| 1. |
- Skotte, Line, et al.
(författare)
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Genome-wide association study of febrile seizures implicates fever response and neuronal excitability genes
- 2022
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 145:2, s. 555-568
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Tidskriftsartikel (refereegranskat)abstract
- Febrile seizures represent the most common type of pathological brain activity in young children and are influenced by genetic, environmental and developmental factors. In a minority of cases, febrile seizures precede later development of epilepsy. We conducted a genome-wide association study of febrile seizures in 7635 cases and 83 966 controls identifying and replicating seven new loci, all with P < 5 × 10-10. Variants at two loci were functionally related to altered expression of the fever response genes PTGER3 and IL10, and four other loci harboured genes (BSN, ERC2, GABRG2, HERC1) influencing neuronal excitability by regulating neurotransmitter release and binding, vesicular transport or membrane trafficking at the synapse. Four previously reported loci (SCN1A, SCN2A, ANO3 and 12q21.33) were all confirmed. Collectively, the seven novel and four previously reported loci explained 2.8% of the variance in liability to febrile seizures, and the single nucleotide polymorphism heritability based on all common autosomal single nucleotide polymorphisms was 10.8%. GABRG2, SCN1A and SCN2A are well-established epilepsy genes and, overall, we found positive genetic correlations with epilepsies (rg = 0.39, P = 1.68 × 10-4). Further, we found that higher polygenic risk scores for febrile seizures were associated with epilepsy and with history of hospital admission for febrile seizures. Finally, we found that polygenic risk of febrile seizures was lower in febrile seizure patients with neuropsychiatric disease compared to febrile seizure patients in a general population sample. In conclusion, this largest genetic investigation of febrile seizures to date implicates central fever response genes as well as genes affecting neuronal excitability, including several known epilepsy genes. Further functional and genetic studies based on these findings will provide important insights into the complex pathophysiological processes of seizures with and without fever.
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| 2. |
- Andersson, J, et al.
(författare)
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Experimental and Theoretical Investigation of the Kinetics of the Sorption of Water Vapour by Silica Gel
- 1985
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Ingår i: Journal of the Chemical Society, Faraday Transactions 1: Physcal Chemistry in Condensed Phases. ; 81, s. 2681-2692
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Tidskriftsartikel (refereegranskat)abstract
- The kinetics and mechanism of the sorption reaction between water vapour and silica gel have been investigated in the pressure range 1–50 Torr using thermogravimetry under controlled temperature and water-vapour pressure. Measurements at equilibrium were carried out in order to determine the pertinent equilibrium parameters and the extent of hysteresis. The influence of particle radius and temperature on the kinetics in the whole of the pressure range investigated are well described by theoretical curves fitted to experimental data by taking into account simultaneous mass- and heat-transfer. Calculations yield a diffusivity of 8 × 10–10 m2 s–1. The sorption kinetics in the pressure range 15–40 Torr are shown to be controlled by heat transfer.
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| 3. |
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| 4. |
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| 5. |
- Bjurström, Henrik, et al.
(författare)
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Air-coupled detection of the S1-ZGV lamb mode in a concrete plate based on backward wave propagation
- 2013
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Ingår i: Review Of Progress In Quantitative Nondestructive Evaluation, Vols 32a And 32b. - : American Institute of Physics (AIP). - 9780735411296 ; , s. 1294-1300
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Konferensbidrag (refereegranskat)abstract
- Impact Echo is commonly used to determine thickness of concrete plate like structures. The method is based on the generation and detection of the plate thickness resonance frequency, where the group velocity of the first higher symmetric Lamb mode goes to zero (S1-ZGV). When using air-coupled microphones as receivers it is hard to determine the correct resonance frequency due to low signal to noise ratio. In this study multichannel signal processing is used to identify the S1-ZGV frequency, based on backward wave propagation instead of the conventional amplitude spectrum approach.
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| 6. |
- Bjurström, Henrik
(författare)
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Air-coupled microphone measurements of guided waves in concrete plates
- 2014
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Quality control and quality assurance of pavements is today primarily based on core samples. Air void content and pavement thickness are parameters that are evaluated. However, no parameter connected to the stiffness is evaluated. There is a need for fast and reliable test methods that are truly non-destructive in order to achieve an effective quality control and quality assurance of pavements. This licentiate thesis presents surface wave testing using air-coupled microphones as receivers. The measurements presented in this work are performed in order to move towards non-contact measurements of material stiffness. The non-contact measurements are compared to conventional accelerometer measurements in order to compare the noncontact measurements to a “reference test”. The two appended papers are focused on evaluating one parameter in each paper. In the first paper all equipment needed to perform non-contact measurements are mounted on a trolley in order to enable measurements while rolling the trolley forward. It is shown that rolling measurements can provide rapid and reliable measurements of the Rayleigh wave velocity over large areas. However, the measurements are shown to be sensitive to misalignments between the microphone array and the measured surface. An uneven surface can thus cause major errors in the calculated results. The second paper presents an alternative method to evaluate the thickness resonance frequency of a concrete plate. It is demonstrated how the established Impact Echo method can give erroneous results when aircoupled microphones are used as receivers. Instead a method based on backward wave propagation is introduced. It is demonstrated how waves with negative phase velocities can be identified in a narrow frequency span close to the thickness resonance.
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| 7. |
- Bjurström, Henrik, et al.
(författare)
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An Exergy Analysis of Sensibel and Latent Heat Storage
- 1985
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Ingår i: Journal of Heat Recovery Systems. - : Elsevier BV. - 0198-7593. ; 5:3, s. 233-250
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Tidskriftsartikel (refereegranskat)abstract
- An analysis of sensible and latent heat storage units is performed in both energy and exergy terms. The stores are compared, through variation of design parameters for both charging and discharging in order to find exergy extrema, i.e. operating conditions that maximize the exergy yield in the transfer of heat to and from the stores. Reference is made to the stratified sensible heat store. The overall conversion efficiency for the thermal exergy supplied by the heat source to the heat load via the heat store is of the order of 10% at NTU = 1. The stratified store is the most efficient at high NTU values. For the charging operation there exists exergy extrema for both the well-mixed sensible store and the PCM store. An energy analysis of the charging of the PCM store shows that the transition temperature should be low. From an exergetic point of view the transition temperature should be the geometric mean of the charging and the initial temperatures, if the charging temperature is fixed. When the end temperature of a store in a changing operation is fixed the transition temperature should be low. Charging with a constant heating rate is advantageous if the transition temperature is low. No optimal stopping time can be recognized for the discharging operation. The merit of a high exergy content is that of a high thermal power during discharging. This favours a PCM store with a high transition temperature.
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| 8. |
- Bjurström, Henrik, 1983-, et al.
(författare)
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Ballastberoende slitage på asfalt och betong : provning enligt Prall
- 2020
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Betongvägsträckan på E4 utanför Uppsala har ett antal år efter konstruktion uppvisat en accelererande spårtillväxt som inte kunnat förklaras av ökad trafik. Entreprenörens egenkontroll visar att ballast från två olika täkter med olika stenkvalitet sammanblandats för att klara kravet på kulkvarnsvärde. I denna rapport undersöks på vilket sätt slitaget påverkas då olika proportioner av en sekundär ballast blandas in i beläggningsmaterialet. Sju serier provkroppar, tillverkade av asfalt respektive betong, med olika andelar primär och sekundär ballast blandas och testas enligt Prall för att studera nötningsmotståndet från dubbdäckstrafik. Resultaten visar en närmast linjär förändring av slitage då andelen sekundär ballast i fraktionen 8–16 mm ändras. Det står också klart att ballasten i fraktionen 4–8 mm inte påverkar nötningsmotståndet.
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| 9. |
- Bjurström, Henrik, et al.
(författare)
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Comparative Seismic Laboratory and Non-Contact Field Measurements of Asphalt Concrete
- 2016
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Ingår i: 2016 Structural Materials Technology Paper Summaries.
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Konferensbidrag (refereegranskat)abstract
- Non-contact acoustic field measurements are performed on a newly built highway to characterize the real part of the dynamicmodulus of the asphalt concrete (AC) top layer. The in situ measurements are performed using an array of 48 micro-electromechanicalsystem (MEMS) sensors. Cores extracted from the field measurement positions are then examined in a laboratory usingseismic modal testing for comparison. The laboratory testing allows master curves to be constructed to characterize the AC over awide temperature and frequency range. It is demonstrated that the real parts of the dynamic moduli are consistent at the fieldtemperatures using the two test methods. The in situ measurements are also shown to be highly repeatable. The presentedcomparative study indicates a possible application for assuring the quality of AC based on mechanical properties using fast noncontactin situ measurements.
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| 10. |
- Bjurström, Henrik, 1983-, et al.
(författare)
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Detecting the thickness mode frequency in a concrete plate using backward wave propagation
- 2016
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Ingår i: Journal of the Acoustical Society of America. - : Acoustical Society of America (ASA). - 0001-4966 .- 1520-8524. ; 139:2, s. 649-657
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Tidskriftsartikel (refereegranskat)abstract
- Material stiffness and plate thickness are the two key parameters when performing quality assurance/quality control on pavement structures. In order to estimate the plate thickness non-destructively, theImpact Echo (IE) method can be utilized to extract the thickness resonance frequency. An alternativeto IE for estimating the thickness resonance frequency of a concrete plate, and to subsequently enablethickness determination, is presented in this paper. The thickness resonance is often revealed as asharp peak in the frequency spectrum when contact receivers are used in seismic testing. Due to a lowsignal-to-noise ratio, IE is not ideal when using non-contact microphone receivers. In studying thecomplex Lamb wave dispersion curves at a frequency infinitesimally higher than the thickness frequency,it is seen that two counter-directed waves occur at the same frequency but with phase velocitiesin opposite directions. Results show that it is possible to detect the wave traveling with anegative phase velocity using both accelerometers and air-coupled microphones as receivers. Thisalternative technique can possibly be used in non-contact scanning measurements based on aircoupled microphones.
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