4,701 research outputs found

    A new class of two-channel biorthogonal filter banks and wavelet bases

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    We propose a novel framework for a new class of two-channel biorthogonal filter banks. The framework covers two useful subclasses: i) causal stable IIR filter banks. ii) linear phase FIR filter banks. There exists a very efficient structurally perfect reconstruction implementation for such a class. Filter banks of high frequency selectivity can be achieved by using the proposed framework with low complexity. The properties of such a class are discussed in detail. The design of the analysis/synthesis systems reduces to the design of a single transfer function. Very simple design methods are given both for FIR and IIR cases. Zeros of arbitrary multiplicity at aliasing frequency can be easily imposed, for the purpose of generating wavelets with regularity property. In the IIR case, two new classes of IIR maximally flat filters different from Butterworth filters are introduced. The filter coefficients are given in closed form. The wavelet bases corresponding to the biorthogonal systems are generated. the authors also provide a novel mapping of the proposed 1-D framework into 2-D. The mapping preserves the following: i) perfect reconstruction; ii) stability in the IIR case; iii) linear phase in the FIR case; iv) zeros at aliasing frequency; v) frequency characteristic of the filters

    Bulk scalar field in DGP braneworld cosmology

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    We investigated the effects of bulk scalar field in the braneworld cosmological scenario. The Friedmann equations and acceleration condition in presence of the bulk scalar field for a zero tension brane and cosmological constant are studied. In DGP model the effective Einstein equation on the brane is obtained with bulk scalar field. The rescaled bulk scalar field on the brane in the DGP model behaves as an effective four dimensional field, thus standard type cosmology is recovered. In present study of the DGP model, the late-time accelerating phase of the universe can be explained .Comment: 10 pages, to appear in JCA

    Second Backbend in the Mass A ~ 180 Region

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    Within the framework of selfconsistent cranked Hartree-Fock- Bogoliubov theory(one-dimensional) we predict second backbend in the yrast line of Os-182 at I40I \approx 40 , which is even sharper than the first one observed experimentally at I14I \approx 14 . Around such a high spin the structure becomes multi-quasiparticle type, but the main source of this strong discontinuity is a sudden large alignment of i_13/2 proton orbitals along the rotation axis followed soon by the alignment of j_15/2 neutron orbitals. This leads to drastic structural changes at such high spins. When experimentally confirmed, this will be observed for the first time in this mass region, and will be at the highest spin so far.Comment: 13 pages, 4 ps figure

    Compared to What? Is BMI Associated with Histopathological Changes in Laparoscopic Sleeve Gastrectomy Specimens?

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    Background: Obesity is a risk for many different cancers. Laparoscopic sleeve gastrectomy (LSG) is common, and benign or pre-malignant histopathology types are reported in the removed gastric specimens. We assessed whether higher BMI was associated with certain benign or pre-malignant histopathological changes. Method: Retrospective chart review of all primary LSG patients (N = 1555). Demographic, clinical, and LSG histopathology data were retrieved. BMI of patients with specific benign or pre-malignant conditions in their gastric specimens was compared with the BMI of the rest of the patients with abnormal histopathology specimens and also compared with the BMI of patients with normal control specimens. Results: Females comprised 70% of the patients. Mean BMI were 46.3 (females) and 48 (males). Normal LSG specimens comprised 52%. Most common abnormal histopathologies were chronic inactive gastritis (33%), chronic active gastritis (6.8%), follicular gastritis (2.7%), lymphoid aggregates (2.2%), intestinal metaplasia (1.4%) and GIST (0.7%). After controlling for confounders (age, gender, H. pylori, diabetes mellitus type 2, hypertension), no significant association was observed between the BMI of patients with specific benign or pre-malignant histopathology compared with the BMI of the rest of the patients with abnormal histopathologies and compared to the BMI of patients with normal histopathologies. Conclusion: When confounders were taken into account, there appeared no significant associations between the BMI of patients with specific benign or pre-malignant histopathology compared with the BMI of the rest of the patients with abnormal histopathologies and compared to the BMI of patients with normal histopathologies of their gastric specimens. There was a very weak correlation between BMI and other covariates. - 2019, The Author(s).Acknowledgements Open Access funding provided by the Qatar National Library. The authors wish to thank Dr. Prem Chandra for assistance with the statistical analysis and the Medical Research Center at HMC for their support for the current study.Scopu

    A looking-out portal (LOP) approach to enhance qualitative aspects of bandwidth utilisation in academic networks

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    Campuses of educational institutions periodically need to increase network bandwidth to keep up with increased demand and this decision is based on the quantitative aspects of the network bandwidth utilisation. The qualitative utilisation of the bandwidth is seldom looked into. Improving the qualitative utilisation of the bandwidth may not even necessitate a network upgrade. Although blacklist-based access control techniques help to a certain degree, the findings of this research indicate otherwise. A multi-tier, whitelist-based, looking-out portal (LOP) approach is presented that promises to improve the qualitative utilisation of the network while positively impacting pertinent resource identification and location of sources on the internet. The authors draw on their years of experience serving as students and staff in various campuses of universities and colleges in various countries while making recommendations

    Gallbladder cancer: 7-Year experience from Qatar

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    Thirty-five patients presented with GC during the study period, 10 females (28.6%) and 25 males (71.4%). Fourteen patients (40%) were diagnosed incidentally after laparoscopic cholecystectomy, 16 (48.6%) were diagnosed pathologically, and 4 (11.4%) were diagnosed radiologically. The median age at diagnosis was 54 years (31–78). 74.3% of the disease occurred in patients less than 60 years old. Metastatic disease was discovered in 25 patients (71.4%) versus no metastasis in 10 patients (28.6%). The most common sites for metastasis were the liver (42.9%), peritoneum (25.7%), and lymph nodes (25.7%). Curative central hepatic resection was done in 8 patients (22.9%). Pathology showed adenocarcinoma in 27 patients (77.1%), neuroendocrine tumor in 3 patients (8.6%) and high-grade dysplasia in 1 patient (2.9%). No histopathology was available for 4 patients (11.4%). Twenty-eight patients (80.0%) had regular follow up, with 22 (62.9%) still alive. Six patients (17.1%) died during follow up with survival after diagnosis ranging from 42 days to 6.8 years
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