Microscale Fluid Behavior during Cryo-EM Sample Blotting

Blotting has been the standard technique for preparing aqueous samples for single-particle electron cryo-microscopy for over three decades. This technique removes the excess solution from a transmission electron microscope grid by pressing absorbent filter paper against the specimen before vitrification. However, this standard technique produces vitreous ice with inconsistent thickness from specimen to specimen and from region to region within the same specimen, the reasons for which are not understood. Here, high-speed interference contrast microscopy is used to demonstrate that the irregular pattern of fibers in the filter paper imposes tortuous, highly variable boundaries during the removal of excess liquid from a flat, hydrophilic surface. As a result, aqueous films of nonuniform thickness are formed while the filter paper is pressed against the substrate. This pattern of nonuniform liquid thickness changes again after the filter paper is pulled away, but the thickness still does not become completely uniform. We suggest that similar topographical features of the liquid film are produced during the standard technique used to blot EM grids and that these manifest in nonuniform ice after vitrification. These observations suggest that alternative thinning techniques, which do not rely on direct contact between the filter paper and the grid, may result in more repeatable and uniform sample thicknesses

Turboelectric distributed propulsion protection system design trades

The NASA N3-X blended-wing body with turboelectric distributed propulsion concept is being studied to achieve N+3 goals such as reduced noise, emissions, and improved energy efficiency. The electrical distribution system is cryogenic in order to maximize its efficiency and increase the power density of all associated components, while the motors, generators, and transmission lines are superconducting. The protection of a superconducting DC network poses unique electrical and thermal challenges due to the low impedance of the superconductor and operation in the superconducting or quenched states. For a given TeDP electrical system architecture with fixed power ratings, conventional and solid-state circuit breakers combined with superconducting fault-current limiters are examined with both voltage and current source control to limit and interrupt the fault current. To estimate the protection system weight and losses, scalable models of cryogenic bidirectional current-source converters, cryogenic bidirectional IGBT solid-state circuit breakers, and resistive-type superconducting fault current limiters are developed to assess how the weight and losses of these components vary as a function of nominal voltage and current and fault current ratings. The scalable models are used to assess the protection system weight for several trade-offs. System studies include the trade-off in fault-current limiting capability of SFCL on CB mass, alongside the fault-current limiting capability of the converter and its impact on CB fault-current interruption ratings and weight

Properties of the warm magnetized ISM, as inferred from WSRT polarimetric imaging

We describe a first attempt to derive properties of the regular and turbulent Galactic magnetic field from multi-frequency polarimetric observations of the diffuse Galactic synchrotron background. A single-cell-size model of the thin Galactic disk is constructed which includes random and regular magnetic fields and thermal and relativistic electrons. The disk is irradiated from behind with a uniform partially polarized background. Radiation from the background and from the thin disk is Faraday rotated and depolarized while propagating through the medium. The model parameters are estimated from a comparison with 350 MHz observations in two regions at intermediate latitudes done with the Westerbork Synthesis Radio Telescope. We obtain good consistency between the estimates for the random and regular magnetic field strengths and typical scales of structure in the two regions. The regular magnetic field strength found is a few microGauss, and the ratio of random to regular magnetic field strength is 0.7 +/- 0.5, for a typical scale of the random component of 15 +/- 10 pc. Furthermore, the regular magnetic field is directed almost perpendicular to the line of sight. This modeling is a potentially powerful method to estimate the structure of the Galactic magnetic field, especially when more polarimetric observations of the diffuse synchrotron background at intermediate latitudes become available.Comment: 12 pages, 6 figures, accepted by A&

Fast solar image classification using deep learning and its importance for automation in solar physics

The volume of data being collected in solar physics has exponentially increased over the past decade and with the introduction of the Daniel K. Inouye Solar Telescope (DKIST) we will be entering the age of petabyte solar data. Automated feature detection will be an invaluable tool for post-processing of solar images to create catalogues of data ready for researchers to use. We propose a deep learning model to accomplish this; a deep convolutional neural network is adept at feature extraction and processing images quickly. We train our network using data from Hinode/Solar Optical Telescope (SOT) Hα images of a small subset of solar features with different geometries: filaments, prominences, flare ribbons, sunspots and the quiet Sun (i.e. the absence of any of the other four features). We achieve near perfect performance on classifying unseen images from SOT (≈ 99.9%) in 4.66 seconds. We also for the first time explore transfer learning in a solar context. Transfer learning uses pre-trained deep neural networks to help train new deep learning models i.e. it teaches a new model. We show that our network is robust to changes in resolution by degrading images from SOT resolution (≈0.33′′ at λ=6563 Å) to Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) resolution (≈1.2′′) without a change in performance of our network. However, we also observe where the network fails to generalise to sunspots from SDO/AIA bands 1600/1700 Å due to small-scale brightenings around the sunspots and prominences in SDO/AIA 304 Å due to coronal emission

Observations of magnetic fields in the Milky Way and in nearby galaxies with a Square Kilometre Array

The role of magnetic fields in the dynamical evolution of galaxies and of the interstellar medium (ISM) is not well understood, mainly because such fields are difficult to directly observe. Radio astronomy provides the best tools to measure magnetic fields: synchrotron radiation traces fields illuminated by cosmic-ray electrons, while Faraday rotation and Zeeman splitting allow us to detect fields in all kinds of astronomical plasmas, from lowest to highest densities. Here we describe how fundamental new advances in studying magnetic fields, both in our own Milky Way and in other nearby galaxies, can be made through observations with the proposed Square Kilometre Array. Underpinning much of what we propose is an all-sky survey of Faraday rotation, in which we will accumulate tens of millions of rotation measure measurements toward background radio sources. This will provide a unique database for studying magnetic fields in individual Galactic supernova remnants and HII regions, for characterizing the overall magnetic geometry of our Galaxy's disk and halo, and for understanding the structure and evolution of magnetic fields in galaxies. Also of considerable interest will be the mapping of diffuse polarized emission from the Milky Way in many narrow bands over a wide frequency range. This will allow us to carry out Faraday tomography of the Galaxy, yielding a high-resolution three-dimensional picture of the magnetic field within a few kpc of the Sun, and allowing us to understand its coupling to the other components of the ISM. Finally, direct synchrotron imaging of a large number of nearby galaxies, combined with Faraday rotation data, will allow us to determine the magnetic field structure in these sources, and to test both the dynamo and primordial field theories for field origin and amplification.Comment: 17 pages, 8 figures. To appear in "Science with the Square Kilometer Array", eds. C. Carilli and S. Rawlings, New Astronomy Reviews (Elsevier: Amsterdam); Typos corrected 26/10/200

RADYNVERSION: Learning to Invert a Solar Flare Atmosphere with Invertible Neural Networks

During a solar flare, it is believed that reconnection takes place in the corona followed by fast energy transport to the chromosphere. The resulting intense heating strongly disturbs the chromospheric structure, and induces complex radiation hydrodynamic effects. Interpreting the physics of the flaring solar atmosphere is one of the most challenging tasks in solar physics. Here we present a novel deep learning approach, an invertible neural network, to understanding the chromospheric physics of a flaring solar atmosphere via the inversion of observed solar line profiles in H{\alpha} and Ca II {\lambda}8542. Our network is trained using flare simulations from the 1D radiation hydrodynamics code RADYN as the expected atmosphere and line profile. This model is then applied to single pixels from an observation of an M1.1 solar flare taken with SST/CRISP instrument just after the flare onset. The inverted atmospheres obtained from observations provide physical information on the electron number density, temperature and bulk velocity flow of the plasma throughout the solar atmosphere ranging from 0-10 Mm in height. The density and temperature profiles appear consistent with the expected atmospheric response, and the bulk plasma velocity provides the gradients needed to produce the broad spectral lines whilst also predicting the expected chromospheric evaporation from flare heating. We conclude that we have taught our novel algorithm the physics of a solar flare according to RADYN and that this can be confidently used for the analysis of flare data taken in these two wavelengths. This algorithm can also be adapted for a menagerie of inverse problems providing extremely fast ($\sim$10 {\mu}s) inversion samples.Comment: Published in Ap

Lymphedema Therapy for the Treatment of Complex Regional Pain Syndrome

Theory: This proposal presents the theory that the use of early lymphatic management techniques for patients who suffer from complex regional pain syndrome (CRPS) can limit CNS remodeling, preventing progression of the disorder. In absence of high quality evidence, we interviewed multiple lymphedema therapists to assist in the generation of a lymphatic management protocol for use with patients experiencing CRPS-associated pain and edema. The pathophysiology of CRPS-associated edema is not fully understood. Potential causes may include vasomotor dysregulation or neurogenic inflammation. Regardless of its cause, edema and pain may lead to excessive muscle guarding and kinesiophobia. Targeting edema early may inhibit progression of the disease before pain becomes centrally mediated. Lymphedema therapy, including manual lymphatic drainage (MLD) and compressive garments, is commonly used to treat patients with compromised circulatory or lymphatic systems. Based on a limited number of low quality studies, MLD has shown conflicted results for improvement of CRPS symptoms. However, these studies have evaluated MLD as an isolated treatment rather than as a component of a comprehensive treatment protocol. None of these studies have investigated the effect of compression garments or early intervention. In light of the limited available research on this topic, expert opinion may provide further insight into the effectiveness of this modality. To support the plausibility of our theory, we have interviewed experienced lymphedema therapists who have treated CRPS with a combination of MLD and compression garments as part of a comprehensive PT treatment plan. Lymphatic drainage applied proximally to the affected limb creates a negative pressure gradient that draws out edematous fluid, providing relief from symptoms without needing to touch the edematous limb. With less pain and discomfort, patients have greater potential to gain functional mobility, which can prevent further complication. Compression garments maintain the pressure gradient for longer treatment effects; interviewed experts report that individual patients have tolerated their use. Traditional protocol for lymphatic drainage is followed for CRPS patients, including teaching independent care, though progression may be slower. No additional contraindications or precautions for the CRPS population were identified. The incorporation of lymphatic management into a comprehensive treatment plan allows for additional tools to decrease disability in CRPS patients with edema. Knowledge of this modality as a treatment option may help improve physical therapy outcomes. Learning to manage CRPS symptoms will help patients decrease kinesiophobia and increase functional capacity

Integrated management tool for water, crop, soil and N-fertilizers: the Saltmed model

Good management will be required to double food production by 2050. Testing management strategies is commonly carried out in the field. Such trials are costly and require quite a long time to produce consistent and reliable results. An alternative option to field trials would be the use of tested models. Models can run with ‘what-if’ scenarios depicting different types of field management. They are a less costly and faster alternative to field trials. In contrast to some existing models, the SALTMED 2013 model is designed for general applications that include various irrigation systems and water application strategies, water of different qualities, variety of crops and trees, different nitrogen based fertilizers and different soil types. The model can simulate up to 20 fields with different treatments, different crops, different irrigation systems and management as well as different N-fertilizer applications. The SALTMED model has been tested using field experiment data from Portugal, Italy, Denmark, Morocco, Egypt, Syria, Brazil and Iran. It successfully simulated soil moisture, salinity, nitrogen content, grain yield and total dry matter. The model provides academics, professionals and extension services with a management tool for crops, soil, water and nitrogen fertilizers. This paper describes the processes, the equations of the model and summarizes the different applications and results obtained