| 51. |
- Kjaergaard, Benedict, et al.
(författare)
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Low plasma potassium in deep hypothermic cardiac arrest indicates that cardiac arrest is secondary to hypothermia : a porcine study
- 2010
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Ingår i: European journal of emergency medicine. - 0969-9546 .- 1473-5695. ; 17:3, s. 131-135
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: In accidental hypothermia, normal signs of death are unreliable. It is generally accepted that a lifeless person is beyond the limits of rescue if plasma potassium (P-potassium) is higher than10 mmol/l. However, the rate of increase in potassium or in other markers after cardiac arrest has not been carefully studied in hypothermic individuals. The aim of this animal study was to assess biochemical changes after anoxic circulatory arrest at hypothermia and at normothermia followed by external cooling. METHODS: Five pigs were treated with heparin and extracorporeal circulation and cooled to 20 degrees C (primary hypothermia group). The animals were weaned from extracorporeal circulation, suffered cardiac arrest, and were cooled externally with ice to mimic victims found in a cold environment. With the use of intermittent external cardiac compressions mixing the blood, arterial P-potassium was followed after cardiac arrest until the level exceeded 10 mmol/l. Another group of five pigs (anoxic cardiac arrest group) were treated with heparin and killed by anoxia at normothermia and were thereafter treated and followed similarly to the primary hypothermia group. RESULTS: In primary hypothermia P-potassium exceeded 10 mmol/l after median 3.5 h, whereas in anoxic cardiac arrest P-potassium exceeded 10 mmol/l after median 1 h. CONCLUSION: This study shows that if cardiac arrest occurs before hypothermia is established, P-potassium increases quickly in contrast to the situation when hypothermia induces cardiac arrest. Thus, a low P-potassium in a hypothermic individual with cardiac arrest indicates that cardiac arrest occurred recently or was secondary to the hypothermic event.
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| 52. |
- Konradsson, Elise, et al.
(författare)
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Establishment and Initial Experience of Clinical FLASH Radiotherapy in Canine Cancer Patients
- 2021
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Ingår i: Frontiers in Oncology. - : Frontiers Media SA. - 2234-943X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- FLASH radiotherapy has emerged as a treatment technique with great potential to increase the differential effect between normal tissue toxicity and tumor response compared to conventional radiotherapy. To evaluate the feasibility of FLASH radiotherapy in a relevant clinical setting, we have commenced a feasibility and safety study of FLASH radiotherapy in canine cancer patients with spontaneous superficial solid tumors or microscopic residual disease, using the electron beam of our modified clinical linear accelerator. The setup for FLASH radiotherapy was established using a short electron applicator with a nominal source-to-surface distance of 70 cm and custom-made Cerrobend blocks for collimation. The beam was characterized by measuring dose profiles and depth dose curves for various field sizes. Ten canine cancer patients were included in this initial study; seven patients with nine solid superficial tumors and three patients with microscopic disease. The administered dose ranged from 15 to 35 Gy. To ensure correct delivery of the prescribed dose, film measurements were performed prior to and during treatment, and a Farmer-type ion-chamber was used for monitoring. Treatments were found to be feasible, with partial response, complete response or stable disease recorded in 11/13 irradiated tumors. Adverse events observed at follow-up ranging from 3-6 months were mild and consisted of local alopecia, leukotricia, dry desquamation, mild erythema or swelling. One patient receiving a 35 Gy dose to the nasal planum, had a grade 3 skin adverse event. Dosimetric procedures, safety and an efficient clincal workflow for FLASH radiotherapy was established. The experience from this initial study will be used as a basis for a veterinary phase I/II clinical trial with more specific patient inclusion selection, and subsequently for human trials.
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| 53. |
- Kristensen, Anders Raastrup, et al.
(författare)
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Symptoms of organization
- 2008
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Ingår i: Ephemera: Theory and Politics in Organization. - 1473-2866. ; 8:1, s. 1-1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 54. |
- Kristensen, Fredrik, et al.
(författare)
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A Flexible FFT Processor
- 2002
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Konferensbidrag (refereegranskat)abstract
- In this paper a flexible FFT processor for OFDM systems is presented. In future wireless systems using OFDM each terminal should be able to handle a wide range of different applications, from pure voice communication to high-speed data transfers, with as little overhead in power consumption and protocol procedure as possible. As the terminals will be battery powered and should be cheap to manufacture an ASIC solution is required. To be able to adapt to different communication schemes and various communication channels the FFT processor must be configurable. To minimize power consumption no more precision than necessary should be used. A pipelined radix22 FFT processor, with the possibility of run time switching between 32-1024 points, have been designed in a standard CMOS 0.35 µm technology. Clock gating and low power memories have been used to reduce power consumption.
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| 55. |
- Kristensen, Fredrik, et al.
(författare)
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A Generic Transmitter for Wireless OFDM Systems
- 2003
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Ingår i: 14th IEEE Proceedings on Personal, Indoor and Mobile Radio Communications, 2003. PIMRC 2003.. - 0780378229 ; 3, s. 2234-2238
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Konferensbidrag (refereegranskat)
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| 56. |
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| 57. |
- Kristensen, Fredrik, et al.
(författare)
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Flexible baseband transmitter for OFDM
- 2003
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Ingår i: Proceedings of the IASTED International Conference on Circuits, Signals, and Systems. - 0889863512 ; , s. 356-361
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Konferensbidrag (refereegranskat)abstract
- To fully utilize the available spectrum for a wireless communication system it is feasible to adapt to different situations on the channel. In this paper a flexible OFDM transmitter is presented together with basic theory behind OFDM transmission. It is shown that high flexibility can be obtained with a reasonable amount of additional hardware. Part of the design, the FFT-processor, has already been fabricated and measurement results are presented.
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| 58. |
- Kristensen, Fredrik, et al.
(författare)
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Reduced transceiver-delay for OFDM systems
- 2004
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Ingår i: 2004 IEEE 59th Vehicular Technology Conference. VTC 2004-Spring. - 0780382552 ; , s. 1242-1245
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Konferensbidrag (refereegranskat)abstract
- In this paper, it is shown that more than half of the data flow buffer, due to a bit reversed FFT output and cyclic prefix in an OFDM transceiver, can be removed. To achieve this, a new pipelined FFT processor is proposed and a cyclic suffix is used instead of the more commonly used cyclic prefix. The FFT processor is used either with a forward or backward data flow, i.e. performing either a decimation in time or a decimation in frequency FFT. However, this approach precludes wordlength optimization in the processor and therefore a semi floating-point arithmetic is used to achieve high signal-to-noise ratio. Total delay through the transceiver is reduced by 25% and for larger transceivers silicon area is reduced by as much as 25%. In addition, the proposed scheme reduces the required amount of memory accesses to insert a cyclic extension, and has the basic properties of a simple interleaver
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| 59. |
- Kristensen, Jeppe A., et al.
(författare)
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Background insect herbivory increases with local elevation but makes minor contribution to element cycling along natural gradients in the Subarctic
- 2020
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Ingår i: Ecology and Evolution. - : John Wiley & Sons. - 2045-7758. ; 10:20, s. 11684-11698
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Tidskriftsartikel (refereegranskat)abstract
- Herbivores can exert major controls over biogeochemical cycling. As invertebrates are highly sensitive to temperature shifts (ectothermal), the abundances of insects in high-latitude systems, where climate warming is rapid, is expected to increase. In subarctic mountain birch forests, research has focussed on geometrid moth outbreaks, while the contribution of background insect herbivory (BIH) to elemental cycling is poorly constrained. In northern Sweden, we estimated BIH along 9 elevational gradients distributed across a gradient in regional elevation, temperature, and precipitation to allow evaluation of consistency in local versus regional variation. We converted foliar loss via BIH to fluxes of C, nitrogen (N), and phosphorus (P) from the birch canopy to the soil to compare with other relevant soil inputs of the same elements and assessed different abiotic and biotic drivers of the observed variability. We found that leaf area loss due to BIH was similar to 1.6% on average. This is comparable to estimates from tundra, but considerably lower than ecosystems at lower latitudes. The C, N, and P fluxes from canopy to soil associated with BIH were 1-2 orders of magnitude lower than the soil input from senesced litter and external nutrient sources such as biological N fixation, atmospheric deposition of N, and P weathering estimated from the literature. Despite the minor contribution to overall elemental cycling in subarctic birch forests, the higher quality and earlier timing of the input of herbivore deposits to soils compared to senesced litter may make this contribution disproportionally important for various ecosystem functions. BIH increased significantly with leaf N content as well as local elevation along each transect, yet showed no significant relationship with temperature or humidity, nor the commonly used temperature proxy, absolute elevation. The lack of consistency between the local and regional elevational trends calls for caution when using elevation gradients as climate proxies.
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| 60. |
- Kristensen, Karl, et al.
(författare)
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Cystatin C, beta-2-microglobulin and beta-trace protein in pre-eclampsia
- 2007
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Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : Wiley. - 1600-0412 .- 0001-6349. ; 86:8, s. 921-926
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Tidskriftsartikel (refereegranskat)abstract
- Background. An altered renal function is an essential component of the patho-physiology of pre-eclampsia. The plasma levels of low molecular mass proteins, e. g. beta-trace protein, beta-2-microglobulin and cystatin C, are increased in the third trimester of normal pregnancy. The plasma levels of cystatin C and beta-2-microglobulin are further increased in preeclampsia, and the cystatin C level has been reported to be a reliable marker for the disease. The aim of this investigation was to study the plasma levels of beta-trace protein, beta-2-microglobulin and cystatin C in pre-eclampsia, and to determine the diagnostic performance of these proteins compared to that of urate and creatinine. Methods. A case-control study of 57 women diagnosed with pre-eclampsia, and 218 healthy women with uncomplicated singleton pregnancies in the third trimester. Women in the catchment area of Lund, Sweden, were included during an 18-month period from October 2003 to April 2005. Venous blood samples were drawn upon inclusion when diagnosis was made. The maternal plasma concentrations of the 3 proteins were analysed by automated particle-enhanced immunoturbidimetric assays. Results. The plasma levels of the 3 proteins were significantly higher in the third trimester of pre-eclamptic patients compared to healthy pregnant women in the third trimester. The upper reference limits ( parametric 97.5 percentile) were 2.57 mg/l for beta-2-microglobulin, 0.72 mg/l for beta-trace protein and 1.37 mg/l for cystatin C. ROC analysis showed similar diagnostic performance for the 3 proteins, with b-trace protein displaying the best diagnostic performance of all the analytes. Conclusions. In this study, the maternal plasma levels of beta 2-microglobulin, beta-trace protein and cystatin C were all significantly elevated in pre-eclampsia compared to those of healthy pregnant women, and displayed similar diagnostic performance for diagnosing pre-eclampsia. The results indicate that low molecular mass proteins are useful as markers of renal impairment in pre-eclampsia.
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