Single nucleotide polymorphisms (SNPs) are highly abundant, amendable to high-throughput genotyping, and useful for a number of breeding and genetics applications in crops. SNP frequencies vary ...depending on the species and populations under study, and therefore target SNPs need to be carefully selected to be informative for each application. While multiple SNP genotyping systems are available for rice (Oryza sativa L. and its relatives), they vary in their informativeness, cost, marker density, speed, flexibility, and data quality. In this study, we report the development and performance of the Cornell-IR LD Rice Array (C7AIR), a second-generation SNP array containing 7,098 markers that improves upon the previously released C6AIR. The C7AIR is designed to detect genome-wide polymorphisms within and between subpopulations of O. sativa, as well as O. glaberrima, O. rufipogon and O. nivara. The C7AIR combines top-performing SNPs from several previous rice arrays, including 4,007 SNPs from the C6AIR, 2,056 SNPs from the High Density Rice Array (HDRA), 910 SNPs from the 384-SNP GoldenGate sets, 189 SNPs from the 44K array selected to add information content for elite U.S. tropical japonica rice varieties, and 8 trait-specific SNPs. To demonstrate its utility, we carried out a genome-wide association analysis for plant height, employing the C7AIR across a diversity panel of 189 rice accessions and identified 20 QTLs contributing to plant height. The C7AIR SNP chip has so far been used for genotyping >10,000 rice samples. It successfully differentiates the five subpopulations of Oryza sativa, identifies introgressions from wild and exotic relatives, and is useful for quantitative trait loci (QTL) and association mapping in diverse materials. Moreover, data from the C7AIR provides valuable information that can be used to select informative and reliable SNP markers for conversion to lower-cost genotyping platforms for genomic selection and other downstream applications in breeding.
Among various diagnostics, acoustic techniques are valuable for characterizing mechanical instabilities associated with lengthy training, premature quenching and other performance limitations of ...high-field accelerator magnets. While acoustic emissions from magnets were studied since early 80 s, techniques involving external acoustic excitation have so far been of limited use. As such techniques are already well-developed in materials science and geoscience, they offer a great potential for the superconducting magnet applications. In a typical magnet coil an acoustic pulse emitted by a coupled ultrasonic transducer would experience multiple scatterings from boundaries and interfaces along its propagation path, in resemblance to a diffusion process. The resulting diffuse ultrasonic field uniquely samples geometrical boundaries, scatterer locations and sound velocity distribution in the propagation medium. Variation of these properties can be tracked in real time and with high accuracy by monitoring shape distortions and temporal shift of the ultrasonic waveforms acquired by sensors coupled to the coil. We discuss key physical principles and capabilities of diffuse field ultrasound, and give examples of using it for detecting interface instabilities in Canted Cosine Theta (CCT) Nb 3 Sn superconducting accelerator magnets built by the US Magnet Development Program.
The nature of the resin used in the impregnation of superconducting magnets plays a crucial role on the magnet's performance. The interfacial region between magnet constituents has been postulated as ...the potential region for training origin. Its characterization and analysis are therefore crucial to understand the phenomena involved in magnet training. In this paper, we focus on the development of an experimental method for the characterization of the interfacial bond strength between individual constituents normally found in superconducting magnets. The sample preparation developed for this method as well as the required hardware for testing are presented and discussed. The initial studies focus on a copper strand and different resins normally used in superconducting magnets, such as CTD-101 K, NHMFL Mix61, paraffin wax and Stycast 2850. The initial results are reported and discussed for experiments at room temperature and 77 K, analyzed based on a shear stress failure criteria, and demonstrating the low energy dissipation of the paraffin wax system that might explain the performance improvement of superconducting magnets based on this resin in terms of training.
Stress managed magnet designs allow to limit the strain and stresses applied to the conductor during assembly and operation. In canted cos(<inline-formula><tex-math ...notation="LaTeX">\theta</tex-math></inline-formula>) (CCT) designs, the conductor is wound around a mandrel: the impregnation process creates a bonding between the two, that can fail during magnet powering. The energy releases due to debonding are considered a potential cause of training quenches. In this study, we investigate these events modeling the mandrel-conductor interfaces by means of cohesive zone material models. The material properties were calibrated by means of measurements performed on representative interfaces, and the models were validated comparing the results with strain gauge measurements. A thermal model was used to compute the local temperature increase in the strands as a function of the energy released by debonding and frictional sliding across the newly formed interfaces. The result was then used to define a quench condition for the model, allowing to simulate the full training process of the CCT magnet. The obtained training curve is in reasonable agreement with the experimental results.
Two populations of interspecific introgression lines (ILs) in a common recurrent parent were developed for use in pre-breeding and QTL mapping. The ILs were derived from crosses between cv Curinga, a
...tropical japonica
upland cultivar, and two different wild donors,
Oryza meridionalis
Ng. accession (W2112) and
Oryza rufipogon
Griff. accession (IRGC 105491). The lines were genotyped using genotyping-by-sequencing (GBS) and SSRs. The 32 Curinga/
O. meridionalis
ILs contain 76.73 % of the donor genome in individual introgressed segments, and each line has an average of 94.9 % recurrent parent genome. The 48 Curinga/
O. rufipogon
ILs collectively contain 97.6 % of the donor genome with an average of 89.9 % recurrent parent genome per line. To confirm that these populations were segregating for traits of interest, they were phenotyped for pericarp color in the greenhouse and for four agronomic traits—days to flowering, plant height, number of tillers, and number of panicles—in an upland field environment. Seeds from these IL libraries and the accompanying GBS datasets are publicly available and represent valuable genetic resources for exploring the genetics and breeding potential of rice wild relatives.
A large aperture dipole magnet for testing inserts and cables at high field is under development at LBNL. Its design targets a 15 T field in a 144 mm by 94 mm rectangular aperture, and is based on ...block coils with flared ends. The coils are inserted in an aluminum shell based structure and prestressed using the bladder and key technology. The quench protection relies on energy extraction. Measurements and computations on cos(<inline-formula><tex-math notation="LaTeX">\theta</tex-math></inline-formula>) magnets have shown that the temperature rise after quench events and its gradient within the windings can significantly increase the mechanical stresses in the superconducting coils. In this study, we couple STEAM-LEDET 2-dimensional (2D) quench simulations to the 2D electro-thermo-mechanical ANSYS model of the magnet, predicting the stress acting on the coils during a quench discharge after activating the energy extraction system. The model is then used to optimize the quench protection system, in terms of hot-spot temperature, peak voltage, and limiting the peak stress reached during an energy discharge below the cooldown and powering one.
Fibroblast growth factor 21 (FGF21) has been suggested to be an endocrine signal of nutritional status and an active regulator of metabolism. However, there is no agreement on the effect of ...weight-loss therapies on circulating levels of FGF21 in humans.
To assess FGF21 circulating levels in adiposity excess and after different weight-loss strategies prescribed in five different groups from four independent centers.
Body composition, ketosis, insulin sensitivity and FGF21 were evaluated in 181 excess body weight and 14 normal-weight subjects. From the excess body weight patients, two independent groups (discovery cohort; n=20 and validation cohort; n=28) undertook a very low-calorie ketogenic (VLCK) diet, a third group followed a low-calorie (LC) diet (n=84) and other two groups underwent bariatric surgery (discovery cohort; n=24 and validation cohort; n=25). The follow-up was 4 to 6 or 12 months, respectively.
FGF21 levels were higher in excess body weight patients than in normal-weight subjects. The energy-restriction therapy to lose weight induced a significant decrease, with respect to baseline, in circulating levels of FGF21 (VLCK: -62.5 pg ml
or -14.8 pg ml
and LC diet: -67.9 pg ml
). There were no differences in FGF21 levels between both energy-restriction treatments. On the contrary, after bariatric surgery morbidly obese patients showed a significant increase in FGF21, especially 1 month after surgery (148.8 pg ml
higher than baseline). The FGF21 differential changes occur concomitantly with a non-induced ketosis situation (0.66±0.56 mm) in bariatric surgery, and an improvement in adiposity and insulin sensitivity induced by the three therapies.
FGF21 levels were reduced after energy-restricted treatments and severely increased after bariatric surgery, independently of the weight reduction magnitude, insulin sensitivity or ketosis. Therefore, FGF21 appears to be a marker of severe nutritional stress.
A test facility dipole is being developed at LBNL, targeting a 16 T field in a 144 mm wide aperture. The magnet uses a block design, with two double-pancake coils. In order to minimize motion under ...the large Lorentz forces, the coils are preloaded against a thick aluminum shell and iron yoke using bladder and key technology. It is then crucial to verify that the performance of the magnet is not degraded due to strain induced on the Nb 3 Sn conductor during assembly, cool-down and powering. The critical current of extracted strands was measured in a varying background magnetic field and as a function of the applied longitudinal strain. Finite element analysis was used to extract the strain state inside the superconducting strands during magnet assembly and operation. This strain was then compared to the measurements to evaluate potential reversible and irreversible effects on the magnet performances. The results suggest that the magnet can reach 16 T with sufficient margin, with no irreversible degradation in the high field region.
Towards 20 T Hybrid Accelerator Dipole Magnets Ferracin, P.; Ambrosio, G.; Arbelaez, D. ...
IEEE transactions on applied superconductivity,
09/2022, Letnik:
32, Številka:
6
Journal Article
Recenzirano
Odprti dostop
The most effective way to achieve very high collision energies in a circular particle accelerator is to maximize the field strength of the main bending dipoles. In dipole magnets using Nb-Ti ...superconductor the practical field limit is considered to be 8-9 T. When Nb 3 Sn superconductor material is utilized, a field level of 15-16 T can be achieved. To further push the magnetic field beyond the Nb 3 Sn limits, High Temperature Superconductors (HTS) need to be considered in the magnet design. The most promising HTS materials for particle accelerator magnets are Bi2212 and REBCO. However, their outstanding performance comes with a significantly higher cost. Therefore, an economically viable option towards 20 T dipole magnets could consist in an "hybrid" solution, where both HTS and Nb 3 Sn materials are used. We discuss in this paper preliminary conceptual designs of various 20 T hybrid magnet concepts. After the definition of the overall design criteria, the coil dimensions and parameters are investigated with finite element models based on simple sector coils. Preliminary 2D cross-section computation results are then presented and three main layouts compared: cos-theta, block, and common-coil. Both traditional designs and more advanced stress-management options are considered.
Rice genetic improvement is a key component of achieving and maintaining food security in Asia and Africa in the face of growing populations and climate change. In this effort, the International Rice ...Research Institute (IRRI) continues to play a critical role in creating and disseminating rice varieties with higher productivity. Due to increasing demand for rice, especially in Africa, there is a strong need to accelerate the rate of genetic improvement for grain yield. In an effort to identify and characterize the elite breeding pool of IRRI’s irrigated rice breeding program, we analyzed 102 historical yield trials conducted in the Philippines during the period 2012–2016 and representing 15,286 breeding lines (including released varieties). A mixed model approach based on the pedigree relationship matrix was used to estimate breeding values for grain yield, which ranged from 2.12 to 6.27 t·ha
−1
. The rate of genetic gain for grain yield was estimated at 8.75 kg·ha
−1
year
−1
(0.23%) for crosses made in the period from 1964 to 2014. Reducing the data to only IRRI released varieties, the rate doubled to 17.36 kg·ha
−1
year
−1
(0.46%). Regressed against breeding cycle the rate of gain for grain yield was 185 kg·ha
−1
cycle
−1
(4.95%). We selected 72 top performing lines based on breeding values for grain yield to create an elite core panel (ECP) representing the genetic diversity in the breeding program with the highest heritable yield values from which new products can be derived. The ECP closely aligns with the indica 1B sub-group of
Oryza sativa
that includes most modern varieties for irrigated systems. Agronomic performance of the ECP under multiple environments in Asia and Africa confirmed its high yield potential. We found that the rate of genetic gain for grain yield found in this study was limited primarily by long cycle times and the direct introduction of non-improved material into the elite pool. Consequently, the current breeding scheme for irrigated rice at IRRI is based on rapid recurrent selection among highly elite lines. In this context, the ECP constitutes an important resource for IRRI and NAREs breeders to carefully characterize and manage that elite diversity.
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