| 1. |
- Englund, Hanna, et al.
(författare)
-
Radiation exposure in patients with inflammatory bowel disease and irritable bowel syndrome in the years 2001-2011
- 2017
-
Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 52:3, s. 300-305
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To compare cumulative ionizing radiation in patients with inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) for the years 2001-2011. To study how radiation exposure change over time in patients with newly diagnosed IBD and factors associated with radiation exposure.MATERIAL AND METHODS: All radiological investigations performed between 1 January 2001 and 31 December 2011 were retrospectively recorded in patients with Crohn's disease (CD) (n = 103), ulcerative colitis (UC) (n = 304) and IBS (n = 149). Analyses were done with Mann-Whitney and Chi-Square test.RESULTS: The median total cumulative radiation exposure in mSv for CD (20.0, inter quartile range (IQR) 34.8), UC (7.01, IQR 23.8), IBS (2.71, IQR 9.15) and the proportion of patients who had been exposed for more than 50 mSv during the study period (CD 19%, UC 11%, IBS 3%) were significantly higher in the patients with CD compared to patients with UC (p < .001) and IBS (p < .001), respectively. In turn, patients with UC had significantly higher doses than patients with IBS (p = .005). Risk factors for radiation exposure were female gender (CD), early onset (UC), ileocolonic location (CD), previous surgery (CD and UC), depression (IBS) and widespread pain (IBS). In newly diagnosed CD, there was a significant decline in median cumulative radiation dose in mSv (17.2 vs. 12.0; p = .048) during the study period.CONCLUSIONS: Patients with CD are at greatest risk for high cumulative radiation exposure, but there is a decline in exposure during the late 2000s. Non-colectomized patients with UC and patients with IBS have a relatively low risk of cumulative radiation exposure.
|
|
| 2. |
- Aarnio, Harri, et al.
(författare)
-
Recombination studies in a polyfluorene copolymer for photovoltaic applications
- 2005
-
Ingår i: Synthetic Metals. - : Elsevier BV. - 0379-6779. ; 155:2, s. 299-302
-
Tidskriftsartikel (refereegranskat)abstract
- We present detailed continuous wave (cw) and transient photoinduced absorption (PA) measurements in thin films of a novel alternating polyfluorene copolymer, poly[2,7-(9,9-dioctyl-fluorene)-alt-5,5-(4',7'-di-2-thienyl-2',1',3-benzo-thiadiazole)] (DiO-PFDTBT), and its blends with the sol. fullerene deriv. [6,6]-phenyl-C61-butyric acid Me ester (PCBM) in wt. ratios of 1:0, 4:1 and 1:4. We measure the frequency, intensity and temp. dependence of the PA signal in the frequency domain, and compare with the results obtained from the transient PA decay measurements in the time domain. In all blends, the PA spectrum shows a broad high energy PA band ranging from .apprx.1 eV to 2 eV as well as a low energy band peaking at .apprx.0.35 eV. We attribute the low energy band to the P1 transition of polarons and part of the high energy band to the correlated P2 transition of polarons. Both frequency and time domain measurements show that the high energy band has two decay components, a faster component in the microsecond time regime and a slower component in the millisecond time regime. The slow component is strongly dispersive, whereas the fast component is practically non-dispersive. [on SciFinder (R)]
|
|
| 3. |
- Andersson, Johan, et al.
(författare)
-
New paradigm of transition metal polypyridine complex photochemistry
- 2004
-
Ingår i: Faraday Discussions. - : Royal Society of Chemistry (RSC). - 1364-5498. ; 127, s. 295-305
-
Tidskriftsartikel (refereegranskat)abstract
- Using polarization sensitive ultrafast transient absorption spectroscopy we have studied energy transfer and excited state relaxation pathways in a tetranuclear transition metal [( osmium)( ruthenium)(3)] polypyridine complex. Contrary to the generally accepted picture of transition metal complex photochemistry we find that ultrafast energy transfer ( less than or equal to 60 fs) occurs from the excited singlet MLCT state of the peripheral Ru-chromophores to the central Os-core, in efficient competition with intersystem crossing. Energy transfer between relaxed triplet MLCT states is more than an order of magnitude slower ( 600 fs).
|
|
| 4. |
- Andersson, Johan, et al.
(författare)
-
Ultrafast singlet energy transfer competes with intersystem crossing in a multi-center transition metal polypyridine complex
- 2004
-
Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 386:4-6, s. 336-341
-
Tidskriftsartikel (refereegranskat)abstract
- Transition metal polypyridine complexes are finding widespread applications within many areas of chemistry. For their light-induced processes, the generally accepted picture is that all function emanates from triplet states because the singlet states initially prepared by light absorption are depopulated via intersystem crossing on the 100-fs time scale, before they are significantly involved in chemical reactions. Here we show that this is not always true. With ultrafast spectroscopy applied to a (ruthenium)(3)-osmium complex we show that transition metal polypyridine complexes can be designed where energy transfer between excited singlet states located on different metal centers efficiently competes with intersystem crossing, thus decreasing population of the lower-lying triplet states and concomitant energy loss. (C) 2004 Elsevier B.V. All rights reserved.
|
|
| 5. |
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Bannbers, Elin, 1984-, et al.
(författare)
-
Prefrontal activity during response inhibition decreases over time in the postpartum period
- 2013
-
Ingår i: Behavioural Brain Research. - : Elsevier BV. - 0166-4328 .- 1872-7549. ; 241, s. 132-138
-
Tidskriftsartikel (refereegranskat)abstract
- The postpartum period is characterized by complex hormonal changes, but human imaging studies in the postpartum period have thus far predominantly focused on the neural correlates of maternal behavior or postpartum depression, whereas longitudinal studies on neural correlates of cognitive function across the postpartum period in healthy women are lacking. The aim of this study was to longitudinally examine response inhibition, as a measure of executive function, during the postpartum period and its neural correlates in healthy postpartum women and non-postpartum controls. Thirteen healthy postpartum women underwent event-related functional magnetic resonance imaging while performing a Go/NoGo task. The first assessment was made within 48 h of delivery, and the second at 4-7 weeks postpartum. In addition, 13 healthy women examined twice during the menstrual cycle were included as non-postpartum controls. In postpartum women region of interest analyses revealed task-related decreased activations in the right inferior frontal gyrus, right anterior cingulate, and bilateral precentral gyri at the late postpartum assessment. Generally, postpartum women displayed lower activity during response inhibition in the bilateral inferior frontal gyri and precentral gyri compared to non-postpartum controls. No differences in performance on the Go/NoGo task were found between time-points or between groups. In conclusion, this study has discovered that brain activity in prefrontal areas during a response inhibition task decreases throughout the course of the first postpartum weeks and is lower than in non-postpartum controls. Further studies on the normal adaptive brain activity changes that occur during the postpartum period are warranted. (C) 2012 Elsevier B.V. All rights reserved.
|
|
| 9. |
- Billsten, Helena, et al.
(författare)
-
Excited-state processes in the carotenoid zeaxanthin after excess energy excitation
- 2005
-
Ingår i: The Journal of Physical Chemistry Part A: Molecules, Spectroscopy, Kinetics, Environment and General Theory. - : American Chemical Society (ACS). - 1520-5215. ; 109:31, s. 6852-6859
-
Tidskriftsartikel (refereegranskat)abstract
- Aiming for better understanding of the large complexity of excited-state processes in carotenoids, we have studied the excitation wavelength dependence of the relaxation dynamics in the carotenoid zeaxanthin. Excitation into the lowest vibrational band of the S-2 state at 485 nm, into the 0-3 vibrational band of the S2 state at 400 nm, and into the B-2(u)+ state at 266 nm resulted in different relaxation patterns. While excitation at 485 nm produces the known four-state scheme (S-2 -> hot S-1 -> S-1 -> S-0), excess energy excitation led to additional dynamics occurring with a time constant of 2.8 ps (400 nm excitation) and 4.9 ps (266 nm excitation), respectively. This process is ascribed to a conformational relaxation of conformers generated by the excess energy excitation. The zeaxanthin S* state was observed regardless of the excitation wavelength, but its population increased after 400 and 266 nm excitation, suggesting that conformers generated by the excess energy excitation are important for directing the population toward the S* state. The S-2-S-1 internal conversion time was shortened from 135 to 70 fs when going from 485 to 400 nm excitation, as a result of competition between the S-2-S-1 internal conversion from the vibrationally hot S2 state and S2 vibrational relaxation. The S, lifetime of zeaxanthin was within experimental error the same for all excitation wavelengths, yielding similar to 9 ps. No long-lived species have been observed after excitation by femtosecond pulses regardless of the excitation wavelength, but excitation by nanosecond pulses at 266 nm generated both zeaxanthin triplet state and cation radical.
|
|
| 10. |
|
|
