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- Hemmendorff, M., et al.
(författare)
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Motion compensated digital subtraction angiography
- 1999
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Ingår i: Proceedings of SPIE's International Symposium on Medical Imaging, vol 3661, 1999.
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Konferensbidrag (refereegranskat)abstract
- Digital subtraction angiography, whether based on traditional X-ray or MR, suers from patient motion artifacts. Until now, the usual remedy is to pixel shift by hand, or in some cases performing a global pixel shift semi-automatically. This is time consuming, and cannot handle rotations or local varying deformations over the image. We have developed a fully automatic algorithm that provides for motion compensation in the presence of large local deformations. Our motion compensation is very accurate for ordinary motions, including large rotations and deformations. It does not matter if the motions are irregular over time. For most images, it takes about a second per image to get adequate accuracy. The method is based on using the phase from lter banks of quadrature lters tuned in dierent directions and frequencies. Unlike traditional methods for optical ow and correlation, our method is more accurate and less susceptible to disturbing changes in the image, e.g. a moving contrast bolus. The implications for common practice are that radiologists' time can be significantly reduced in ordinary peripheral angiographies and that the number of retakes due to large or local motion artifacts will be much reduced.
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- Jernström, Helena, et al.
(författare)
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Temporary increase of FSH levels in healthy, nulliparous, young women after cessation of low-dose oral contraceptive use
- 1995
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Ingår i: Contraception. - 0010-7824. ; 52:1, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- PIP: At the University Hospital in Lund, Sweden, researchers grouped healthy nulliparous women aged 19-25 into current, former, and never users of low-dose combined oral contraceptives (OCs) to examine the effect of the OCs on the levels of follicle stimulating hormone (FSH) and luteinizing hormone (LH). The subjects were from two independent samples. Based on the day the blood was sampled, their hormone level readings were divided into follicular and luteal phases. Former OC users had higher FSH levels than did never users, regardless of menstrual cycle phase (group 1: 1.9 vs. 1.6 mcg/l for follicular phase, 1.6 vs. 1 mcg/l for luteal phase; p = 0.004) (group 2: 2.05 vs. 1.7 mcg/l, 1.55 vs. 1.25 mcg/l; p = 0.028). The transient increase of FSH levels appeared to peak 12 months after the women stopped using the OC. The researchers found that the temporary increase in FSH levels was still significant after they excluded eight women with low progesterone levels (10 nmol/l in luteal phase and 3.5 nmol/l in follicular phase) and adjusted for age (p = 0.015). LH levels were much higher in former users than never users in the first sample (1.6 vs. 1 mcg/l for follicular phase, 1.8 vs. 1.15 mcg/l for luteal phase; p = 0.014), but not in the second sample. Smoking and time since awakening had no effect on FSH and LH levels. Present users experienced suppressed FSH and LH levels. These findings indicate that former OC users experience a rebound-like phenomenon in FSH levels. Since the sample size was small and only one blood sample was taken from each woman at each of the sampling times, the researchers caution that these findings are preliminary and unconfirmed.
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- Knutsson, B, et al.
(författare)
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Adaptive end-to-end compression for variable-bandwidth communication
- 1999
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Ingår i: COMPUTER NETWORKS-THE INTERNATIONAL JOURNAL OF COMPUTER AND TELECOMMUNICATIONS NETWORKING. - : ELSEVIER SCIENCE BV. - 1389-1286. ; 31:7, s. 767-779
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In this paper, we present a model for transport level compression with dynamic compression level adaptation, and we present an implementation of this model in Linux TCP, together with measurements showing what performance to expect when using adaptable en
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