| 1. |
- Ahmad, Sajjad, et al.
(författare)
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Novel mutations in genes of the IL-12/IFN-γ axis cause susceptibility to tuberculosis
- 2023
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Ingår i: Journal of Infection and Public Health. - : Elsevier. - 1876-0341 .- 1876-035X. ; 16:9, s. 1368-1378
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Tidskriftsartikel (refereegranskat)abstract
- Background: The IL-12/23/ISG15-IFN-γ pathway is the main immunological pathway for controlling intra-macrophagic microorganisms such as Mycobacteria, Salmonella, and Leishmania spp. Consequently, upon mutations in genes of the IL-12/23/ISG15-IFN-γ pathway cause increased susceptibility to intra-macrophagic pathogens, particularly to Mycobacteria. Therefore, the purpose of this study was to characterize the mutations in genes of the IL-12/23/ISG15-IFN-γ pathway in severe tuberculosis (TB) patients.Methods: Clinically suspected TB was initially confirmed in four patients (P) (P1, P2, P3, and P4) using the GeneXpert MTB/RIF and culturing techniques. The patients' Peripheral blood mononuclear cells (PBMCs) were then subjected to ELISA to measure Interleukin 12 (IL-12) and interferon gamma (IFN-γ). Flow cytometry was used to detect the surface expressions of IFN-γR1 and IFN-γR2 as well as IL-12Rβ1and IL-12Rβ2 on monocytes and T lymphocytes, respectively.The phosphorylation of signal transducer and activator of transcription 1(STAT1) on monocytes and STAT4 on T lymphocytes were also detected by flow cytometry. Sanger sequencing was used to identify mutations in the IL-12Rβ1, STAT1, NEMO, and CYBB genes.Results: P1's PBMCs exhibited reduced IFN-γ production, while P2's and P3's PBMCs exhibited impaired IL-12 induction. Low IL-12Rβ1 surface expression and reduced STAT4 phosphorylation were demonstrated by P1's T lymphocytes, while impaired STAT1 phosphorylation was detected in P2's monocytes. The impaired IκB-α degradation and abolished H2O2 production in monocytes and neutrophils of P3 and P4 were observed, respectively. Sanger sequencing revealed novel nonsense homozygous mutation: c.191 G>A/p.W64 * in exon 3 of the IL-12Rβ1 gene in P1, novel missense homozygous mutation: c.107 A>T/p.Q36L in exon 3 of the STAT1 gene in P2, missense hemizygous mutation:: c.950 A>C/p.Q317P in exon 8 of the NEMO gene in P3, and nonsense hemizygous mutation: c.868 C>T/p.R290X in exon 8 of CYBB gene in P4.Conclusion: Our findings broaden the clinical and genetic spectra associated with IL-12/23/ISG15-IFN-γ axis anomalies. Additionally, our data suggest that TB patients in Pakistan should be investigated for potential genetic defects due to high prevalence of parental consanguinity and increased incidence of TB in the country.
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| 2. |
- Ahmed, Sairah, et al.
(författare)
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Impact of type of reduced-intensity conditioning regimen on the outcomes of allogeneic haematopoietic cell transplantation in classical Hodgkin lymphoma
- 2020
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Ingår i: British Journal of Haematology. - : WILEY. - 0007-1048 .- 1365-2141. ; 190:4, s. 573-582
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Tidskriftsartikel (refereegranskat)abstract
- Reduced-intensity conditioning (RIC) allogeneic haematopoietic cell transplantation (allo-HCT) is a curative option for select relapsed/refractory Hodgkin lymphoma (HL) patients; however, there are sparse data to support superiority of any particular conditioning regimen. We analyzed 492 adult patients undergoing human leucocyte antigen (HLA)-matched sibling or unrelated donor allo-HCT for HL between 2008 and 2016, utilizing RIC with either fludarabine/busulfan (Flu/Bu), fludarabine/melphalan (Flu/Mel140) or fludarabine/cyclophosphamide (Flu/Cy). Multivariable regression analysis was performed using a significance level of <0 center dot 01. There were no significant differences between regimens in risk for non-relapse mortality (NRM) (P = 0 center dot 54), relapse/progression (P = 0 center dot 02) or progression-free survival (PFS) (P = 0 center dot 14). Flu/Cy conditioning was associated with decreased risk of mortality in the first 11 months after allo-HCT (HR = 0 center dot 28; 95% CI = 0 center dot 10-0 center dot 73; P = 0 center dot 009), but beyond 11 months post allo-HCT it was associated with a significantly higher risk of mortality, (HR = 2 center dot 46; 95% CI = 0 center dot 1.32-4 center dot 61; P = 0 center dot 005). Four-year adjusted overall survival (OS) was similar across regimens at 62% for Flu/Bu, 59% for Flu/Mel140 and 55% for Flu/Cy (P = 0 center dot 64), respectively. These data confirm the choice of RIC for allo-HCT in HL does not influence risk of relapse, NRM or PFS. Although no OS benefit was seen between Flu/Bu and Flu/Mel 140; Flu/Cy was associated with a significantly higher risk of mortality beyond 11 months from allo-HCT (possibly due to late NRM events).
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| 3. |
- Badshah, Munair, et al.
(författare)
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Development and Evaluation of Drug Loaded Regenerated Bacterial Cellulose-Based Matrices as a Potential Dosage Form
- 2020
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Ingår i: Frontiers in Bioengineering and Biotechnology. - : Frontiers Media SA. - 2296-4185. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Bacterial cellulose (BC) is a highly pure form of cellulose and possesses superior physico-mechanical properties with wide range of applications. These properties of BC can further be improved by various modifications, including its regeneration from the BC solution. In the current research work, regenerated BC (R-BC) matrices were prepared using N-methyl-morpholine-oxide (NMMO; 50% w/w solution in water) and loaded with model drugs, i.e., famotidine or tizanidine. The characterization of drug loaded regenerated BC (R-BC-drug) matrices was carried out using Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD) analysis, scanning electron microscopy (SEM) and thermogravimetric analysis (TGA), which revealed the stability of matrices and successful drug loading. Results of dissolution studies showed immediate (i.e., >90%) drug release in 30 min. The drugs release data was found to best fit into first order kinetics model having R2 values >0.99 for all the formulations. These results indicated that regenerated BC-based matrices had the ability to be used for delivery of orally administered drugs.
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| 4. |
- Casulo, Carla, et al.
(författare)
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Autologous Transplantation in Follicular Lymphoma with Early Therapy Failure : A National LymphoCare Study and Center for International Blood and Marrow Transplant Research Analysis
- 2018
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Ingår i: Biology of blood and marrow transplantation. - : Elsevier BV. - 1083-8791 .- 1523-6536. ; 24:6, s. 1163-1171
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Tidskriftsartikel (refereegranskat)abstract
- Patients with follicular lymphoma (FL) experiencing early therapy failure (ETF) within 2 years of frontline chemoimmunotherapy have poor overall survival (OS). We analyzed data from the Center for International Blood and Marrow Transplant Research (CIBMTR) and the National LymphoCare Study (NLCS) to determine whether autologous hematopoietic cell transplant (autoHCT) can improve outcomes in this high-risk FL subgroup. ETF was defined as failure to achieve at least partial response after frontline chemoimmunotherapy or lymphoma progression within 2 years of frontline chemoimmunotherapy. We identified 2 groups: the non-autoHCT cohort (patients from the NLCS with ETF not undergoing autoHCT) and the autoHCT cohort (CIBMTR patients with ETF undergoing autoHCT). All patients received rituximab-based chemotherapy as frontline treatment; 174 non-autoHCT patients and 175 autoHCT patients were identified and analyzed. There was no difference in 5-year OS between the 2 groups (60% versus 67%, respectively; P = .16). A planned subgroup analysis showed that patients with ETF receiving autoHCT soon after treatment failure (≤1 year of ETF; n = 123) had higher 5-year OS than those without autoHCT (73% versus 60%, P = .05). On multivariate analysis, early use of autoHCT was associated with significantly reduced mortality (hazard ratio, .63; 95% confidence interval, .42 to .94; P = .02). Patients with FL experiencing ETF after frontline chemoimmunotherapy lack optimal therapy. We demonstrate improved OS when receiving autoHCT within 1 year of treatment failure. Results from this unique collaboration between the NLCS and CIBMTR support consideration of early consolidation with autoHCT in select FL patients experiencing ETF.
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| 5. |
- Chauhan, Shakti, et al.
(författare)
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Designing peptide-based vaccine candidates for Plasmodium falciparum erythrocyte binding antigen 175
- 2020
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Ingår i: Biologicals (Print). - : Elsevier. - 1045-1056 .- 1095-8320. ; 67, s. 42-48
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Tidskriftsartikel (refereegranskat)abstract
- Plasmodium falciparum leads to a virulent form of malaria. Progress has been achieved in understanding the mechanisms involved in the malarial infection, still there is no effective vaccine to prevent severe infection. An effective vaccine against malaria should be one which can induce immune responses against multiple epitopes in the context of predominantly occurring HLA alleles. In this study, an integrated approach was employed to identify promiscuous peptides of a well-defined sequence of erythrocyte binding antigen-175 and promiscuous peptides for HLA alleles were designed using bioinformatics tools. A peptide with 15 amino acids (ILAIAIYESRILKRK) was selected based on its high binding affinity score and synthesized. This promiscuous peptide was used as stimulating antigen in lymphoproliferative responses to evaluate the cellular immune response. It was observed this peptide evokes lymphoproliferative and cytokine responses in individuals naturally exposed to the malaria parasite. The intensity of PBMCs proliferation was observed to be higher in sera obtained from P. falciparum exposed as compared to unexposed healthy individuals, suggesting earlier recognition of peptide of this region by T cells. Furthermore, the binding mode of HLA–peptide complex and their interaction may lead to a rational and selective peptide-based vaccine candidate design approach which can be used as a malaria prophylaxis.
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| 6. |
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| 7. |
- Farooq, Muhammad Umar, 1973, et al.
(författare)
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EBSD characterization of carbide-carbide boundaries in WC-Co
- 2004
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Ingår i: Journal of Microscopy. ; 213:March, s. 306-312
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Tidskriftsartikel (refereegranskat)abstract
- A sample of WC-6wt%Co was investigated for grain boundary character distribution and occurence of coincidence site lattice (CSL) boundaries on a statistical basis. For this purpose orientation measurements of the grains were carried out using electron back-scattered diffraction (EBSD). The dominant misorientation relationships were determined by complementary EBSD data representation tools such as orientatin maps, misorientation angle distribution histograms and the sectioned three-dimensional misorientation space. It was found that the grain boundary character distribution of the material is nearly random and the CSL boundaries are not present in statistically significant amounts. It was also found that the amount of binder phase does not play a role in the formation of special boundaries. The paper focuses on the methodology of characterizing grain boundaries in a hexagonal material using EBSD.
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| 8. |
- Farooq, Muhammad Umar, et al.
(författare)
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Improving the Thresholds of Generalized LDPC Codes with Convolutional Code Constraints
- 2023
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Ingår i: IEEE Communications Letters. - 1558-2558 .- 1089-7798. ; 27:7, s. 1679-1683
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Tidskriftsartikel (refereegranskat)abstract
- CC-GLPDC codes are a class of generalized low-density parity-check (GLDPC) codes where the constraint nodes (CNs) represent convolutional codes. This allows for efficient decoding in the trellis with the forward-backward algorithm, and the strength of the component codes easily can be controlled by the encoder memory without changing the graph structure. In this letter, we extend the class of CC-GLDPC codes by introducing different types of irregularity at the CNs and investigating their effect on the BP and MAP decoding thresholds for the binary erasure channel (BEC). For the considered class of codes, an exhaustive grid search is performed to find the BP-optimized and MAP-optimized ensembles and compare their thresholds with the regular ensemble of the same design rate. The results show that irregularity can significantly improve the BP thresholds, whereas the thresholds of the MAP-optimized ensembles are only slightly different from the regular ensembles. Simulation results for the AWGN channel are presented as well and compared to the corresponding thresholds.
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| 9. |
- Farooq, Muhammad Umar, 1973, et al.
(författare)
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Microstructual investigation of Co-Cr clad applied on railway wheels
- 2004
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Ingår i: Proceedings of the Channel User Meeting 2004, Ribe, Denmark.. ; , s. 25-30
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Laser cladding is applied to locally improve the functional surface properties of parts such as wear resistance (increased surface hardness) and corrosion resistance. In the present study the EBSD technique was used to investigate microstructure and textur of a Co-Cr-clad applied on railway wheels. The investigations showed that the clad consists of elongated grains that grow perpendicular to the clad surface with a [001] fibre texture. The investigations also revealed that no dominant orientation relationship (angle/axis pair) occurs between the alpha-Co grains of the clad. The relative orientation between the alpha-Co (high temperature) and gamma-Co (low temperature) phase is determined by comparing the pole figures of the respective phases. Different reasons of aprupt changes in the colors of the orientation maps are also discussed.
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| 10. |
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| 11. |
- Farooq, Muhammad Umar, et al.
(författare)
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Spatially-Coupled Serially Concatenated Codes with Periodic Convolutional Permutors
- 2021
-
Ingår i: 2021 11th International Symposium on Topics in Coding, ISTC 2021. - 9781665409438
-
Konferensbidrag (refereegranskat)abstract
- Spatially-coupled serially concatenated codes (SC-SCCS) are a class of turbo-like codes constructed by interconnecting a sequence of SCCS using a set of block permutors. At short block lengths, however, the bit-error-rate (BER) performance of SC-SCCS constructed by independent block permutors exhibits a high error floor. In this paper, we propose an alternative method for constructing SC-SCCS to mitigate this problem. Particularly, we use a family of periodically time-varying blockwise convolutional permutors with flexible block length. We derive these convolutional permutors from a block permutor of an optimized spread by applying an unwrapping procedure. We prove that for any chosen block length, the unwrapping procedure preserves the spread of the original block permutor. We further present an efficient implementation method for the blockwise convolutional permutor that derives the permutation indices directly from those of the underlying block permutor. Considering both S-random permutors and quadratic permutation polynomial (QPP) permutors, we perform BER simulations for SC-SCCS with decoding latencies 4096 and 16384. Numerical results show that SC-SCCS based on the proposed convolutional permutors have no visible error floor, which is especially notable at short block lengths.
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| 12. |
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| 13. |
- Farooq, Muhammad Umar, et al.
(författare)
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Threshold Computation for Spatially Coupled Turbo-Like Codes on the AWGN Channel
- 2021
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Ingår i: Entropy. - : MDPI AG. - 1099-4300. ; 23:2
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we perform a belief propagation (BP) decoding threshold analysis of spatially coupled (SC) turbo-like codes (TCs) (SC-TCs) on the additive white Gaussian noise (AWGN) channel. We review Monte-Carlo density evolution (MC-DE) and efficient prediction methods, which determine the BP thresholds of SC-TCs over the AWGN channel. We demonstrate that instead of performing time-consuming MC-DE computations, the BP threshold of SC-TCs over the AWGN channel can be predicted very efficiently from their binary erasure channel (BEC) thresholds. From threshold results, we conjecture that the similarity of MC-DE and predicted thresholds is related to the threshold saturation capability as well as capacity-approaching maximum a posteriori (MAP) performance of an SC-TC ensemble.
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| 14. |
- Farooq, Muhammad Umar, et al.
(författare)
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Thresholds of Braided Convolutional Codes on the AWGN Channel
- 2018
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Ingår i: 2018 IEEE International Symposium on Information Theory, ISIT 2018. - 9781538647806 ; 2018-June, s. 1375-1379
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Konferensbidrag (refereegranskat)abstract
- In this paper, we perform a threshold analysis of braided convolutional codes on the additive white Gaussian noise (AWGN) channel. The decoding thresholds are estimated by Monte-Carlo density evolution techniques and compared with approximate thresholds from an erasure channel prediction. The results show that, with spatial coupling, the predicted thresholds are very accurate and quickly approach capacity if the coupling memory is increased. For uncoupled ensembles with random puncturing, the prediction can be improved with help of the AWGN threshold of the unpunctured ensemble.
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| 15. |
- Farooq, Muhammad Umar, 1973
(författare)
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Use of EBSD Technique as a Means to Investigate the Microstructure of Engineering Materials
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- AbstractMaterials Science and Engineering has the aim to design or engineer the structure of a material to produce a predetermined set of properties. To be able to understand and predict the properties and observable characteristics of engineering materials, it is therefore necessary to understand their microstructure. With the evolution of new measuring techniques, the range of obtainable information is usually extended, i.e. materials features can be investigated which were not accessible before and/or the data can be obtained easier or in a statistical more significant amount. This work was executed with the aim to provide knowledge on to which extent the electron backscatter diffraction technique, a relatively new method in the field of electron microscopy, can be used to characterise engineering materials. Hence, the study includes investigations of three different types of materials such as WC-Co composite, Co-Cr-Mo laser clad, and coronary artery stents respectively thin steel wires, and describes conventional as well as more dedicated EBSD work.EBSD was able to provide statistical information on the occurrence of special boundaries in WC-Co composites. Furthermore, it could be shown that the frequency of occurrence of Σ2 boundaries in the composite is not affected by the Co content (the binder phase). Combined with TEM investigations and ab initio calculations, EBSD could provide a better understanding of the deformation behaviour of WC-Co composites. The example of Co-Cr-Mo clad has shown that by combining EBSD and EDX analysis, a complete overview of the microstructure is obtained. It has also been shown that the EBSD technique is an effective tool for investigating the microstructure evolution during deformation and for describing the microstructuremechanical properties relationship. EBSD was also applied to materials with oligocrystalline structures (coronary stents/thin steel wires). The preliminary results on the thin wires have shown that it is possible to perform deformation series experiments and to obtain useful orientation data on individual grains.
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| 16. |
- Mahdavi, Mojtaba, et al.
(författare)
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The Effect of Coupling Memory and Block Length on Spatially Coupled Serially Concatenated Codes
- 2020
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Ingår i: IEEE 93rd Vehicular Technology Conference (VTC). - 9781728189659 - 9781728189642 ; , s. 1-7
-
Konferensbidrag (refereegranskat)abstract
- Spatially coupled serially concatenated codes (SC-SCCs) are a class of spatially coupled turbo-like codes, which have a close-to-capacity performance and low error floor. In this paper, we perform a comprehensive design space exploration, revealing different aspects of SC-SCCs and discussing various design trade-offs. In particular, we investigate the impact of coupling memory, block length, decoding window size, and number of iterations on the performance, complexity, and latency of SC-SCCs. As a result, we propose design guidelines to make the code design independent of the block length. By introducing a modified window decoding schedule, we are able to demonstrate that the block length and coupling memory can be exchanged flexibly without changing the latency and complexity of decoding and without performance loss. Thus, thanks to spatial coupling, a certain code strength and performance can be achieved by either a very small block length or a large one, while the complexity and latency are fixed. Moreover, our results show that using higher coupling memory with smaller blocks can even improve the performance without increasing the latency and complexity. For all considered cases we observe that the performance of SC-SCCs is improved with respect to the uncoupled ensembles for a fixed latency and complexity.
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| 17. |
- Olszewski, Adam J., et al.
(författare)
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Burkitt Lymphoma International Prognostic Index
- 2021
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Ingår i: Journal of clinical oncology : official journal of the American Society of Clinical Oncology. - 0732-183X. ; 39:10, s. 1129-1138
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Burkitt lymphoma (BL) has unique biology and clinical course but lacks a standardized prognostic model. We developed and validated a novel prognostic index specific for BL to aid risk stratification, interpretation of clinical trials, and targeted development of novel treatment approaches. METHODS: We derived the BL International Prognostic Index (BL-IPI) from a real-world data set of adult patients with BL treated with immunochemotherapy in the United States between 2009 and 2018, identifying candidate variables that showed the strongest prognostic association with progression-free survival (PFS). The index was validated in an external data set of patients treated in Europe, Canada, and Australia between 2004 and 2019. RESULTS: In the derivation cohort of 633 patients with BL, age ≥ 40 years, performance status ≥ 2, serum lactate dehydrogenase > 3× upper limit of normal, and CNS involvement were selected as equally weighted factors with an independent prognostic value. The resulting BL-IPI identified groups with low (zero risk factors, 18% of patients), intermediate (one factor, 36% of patients), and high risk (≥ 2 factors, 46% of patients) with 3-year PFS estimates of 92%, 72%, and 53%, respectively, and 3-year overall survival estimates of 96%, 76%, and 59%, respectively. The index discriminated outcomes regardless of HIV status, stage, or first-line chemotherapy regimen. Patient characteristics, relative size of the BL-IPI groupings, and outcome discrimination were consistent in the validation cohort of 457 patients, with 3-year PFS estimates of 96%, 82%, and 63% for low-, intermediate-, and high-risk BL-IPI, respectively. CONCLUSION: The BL-IPI provides robust discrimination of survival in adult BL, suitable for use as prognostication and stratification in trials. The high-risk group has suboptimal outcomes with standard therapy and should be considered for innovative treatment approaches.
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| 18. |
- Umar Farooq, Muhammad
(författare)
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Sparse Codes on Graphs with Convolutional Code Constraints
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern coding theory is based on the foundation of the sparse codes on graphs, such as the low-density parity-check (LDPC) codes, and the turbo-like codes (TCs) with component convolutional codes. The success of the LDPC codes and the TCs lies in their ability to perform low-complexity iterative message passing decoding procedures. The iterative message passing decoders that exchange messages probabilities, or beliefs, within the code graph are known as the belief propagation (BP) decoders. The BP decoders are sub-optimal, whereas maximum-a-posteriori (MAP) decoders for these codes are computationally infeasible. These codes can be optimized for their BP decoding performance, which improves their error rate performance in the waterfall region at the cost of a performance loss in the error-floor region. On the contrary, optimizing these codes for the MAP performance results in an improved performance in the error-floor region at the expense of a degraded performance in the waterfall region.In practice, the BP decoding performance of the LDPC codes and the TCs, in the asymptotic block length regime, is determined by computing their BP decoding thresholds from the density evolution (DE), or the extrinsic information transfer (EXIT) chart techniques. The MAP decoding thresholds can be obtained with an application of the area theorem to the BP decoder performance. The graphs of the LDPC codes and the TCs are optimized for the BP, and the MAP decoding performance by using their decoding thresholds. For very large block lengths, spatially coupled (SC) versions of LDPC codes, and the TCs-which are optimized for MAP decoding performance- were shown to achieve excellent BP decoding performance in both the waterfall and the error-floor region, thanks to the threshold saturation. However, the BP decoding performance of these spatially coupled codes suffer from a high error-floor at a moderate to short code block length.BP and MAP decoding thresholds of TCs on a binary erasure channel (BEC) have previously been investigated via the DE analysis. The capacity achieving SC-TCs were determined, where the underlying TCs were optimized for the BP and MAP performance. The TCs ensembles, parallel concatenated codes, serially concatenated codes, braided convolutional codes, and hybrid concatenated codes, with varying component convolutional codes strengths were considered in these investigations.This thesis focuses on investigating the BP decoding performance of SC-TCs- which were earlier investigated for the BEC- on an additive white Gaussian noise (AWGN) channel. Furthermore, the problem of high error-floor of SC-TCs for short to moderate block lengths is investigated and addressed with a design of an optimized convlutional permutor in constructing the SC-TCs. Finally, the connection of the TCs and the LDPC codes is explored by introducing a family of convolutional codes (CC) based generalized LDPC codes (GLDPCs). These research areas are summarized under the following three topics.In the first topic, we have computed the iterative decoding thresholds of SC-TCs on the AWGN channel via the Monte Carlo density evolution (MC-DE) methods. The MC-DE methods are time consuming, which has motivated us to introduce an efficient alternative that predicts the AWGN thresholds of SC-TCs with the knowledge of their BEC thresholds. The results show that the estimated thresholds via the MC-DE method and the predicted thresholds are very close for the capacity achieving randomly punctured SC-TCs. For the high rate uncoupled TCs, which are obtained by randomly puncturing their mother code, the predicted thresholds are improved by incorporating the estimated AWGN threshold of the mother code ensemble into the threshold prediction method.In the second topic, we have introduced the design of a single block-wise periodic time-varying convolutional permutor to construct the SC-TCs. The convolutional permutor is designed by applying the unwrapping procedure to an optimized block permutor, which optimize the bit error rate (BER) performance of a TC in an error-floor region. We showed that a convolutional permutor obtained via the unwrapping procedure inherits the properties of its parent permutor. Due to this reason, the BER performance of block-wise periodically time-varying convolutional permutor based SC-SCCs does not suffer from a high error-floor problem at short block lengths, which was demonstrated through the simulation results.In the third topic, we have introduced the families of regular and irregular CC-GLDPCs. The CC-GLDPCs enabled us to connect TCs and LDPC codes in terms of their graph structures. The BEC thresholds and the minimum distance properties of the regular CC-GLDPCs were compared to the regular LDPC codes. Furthermore, we performed an exhaustive grid search using the BEC thresholds of the class of CC-GLDCPs, and determined the design configurations of optimized CC-GLDPCs. The results suggest that, for regular graphs, it is possible to find a sparser CC-GLDPCs than the LDPC codes at the expense of a slightly negligible loss in the performance. Furthermore, the BP optimized CC-GLDPC is observed to have a better BP and MAP thresholds than the turbo codes on the BEC.
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| 19. |
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| 20. |
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| 21. |
- Östberg, Gustaf, 1971, et al.
(författare)
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Effect of Sigma2 grain boundaries on plastic deformation of WC-Co cemented carbides
- 2006
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Ingår i: Mat. Sci. and Eng. A.. ; 416, s. 119-
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Tidskriftsartikel (refereegranskat)abstract
- Cutting inserts of WC–6 wt.% Co were investigated before and after plastic deformation. The deformation tests were performed with a turning operation under realistic, yet controlled, conditions. SEM studies showed that after deformation the WC skeleton structure had broken up and thin lamellae of binder phase had formed in less than 10% of the grain boundaries. Ab initio calculations showed that ∑2 twist WC/WC boundaries have a high work of separation and the interface energy is not lowered by forming two Co/WC boundaries. Electron backscattered diffraction (EBSD) measurements showed an apparent increase in the relative occurrence of ∑2 boundaries due to poor indexing of the deformed material. The accumulation of dislocations in general boundaries is held responsible for the difficulty in identifying them compared with ∑2 boundaries. At the ∑2 tilt boundary the grains have the glide planes {1 0 -1 0} in common and at the ∑2 twist boundary there are three glide planes intersecting, which facilitate dislocation movements across the ∑2 boundaries.
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| 22. |
- Bravo, L, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 23. |
- Tabiri, S, et al.
(författare)
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- 2021
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swepub:Mat__t
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