bias estimation
Recently Published Documents


TOTAL DOCUMENTS

431
(FIVE YEARS 118)

H-INDEX

28
(FIVE YEARS 6)

2022 ◽  
Vol 8 (4) ◽  
pp. 265-273
Author(s):  
Deepa K Vijayan ◽  
Jiby Krishna K G ◽  
Dinimol Danniel ◽  
Ashily Shaji ◽  
Jojo Mathew ◽  
...  

: Impedance technology was a revolution in the history of Hematology. Mispa Count X is the first indigenous 3-part hematology analyzer in India, which works on the principle of impedance technology. : Performance evaluation of Mispa Count X.: The analyzer produces the measurement results of 18 parameters with throughput of 60 samples per hour. Mispa Count X was compared with benchmark analyzers Coulter DxH 800 and Sysmex XN 1000 to validate its performance. : Mispa Count X exhibited a wide linearity range for WBC, RBC, platelet and hemoglobin. The carry over for WBC, RBC, PLT and Hb was estimated and found to be well within the acceptable limits. The r values (> 0.90) and bias estimation of Mispa Count X on comparing with Coulter DxH 800 and Sysmex XN 1000 were acceptable, except for mid cell counts and for MPV. Mispa Count X exhibited good precision with an acceptable CV% (< 10%). The primary parameters of the stored samples were stable at room temperature for 24 hours. : So we conclude our study by proving that the Mispa Count X would be an affordable-reliable alternative for Indian healthcare sector instead of expensive imported hematology analyzers.


Sensors ◽  
2022 ◽  
Vol 22 (2) ◽  
pp. 509
Author(s):  
Dipayan Mitra ◽  
Aranee Balachandran ◽  
Ratnasingham Tharmarasa

Airborne angle-only sensors can be used to track stationary or mobile ground targets. In order to make the problem observable in 3-dimensions (3-D), the height of the target (i.e., the height of the terrain) from the sea-level is needed to be known. In most of the existing works, the terrain height is assumed to be known accurately. However, the terrain height is usually obtained from Digital Terrain Elevation Data (DTED), which has different resolution levels. Ignoring the terrain height uncertainty in a tracking algorithm will lead to a bias in the estimated states. In addition to the terrain uncertainty, another common source of uncertainty in angle-only sensors is the sensor biases. Both these uncertainties must be handled properly to obtain better tracking accuracy. In this paper, we propose algorithms to estimate the sensor biases with the target(s) of opportunity and algorithms to track targets with terrain and sensor bias uncertainties. Sensor bias uncertainties can be reduced by estimating the biases using the measurements from the target(s) of opportunity with known horizontal positions. This step can be an optional step in an angle-only tracking problem. In this work, we have proposed algorithms to pick optimal targets of opportunity to obtain better bias estimation and algorithms to estimate the biases with the selected target(s) of opportunity. Finally, we provide a filtering framework to track the targets with terrain and bias uncertainties. The Posterior Cramer–Rao Lower Bound (PCRLB), which provides the lower bound on achievable estimation error, is derived for the single target filtering with an angle-only sensor with terrain uncertainty and measurement biases. The effectiveness of the proposed algorithms is verified by Monte Carlo simulations. The simulation results show that sensor biases can be estimated accurately using the target(s) of opportunity and the tracking accuracies of the targets can be improved significantly using the proposed algorithms when the terrain and bias uncertainties are present.


2022 ◽  
Vol 14 (1) ◽  
pp. 191
Author(s):  
Chuang Shi ◽  
Yuan Tian ◽  
Fu Zheng ◽  
Yong Hu

Due to different designs of receiver correlators and front ends, receiver-related pseudorange biases, called signal distortion biases (SDBs), exist. Ignoring SDBs that can reach up to 0.66 cycles and 10 ns in Melbourne-Wübbena (MW) and ionosphere-free (IF) combinations can negatively affect phase bias estimation. In this contribution, we investigate the SDBs and evaluate the impacts on wide-lane (WL) and narrow-lane (NL) phase bias estimations, and further propose an approach to eliminating these SDBs to improve phase bias estimation. Based on a large data set of 302 multi-global navigation satellite system (GNSS) experiment (MGEX) stations, including 5 receiver brands, we analyze the characteristics of these SDBs The SDB characteristics of different receiver types for different GNSS systems differ from each other. Compared to the global positioning system (GPS) and BeiDou navigation satellite system (BDS), SDBs of Galileo are not significant; those of BDS-3 are significantly superior to BDS-2; Septentrio (SEPT) receivers show the most excellent consistency among all receiver types. Then, we apply the corresponding corrections to phase bias estimation for GPS, Galileo and BDS. The experimental results reveal that the calibration can greatly improve the performance of phase bias estimation. For WL phase biases estimation, the consistencies of WL phase biases among different networks for GPS, Galileo, BDS-2 and BDS-3 improve by 89%, 77%, 76% and 78%, respectively. There are scarcely any improvements of the fixing rates for Galileo due to its significantly small SDBs, while for GPS, BDS-2 and BDS-3, the WL ambiguity fixing rates can improve greatly by 13%, 27% and 14% after SDB calibrations with improvements of WL ambiguity fixing rates, the corresponding NL ambiguity fixing rates can further increase greatly, which can reach approximately 16%, 27% and 22%, respectively. Additionally, after the calibration, both WL and NL phase bias series become more stable. The standard deviations (STDs) of WL phase bias series for GPS and BDS can improve by more than 46%, while those of NL phase bias series can yield improvements of more than 13%. Ultimately, the calibration can make more WL and NL ambiguity residuals concentrated in ranges within ±0.02 cycles. All these results demonstrate that SDBs for phase bias estimation cannot be ignored and must be considered when inhomogeneous receivers are used.


2021 ◽  
Author(s):  
Kevin A Bird ◽  
J Chris Pires ◽  
Robert VanBuren ◽  
Zhiyong Xiong ◽  
Patrick P. Edger

Allopolyploidy involves the hybridization of two evolutionary diverged species and the doubling of genomic material. Frequently, allopolyploids exhibit genomic rearrangements that recombine, duplicate, or delete homoeologous regions of the newly formed genome. While decades of investigation have focused on how genome duplication leads to systematic differences in the retention and expression of duplicate genes, the impact of genomic rearrangements on genome evolution has received less attention. We used genomic and transcriptomic data for six independently resynthesized, isogenic Brassica napus lines in the first, fifth, and tenth generation to identify genomic rearrangements and assess their impact on gene expression dynamics related to subgenome dominance and gene dosage constraint. We find that dosage constraints on the gene expression response to polyploidy begin to loosen within the first ten generations of evolution and systematically differ between dominant and non-dominant subgenomes. We also show that genomic rearrangements can bias estimation of homoeolog expression bias, but fail to fully obscure which subgenome is dominantly expressed. Finally, we demonstrate that dosage-sensitive genes exhibit the same kind of coordinated response to homoeologous exchange as they do for genome duplication, suggesting constraint on dosage balance also acts on these changes to gene dosage.


2021 ◽  
Author(s):  
Michael Moret ◽  
Francesca Grisoni ◽  
Paul Katzberger ◽  
Gisbert Schneider

Chemical language models (CLMs) can be employed to design molecules with desired properties. CLMs generate new chemical structures in the form of textual representations, such as the simplified molecular input line entry systems (SMILES) strings, in a rule-free manner. However, the quality of these de novo generated molecules is difficult to assess a priori. In this study, we apply the perplexity metric to determine the degree to which the molecules generated by a CLM match the desired design objectives. This model-intrinsic score allows identifying and ranking the most promising molecular designs based on the probabilities learned by the CLM. Using perplexity to compare “greedy” (beam search) with “explorative” (multinomial sampling) methods for SMILES generation, certain advantages of multinomial sampling become apparent. Additionally, perplexity scoring is performed to identify undesired model biases introduced during model training and allows the development of a new ranking system to remove those undesired biases.


2021 ◽  
Author(s):  
Shengen Shawn Hu ◽  
Lin Liu ◽  
Qi Li ◽  
Wenjing Ma ◽  
Michael J Guertin ◽  
...  

Genome-wide profiling of chromatin accessibility by DNase-seq or ATAC-seq has been widely used to identify regulatory DNA elements and transcription factor binding sites. However, enzymatic DNA cleavage exhibits intrinsic sequence biases that confound chromatin accessibility profiling data analysis. Existing computational tools are limited in their ability to account for such intrinsic biases. Here, we present Simplex Encoded Linear Model for Accessible Chromatin (SELMA), a computational method for systematic estimation of intrinsic cleavage biases from genomic chromatin accessibility profiling data. We demonstrate that SELMA yields accurate and robust bias estimation from both bulk and single-cell DNase-seq and ATAC-seq data. We show that transcription factor binding inference from DNase footprints can be improved by incorporating estimated biases using SELMA. We also demonstrate improved cell clustering of single-cell ATAC-seq data by considering the SELMA-estimated bias effect. SELMA can be applied to existing bioinformatics tools to improve the analysis of chromatin accessibility sequencing data.


Assessment ◽  
2021 ◽  
pp. 107319112110429
Author(s):  
Allison J. Ames ◽  
Brian C. Leventhal

Traditional psychometric models focus on studying observed categorical item responses, but these models often oversimplify the respondent cognitive response process, assuming responses are driven by a single substantive trait. A further weakness is that analysis of ordinal responses has been primarily limited to a single substantive trait at one time point. This study applies a significant expansion of this modeling framework to account for complex response processes across multiple waves of data collection using the item response tree (IRTree) framework. This study applies a novel model, the longitudinal IRTree, for response processes in longitudinal studies, and investigates whether the response style changes are proportional to changes in the substantive trait of interest. To do so, we present an empirical example using a six-item sexual knowledge scale from the National Longitudinal Study of Adolescent to Adult Health across two waves of data collection. Results show an increase in sexual knowledge from the first wave to the second wave and a decrease in midpoint and extreme response styles. Model validation revealed failure to account for response style can bias estimation of substantive trait growth. The longitudinal IRTree model captures midpoint and extreme response style, as well as the trait of interest, at both waves.


Sign in / Sign up

Export Citation Format

Share Document