| 1. |
- Wannberg, Gudmund, et al.
(författare)
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EISCAT_3D - a next-generation European radar system for upper atmosphere and geospace research
- 2010
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Ingår i: Radio Science Bulletin. - 1024-4530. ; :333, s. 75-88
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Tidskriftsartikel (refereegranskat)abstract
- The EISCAT Scientifi c Association, together with a number of collaborating institutions, has recently completed a feasibility and design study for an enhanced performance research radar facility to replace the existing EISCAT UHF and VHF systems. This study was supported by EU Sixth-Framework funding. The new radar retains the powerful multi-static geometry of the EISCAT UHF, but will employ phased arrays, direct-sampling receivers, and digital beamforming and beam steering. Design goals include, inter alia, a tenfold improvement in temporal and spatial resolution, an extension of the instantaneous measurement of full-vector ionospheric drift velocities from a single point to the entire altitude range of the radar, and an imaging capability to resolve small-scale structures. Prototype receivers and beamformers are currently being tested on a 48-element, 224 MHz array (the "Demonstrator") erected at the Kiruna EISCAT site, using the EISCAT VHF transmitter as an illuminator.
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| 2. |
- Lazurova, I., et al.
(författare)
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Effect of Growth Hormone Replacement Therapy on Plasma Brain Natriuretic Peptide Concentration, Cardiac Morphology and Function in Adults with Growth Hormone Deficiency
- 2010
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Ingår i: Experimental and clinical endocrinology & diabetes. - : Georg Thieme Verlag KG. - 0947-7349 .- 1439-3646. ; 118:3, s. 172-176
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The impact of growth hormone (GH) replacement on plasma brain natriuretic peptide (BNP) in association with cardiac morphology and function in adults with growth hormone deficiency (GHD) was evaluated. Subjects and Methods: Fifty nine adult patients with GHD (29 men, age 19-59 years) received a starting dose of 0.1-0.2 mg/day recombinant GH, which was subsequently adjusted to the 50th percentile of normal serum insulin-like growth factor (IGF-1) over a 6 month period. Plasma BNP and IGF-I levels before, 3 and 6 months after treatment were determined, as were the echocardiographic data, such as ejection fraction (EF), left ventricular end-diastolic volume (LVEDV), left ventricular end-diastolic diameter (LVEDD), interventricular septal thickness (IVST), posterior wall thickness (PWT), left ventricular mass (LVM), E/A wave and deceleration time (DT). Results: Mean plasma BNP levels (53.1 +/- 8 pg/ml) and echocardiographic parameters were within the normal range at baseline, although men had higher LVM, IVST, PWT, LVEDV and LVEDD, respectively. A significant decrease in plasma BNP was observed after 6 months (27 +/- 5.6 pg/ml, P < 0.05). No significant changes in echocardiographic parameters were observed except for a mild tendency to increase in LVM, and a borderline decrease in DT (181 +/- 8.1 vs. 155 +/- 9 ms, P < 0.01). Conclusions: Six months GH replacement therapy induced a significant decrease in plasma BNP levels despite the majority of patients having plasma BNP within the normal range at baseline. A borderline decrease in diastolic deceleration time was observed, the clinical significance of which is unclear.
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| 3. |
- Sjöberg, Richard L, et al.
(författare)
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Verbal fluency in patients receiving bilateral versus left-sided deep brain stimulation of the subthalamic nucleus for Parkinson's disease
- 2012
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Ingår i: Journal of the International Neuropsychological Society. - : Cambridge University Press. - 1355-6177 .- 1469-7661. ; 18:3, s. 606-611
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to investigate the relative effects of unilateral (left-sided) versus bilateral deep brain stimulation (DBS) of the subthalamic nucleus (STN) on verbal fluency. To do this, 10 Parkinson's disease patients with predominantly bilateral motor symptoms who received bilateral STN DBS were compared with 6 patients suffering from predominantly unilateral symptoms who received STN DBS on the left side only. The results suggest that unilateral STN DBS of the speech dominant hemisphere is associated with significantly less declines in measures of verbal fluency as compared to bilateral stimulation. (JINS, 2012, 18, 606-611)
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| 4. |
- Wallstén, Elin, et al.
(författare)
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The Influence of Time Sampling on Parameters in the Logan Plot
- 2013
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Ingår i: 2013 IEEE NUCLEAR SCIENCE SYMPOSIUM AND MEDICAL IMAGING CONFERENCE (NSS/MIC). - 9781479905348
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Konferensbidrag (refereegranskat)abstract
- The Logan plot is a graphical method for reversible tracer bindings. The bias and uncertainties of this method have previously been analyzed with respect to noise, but little is known about the direct effects from varying the time sampling scheme. This study aims to investigate the effect of time sampling on the binding potential from the reference Logan plot. Image data from seven healthy subjects imaged with [11C]raclopride was reconstructed into six dynamic series of equal length time frames with frame times between 15 s and 480 s. Images were reconstructed using both filtered back projection (FBP) and a resolution enhanced ordered subset expectation maximization (OSEM) algorithm, SharpIR. For each sampling scheme, the nondisplaceable binding potential (BPND) parameter was calculated from the reference Logan plot with cerebellum as a reference region. The variation in BPND was analyzed as percentage deviations from the BPND for the 480 s scheme. R-2 of the linear fit was also analyzed. Comparison between all sampling schemes showed that the largest deviation in BPND was 7.4% between the 15 s sampling scheme and the 480 s sampling scheme reconstructed with SharpIR. The corresponding deviation for FBP images was 1.6%. R-2 was highest for long time frames, but all R-2 values were above 0.997 in this study.
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