Anion engineering has proven to be an effective strategy to tailor the physical and chemical properties of metal oxides by modifying their existing crystal structures. In this work, a low-temperature ...synthesis for rare earth (RE)-doped Y2O2SO4 and Y2O2S was developed via annealing of Y(OH)3 intermediates in the presence of elemental sulfur in a sealed tube, followed by a controlled reduction step. The crystal structure patterns (X-ray diffraction) and optical spectra (UV-IR) of Y2O2SO4, Y2O2S, and crystalline Y2O3 were collected throughout the treatment steps to correlate the structural transformations (via thermogravimetric analysis) with the optical properties. Local and long-range crystallinities were characterized by using X-ray and optical spectroscopy approaches. Systematic shifts in the Eu3+ excitation and emission peaks were observed as a function of SO4 2– and S2– concentrations resulting from a crystal evolution from cubic (Y2O3) to trigonal (Y2O2S) and monoclinic (Y2O2SO4), which can modify the local hybridization of sensitizer dopants (i.e., Ce3+). Ultimately, Tb3+ and Tb3+/Ce3+ doping was employed in these hosts (Y2O2SO4, Y2O2S, and Y2O3) to understand energy transfer between sensitizer and activator ions, which showed significant enhancement for the monoclinic sulfate structure.
Anion engineering has proven to be an effective strategy to tailor the physical and chemical properties of metal oxides by modifying their existing crystal structures. In this work, a low-temperature ...synthesis for rare earth (RE)-doped Y
O
SO
and Y
O
S was developed via annealing of Y(OH)
intermediates in the presence of elemental sulfur in a sealed tube, followed by a controlled reduction step. The crystal structure patterns (X-ray diffraction) and optical spectra (UV-IR) of Y
O
SO
, Y
O
S, and crystalline Y
O
were collected throughout the treatment steps to correlate the structural transformations (via thermogravimetric analysis) with the optical properties. Local and long-range crystallinities were characterized by using X-ray and optical spectroscopy approaches. Systematic shifts in the Eu
excitation and emission peaks were observed as a function of SO
and S
concentrations resulting from a crystal evolution from cubic (Y
O
) to trigonal (Y
O
S) and monoclinic (Y
O
SO
), which can modify the local hybridization of sensitizer dopants (i.e., Ce
). Ultimately, Tb
and Tb
/Ce
doping was employed in these hosts (Y
O
SO
Y
O
S, and Y
O
) to understand energy transfer between sensitizer and activator ions, which showed significant enhancement for the monoclinic sulfate structure.
In singleton pregnancies, studies investigating cell-free DNA in maternal blood have consistently reported high detection rate and low false-positive rate for the 3 common fetal trisomies (trisomies ...21, 18, and 13). The potential advantages of noninvasive prenatal testing in twin pregnancies are even greater than in singletons, in particular lower need for invasive testing and consequent fetal loss rate. However, several organizations do not recommend cell-free DNA in twin pregnancies and call for larger prospective studies.
In response to this, we undertook a large prospective multicenter study to establish the screening performance of cell-free DNA for the 3 common trisomies in twin pregnancies. Moreover, we combined our data with that reported in published studies to obtain the best estimate of screening performance.
This was a prospective multicenter blinded study evaluating the screening performance of cell-free DNA in maternal plasma for the detection of fetal trisomies in twin pregnancies. The study took place in 6 fetal medicine centers in England, United Kingdom. The primary outcome was the screening performance and test failure rate of cell-free DNA using next generation sequencing (the IONA test). Maternal blood was taken at the time of (or after) a conventional screening test. Data were collected at enrolment, at any relevant invasive testing throughout pregnancy, and after delivery until the time of hospital discharge. Prospective detailed outcome ascertainment was undertaken on all newborns. The study was undertaken and reported according to the Standards for Reporting of Diagnostic Accuracy Studies. A pooled analysis was also undertaken using our data and those in the studies identified by a literature search (MEDLINE, Embase, CENTRAL, Cochrane Library, and ClinicalTrials.gov) on June 6, 2020.
A total of 1003 women with twin pregnancies were recruited, and complete data with follow-up and reference data were available for 961 (95.8%); 276 were monochorionic and 685 were dichorionic. The failure rate was 0.31%. The mean fetal fraction was 12.2% (range, 3%–36%); all 9 samples with a 3% fetal fraction provided a valid result. There were no false-positive or false-negative results for trisomy 21 or trisomy 13, whereas there was 1 false-negative and 1 false-positive result for trisomy 18. The IONA test had a detection rate of 100% for trisomy 21 (n=13; 95% confidence interval, 75–100), 0% for trisomy 18 (n=1; 95% confidence interval, 0–98), and 100% for trisomy 13 (n=1; 95% confidence interval, 3–100). The corresponding false-positive rates were 0% (95% confidence interval, 0–0.39), 0.10% (95% confidence interval, 0–0.58), and 0% (95% confidence interval, 0–0.39), respectively. By combining data from our study with the 11 studies identified by literature search, the detection rate for trisomy 21 was 95% (n=74; 95% confidence interval, 90–99) and the false-positive rate was 0.09% (n=5598; 95% confidence interval, 0.03–0.19). The corresponding values for trisomy 18 were 82% (n=22; 95% confidence interval, 66–93) and 0.08% (n=4869; 95% confidence interval, 0.02–0.18), respectively. There were 5 cases of trisomy 13 and 3881 non–trisomy 13 pregnancies, resulting in a computed average detection rate of 80% and a false-positive rate of 0.13%.
This large multicenter study confirms that cell-free DNA testing is the most accurate screening test for trisomy 21 in twin pregnancies, with screening performance similar to that in singletons and very low failure rates (0.31%). The predictive accuracy for trisomies 18 and 13 may be less. However, given the low false-positive rate, offering first-line screening with cell-free DNA to women with twin pregnancy is appropriate in our view and should be considered a primary screening test for trisomy 21 in twins.
In this work, we train controllers (models) using Genetic Fuzzy Methodology (GFM) for learning cooperative behavior in a team of decentralized UAVs to transport a shared slung payload. The training ...is done in a reinforcement learning fashion where the models learn strategies based on feedback received from the environment. The controllers in the UAVs are modeled as fuzzy systems. Genetic Algorithm is used to evolve the models to achieve the overall goal of bringing the payload to the desired locations while satisfying the physical and operational constraints. The UAVs do not explicitly communicate with one another, and each UAV makes its own decisions, thus making it a decentralized system. However, during the training, the cost function is defined such that it is a representation of the team’s effectiveness in achieving the overall goal of bringing the shared payload to the target. By including a penalization term for any constraint violation during the training, the UAVs learn strategies that do not require explicit communication to achieve efficient transportation of payload while satisfying all constraints. We also present the performance metrics by testing the trained UAVs on new scenarios with different target locations and with different number of UAVs in the team.
This paper introduces a new genetic fuzzy based paradigm for developing scalable set of decentralized homogenous robots for a collaborative task. In this work, the number of robots in the team can be ...changed without any additional training. The dynamic problem considered in this work involves multiple stationary robots that are assigned with the goal of bringing a common effector, which is physically connected to each of these robots through cables, to any arbitrary target position within the workspace of the robots. The robots do not communicate with each other. This means that each robot has no explicit knowledge of the actions of the other robots in the team. At any instant, the robots only have information related to the common effector and the target. Genetic Fuzzy System (GFS) framework is used to train controllers for the robots to achieve the common goal. The same GFS model is shared among all robots. This way, we take advantage of the homogeneity of the robots to reduce the training parameters. This also provides the capability to scale to any team size without any additional training. This paper shows the effectiveness of this methodology by testing the system on an extensive set of cases involving teams with different number of robots. Although the robots are stationary, the GFS framework presented in this paper does not put any restriction on the placement of the robots. This paper describes the scalable GFS framework and its applicability across a wide set of cases involving a variety of team sizes and robot locations. We also show results in the case of moving targets.
Molecular diagnostic investigations, following the identification of foetal abnormalities, are routinely performed using array comparative genomic hybridisation (aCGH). Despite the utility of this ...technique, contemporary approaches for the detection of copy number variation are typically based on next-generation sequencing (NGS). We sought to compare an in-house NGS-based workflow (CNVseq) with aCGH, for invasively obtained foetal samples from pregnancies complicated by foetal structural abnormality. DNA from 40 foetuses was screened using both 8 × 60 K aCGH oligoarrays and low-coverage whole genome sequencing. Sequencer-compatible libraries were combined in a ten-sample multiplex and sequenced using an Illumina HiSeq2500. The mean resolution of CNVseq was 29 kb, compared to 60 kb for aCGH analyses. Four clinically significant, concordant, copy number imbalances were detected using both techniques, however, genomic breakpoints were more precisely defined by CNVseq. This data indicates CNVseq is a robust and sensitive alternative to aCGH, for the prenatal investigation of foetuses with structural abnormalities.
Impact statement
What is already known about this subject? Copy number variant analysis using next-generation sequencing has been successfully applied to investigations of tumour specimens and patients with developmental delays. The application of our approach, to a prospective prenatal diagnosis cohort, has not hitherto been assessed.
What do the results of this study add? Next-generation sequencing has a comparable turnaround time and assay sensitivity to copy number variant analysis performed using array CGH. We demonstrate that having established a next-generation sequencing facility, high-throughput CNVseq sample processing and analysis can be undertaken within the framework of a regional diagnostic service.
What are the implications of these findings for clinical practice and/or further research? Array CGH is a legacy technology which is likely to be superseded by low-coverage whole genome sequencing, for the detection of copy number variants, in the prenatal diagnosis of structural abnormalities
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