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- Thorsson, Sofia, 1972, et al.
(author)
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Adapting cities to climate induced risks - a coordinated approach
- 2011
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In: Climate and Construction. ; , s. 173-180
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Conference paper (peer-reviewed)abstract
- In an era of changing climate there is a growing interest to create resilient cities, which can absorb and manage climate induce risks, such as heat waves and natural hazards (flooding, landslides etc). The increased frequencies and magnitudes of these climate hazards are expected to have a major impact on society. In order to maintain risks to society at acceptable levels, measures to reduce the vulnerability need to be taken. Such measures may, however, have significant non-expected and non-wanted impacts elsewhere on society. The need of holistic planning strategies becomes apparent. The overall aim of this new transdisciplinary research project is to develop knowledge and methods that enable an integrated assessment of the impact of climate induced risks on society. The free-port area in Gothenburg, Sweden, will has been selected for a case study that will sharpen both the individual scientific methods and the interdisciplinary and intersectoral cooperation and integration. The project brings together experts in urban climate, atmospheric science, natural risk assessment, stratified vulnerability and multi-criteria analyses with local city planners in an integrated research effort. Strategic plans for climate adaptation will be developed and proposed. The stakeholder involvement will promote transfer of knowledge and applicability of results.
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- Andersson-Sköld, Yvonne, et al.
(author)
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An integrated method for assessing climate-related risks and adaptation alternatives in urban areas
- 2015
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In: Climate Risk Management. - : Elsevier BV. - 2212-0963. ; 7, s. 31-50
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Journal article (peer-reviewed)abstract
- © 2015 The Authors. The urban environment is a complex structure with interlinked social, ecological and technical structures. Global warming is expected to have a broad variety of impacts, which will add to the complexity. Climate changes will force adaptation, to reduce climate-related risks. Adaptation measures can address one aspect at the time, or aim for a holistic approach to avoid maladaptation. This paper presents a systematic, integrated approach for assessing alternatives for reducing the risks of heat waves, flooding and air pollution in urban settings, with the aim of reducing the risk of maladaptation. The study includes strategies covering different spatial scales, and both the current climate situation and the climate predicted under climate change scenarios. The adaptation strategies investigated included increasing vegetation; selecting density, height and colour of buildings; and retreat or resist (defend) against sea-level rise. Their effectiveness was assessed with regard to not only flooding, heat stress and air quality but also with regard to resource use, emissions to air (incl. GHG), soil and water, and people's perceptions and vulnerability. The effectiveness of the strategies were ranked on a common scale (from -3 to 3) in an integrated assessment. Integrated assessments are recommended, as they help identify the most sustainable solutions, but to reduce the risk of maladaptation they require experts from a variety of disciplines. The most generally applicable recommendation, derived from the integrated assessment here, taking into account both expertise from different municipal departments, literature surveys, life cycle assessments and publics perceptions, is to increase the urban greenery, as it contributes to several positive aspects such as heat stress mitigation, air quality improvement, effective storm-water and flood-risk management, and it has several positive social impacts. The most favourable alternative was compact, mid-rise, light coloured building design with large parks/green areas and trees near buildings.
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- Chroinin, Danielle Ni, et al.
(author)
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Statin Therapy and Outcome After Ischemic Stroke : Systematic Review and Meta-Analysis of Observational Studies and Randomized Trials
- 2013
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In: Stroke. - 0039-2499 .- 1524-4628. ; 44:2, s. 448-456
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Research review (peer-reviewed)abstract
- Background and Purpose-Although experimental data suggest that statin therapy may improve neurological outcome after acute cerebral ischemia, the results from clinical studies are conflicting. We performed a systematic review and meta-analysis investigating the relationship between statin therapy and outcome after ischemic stroke. Methods-The primary analysis investigated statin therapy at stroke onset (prestroke statin use) and good functional outcome (modified Rankin score 0 to 2) and death. Secondary analyses included the following: (1) acute poststroke statin therapy (<= 72 hours after stroke), and (2) thrombolysis-treated patients. Results-The primary analysis included 113 148 subjects (27 studies). Among observational studies, statin treatment at stroke onset was associated with good functional outcome at 90 days (pooled odds ratio [OR], 1.41; 95% confidence interval [CI], 1.29-1.56; P<0.001), but not 1 year (OR, 1.12; 95% CI, 0.9-1.4; P=0.31), and with reduced fatality at 90 days (pooled OR, 0.71; 95% CI, 0.62-0.82; P<0.001) and 1 year (OR, 0.80;95% CI, 0.67-0.95; P=0.01). In the single randomized controlled trial reporting 90-day functional outcome, statin treatment was associated with good outcome (OR, 1.5; 95% CI, 1.0-2.24; P=0.05). No reduction in fatality was observed on meta-analysis of data from 3 randomized controlled trials (P=0.9). In studies restricted to of thrombolysis-treated patients, an association between statins and increased fatality at 90 days was observed (pooled OR, 1.25; 95% CI, 1.02-1.52; P=0.03, 3 studies, 4339 patients). However, this association was no longer present after adjusting for age and stroke severity in the largest study (adjusted OR, 1.14; 95% CI, 0.90-1.44; 4012 patients). Conclusion-In the largest meta-analysis to date, statin therapy at stroke onset was associated with improved outcome, a finding not observed in studies restricted to thrombolysis-treated patients. Randomized trials of statin therapy in acute ischemic stroke are needed.
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| 7. |
- Jonsson, Fredrik, 1972-
(author)
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A frequency synthesizer and a method for synthesizing a frequency
- 2000
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Patent (pop. science, debate, etc.)abstract
- This invention relates to a method of synthesizing a frequency by means of a frequency synthesizer comprising a local oscillator, which generates an output signal, a phase locked loop, which provides a control signal to the local oscillator, and a frequency divider, which divides the frequency of said output signal and provides a frequency divided input signal to the phase locked loop, wherein the method comprises the steps of: providing, in a receiving mode, said output signal to a receiver for tuning thereof; locking, by means of said phase locked loop, the frequency of said output signal to a channel frequency of a channel to be received; and turning off said phase locked loop when said output signal frequency is locked to said channel frequency and keeping the phase locked loop off during a following receive cycle. The invention also relates to a frequency synthesizer and a transceiver respectively, for performing the method.
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| 8. |
- Jonsson, Fredrik, 1972-
(author)
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Design and Calibration of integrated PLL Frequency Synthesizers
- 2008
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Doctoral thesis (other academic/artistic)abstract
- Thanks to its ability to generate a stable yet programmable output frequency, Phase Locked Loop (PLL) frequency synthesizers are found in most modern radio transceivers. All practical PLL implementations suffer from unwanted frequency components such as phasenoise and spurious tones, and since these components affect system performance they must be predicted and minimized. This thesis discuss the design and implementation of fully integrated PLL circuits. Techniques to predict system performance are investigated. The strongly non-linear operation of PLL building blocks are analyzed, using both analytical and numerical methods. Techniques to reduce impact of interferer down-conversion and noise folding are suggested. Methods to perform automatic calibration in order to make circuits less sensitive to process variations are proposed. The techniques are verified through a number of PLL implementations. The design and implementation of a transceiver targeting a dual band IEEE 802.11 a/b/g wireless LAN operation is discussed. The circuit use two PLL:s operating at 1310 to 1510 MHz and 3.84 GHz respectively. Noise contributions of various PLL building blocks and their impact on over all system performance are analyzed. The combined integrated phase noise is below -34 dBc, and measured transceiver Error Vector Magnitude (EVM) is better than 2.5 dB in both the 2.4 and 5 GHz bands. A low power frequency synthesizer targeting Frequency Shift Keying applications such as ZigBee and BlueTooth is presented. The synthesizer use open-loop direct modulation of the carrier, but unlike conventional implementations, the proposed synthesizer is open both when transmitting and receiving data. This allows the use of a small area on-chip loop filter without violating noise or spurious requirements. To handle the frequency drift normally associated with open-loop implementations, a low-leakage charge-pump is proposed. The synthesizer is implemented using a 0.18μm CMOS process. Total power consumption is 9 mW and the circuit area including the VCO inductors and on-chip loopfilter is 0.32mm2. Measured leakage current is less than 2 fA. A small area amplitude detector circuit is proposed. The wide-band operation and small input capacitance make the circuit suitable for embedding in an RF system on-chip, allowing measurement of on-chip signal levels and automatic calibration. Finally an oscillator topology reducing the phase noise in voltage controlled oscillators is suggested. By using on-chip decoupling and an amplitude control circuit to adjust oscillator bias, the impact of current source noise is eliminated. The theoretical phase noise is reduced 3.9 dB compared to a conventional LC oscillator using the same bias current.
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