and immunosuppressant medications were independent risk factors of ICU admission. Oral anticoagulants were associated with a protective effect. Stroke, asthma, chronic obstructive pulmonary disease and treatment with renin-angiotensin-aldosterone inhibitors were independent risk factors of ICU mortality. Treatment with statins was protective. Our findings suggest that there are several independent risk factors of ICU admission and ICU mortality in COVID-19.Björn Ahlström, Department of Surgical Sciences, Anaesthesiology and Intensive Care, Uppsala University, SE-75185 Uppsala, Sweden and Centre of clinical research, Region Dalarna, SE-79182 Falun, Sweden.
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| 15. |
- Ahmad, Noor Azlinda
(författare)
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Broadband and HF radiation from cloud flashes and narrow bipolar pulses
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Remote measurement of electric field generated by lightning has played a major role in understanding the lightning phenomenon. Even though other measurements such as optical, photographic, channel base current and thunder signatures have contributed in this regards, due to practical reasons remote measurements of electric field is considered as the most useful tool in lightning research. This thesis discussed about the remotely measured radiation field component of electric field generated by cloud flashes (ICs) and narrow bipolar pulses (NBPs). The associated HF radiation of these events at 3 MHz and 30 MHz were also discussed. To understand the initiation process of these discharges, a comparative study of the initial pulse of cloud flashes with the initial pulse of cloud to ground flashes was conducted. The result suggests that both discharges might have been initiated by similar physical process inside the thunderclouds. Comparing the features of initial pulse of cloud and ground flashes with that of pulses appeared in the later stages of cloud flashes suggests that the initiation process involved in both flashes are not very much differ from the initiation of cloud flashes at the later stage. The average spectral amplitudes of electric field for first 120 ms of cloud flashes showed f-1 frequency dependence within the interval of 100 kHz to about 2 MHz and does not follow the standard f-2 decrease (or even more) at high frequency region. It was suggested that small pulses which repeatedly appeared at the later stage of cloud flashes might have contribute to enhance the spectral amplitude at higher frequencies. Electric fields generated by Narrow Bipolar Pulses (NBPs), which are considered as one of the strongest source of HF radiation were measured in Malaysia in the tropic and their features were also studied. Result shows a good agreement with previously published observations of NBPs in other geographical regions. The pulse duration of NBPs is varied within 20 – 30μs with the normalized peak amplitude is of the order of 10 V/m, averagely 2– 3 times larger than the peak amplitude of ordinary return strokes. They were observed to emit intense burst of HF radiation at 30 MHz. Thorough analyses and observation of these pulses found previously unreported sharp, fine peaks embedded at the rising and decaying edge of the electric field change of NBPs. Therefore it was suggested that these fine peaks were most probably to be responsible for the intense HF radiation at 30 MHz.
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| 17. |
- Akiyama, Tomoko
(författare)
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Ionization Influence on the Dynamics of Simple Organic Molecules
- 2023
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This licentiate thesis is devoted to the investigation of how bonding in simple organic molecules are affected by X-ray beam irradiation. The investigation targets molecules with three carbons as their main-chain structure. The stability of the bonds under ionization are simulated using the SIESTA package. SIESTA is a simulation package that provides molecular dynamics simulations based on density functional theory within the Born-Oppenheimer approximation. The aim of this study is to understand statistically the damaging process and selectivity among different types of bond. As the first targets, 4 hydrocarbons are investigated. They are propane, propene, propyne and propadiene, which have different combinations of single, double and triple bonds as their main-chain structures. Depending on the combinations, the structures can be either symmetric around the central atom or not. The structure of the symmetric molecules propane and propadiene are stable until charge +3. In contrast, the asymmetric molecules propene and propyne, the main-chain bonds show a tendency towards a more similar bond-distance as the level of ionization increases. In addition, hydrogens relocation occurs in propene, leading to a symmetric structure. Secondly, the bond fluctuations are investigated among 4 types of three-carbon molecules which have functional parts. Alcohol and carboxyl groups molecules show the stable bond integrities at charging 0 to +2. On the other hand, the carbon-carbon bonds in molecules with acetyl and ketone groups are broken by ionization. Comparing the 8 kinds of bond breaking processes in these molecules, this statistical study gives an insight to organic molecules bonding systems.
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| 18. |
- Akram, Adeel
(författare)
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Towards a realistic hyperon reconstruction with PANDA at FAIR
- 2021
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The goal of the PANDA (anti-Proton ANnihilation at DArmstadt) experiment at FAIR (Facility for Anti-proton and Ion Research) is to study strong interactions in the confinement domain. In PANDA, a continuous beam of anti-protons () will impinge on a fixed hydrogen (p) target inside the High Energy Storage Ring (HESR), a feature intended to attain high interaction rates for various physics studies e.g. hyperon production. Two types of hydrogen targets are under development: a pellet target and a cluster-jet target where either high-density pellets or clusters of cooled hydrogen gas will be injected at the interaction point. The residual gas from the target system is expected to dissipate along the beam pipe resulting in a target that is effectively extended outside the designed interaction point. The realistic density profile of target and residual gas has implications for physics studies, e.g. in the ability to select signals of interest and, at the same time, suppress background. All hyperon simulations in PANDA until now have been performed under ideal conditions. In this work, I will for the first time implement more realistic conditions for the beam-target interaction and carry out simulations using the as benchmark channel. The impact of the different configurations of the vacuum system will be discussed in detail.In addition, I will present tests of some of the PANDA's particle track finders that are not based on ideal pattern recognition approaches. The results will provide important guidance for future tracking developments within PANDA.
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| 19. |
- Akrami, N
(författare)
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Social categories and stereotypes: A case of intimacy?
- 2003
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In Study 1, stereotypic knowledge about the social category immigrants and its subcategories was examined and related to participants’ degree of explicit prejudice. Study 2 examined differences in implicit prejudice (negative evaluations of outgroups) as
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| 20. |
- Al-Adili, Ali
(författare)
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Investigation of 234U(n,f) with a Frisch-grid ionization chamber
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work treats three topics. The main topic concerns neutron-induced fission of 234U. The main goal is to investigate the fission-fragments properties as a function of the incident neutron energy. The study was carried out using a twin Frisch-grid ionization chamber. The first fluctuations on fragment properties are presented, in terms of strong angular anisotropy oscillation. The second part of the work treats the data-acquisition systems in use, particularly for neutron-induced fission experiments. Modern digital systems are studied and compared with the conventional analogue systems. It was shown that the digital systems are superior in drift stability, pile-up correction and extended the possibilities of offline analysis. The third part of the work concerns the Frisch-grid inefficiency. The Frisch grid was introduced in the chamber to remove the angular dependency from the induced charge. However, the shielding is not perfect and a correction is needed for the small angular dependency. Two contradicting methods have been presented in literature, one adding, and the second subtracting the angular-dependent part from the detected signal. An experiment with Cf(sf) was designed and performed to solve the pending ambiguity. The results support the additive model.
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