Iterative Time-Varying Filter Algorithm Based on Discrete Linear Chirp Transform

Denoising of broadband non--stationary signals is a challenging problem in communication systems. In this paper, we introduce a time-varying filter algorithm based on the discrete linear chirp transform (DLCT), which provides local signal decomposition in terms of linear chirps. The method relies on the ability of the DLCT for providing a sparse representation to a wide class of broadband signals. The performance of the proposed algorithm is compared with the discrete fractional Fourier transform (DFrFT) filtering algorithm. Simulation results show that the DLCT algorithm provides better performance than the DFrFT algorithm and consequently achieves high quality filtering.Comment: 6 pages, conference pape

Effects of cryoprotectant concentration and cooling rate on vitrification of aqueous solutions

Vitrification of aqueous cryoprotectant mixtures is essential in cryopreservation of proteins and other biological samples. We report systematic measurements of critical cryoprotective agent (CPA) concentrations required for vitrification during plunge cooling from T=295 K to T=77 K in liquid nitrogen. Measurements on fourteen common CPAs including alcohols (glycerol, methanol, isopropanol), sugars (sucrose, xylitol, dextrose, trehalose), PEGs (ethylene glycol, PEG 200, PEG 2 000, PEG 20 000), glycols (DMSO, MPD), and salt (NaCl) were performed for volumes ranging over four orders of magnitude from ~nL to 20 mkL, and covering the range of interest in protein crystallography. X-ray diffraction measurements on aqueous glycerol mixtures confirm that the polycrystalline-to-vitreous transition occurs within a span of less than 2% w/v in CPA concentration, and that the form of polycrystalline ice (hexagonal or cubic) depends on CPA concentration and cooling rate. For most of the studied cryoprotectants, the critical concentration decreases strongly with volume in the range from ~5 mkL to ~0.1 mkL, typically by a factor of two. By combining measurements of the critical concentration versus volume with cooling time versus volume, we obtain the function of greatest intrinsic physical interest: the critical CPA concentration versus cooling rate during flash cooling. These results provide a basis for more rational design of cryoprotective protocols, and should yield insight into the physics of glass formation in aqueous mixtures.Comment: 8 pages, 6 jpg figure, 2 table

Numerical investigation of leakage behaviour in long radius elbows

This paper focuses on the relationship between leakage opening areas and pressure heads for 90° long radiuselbows under elastic limits using finite element analysis (SAP 2000). The results indicate that leakage opening areas grow linearly as the system pressure increases and the relation is described by the pressure–area slope (M). A sensitivity study was performed to show the effect of various parameters on M, as well as the leakage exponent (N). It was found that elbow internal diameter has the largest influence on the pressure–area slope, followed by the modulus of elasticity and finally elbow wall thickness. The longitudinal stress and Poisson’s ratio have a negligible effect on M. Furthermore, leak quantity is related to the pressure raised to a power ranging from 0.495 to 0.592. Regression analysis was used to derive an empirical equation to predict the pressure–area slope of round holes within elbows with different properties.Keywords: finite element analysis, leakage, leakage exponent, long radius elbows, pressur

Subband vector quantization of images using hexagonal filter banks

Journal ArticleAbstract Results of psychophysical experiments on human vision conducted in the last three decades indicate that the eye performs a multichannel decomposition of the incident images. This paper presents a subband vector quantization algorithm that employs hexagonal filter banks. The hexagonal filter bank provides an image decomposition similar to what the eye is believed to do. Consequently, the image coder is able to make use of the properties of the human visual system and produce compressed images of high quality at low bit rates. We present a systematic approach for optimal allocation of available bits among the subbands and also for the selection of the size of the vectors in each of the subbands

TARGET(R) Intracranial Aneurysm Coiling Prospective Multicenter Registry: Final Analysis of Peri-Procedural and Long-Term Safety and Efficacy Results

Background and Purpose: To describe the final results of the TARGET Registry, a multicenter, real-world study of patients with intracranial aneurysms treated with new generation TARGET Coils. . Methods: The TARGET Registry is a prospective, single-arm study with independent medical event monitoring and core-lab adjudication. Patients with de novo intracranial aneurysms were embolized with either TARGET-360 degrees or helical coils in 12 US centers. The primary outcome was aneurysm packing density (PD), which was assessed immediately post-procedure. The secondary outcomes were immediate and long-term aneurysm occlusion rate using the Raymond Scale, and independent functional outcome using the modified Rankin Scale (mRS). A secondary analysis investigated the influence of the use of 100% 360-complex coils on clinical and angiographic outcomes. Results: 148 patients with 157 aneurysms met the inclusion and exclusion criteria. 58 (39.2%) patients with ruptured and 90 (61.8%) with unruptured aneurysms were treated using TARGET 360 degrees , helical Coils, or both. Median age was 58.3 (IQR 48.1-67.4), 73% female, and 71.6% were Caucasian. Median follow-up time was 5.9 (IQR 4.0-6.9) months. The majority were treated with TARGET 360-coils (63.7%), followed by mixed and helical coils only. Peri-procedural morbidity and mortality was seen in 2.7% of patients. A good outcome at discharge (mRS 0-2) was seen in 89.9% of the full cohort, and in 84.5 and 93.3% in the ruptured and unruptured patients, respectively. The median packing density was 28.8% (IQR 20.3-41.1). Long-term complete and near complete occlusion rate was seen in 90.4% of aneurysms and complete obliteration was seen in 66.2% of the aneurysms. No significant difference in clinical and angiographic outcomes were noted between the pure 360-complex coiling vs. mixed 360-complex/Helical coiling strategies. In a multivariate analysis, predictors for long-term aneurysm occlusion were aneurysm location, immediate occlusion grade, and aneurysm size. The long-term independent functional outcome was achieved in 128/135 (94.8%) patients and all-cause mortality was seen in 3/148 (2%) patients. Conclusion: In the multicenter TARGET Registry, two-thirds of aneurysms achieved long-term complete occlusion and 91.0% achieved complete or near complete occlusion with excellent independent functional outcome. Clinical Trial Registration: www.ClinicalTrials.gov, identifier: NCT01748903

Time Dependent Capacity Increase for Driven Pile in Cohesionless Soil

The increase in driven pile capacity with time is termed set-up. The mechanism contributing to this phenomenon is not yet fully understood. Moreover, a rational approach to account for the increase in driven pile capacity with time in design has not yet been developed. In this study, a database comprising of 55 pile load tests (static and dynamic tests) were collected from the current engineering literature. The piles were driven in cohesionless soils with sand relative density varying from loose to dense. The measured capacities of the database piles with time were correlated to pile characteristics and soil properties. Pile set-up was found to be a phenomenon related to an increase in pile shaft friction with time and increases with decreasing pile diameter. On the other hand, pile setup was found to increase with increasing pile penetration depth and thus with pile slenderness ratio. A new approach for the estimation of pile set-up in cohesionless soils is presented in this study. The new approach considers the effects of pile characteristics and soil properties. Comparison of predicted and measured pile set-up using the developed method in this study indicates reasonable agreement. Also, comparison of prediction using the new approach with those made using previously published methods indicates that the developed method in this study yields better results

Abdominal Wall Mycetoma Presented as Obstructed Incisional Hernia of Cesarean Section in Eastern Sudan

Mycetoma a worldwide disease frequently occurs in the tropics with the highest prevalence being in Africa. Madurella mycetomatis is the main causative organism of human eumycetoma in Sudan. The legs and feet were commonly the sites of the infection. A 22-year-old lady was presented with painful abdominal swelling around a previous caesarian section scar. A provisional diagnosis of obstructed incisional hernia was put. Histopathological examination revealed macroscopically four masses of soft tissue. Microscopic sections showed grains of Madurella mycetomatis