Abstract-In this paper we propose a novel approach to implement multiplierless unity-gain SDF FFTs. Previous methods achieve unity-gain FFTs by using either complex multipliers or non-unity-gain rotators with additional scaling compensation. Conversely, this paper proposes unity-gain FFTs without compensation circuits, even when using non-unity-gain rotators. This is achieved by a joint design of rotators so that the entire FFT is scaled by a power of two, which is then shifted to unity. This reduces the amount of hardware resources of the FFT architecture, while having high accuracy in the calculations. The proposed approach can be applied to any FFT size and various designs for different FFT sizes are presented.
In this paper, we present a new approach to simplify fast Fourier transform (FFT) hardware architectures. The new approach is based on a group of transformations called decimation, reduction, center, move and merge. By combining them it is possible to transform the rotators at different FFT stages, move them to other stages and merge them in such a way that the resulting rotators are simpler than the original ones. The proposed approach can be combined with other existing techniques such coefficient selection and shift-and-add implementation, or rotator allocation in order to obtain low-complexity FFT hardware architectures. To show the effectiveness of the proposed approach, it has been applied to single-path delay feedback (SDF) FFT hardware architectures, where it is observed that the complexity of the rotators is reduced up to 33%.
Background Colectomy and reconstruction in patients with inflammatory bowel disease (IBD) may adversely affect fertility, but few population-based studies are available. Methods Fertility was assessed in 2,989 women and 3,771 men with IBD and prior colectomy 1964-2014, identified from the Swedish National Patient Register, and 35,092 matched population-based individuals. Results Reconstruction with ileoanal pouch anastomosis (IPAA) was as common as ileorectal anastomosis (IRA) in ulcerative colitis (UC) and IBD-unclassified (IBD-U) while rare in Crohn’s disease (CD). Compared with the matched non-IBD cohort, women with IBD had lower fertility overall post colectomy (HR 0.65, CI 0.61-0.69). The impact was least in patients with colectomy only with the rectum left intact (HR 0.79, CI 0.70–0.90) and more pronounced after reconstructive surgery. Comparing the surgical options within the cohort of women with colectomy for IBD using colectomy only as reference, fertility in female patients remained unaffected after IRA (HR 0.86, CI 0.63-1.17 for UC, 0.86, CI 0.68-1.08 for IBD-U and 1.07, CI 0.70-1.63 for CD), but was impaired after IPAA, especially in UC (HR 0.67 CI 0.50-0.88), and after completion proctectomy (HR 0.65, CI 0.49-0.85 for UC, 0.68, CI 0.55-0.85 for IBD-U and 0.61, CI 0.38-0.96 for CD). In men, fertility was marginally reduced in the entire cohort post colectomy (HR 0.89, CI 0.85-0.94), regardless of reconstruction. Conclusion Fertility was reduced in women after colectomy for IBD. The least impact was seen with a deviated rectum left in situ. IRA was associated with no further reduction in fertility, whereas proctectomy with or without IPAA were associated with the strongest impairment. IRA therefore seems to be the preferred reconstruction to preserve fertility in selected female patients. Fertility in men was only moderately reduced after colectomy and reconstructive choice.
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