| 591. |
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IVIM reveals increased blood perfusion of liver metastases after oral intake of Salovum®
- 2015
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Ingår i: Magnetic Resonance Materials in Physics, Biology and Medicine. - : Springer Science and Business Media LLC. - 0968-5243 .- 1352-8661.
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Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Introduction Elevated interstitial fluid pressure (IFP) of tumours impairs perfusion, which hinders anti-cancer drugs and oxygen to reach tumour cells1-3. AF-16, a 16 amino acid long sequence from the amino terminal end of the endogenous protein Antisecretory Factor (AF), supresses IFP in animal models of solid tumours4, and could improve drug delivery to tumour cells. Salovum®, a spray-dried egg yolk powder with high content of antisecretory peptides, should be tested on humans, but requires non-invasive tumour IFP/perfusion assessment methods. The IntraVoxel Incoherent Motion (IVIM) model applied to multi-b DWI enables measurement of tissue diffusion (D), pseudo-diffusion (D*) and voxel volume fraction of actively perfused capillaries (f) 5. The aim of this study was to investigate if f could be used to monitor changes induced by Salovum® in colorectal liver metastases in vivo Subjects and Methods Previously untreated patients (n=6) with colorectal liver metastases were imaged before, and 24h after intake of Salovum®, using IVIM-MRI (3T Philips, 16‐channel receiver; Single-shot, SE‐EPI (breath-hold); FOV covering liver, 3x3x5mm3 voxels; TR/TE/NSA/SENSE=1900ms/50ms/2/2; 11 b‐values (0-600); acquisition~10 min. MATLAB-based images processing comprised 1) Inter-scan image registration (volume preserving free-form deformation6); 2) Voxelwise fitting of D and A [eq.2] to S(b200-600) (for b>200, [eq.1] reduces to [eq.2], assuming D<2cm) on DWI (b=600), transfer of ROIs to corresponding f-maps for calculation of median ROI f before and after Salovum® intake and 4) Mann-Whitney U-test for statistical significance (α-level=0.05). Results Liver and metastases were well visualised on DWIs and f-maps Median f in metastatic tissue increased after intake of Salovum® in 5/6 patients, but decreased in one patient (Fig.2) (p<0.0001). Discussion/Conclusion The increased perfusion fraction on day 2 may offer a “window of opportunity” for improved transport of drugs to tumour cells. The increase in f was small, and perhaps not clinically significant, suggesting that additional time points after Salovum® intake and dose escalation be investigated, as well as intra-tumour effect heterogeneity. The proposed IVIM approach is a promising, non-invasive method for studying Salovum® induced changes in liver metastases in vivo. Further optimisation and fractionation studies should be conducted, and IVIM derived parameters should be compared to other techniques for perfusion or IFP measurements. References 1Rofstad,E.K.,et al.,Neoplasia. 2009;11(11):1243-51. 2Milosevic,M.F.,et al.,1999;43(5):1111-23. 3Wiig, H.,et al.,1982;42(2):159-64. 4Al-Olama, M.et al., 2011;50(7):1098-104. 5Le Bihan, D., et al., 1988;168(2):497-505. 6Rueckert, D., et al., 1999;18(8):712-21.
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| 592. |
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| 593. |
- Janhäll, Sara, 1965-, et al.
(författare)
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Utvärdering av städmaskiners förmåga att reducera vägdammsförrådet i gatu- och tunnelmiljöer i Trondheim
- 2016
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- För att undvika överskridande av miljökvalitetsnormerna för partiklar (PM10) har Statens vegvesen Vegdirektoratet i Trondheim genomfört ett försök att rengöra en vägtunnel och en vägsträcka med tre olika städmaskiner för att minska mängden vägdamm. Ett stort antal andra tester redovisas i huvudrapporten, medan föreliggande rapport fokuserar på hur stort vägdammsförrådet varit före och efter städningen med olika maskiner i de olika miljöerna.Resultatet visar att städning minskar vägdammsförrådet effektivt i gatumiljö med två av de tre olika maskinerna, medan vägdammsförrådet ökar av städning i tunnelmiljö. En teori kan vara att detta kan bero på att även väggar och tak städas i tunnelmiljön, vilket skulle kunna medföra att städningen flyttar partiklar från tak och väggar till vägytan. Tunnelstädningen utförs med rengöringsmedel, vilket ger en annan kemisk miljö, som kan lösa upp vägdammet längre ner i texturen och tillgängliggöra det för provtagningsutrustningen.
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| 594. |
- Janszky, I., et al.
(författare)
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Heart rate variability in long-term risk assessment in middle-aged women with coronary heart disease : The Stockholm Female Coronary Risk Study
- 2004
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 255:1, s. 13-21
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. Low heart rate variability (HRV) is associated with poor prognosis after acute coronary events in men. In women, the prognostic impact is not well documented. The objective of this study was to assess the long-term predictive power of HRV on mortality amongst middle-aged women with coronary heart disease (CHD). Design, Settings and Subjects. Consecutive women below 65 years hospitalized for an acute coronary syndrome during a 3-year period in Stockholm were examined for cardiovascular prognostic factors including HRV, and followed for a median of 9 years. An ambulatory 24-h electrocardiograph was recorded during normal activities, 3-6 months after hospitalization. SDNN index (mean of the standard deviations of all normal to normal intervals for all 5-min segments of the entire recording) and the following frequency domain parameters were assessed: total power, high-frequency (HF) power, low-frequency (LF) power, very-low frequency (VLF) power and LF/HF ratio. Using Cox proportional hazards regression, the hazard ratios (HR) for each 25% decrease of the HRV parameters were assessed. Results. After controlling for the independent, significant predictors of mortality amongst the clinical variables, the following HRV parameters were found to be significant predictors of all-cause mortality: SDNN index [HR 1.56, 95% confidence intervals (CI) 1.19-2.05], total power (HR 1.21, 95% CI 1.08-1.35), VLF power (HR 1.22, 95% CI 1.09-1.36), LF power (HR 1.18 95%, CI 1.07-1.30) and HF power (HR 1.18, 95% CI 1.05-1.33). The results were essentially the same when cardiovascular mortality was used as end-points. The HRV parameters were stronger predictors of mortality in the first 5 years following the index event. Conclusion. Low HRV is a predictor of long-term mortality amongst middle-aged women with CHD when measured 3-6 months after hospitalization for an acute coronary syndrome, even after controlling for established clinical prognostic markers.
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| 595. |
- Jash, Asmita, et al.
(författare)
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Excitonic Dynamics at the Type-II Polytype Interface of InP Platelets
- 2023
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Ingår i: ACS Photonics. - 2330-4022. ; 10:9, s. 3143-3148
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Tidskriftsartikel (refereegranskat)abstract
- Indirect excitons are the focus of intense research due to the opportunity of studying degenerate quantum gases and liquids in an excitonic system. To realize such systems, it is highly advantageous to have as little scattering as possible. A polytype type-II interface is formed between wurtzite and zincblende InP due to the band alignment. Electrons gather on the zincblende and holes on the wurtzite side of the interface. Therefore, electrons and holes that are spatially separated by the interface form indirect excitons with aligned dipoles. This polytype type-II interface is perfectly flat, which limits scattering. Here we report that repulsive interaction between the indirect excitons is the driving force behind the long-range transport of indirect excitons along the interface at high exciton densities. This is indicative of less scattering than in conventional type-II heterostructures. The spatial separation of the charge carriers across the interface leads to a low recombination rate of the indirect excitons since the overlap of the electron-hole wavefunction at the interface is small. Emission from the long-lived indirect excitons can be detected even after 40 μs. Our studies have been performed by using spatially and temporally resolved photoluminescence at the low temperature.
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| 596. |
- Jash, Asmita, et al.
(författare)
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Time-resolved photoluminescence studies of single interface wurtzite/zincblende heterostructured InP nanowires
- 2022
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 120:11
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Tidskriftsartikel (refereegranskat)abstract
- The interface between wurtzite and zinc blende InP has been identified as type-II, where electrons gather on the zinc blende side and holes on the wurtzite side of the interface. The photoluminescence resulting from recombination across the interface is expected to be long-lived and to exhibit non-exponential decay of emission intensity after pulsed excitation. We verify this prediction using time-resolved photoluminescence spectroscopy on nanowires containing a single heterostructure between a single segment of wurtzite and zinc blende. We find that a significant intensity of type-II emission remains even more than 30 ns after excitation. The decay of the emission intensity is also non-exponential and considerably longer than the exponential decay of the wurtzite InP segment (260 ps). Our results are consistent with the expected photoluminescence characteristics of a type-II interface between the two polytypes. We also find that the lifetime becomes shorter if we create an electron gas at the interface by n-type doping the entire wurtzite segment of the nanowire. This is expected since there are many electrons that a given hole can recombine with, in contrast to the undoped case.
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| 597. |
- Jelinek, Lukas, et al.
(författare)
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Fundamental bounds on the performance of monochromatic passive cloaks
- 2021
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Ingår i: Optics Express. - 1094-4087. ; 29:15
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Tidskriftsartikel (refereegranskat)abstract
- Fundamental bounds on the performance of monochromatic scattering-cancellation and field-zeroing cloaks made of prescribed linear passive materials occupying a predefined design region are formulated by projecting field quantities onto a sub-sectional basis and applying quadratically constrained quadratic programming. Formulations are numerically tested revealing key physical trends as well as advantages and disadvantages between the two classes of cloaks. Results show that the use of low-loss materials with high dielectric contrast affords the highest potential for effective cloaking.
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| 598. |
- Jelinek, Lukas, et al.
(författare)
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Maximum Radiation Efficiency of Implanted Antennas Employing a Novel Hybrid Method
- 2021
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Ingår i: 2021 IEEE International Symposium on Antennas and Propagation and North American Radio Science Meeting, APS/URSI 2021 - Proceedings. - 9781728146706 ; , s. 1339-1340
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Konferensbidrag (refereegranskat)abstract
- A hybrid combining T-matrix method and electric field integral equation is used to formulate fundamental bounds on radiation efficiency of an implanted antenna. Resulting quadratic optimization problem is solved using a dual formulation. The results present the versatility of the described computational scheme and show the optimal current densities that are the least impaired by dissipation in the tissue.
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| 599. |
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| 600. |
- Johannesson, Mikael, 1959-, et al.
(författare)
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Redovisning av regeringsuppdrag om mikroplast från vägtrafiken
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Denna rapport är en redovisning av det regeringsuppdrag VTI fick i december 2017 om att ta fram och sprida kunskap om mikroplast från vägtrafiken och som löpte fram till den 1 juni 2021. Uppdraget omfattade en budget på totalt 20 Mkr. Anledningen till uppdraget var bl.a. att kunskapen om mikroplast från vägtrafiken är mycket begränsad samtidigt som däck- och vägslitagepartiklar från vägtrafiken är en stor källa. Uppdraget var ett led i regeringens arbete att nationellt och internationellt genomföra insatser för att minska problemen med plast i miljön. Rapporten är strukturerad utifrån den kunskap som specifikt efterfrågas i uppdraget, som t.ex. kunskap om hur partiklarna sprids och vad man kan göra åt det, samt vad regeringen önskar att VTI ska göra, som t.ex. skriva vetenskapliga artiklar, samverka med myndigheter och sprida kunskap.Denna rapport är en sammanfattning av de aktiviteter som genomförts och de resultat som kommit fram inom ramen för uppdraget. Kunskapen om mikroplast från däck- och vägslitagepartiklar har från en låg nivå ökat snabbt under senare år genom forskning som bedrivits inom och utanför regerings-uppdraget. Det gäller t.ex. kunskap om beredning och analys av prover, däckpartiklars fysiska och kemiska egenskaper, däck- och vägslitagepartiklars förekomst i väg- och gatumiljö, deras potentiella spridningsvägar, vilka potentiella styrmedel och åtgärder som finns.
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