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- Ahmad, Bilal, et al.
(author)
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The Perfect Match : RIS-enabled MIMO Channel Estimation Using Tensor Decomposition
- 2023
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Other publication (other academic/artistic)abstract
- The deployment of reconfigurable intelligent surfaces (RISs) in a communication system provides control over the propagation environment, which facilitates the augmentation of a multitude of communication objectives. As these performance gains are highly dependent on the applied phase shifts at the RIS, accurate channel state information at the transceivers is imperative. However, not only do RISs traditionally lack signal processing capabilities, but their end-to-end channels also consist of multiple components. Hence, conventional channel estimation (CE) algorithms become incompatible with RIS-aided communication systems as they fail to provide the necessary information about the channel components, which are essential for a beneficial RIS configuration. To enable the full potential of RISs, we propose to use tensor-decomposition-based CE, which facilitates smart configuration of the RIS by providing the required channel components. We use canonical polyadic (CP) decomposition, that exploits a structured time domain pilot sequence. Compared to other state-of-the-art decomposition methods, the proposed Semi-Algebraic CP decomposition via Simultaneous Matrix Diagonalization (SECSI) algorithm is more time efficient as it does not require an iterative process. The benefits of SECSI for RIS-aided networks are validated with numerical results, which show the improved individual and end-to-end CE accuracy of SECSI.
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- Ullah, Zia, et al.
(author)
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Perceived accuracy of electronic performance appraisal systems : The case of a non‐for‐profit organization from an emerging economy
- 2021
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In: Sustainability (Switzerland). - : MDPI AG. - 2071-1050. ; 13:4
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Journal article (peer-reviewed)abstract
- Performance appraisal reports provide vital information for making strategic decisions. Uniting HR practices and IT is an attempt to maximize value creation. Organizations are transforming their performance management systems from traditional to web‐technology based systems to enhance accuracy and objectivity. The present study is an effort to assess employees’ perception of the accuracy of e‐performance appraisal systems. To that effect, 500 close‐ended questionnaires were administered to randomly selected employees working for a non‐for‐profit organization where e‐performance appraisal is practiced. A total of 352 questionnaires were included for analysis and structural equation modeling was used to analyze the data. The results indicate that rater competence and the possibility to challenge performance appraisals judged as unfair or inaccurate highly influence the employees’ perception of accuracy of e‐performance appraisals. Furthermore, a clear communication of standards and the reaction to the last rating moderately affect the employees’ perception of the accuracy of e‐PA.
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- Ahmad, Sarosh, et al.
(author)
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A Compact CPW-Fed Ultra-Wideband Multi-Input-Multi-Output (MIMO) Antenna for Wireless Communication Networks
- 2022
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In: IEEE Access. - : Institute of Electrical and Electronics Engineers (IEEE). - 2169-3536. ; 10, s. 25278-25289
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Journal article (peer-reviewed)abstract
- In this article, a compact coplanar waveguide (CPW) technique based ultra-wideband multiple-input-multiple-output (MIMO) antenna is proposed. The design is characterized by a broad impedance bandwidth starting from 3 GHz to 11 GHz. The overall size of the MIMO design is 60 x 60 mm(2) (1.24 x 1.24 lambda(2)(g) @ 3 GHz) with a thickness of 1.6 mm. To make the design ultra-wideband, the proposed MIMO antenna design has four jug-shaped radiating elements. The design is printed on a FR-4 substrate (relative permittivity of epsilon(r) = 4.4 and loss tangent of tan delta = 0.025). The polarization diversity phenomenon is realized by placing four antenna elements orthogonally. This arrangement increases the isolation among the MIMO antenna elements. The simulated results of the ultra-wideband MIMO antenna are verified by measured results. The proposed MIMO antenna has a measured diversity gain greater than 9.98, envelope correlation coefficient (ECC) less than 0.02, and good MIMO performance where the isolation is more than -20dB between the elements. The group delay, channel capacity loss (CCL), and the total active reflection coefficient (TARC) multiplexing efficiency and mean effective gain results are also analyzed. The group delay is found to be less than 1.2ns, CCL values calculated to be less than 0.4 bits/sec/Hz, while the TARC is below -10dB for the whole operating spectrum. The proposed design is a perfect candidate for ultra-wideband wireless communication systems and portable devices.
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- Ahmad, Sarosh, et al.
(author)
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A Wideband Bear-Shaped Compact Size Implantable Antenna for In-Body Communications
- 2022
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In: Applied Sciences. - : MDPI AG. - 2076-3417. ; 12:6, s. 2859-
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Journal article (peer-reviewed)abstract
- Biomedical implantable antennas play a vital role in medical telemetry applications. These types of biomedical implantable devices are very helpful in improving and monitoring patients' living situations on a daily basis. In the present paper, a miniaturized footprint, thin-profile bear-shaped in-body antenna operational at 915 MHz in the industrial, scientific, and medical (ISM) band is proposed. The design is a straightforward bear-shaped truncated patch excited by a 50-Omega coaxial probe. The radiator is made up of two circular slots and one rectangular slot at the feet of the patch, and the ground plane is sotted to achieve a broadsided directional radiation pattern, imprinted on a Duroid RT5880 roger substrate with a typical 0.254-mm thickness (epsilon(r) = 2.2, tan delta = 0.0009). The stated antenna has a complete size of 7 mm x 7 mm x 0.254 mm and, in terms of guided wavelength, of 0.027 lambda(g) x 0.027 lambda(g) x 0.0011 lambda(g). When operating inside skin tissues, the antenna covers a measured bandwidth from 0.86 GHz to 1.08 GHz (220 MHz). The simulations and experimental outcomes of the stated design are in proper contract. The obtained results show that the calculated specific absorption rate (SAR) values inside skin of over 1 g of mass tissue is 8.22 W/kg. The stated SAR values are lower than the limitations of the federal communications commission (FCC). Thus, the proposed miniaturized antenna is an ultimate applicant for in-body communications.
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- Andrabi, Syed Bilal Ahmad, et al.
(author)
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Long noncoding RNA LIRIL2R modulates FOXP3 levels and suppressive function of human CD4+ regulatory T cells by regulating IL2RA
- 2024
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences (PNAS). - 0027-8424 .- 1091-6490. ; 121:23
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Journal article (peer-reviewed)abstract
- Regulatory T cells (Tregs) are central in controlling immune responses, and dysregulation of their function can lead to autoimmune disorders or cancer. Despite extensive studies on Tregs, the basis of epigenetic regulation of human Treg development and function is incompletely understood. Long intergenic noncoding RNAs (lincRNA)s are important for shaping and maintaining the epigenetic landscape in different cell types. In this study, we identified a gene on the chromosome 6p25.3 locus, encoding a lincRNA, that was up-regulated during early differentiation of human Tregs. The lincRNA regulated the expression of interleukin-2 receptor alpha (IL2RA), and we named it the lincRNA regulator of IL2RA (LIRIL2R). Through transcriptomics, epigenomics, and proteomics analysis of LIRIL2R-deficient Tregs, coupled with global profiling of LIRIL2R binding sites using chromatin isolation by RNA purification, followed by sequencing, we identified IL2RA as a target of LIRIL2R. This nuclear lincRNA binds upstream of the IL2RA locus and regulates its epigenetic landscape and transcription. CRISPR-mediated deletion of the LIRIL2R-bound region at the IL2RA locus resulted in reduced IL2RA expression. Notably, LIRIL2R deficiency led to reduced expression of Treg-signature genes (e.g., FOXP3, CTLA4, and PDCD1), upregulation of genes associated with effector T cells (e.g., SATB1 and GATA3), and loss of Treg-mediated suppression.
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- Bilal, Muhammad, et al.
(author)
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Exploring the potential of ligninolytic armory for lignin valorization : A way forward for sustainable and cleaner production
- 2021
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In: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 326
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Research review (peer-reviewed)abstract
- Lignin is a key structural constituent of lignocellulosic biomasses that have substantial untapped potential to substitute environmentally unfriendly and non-renewable fossil-based resources. Unfortunately, multifaceted composition, heterogeneity, and structural recalcitrance of the lignin are the biggest technical challenges for its effective deconstruction and bioconversions to an array of bio-based products, e.g., specialty chemicals and biomaterials. Physicochemical methods for lignin depolymerization require strict reaction conditions, high en-ergy to execute processes, and environmental apprehensions. In contrast, biological platforms harnessing the catalytic potentiality of microorganisms and their robust enzymatic armory are thought to be efficient means for lignin decomposition. Enzymes, derived from natural origin, are highly proficient and eco-friendly biocatalysts that manifest high selectivity, require milder reaction conditions, and reduce resource requirements. The utili-zation of enzymes for lignin conversion and pre-treatment of biomass for detergent, textile, pulp and papers, and food sector applications has been investigated for decades. Herein, we reviewed lignin bioconversion by bio-logical means, focusing on ligninolytic enzyme-assisted pretreatment approaches. In the first half, we outlined the lignin as a multipurpose raw feedstock, fixation of CO2 to lignin biosynthesis and tailored lignin approach, and sources and types of lignin. The bio-based pre-treatment approaches for lignin depolymerization, including white-rot fungi, brown-rot fungi, bacteria, and ligninolytic enzymes, i.e., manganese peroxidase (MnP) lignin peroxidase (LiP), Laccase (Lac), versatile peroxidase (VP), and dye-decolorizing peroxidases (DyP) are thor-oughly vetted in the second half.
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- Bompada, Pradeep, et al.
(author)
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Epigenome-Wide Histone Acetylation Changes in Peripheral Blood Mononuclear Cells in Patients with Type 2 Diabetes and Atherosclerotic Disease
- 2021
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In: Biomedicines. - : MDPI AG. - 2227-9059. ; 9:12
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Journal article (peer-reviewed)abstract
- There is emerging evidence of an association between epigenetic modifications, glycemic control and atherosclerosis risk. In this study, we mapped genome-wide epigenetic changes in patients with type 2 diabetes (T2D) and advanced atherosclerotic disease. We performed chromatin immunoprecipitation sequencing (ChIP-seq) using a histone 3 lysine 9 acetylation (H3K9ac) mark in peripheral blood mononuclear cells from patients with atherosclerosis with T2D (n = 8) or without T2D (ND, n = 10). We mapped epigenome changes and identified 23,394 and 13,133 peaks in ND and T2D individuals, respectively. Out of all the peaks, 753 domains near the transcription start site (TSS) were unique to T2D. We found that T2D in atherosclerosis leads to an H3K9ac increase in 118, and loss in 63 genomic regions. Furthermore, we discovered an association between the genomic locations of significant H3K9ac changes with genetic variants identified in previous T2D GWAS. The transcription factor 7-like 2 (TCF7L2) rs7903146, together with several human leukocyte antigen (HLA) variants, were among the domains with the most dramatic changes of H3K9ac enrichments. Pathway analysis revealed multiple activated pathways involved in immunity, including type 1 diabetes. Our results present novel evidence on the interaction between genetics and epigenetics, as well as epigenetic changes related to immunity in patients with T2D and advanced atherosclerotic disease.
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