In 2022, the Facility for Rare Isotope Beams (FRIB) has been established as one of the world-class user facilities for the study of physics of atomic nuclei. The key feature is to provide a variety of nuclei with an energy of 200 MeV per nucleon with a beam power up to 400 kW in the FRIB driver linear accelerator (linac). The linac driven beam experiences a series of the FRIB fragment separator, consisting of the hot-cell target hall, vertical pre-separator, and A1900 fragment separator, which eventually allows a successful delivery of the final rare isotope of interest into the experimental vaults. The superconducting magnet commissioning with heavy ion beams has been progressed by the completion of each area sequentially, and finally the first rare isotope of selenium-84 was successfully produced with the FRIB target using a krypton-86 primary beam, demonstrating FRIB's capability for scientific discovery. This paper presents the FRIB superconducting magnet scope, series fabrication and installation, and the energization at the FRIB premises. The discussion deals with the major test results, and also suggests the significance of advanced technology development for the FRIB next-generation superconducting magnet.
An SRF photo-injector (low frequency, quarter-wave resonator plus emittance compensation magnet) is planned for LCLS-II-HE as it can provide a higher cathode gradient and better electron beam quality than other types of CW electron guns. The magnet package is located immediately downstream of the SRF cavity, and incorporates a solenoid doublet, bucking coils for reduction of the fringe field, normal/skew quadrupoles and horizontal/vertical dipoles. All the magnets are wound of NbTi wire and operate in liquid helium environment. The solenoid package is located inside the SRF gun cryomodule. Design considerations include space limitations, optimal emittance compensation, the magnetic field limits in the superconducting wire and quench protection. The solenoid coils must provide a peak excitation > 25 kgauss <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ·cm, a fringe field < 20 gauss at the wall of the SRF cavity, an integrated dipole field < 90 gauss·cm and an integrated quadrupole field < 10 gauss. A genetic algorithm was used to optimize the solenoid design. Correction dipoles and quadrupoles were designed using coil dominated Walstrom style coils.
With the standard material and cavity production guidelines, the properties and performance of industrially produced high-purity niobium superconducting radiofrequency (SRF) cavities are unpredictably variable. Currently, assembled niobium SRF cavities undergo post-purification vacuum heat treatment at 800°C for three hours to remove hydrogen; however, recent work has shown significant improvements in cavity performance when annealed between 900-1000°C, causing recrystallization (Rx). Rx is a thermally activated process, so increasing the annealing temperature and/or the heating rate should facilitate the onset of Rx, resulting in a greater reduction in the density of geometrically necessary dislocations (GNDs) that are strongly associated with the degradation of cavity performance via trapped magnetic flux. Improving the SRF community's understanding of the influence of both heat treatment and deformation history on the resulting microstructure and Rx behavior in high-purity niobium is needed. This fundamental metallurgy is critical for identifying improved specifications for the consistent production of high-performing niobium SRF cavities. This research investigates the effects of heat treatment variations with different deformation paths, heating rates, and annealing temperatures on deformed samples of polycrystalline high-purity niobium. To assess the effects of strain path, samples were cold-rolled to ∼30% reduction prior to annealing, with half of the sample set rolled parallel to the original rolling direction of the as-received niobium sheet and the other half in the transverse direction.
Iron-dominated superconducting magnets are one of the most popular and most used design choices for superconducting magnetic quadrupoles for accelerator systems. While the iron yoke and pole tips are economic and effective in shaping the field, the large amount of iron also leads to certain drawbacks, namely, unwanted harmonics from the sextupole correctors nested inside of quadrupole iron pole tips. Additional problems include the cryogenic design challenges of the iron yoke being part of the cold mass, and the mechanical challenges of mounting the sextupole and octupole. The Facility for Rare Isotope Beams (FRIB) plans to implement a coil-dominated cosine-theta type quadrupole as a future upgrade, and the advantages of using an iron-free quadrupole, along with the methods and choices of the design and the approach for the planned fabrication, as well as current status of the project are overviewed in this paper.
Josephson junctions containing magnetic materials may be useful in superconducting electronics and memory. One design for a memory cell uses a junction containing an S/F/F'/S spin valve where the two ferromagnetic layers (F, F') have different switching fields. Such a spin valve can be made more robust if the hard layer is pinned by exchange bias with an adjacent antiferromagnetic (AF) layer. We report on the magnetic characterization of NiFe/NiMn and Ni/NiMn bilayer sheet films to confirm the pinning behavior of Ni <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">41</sub> Mn <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">59</sub> . We then report on the fabrication and measurement of S/N/AF/N/S Josephson junctions where NiMn is used as the AF layer, Nb as the S layer, and Cu as the N layer. From measurement of critical current in samples with NiMn thicknesses in the range from 1.2 nm to 6.0 nm, we measure the characteristic supercurrent decay length within NiMn to be 1.0 nm.
Federated Learning (FL) is a distributed machine learning technique that allows numerous Internet of Things (IoT) devices to jointly train a machine learning model using a centralized server for help. Local data never leaves each IoT device in FL, so the local data of IoT devices are protected. In FL, distributed IoT devices usually collect their local data independently, so the dataset of each IoT device may naturally form a distinct source domain. In real-world applications, the model trained over multi-source domains may have poor generalization performance on unseen target domains. To address this issue, we propose FedADG to equip federated learning with domain generalization capability. FedADG employs the federated adversarial learning approach to measure and align the distributions among different source domains via matching each distribution to a reference distribution. The reference distribution is adaptively generated (by accommodating all source domains) to minimize the domain shift distance during alignment. Therefore, the learned feature representation tends to be universal, and thus, it has good generalization performance over the unseen target domains while protecting local data privacy. Intensive experiments on various datasets demonstrate that FedADG has comparable performance with the state-of-the-art.
Background: Targeted therapy with type II kinase inhibitors (KIs) is one of the preferred choices in cancer treatment. However, type II KI therapy can be associated to serious cardiac risks. Objectives: This study aimed to assess the occurrence of cardiac events reported with type II KIs in Eudravigilance (EV) and VigiAccess databases. Methods: To evaluate reporting frequency of individual case safety reports (ICSRs) related to cardiac events, we referred EV and VigiAccess databases. The data was retrieved for the period from date of marketing authorization of respective type II KI till 30 July 2022. Computational analysis was conducted with data from EV and VigiAccess using reporting odds ratio (ROR) along with its 95% confidence interval (CI) under Microsoft excel. Results: In total, 14429 ICSRs in EV and 11522 ICSRs from VigiAccess were retrieved concerning cardiac events with at least one type II KI as the suspected drug. In both databases, most of the ICSRs were reported for Imatinib, Nilotinib, and Sunitinib, while most reported cardiac events were myocardial infarction/acute myocardial infarction, cardiac failure/congestive heart failure and atrial fibrillation. As per EV, 98.8% ICSRs with cardiac ADRs were assessed as serious and of which, 17.4% ICSRs were associated with fatal outcomes and approximately 47% included patient's recovery as a favorable outcome. Nilotinib (ROR 2.87, 95% CI 3.01-2.74) and Nintedanib (ROR 2.17, 95% CI 2.3-2.04) were associated with a significant increase in reporting frequency of ICSRs related to cardiac events. Conclusions: Type II KI related cardiac events were serious and associated with unfavorable outcomes. A significant increase in ICSRs reporting frequency was observed with Nilotinib and Nintedanib. These results insist for a consideration of revision of cardiac safety profile of Nilotinib and Nintedanib, specifically for risks of myocardial infarction and atrial fibrillation. Additionally, the need for other ad-hoc studies is indicated.
A systematic evaluation of syntactic behavior of nouns that take as their possessor the topic of the possessive topic constructions in Mandarin Chinese calls for an understanding of the syntactic and semantic nature of relational nouns (RNs) and non-RNs. This evaluation leads to four empirical generalizations that divide NP possessees into four subtypes, some important differences between which are understudied in the literature. These generalizations are then explained with differences in the lexical syntactic and semantic properties of the four NP subtypes, namely, non-RNs, kinship type nouns, body-part type nouns, and whole-part nouns: whether the nouns bear a local or long-distance syntactic reflexive argument, or a pronominal argument, or no argument at all, is the determining factor of their distinctive syntactic behavior in the possessive topic construction. This study sheds light on long-standing problems concerning the nature of empty categories in connection with the topic in possessive topic constructions. Critical aspects of the nouns’ syntactic behavior are arguably orthogonal to a movement or base-generation approach to topicalization in Mandarin Chinese. Instead, this article proposes that the semantic or syntactic arguments of the nominal possessees relate to the topic via some general mechanisms other than movement or base-generation: reflexive and pronominal reference resolution. This study thus offers us a novel viewpoint on the syntax and semantics of nouns as well as their typology in the context of possession and inalienability.
Measurement error in agricultural field area and productivity data for developing countries is widely acknowledged, but there is a shortage of evidence on what this implies, especially for farmers. By comparing self-reported to global positioning system measurements, we investigate area measurement errors using a nationally representative dataset of Zambian smallholder maize plots. We examine the implications for researchers' understanding of productivity , but also how actual productivity may be affected. We find land area tends to be overstated on smaller fields and understated on larger fields. Correcting measurement error strengthens evidence of an inverse relationship between field size and productivity. Input use patterns indicate farmers believe the inaccurately reported area figures, suggesting measurement errors affect input choices and thus actual productivity. Improving farmer understanding of area measurements could improve productivity. Improving the accuracy of area data will improve researchers' understanding of productivity.
Two-dimensional (2D) material research is rapidly evolving to broaden the spectrum of emergent 2D systems. Here, we review recent advances in the theory, synthesis, characterization, device, and quantum physics of 2D materials and their heterostructures. First, we shed insight into modeling of defects and intercalants, focusing on their formation pathways and strategic functionalities. We also review machine learning for synthesis and sensing applications of 2D materials. In addition, we highlight important development in the synthesis, processing, and characterization of various 2D materials (e.g., MXnenes, magnetic compounds, epitaxial layers, low-symmetry crystals, etc.) and discuss oxidation and strain gradient engineering in 2D materials. Next, we discuss the optical and phonon properties of 2D materials controlled by material inhomogeneity and give examples of multidimensional imaging and biosensing equipped with machine learning analysis based on 2D platforms. We then provide updates on mix-dimensional heterostructures using 2D building blocks for next-generation logic/memory devices and the quantum anomalous Hall devices of high-quality magnetic topological insulators, followed by advances in small twist-angle homojunctions and their exciting quantum transport. Finally, we provide the perspectives and future work on several topics mentioned in this review.
The thylakoid membrane is in a temperature-sensitive equilibrium that shifts repeatedly during the life cycle in response to ambient temperature or solar irradiance. Plants respond to seasonal temperature variation by changing their thylakoid lipid composition, while a more rapid mechanism for short-term heat exposure is required. The emission of the small organic molecule isoprene has been postulated as one such possible rapid mechanism. The protective mechanism of isoprene is unknown, but some plants emit isoprene at high temperature. We investigate the dynamics and structure for lipids within a thylakoid membrane across temperatures and varied isoprene content using classical molecular dynamics simulations. The results are compared with experimental findings for temperature-dependent changes in the lipid composition and shape of thylakoids. The surface area, volume, and flexibility of the membrane, as well as the lipid diffusion, increase with temperature, while the membrane thickness decreases. Saturated thylakoid 34:3 glycolipids derived from eukaryotic synthesis pathways exhibit altered dynamics relative to lipids from prokaryotic synthesis paths, which could explain the upregulation of specific lipid synthesis pathways at different temperatures. Increasing isoprene concentration was not observed to have a significant thermoprotective effect on the thylakoid membranes, and that isoprene readily permeated the membrane models tested.
Interpreting and creating computational systems models is an important goal of science education. One aspect of computational systems modeling that is supported by modeling, systems thinking, and computational thinking literature is “testing, evaluating, and debugging models.” Through testing and debugging, students can identify aspects of their models that either do not match external data or conflict with their conceptual understandings of a phenomenon. This disconnect encourages students to make model revisions, which in turn deepens their conceptual understanding of a phenomenon. Given that many students find testing and debugging challenging, we set out to investigate the various testing and debugging behaviors and behavioral patterns that students use when building and revising computational system models in a supportive learning environment. We designed and implemented a 6-week unit where students constructed and revised a computational systems model of evaporative cooling using SageModeler software. Our results suggest that despite being in a common classroom, the three groups of students in this study all utilized different testing and debugging behavioral patterns. Group 1 focused on using external peer feedback to identify flaws in their model, group 2 used verbal and written discourse to critique their model’s structure and suggest structural changes, and group 3 relied on systemic analysis of model output to drive model revisions. These results suggest that multiple aspects of the learning environment are necessary to enable students to take these different approaches to testing and debugging.
Key Clinical Message This case report discusses the effectiveness of the Inari FlowTriever system in treating a right atrial (RA) clot in‐transit in a 55‐year‐old male patient with Becker's muscular dystrophy (BMD). BMD is an X‐linked recessive muscle disease caused by mutations in the gene that code for the protein dystrophin, which is associated with partially functional dystrophin in variable amounts. Right heart thrombi (RHT) are thrombi that can be visualized in the right atrium, right ventricle, or proximal surrounding vasculature. The Inari FlowTriever system was used to treat RA clot in‐transit and removed acute, subacute, and chronic clot in a single session without the use of thrombolytics and subsequent ICU stay. The estimated blood loss with the FlowSaver system was approximately 150 mL. This report complements the FLARE study by highlighting the effectiveness of the FlowTriever system for mechanical thrombectomy of RA clot‐in‐transit in a patient with BMD.
Listeria monocytogenes (Lm) is an intracellular foodborne pathogen which causes the severe disease listeriosis in immunocompromised individuals. Macrophages play a dual role during Lm infection by both promoting dissemination of Lm from the gastrointestinal tract and limiting bacterial growth upon immune activation. Despite the relevance of macrophages to Lm infection, the mechanisms underlying phagocytosis of Lm by macrophages are not well understood. To identify host factors important for Lm infection of macrophages, we performed an unbiased CRISPR/Cas9 screen which revealed pathways that are specific to phagocytosis of Lm and those that are required for internalization of bacteria generally. Specifically, we discovered the tumor suppressor PTEN promotes macrophage phagocytosis of Lm and L. ivanovii, but not other Gram-positive bacteria. Additionally, we found that PTEN enhances phagocytosis of Lm via its lipid phosphatase activity by promoting adherence to macrophages. Using conditional knockout mice lacking Pten in myeloid cells, we show that PTEN-dependent phagocytosis is important for host protection during oral Lm infection. Overall, this study provides a comprehensive identification of macrophage factors involved in regulating Lm uptake and characterizes the function of one factor, PTEN, during Lm infection in vitro and in vivo. Importantly, these results demonstrate a role for opsonin-independent phagocytosis in Lm pathogenesis and suggest that macrophages play a primarily protective role during foodborne listeriosis.
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