High-speed 4-dimensional scanning transmission electron microscopy using compressive sensing techniques.

Here we show that compressive sensing allows 4-dimensional (4-D) STEM data to be obtained and accurately reconstructed with both high-speed and reduced electron fluence. The methodology needed to achieve these results compared to conventional 4-D approaches requires only that a random subset of probe locations is acquired from the typical regular scanning grid, which immediately generates both higher speed and the lower fluence experimentally. We also consider downsampling of the detector, showing that oversampling is inherent within convergent beam electron diffraction (CBED) patterns and that detector downsampling does not reduce precision but allows faster experimental data acquisition. Analysis of an experimental atomic resolution yttrium silicide dataset shows that it is possible to recover over 25 dB peak signal-to-noise ratio in the recovered phase using 0.3% of the total data. Lay abstract: Four-dimensional scanning transmission electron microscopy (4-D STEM) is a powerful technique for characterizing complex nanoscale structures. In this method, a convergent beam electron diffraction pattern (CBED) is acquired at each probe location during the scan of the sample. This means that a 2-dimensional signal is acquired at each 2-D probe location, equating to a 4-D dataset. Despite the recent development of fast direct electron detectors, some capable of 100kHz frame rates, the limiting factor for 4-D STEM is acquisition times in the majority of cases, where cameras will typically operate on the order of 2kHz. This means that a raster scan containing 256^2 probe locations can take on the order of 30s, approximately 100-1000 times longer than a conventional STEM imaging technique using monolithic radial detectors. As a result, 4-D STEM acquisitions can be subject to adverse effects such as drift, beam damage, and sample contamination. Recent advances in computational imaging techniques for STEM have allowed for faster acquisition speeds by way of acquiring only a random subset of probe locations from the field of view. By doing this, the acquisition time is significantly reduced, in some cases by a factor of 10-100 times. The acquired data is then processed to fill-in or inpaint the missing data, taking advantage of the inherently low-complex signals which can be linearly combined to recover the information. In this work, similar methods are demonstrated for the acquisition of 4-D STEM data, where only a random subset of CBED patterns are acquired over the raster scan. We simulate the compressive sensing acquisition method for 4-D STEM and present our findings for a variety of analysis techniques such as ptychography and differential phase contrast. Our results show that acquisition times can be significantly reduced on the order of 100-300 times, therefore improving existing frame rates, as well as further reducing the electron fluence beyond just using a faster camera.

The Potential of Subsampling and Inpainting for Fast Low-Dose Cryo FIB-SEM Imaging.

Traditional image acquisition for cryo focused ion-beam scanning electron microscopy (FIB-SEM) tomography often sees thousands of images being captured over a period of many hours, with immense data sets being produced. When imaging beam sensitive materials, these images are often compromised by additional constraints related to beam damage and the devitrification of the material during imaging, which renders data acquisition both costly and unreliable. Subsampling and inpainting are proposed as solutions for both of these aspects, allowing fast and low-dose imaging to take place in the Focused ion-beam scanning electron microscopy FIB-SEM without an appreciable loss in image quality. In this work, experimental data are presented which validate subsampling and inpainting as a useful tool for convenient and reliable data acquisition in a FIB-SEM, with new methods of handling three-dimensional data being employed in the context of dictionary learning and inpainting algorithms using a newly developed microscope control software and data recovery algorithm.

Towards real-time STEM simulations through targeted subsampling strategies.

Scanning transmission electron microscopy images can be complex to interpret on the atomic scale as the contrast is sensitive to multiple factors such as sample thickness, composition, defects and aberrations. Simulations are commonly used to validate or interpret real experimental images, but they come at a cost of either long computation times or specialist hardware such as graphics processing units. Recent works in compressive sensing for experimental STEM images have shown that it is possible to significantly reduce the amount of acquired signal and still recover the full image without significant loss of image quality, and therefore it is proposed here that similar methods can be applied to STEM simulations. In this paper, we demonstrate a method that can significantly increase the efficiency of STEM simulations through a targeted sampling strategy, along with a new approach to independently subsample each frozen phonon layer. We show the effectiveness of this method by simulating a SrTiO3 grain boundary and monolayer 2H-MoS2 containing a sulphur vacancy using the abTEM software. We also show how this method is not limited to only traditional multislice methods, but also increases the speed of the PRISM simulation method. Furthermore, we discuss the possibility for STEM simulations to seed the acquisition of real data, to potentially lead the way to self-driving (correcting) STEM.

Experiences of Maternity Healthcare Professionals Returning to Work Following a Personal Perinatal Loss: A Scoping Review of the Literature.

BACKGROUND: In Australia, midwives care closely for women during pregnancy and birth and the immediate postnatal period. This scoping review aimed to explore the experiences of female maternity healthcare professionals when they return to work following a personal pregnancy loss or neonatal death.Methodology: A scoping review was carried out on published and unpublished research and grey literature looking at how maternity healthcare professionals who have had a personal perinatal loss experience working in a maternity setting following the loss. A search of the literature was performed between October and December 2018, with no set limitations. A search for relevant references from included papers was also carried out. The literature was analysed thematically. The types of perinatal loss were defined as per Australian guidelines. RESULTS: 10 articles were included in this scoping review. Four themes emerged from the literature and these were: 1) Impact of being asked, "have you got children?"; 2) Impact on professional practice; 3) Impact of pre-existing professional knowledge; 4) Importance of collegial support on return to work. CONCLUSIONS: Return to work in a maternity setting following a personal perinatal loss is emotionally challenging and requires a range of supports. Further research is needed in this area.

SIM-STEM Lab: Incorporating Compressed Sensing Theory for Fast STEM Simulation.

Recently it has been shown that precise dose control and an increase in the overall acquisition speed of atomic resolution scanning transmission electron microscope (STEM) images can be achieved by acquiring only a small fraction of the pixels in the image experimentally and then reconstructing the full image using an inpainting algorithm. In this paper, we apply the same inpainting approach (a form of compressed sensing) to simulated, sub-sampled atomic resolution STEM images. We find that it is possible to significantly sub-sample the area that is simulated, the number of g-vectors contributing the image, and the number of frozen phonon configurations contributing to the final image while still producing an acceptable fit to a fully sampled simulation. Here we discuss the parameters that we use and how the resulting simulations can be quantifiably compared to the full simulations. As with any Compressed Sensing methodology, care must be taken to ensure that isolated events are not excluded from the process, but the observed increase in simulation speed provides significant opportunities for real time simulations, image classification and analytics to be performed as a supplement to experiments on a microscope to be developed in the future.

Use of mechanical thresholds in a model of feline clinical acute pain and their correlation with the Glasgow Feline Composite Measure Pain Scale scores.

OBJECTIVES: The aim of this study was to evaluate the use of mechanical thresholds (MT), measured with the SMALGO (Small Animal ALGOmeter), and to determine whether there was a correlation between MT and Glasgow Feline Composite Measure Pain Scale (CMPS-Feline) scores in cats undergoing ovariohysterectomy. METHODS: Client-owned cats undergoing flank ovariohysterectomy were recruited. Pain scores for the pre- and postoperative periods were obtained using the CMPS-Feline in each cat by two independent investigators (A and B). Following CMPS-Feline scoring, MT were measured with the SMALGO, in the surgical area, pre- and postoperatively, only by investigator A. Each cat served as its own control for the comparison of pre- and postoperative variables. Reliability statistics were used to assess the level of inter-observer agreement (A vs B) with respect to pre- and postoperative CMPS-Feline scores, while Spearman's correlation statistics were used to analyse the relationship between MT and CMPS-Feline scores. RESULTS: Twenty-nine cats completed the study. Preoperative MT (340 g [range 108-691]) were significantly higher than postoperatively (233 g [range 19-549]; P = 0.001). CMPS-Feline scores were not found to differ significantly between the preoperative period (2 [range 0-7] for investigator A and 3.2 ± 2.3 for investigator B) and postoperative period (2 [range 0-10] for investigator A and 3 [range 0-8] for investigator B) for either investigator. Reliability statistics revealed that the level of inter-observer agreement with respect to CMPS-Feline was fair for the preoperative assessments but poor for the postoperative evaluations. There was no correlation between MT and CMPS-Feline scores. CONCLUSIONS AND RELEVANCE: Although there was no correlation with CMPS-Feline scores performed at the same timepoint, MT increased postoperatively vs baseline. Assuming that, despite analgesia, susceptibility of the surgical area to mechanical stimulation would increase after surgery, this finding suggests that MT might be useful to assess feline surgical pain. The poor level of inter-observer agreement with respect to postoperative CMPS-Feline scores highlights the potential limitations of this scale.

Sub-Sampled Imaging for STEM: Maximising Image Speed, Resolution and Precision Through Reconstruction Parameter Refinement.

Sub-sampling during image acquisition in scanning transmission electron microscopy (STEM) has been shown to provide a means to increase the overall speed of acquisition while at the same time providing an efficient means to control the dose, dose rate and dose overlap delivered to the sample. In this paper, we discuss specifically the parameters used to reconstruct sub-sampled images and highlight their effect on inpainting using the beta-process factor analysis (BPFA) methodology. The selection of the main control parameters can have a significant effect on the resolution, precision and sensitivity of the final inpainted images, and here we demonstrate a method by which these parameters can be optimised for any image in STEM. As part of this work, we also provide a link to open source code and a tutorial on its use, whereby these parameters can be tested for any datasets. When coupled with the hardware necessary to rapidly sub-sample images in STEM, this approach can have significant implications for imaging beam sensitive materials and dynamic processes.

High temporal-resolution scanning transmission electron microscopy using sparse-serpentine scan pathways.

Scanning transmission electron microscopy (STEM) provides structural analysis with sub-angstrom resolution. But the pixel-by-pixel scanning process is a limiting factor in acquiring high-speed data. Different strategies have been implemented to increase scanning speeds while at the same time minimizing beam damage via optimizing the scanning strategy. Here, we achieve the highest possible scanning speed by eliminating the image acquisition dead time induced by the beam flyback time combined with reducing the amount of scanning pixels via sparse imaging. A calibration procedure was developed to compensate for the hysteresis of the magnetic scan coils. A combination of sparse and serpentine scanning routines was tested for a crystalline thin film, gold nanoparticles, and in an in-situ liquid phase STEM experiment. Frame rates of 92, 23 and 5.8 s-1 were achieved for images of a width of 128, 256, and 512 pixels, respectively. The methods described here can be applied to single-particle tracking and analysis of radiation sensitive materials.

Comparison of two protocols for insulin administration and fasting time in diabetic dogs anaesthetised for phacoemulsification: A prospective clinical trial.

BACKGROUND: There is a lack of evidence-based guidelines on perioperative insulin administration and fasting time in diabetic dogs. The aim of this study was to compare two protocols with respect to intraoperative changes in blood glucose (BG) concentrations compared to preoperative values. METHODS: Thirty-two dogs were included. Dogs of group AM (n = 15) underwent anaesthesia in the morning after 12 hours fasting and received half their usual insulin dose, while dogs of group PM (n = 17) had surgery in the afternoon after 6 hours fasting and received their usual insulin dose; BG was measured before premedication (baseline), after anaesthetic induction, every 30 minutes throughout surgery, at extubation and after anaesthetic recovery. The occurrence of intraoperative complications was recorded. RESULTS: There were no differences between groups in perioperative changes in BG over time, and in the proportion of dogs experiencing complications. Common complications were hypotension (53 per cent of dogs in either groups), hyperglycaemia (67 and 65 per cent in groups AM and PM) and hyperkalaemia (20 and 11 per cent in groups AM and PM). CONCLUSIONS: Either protocols may be used in diabetic dogs undergoing anaesthesia. The occurrence of hyperkalaemia in the study population supports routine intraoperative monitoring of blood potassium concentration.

Controlling radiolysis chemistry on the nanoscale in liquid cell scanning transmission electron microscopy.

When high-energy electrons from a scanning transmission electron microscope (STEM) are incident on a liquid, the vast majority of the chemical reactions that are observed are induced by the radiolysis breakdown of the liquid molecules. In the study of liquids, the radiolysis products of pure water are well known, and their rate of formation for a given flux of high-energy electrons has been studied intensively over the last few years for uniform TEM illumination. In this paper, we demonstrate that the temporal and spatial distribution of the electron illumination can significantly affect the final density of radiolysis products in water and even change the type of reaction taking place. We simulate the complex array of possible spatial/temporal distributions of electrons that are accessible experimentally by controlling the size, the scan rate and the hopping distance of the electron probe in STEM mode and then compare the results to the uniformly illuminated TEM mode of imaging. By distributing the electron dose both spatially and temporally in the STEM through a randomised "spot-scan" mode of imaging, the diffusion overlap of the radiolysis products can be reduced, and the resulting reactions can be more readily controlled. This control allows the resolution of the images to be separated from the speed of the induced reaction (which is based on beam current alone) and this facet of the experiment will allow a wide range of chemical reactions to be uniquely tailored and observed in all liquid cell STEM experiments.

Minimising damage in high resolution scanning transmission electron microscope images of nanoscale structures and processes.

Beam damage caused during acquisition of the highest resolution images is the current limitation in the vast majority of experiments performed in a scanning transmission electron microscope (STEM). While the principles behind the processes of knock-on and radiolysis damage are well-known (as are other contributing effects, such as heat and electric fields), understanding how and especially when beam damage is distributed across the entire sample volume during an experiment has not been examined in detail. Here we use standard models for damage and diffusion to elucidate how beam damage spreads across the sample as a function of the microscope conditions to determine an "optimum" sampling approach that maximises the high-resolution information in any image acquisition. We find that the standard STEM approach of scanning an image sequentially accelerates damage because of increased overlap of diffusion processes. These regions of accelerated damage can be significantly decelerated by increasing the distance between the acquired pixels in the scan, forming a "spotscan" mode of acquisition. The optimum distance between these pixels can be broadly defined by the fundamental properties of each material, allowing experiments to be designed for specific beam sensitive materials. As an added bonus, if we use inpainting to reconstruct the sparse distribution of pixels in the image we can significantly increase the speed of the STEM process, allowing dynamic phenomena, and the onset of damage, to be studied directly.

The application and tailoring of Colaizzi's phenomenological approach in a hospital setting.

BACKGROUND: Husserl's descriptive phenomenology is a popular methodology in health research as it provides a way to understand people's experiences. Positioned in Husserl's phenomenology, Colaizzi's approach offers a way to analyse data and develop trustworthy findings. However, it can pose methodological and practical challenges. AIM: To present a discussion of the application and tailoring of Colaizzi's phenomenological approach to a study conducted in a hospital. DISCUSSION: Applying Colaizzi's approach to interview data concerning health professionals' decisions about transferring older people in hospital to residential care provided a decision trail. However, Colaizzi's final step - member-checking - is controversial so was tailored to enhance the development of trustworthy findings. CONCLUSION: Validating findings is an important part of conducting research. Tailoring the final step of member-checking in Colaizzi's approach supports trustworthy findings while staying connected to phenomenological epistemology. IMPLICATIONS FOR PRACTICE: Phenomenology is a popular methodology for nurse researchers. Tailoring Colaizzi's approach provides strategies to augment phenomenological methods, ensuring dependable findings. Nurse researchers conducting phenomenological research can use these strategies.

A new crystalline form of αß-D-lactose prepared by oven drying a concentrated aqueous solution of D-lactose.

A new crystalline form of αß-D-lactose (C12H22O11) has been prepared by the rapid drying of an approximately 40% w/v syrup of D-lactose. Initially identified from its novel powder X-ray diffraction pattern, the monoclinic crystal structure was solved from a microcrystal recovered from the generally polycrystalline mixed-phase residue obtained at the end of the drying step. This is the second crystalline form of αß-D-lactose to be identified and it has a high degree of structural three-dimensional similarity to the previously identified triclinic form.

Elucidating spray-dried dispersion dissolution mechanisms with focused beam reflectance measurement: contribution of polymer chemistry and particle properties to performance.

Amorphous spray-dried dispersions (SDDs) are a key enabling technology for oral solid dosage formulations, used to improve dissolution behaviour and clinical exposure of poorly soluble active pharmaceutical ingredients (APIs). Appropriate assessment of amorphous dissolution mechanisms is an ongoing challenge. Here we outline the novel application using focused beam reflectance measurement (FBRM) to analyse particle populations orthogonal to USP 2 dissolution. The relative impact of polymer substitution and particle attributes on 25% BMS-708163/HPMC-AS SDD dissolution was assessed. Dissolution mechanisms for SDDs were categorized into erosion versus disintegration. Beyond an initial mixing period, FBRM particle counts diminish slowly and particles are detectable until the point where API dissolution is complete. There is correlation between FBRM particle count decay rate, representing loss of SDD particles in the dissolution media, and UV dissolution rate, measuring dissolved API. For the SDD formulation examined, the degree of succinoyl substitution for HPMC-AS, SDD particle size and surface area all had an impact on dissolution. These data indicate the SDD displayed an erosion mechanism and that FBRM is capturing a rate-limiting step. From this screening tool, the mechanistic understanding and measured impact of polymer chemistry and particle properties can inform a risk-assessment and control strategy for this compound.

Generation of a function affect model for residents with advanced dementia.

AIMS AND OBJECTIVES: This article presents the generation of a model of care encompassing "function" and "affect" based on findings from a 2011 research project aimed at improving care delivery for people with advanced dementia. Objectives were to provide comprehensive and sustainable care, honouring and respecting the person. BACKGROUND: Dementia is a debilitating, progressive, and terminal disease with a trajectory ranging from approximately 3 to 16 years, yet attention to end-of-life care, promoting comfort, alleviating suffering, and maximizing quality of life is frequently overlooked for people living in the advanced stages of the disease. METHODS: The research project from which the model was drawn used a three-phase mixed methods approach at three residential aged care facilities (nursing homes) providing high care in New South Wales, Australia. Thematic analysis was elicited from focus group discussions with staff, family members, and carers of residents. FINDINGS: Themes describe distinct dimensions of a model of care: "function" (dedication, designation, and deliberation) and "affect" (the personal outcomes revealed in relaxation, stimulation, and transformation). CONCLUSION: Reframing nursing practice from task and disease orientation to person centred and relationship focused is essential in meeting the complete needs of people with advanced dementia. This transformational model of care may be useful in adapting to other end-of-life care settings.

A constructivist grounded theory of generalist health professionals and their mental health work.

Generalist health professionals, often without formal mental health training, provide treatment and care to people with serious mental illness who present with physical health problems in general hospital settings. This article will present findings from a constructivist grounded theory study of the work delivered by generalist health staff to consumers with mental illness on the general medical/surgical wards of two metropolitan hospitals in Sydney, Australia. The results analysed included three participant observations, two focus groups, and 21 interviews and hospital policy and protocol documents. A substantive theory of mental health work in general hospital settings is illustrated which conceptualizes the following categories: (i) the experience: conflicting realities and ideals; (ii) The Context: facilitating social distancing; and (iii) the social processes: invisibility affecting confidence. The categories are understood through the theoretical lens of symbolic interactionism with the theory providing insights into how the generalist health professionals understand their sense of self or identity.

Generalist health professional's interactions with consumers who have a mental illness in nonmental health settings: A systematic review of the qualitative research.

Generalist health professionals (GHPs) or those healthcare professionals working in nonmental health facilities are increasingly being required to provide care to consumers with a mental illness. The review aimed to synthesize the qualitative research evidence on the meanings and interpretations made by GHPs (nonmental health professional) who interact with consumers with mental illness in nonmental health settings. A systematic review of the qualitative literature was undertaken for the years 1994-2016. The following electronic databases were searched: CINAHL, MEDLINE, PsycINFO, and Sociological Abstracts. Using narrative synthesis methods, the following themes were identified: mental health knowledge (the GHPs' knowledge level about mental illness and how this impacts their experiences and perceptions); GHPs perceive mental illness as a safety risk (GHPs concern over harm to the consumer and themselves); organizational support (the system response from the environmental design, and expert support and care); and emotional consequences of care (the feelings expressed by GHPs based on their experiences and perceptions of consumers). The results suggest that GHPs provide care in a setting which consists of multiple understandings of what care means. Efforts beyond educational initiatives such as organizational and system-level changes will need to be implemented if we are to progress care for this consumer group.

Understanding the experience of women admitted to a psychiatric hospital in Sydney with psychosis or mania following childbirth after World War II (1945-1955).

In the present study, we investigated a unique set of historical health-care records of women admitted to a psychiatric hospital in Sydney, Australia with a diagnosis of psychosis or mania after childbirth in the post-World War II (WWII) period, from 1945 to 1955. This research is part of a larger project examining how the descriptions of these women documented in the health-care records from 1885 to 1975 affected their treatment and the outcome of their admission. In the present paper, we report on the findings from an intensive examination of the post WWII documents. Eighteen health-care records from a psychiatric facility (Gladesville Hospital) were identified from admission registers housed in the State Records Office of New South Wales in 2014. Although seven records had been destroyed, 11 were transcribed verbatim. The records contain demographic information; descriptions of the women's signs and symptoms on admission; and information about the women before, during, and after their admission found in letters from relatives or medical staff. A content analysis of admission information showed how the women were described by health-care professionals, but a textual analysis of the records revealed that there were other factors that could have contributed to the women's condition, which might not have been taken into consideration when treatment and care were devised. The present study demonstrates the value of investigating historical health-care records to understand how prevailing attitudes and practices might affect diagnosis and treatment.