Dynamics experiments are an important use-case for X-ray free-electron lasers (XFELs), but time-domain measurements of the X-ray pulses themselves remain a challenge. Shot-by-shot X-ray diagnostics ...could enable a new class of simpler and potentially higher-resolution pump-probe experiments. Here, we report training neural networks to combine low-resolution measurements in both the time and frequency domains to recover X-ray pulses at high-resolution. Critically, we also recover the phase, opening the door to coherent-control experiments with XFELs. The model-based generative neural-network architecture can be trained directly on unlabeled experimental data and is fast enough for real-time analysis on the new generation of MHz XFELs.
Adsorbed proteins on implanted biomedical devices mediate platelet and leukocyte adhesion. Radio frequency plasma deposited tetraglyme (CH3O(CH2CH2O)4CH3), which forms a PEO-like coating, has been ...shown to resist protein adsorption and monocyte adhesion in vitro. By using different plasma deposition powers (5−80 W), we produced a series of plasma-deposited tetraglyme surfaces that varied in surface chemistry as measured by electron spectroscopy for chemical analysis (ESCA) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Both fibrinogen and IgG adsorption were increased on surfaces made at high plasma power. Monocyte adhesion correlated linearly with the amount of adsorbed protein. To identify the surface chemical features that contributed to the nonfouling properties of plasma-deposited tetraglyme, multivariate analysis using partial least squares (PLS) regression was applied. A PLS calibration model based on deposited tetraglyme samples placed downstream in the plasma reactor successfully predicted fibrinogen adsorption to deposited tetraglyme samples placed midstream in the reactor. The model identified how each surface spectral variable from ESCA and ToF-SIMS contributed to protein adsorption. The fraction of carbon in ether carbon linkages as measured by ESCA and ToF-SIMS peaks at m/z 59 and 103 was higher on surfaces that exhibited ultralow fibrinogen adsorption (<10 ng/cm2). The fraction of hydrocarbon-like carbons as measured by ESCA and low-mass ToF-SIMS peaks such as m/z 29 and 31 was greater on surfaces exhibiting high fibrinogen adsorption (>200 ng/cm2). This study elucidated the surface chemical features of deposited tetraglyme that most affect its resistance to protein and cell uptake and provided guidelines for engineering improved nonfouling biomaterial surfaces.
Multistakeholder platforms (MSPs) are the subject of increasing attention and investment in the domain of collaborative natural resource governance, yet evidence-based guidance is slim on policy and ...investment priorities to leverage the MSP approach. We provide a comparative analysis of eight landscape-level MSPs spanning seven countries (Peru, Brazil, India, Tanzania, Ethiopia, and a cross-border case from Kenya and Somalia), representing a diversity of resource systems covering forests, rangelands, and multiuse agricultural landscapes. Applying an adapted social-ecological systems framework, our synthesis identifies the influence of these MSPs on patterns of stakeholder interaction and draws implications for the design and organization of MSPs that are both appropriate and effective. From the cases, we distill lessons addressing: (1) how to design an MSP in relation to the governance context, including the fit between institutional and ecological dimensions of the system and with attention to cross-scale linkages; (2) how to implement inclusive processes that address power inequities, including through capacity building and procedural rules; and (3) how to support adaptive learning to expand the MSP's influence over time, including monitoring outcomes, adapting the scope of stakeholder engagement, and investing in MSP durability.
The microbunching instability (MBI) is a well-known problem for high brightness electron beams and has been observed at accelerator facilities around the world. Free-electron lasers (FELs) are ...particularly susceptible to MBI, which can distort the longitudinal phase space and increase the beam’s slice energy spread (SES). Past studies of MBI at the Linac Coherent Light Source (LCLS) relied on optical transition radiation to infer the existence of microbunching. With the development of the x-band transverse deflecting cavity (XTCAV), we can for the first time directly image the longitudinal phase space at the end of the accelerator and complete a comprehensive study of MBI, revealing both detailed MBI behavior as well as insights into mitigation schemes. The fine time resolution of the XTCAV also provides the first LCLS measurements of the final SES, a critical parameter for many advanced FEL schemes. Detailed MBI and SES measurements can aid in understanding MBI mechanisms, benchmarking simulation codes, and designing future high-brightness accelerators.
Characterizing the phase space distribution of particle beams in accelerators is a central part of understanding beam dynamics and improving accelerator performance. However, conventional analysis ...methods either use simplifying assumptions or require specialized diagnostics to infer high-dimensional (>2D) beam properties. In this Letter, we introduce a general-purpose algorithm that combines neural networks with differentiable particle tracking to efficiently reconstruct high-dimensional phase space distributions without using specialized beam diagnostics or beam manipulations. We demonstrate that our algorithm accurately reconstructs detailed 4D phase space distributions with corresponding confidence intervals in both simulation and experiment using a limited number of measurements from a single focusing quadrupole and diagnostic screen. This technique allows for the measurement of multiple correlated phase spaces simultaneously, which will enable simplified 6D phase space distribution reconstructions in the future.
Extracellular matrix (ECM)-based scaffold materials have been used successfully in both preclinical and clinical tissue engineering and regenerative medicine approaches to tissue reconstruction. ...Results of numerous studies have shown that ECM scaffolds are capable of supporting the growth and differentiation of multiple cell types in vitro and of acting as inductive templates for constructive tissue remodeling after implantation in vivo. Adipose tissue represents a potentially abundant source of ECM and may represent an ideal substrate for the growth and adipogenic differentiation of stem cells harvested from this tissue. Numerous studies have shown that the methods by which ECM scaffold materials are prepared have a dramatic effect upon both the biochemical and structural properties of the resultant ECM scaffold material as well as the ability of the material to support a positive tissue remodeling outcome after implantation. The objective of the present study was to characterize the adipose ECM material resulting from three methods of decellularization to determine the most effective method for the derivation of an adipose tissue ECM scaffold that was largely free of potentially immunogenic cellular content while retaining tissue-specific structural and functional components as well as the ability to support the growth and adipogenic differentiation of adipose-derived stem cells. The results show that each of the decellularization methods produced an adipose ECM scaffold that was distinct from both a structural and biochemical perspective, emphasizing the importance of the decellularization protocol used to produce adipose ECM scaffolds. Further, the results suggest that the adipose ECM scaffolds produced using the methods described herein are capable of supporting the maintenance and adipogenic differentiation of adipose-derived stem cells and may represent effective substrates for use in tissue engineering and regenerative medicine approaches to soft tissue reconstruction.
Abstract As conventional cancer therapies struggle with toxicity issues and irregular remedial efficacy, the preparation of novel gene therapy vectors could offer clinicians the tools for addressing ...the genetic errors of diseased tissue. The transfer of gene therapy to the clinic has proven difficult due to safety, target specificity, and transfection efficiency concerns. Polyethylenimine (PEI) nanoparticles have been identified as promising gene carriers that induce gene transfection with high efficiency. However, the inherent toxicity of the material and non-selective delivery are the major concerns in applying these particles clinically. Here, a non-viral nanovector has been developed by PEGylation of DNA-complexing PEI in nanoparticles functionalized with an Alexa Fluor 647 near infrared fluorophore, and the chlorotoxin (CTX) peptide which binds specifically to many forms of cancer. With this nanovector, the potential toxicity to healthy cells is minimized by both the reduction of the toxicity of PEI with the biocompatible copolymer and the targeted delivery of the nanovector to cancer cells, as evaluated by viability studies. The nanovector demonstrated high levels of targeting specificity and gene transfection efficiency with both C6 glioma and DAOY medulloblastoma tumor cells. Significantly, with the CTX as the targeting ligand, the nanovector may serve as a widely applicable gene delivery system for a broad array of cancer types.
Biological encapsulation and the foreign body reaction can impair the performance of implanted drug release devices. In this article, the classic definition of biocompatibility is questioned. ...Examples are presented of biomaterials showing unique healing behavior. A new paradigm for biomaterials healing is proposed in which non-specific protein adsorption is inhibited and matricellular proteins are controlled at the surfaces of implants.
High-dimensional optimization is a critical challenge for operating large-scale scientific facilities. We apply a physics-informed Gaussian process (GP) optimizer to tune a complex system. Typical GP ...models learn from past observations to make predictions, but this reduces their applicability to systems where there is limited relevant archive data. Instead, here we use a fast approximate model from physics simulations to design the GP model. The GP is then employed to make inferences from sequential online observations in order to optimize the system. Simulation and experimental studies were carried out to demonstrate the method for online control of a storage ring. Our method is a simple prescription to construct a custom GP model, including correlations between the high-dimensional input space, while encoding the physical response of a system. The ability to inform the machine-learning model with physics, without relying on the availability and range of prior data, may have wide applications in science.
Extreme wind waves in the Black Sea Divinsky, Boris V.; Fomin, Vladimir V.; Kosyan, Ruben D. ...
Oceanologia,
January-March 2020, 2020-01-00, 20200101, 2020-01-01, Letnik:
62, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Results of the analysis of a long-term data set, including fields of significant wave heights of the surface wave components, and mixed (total) wave field in the Black Sea are presented. The data set ...was collected on the basis of retrospective calculations using the MIKE 21 SW spectral wave model with the atmospheric forcing based on the ERA-Interim data in the period from 1979 to 2017. A criterion is used to isolate the swell waves from the initial wave data set that takes into account the wave age. We used the experimental data to develop a regression relationship showing that the maximum possible wave height can exceed the significant wave height approximately one and a half times. Analysis of the spatial distribution of wave heights in the Black Sea suggests that a possibility exists that significant wave height of storm waves can be as high as ∼12m. This result indicates that the actual heights of maximum waves in the Black Sea can reach 18–19m. Three regions are distinguished on the basis of the wave potential. The times of manifestation of extreme situations in these regions are different: in the southwestern part of the sea, extreme storm situations occur, as a rule, in December–January; in the region south of the Crimea Peninsula this happens in February; in the northeastern part of the sea they occur in November. It was also found that the south-southeastern and eastern parts of the sea are most affected by swell.
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