537 research outputs found
HYDROGEN TRAPPING IN NIOBIUM VANADIUM ALLOYS
The authors have measured the localised vibrational modes of hydrogen in a Nd0.93V0.07 alloy. As one cools the sample for the first time to 10K one observes that hydrogen is trapped at octahedral sites associated with two substitutional vanadium atoms. The trap energy is small (10-20 meV) and less than the precipitation enthalpy. The phenomenon exhibits an interesting hysteresis. On repeated cooling cycles the hydrogen atoms tend to precipitate rather than stay in the trap sites. This is due to the formation of additional nucleation sites on the first cooling cycle
Inspiratory muscle training (IMT) for adults discharged from hospital with community acquired pneumonia (CAP) – a feasibility study
Patients report significant morbidity following community-acquired pneumonia (CAP); 70% report persistent symptoms and up to 50% impaired daily activity at 4 weeks post-discharge. Respiratory muscle weakness is one possible mechanism for delayed recovery. Inspiratory muscle training (IMT) increases strength and endurance of inspiratory muscles, with improvements in patient-reported outcomes in other conditions. To our knowledge IMT has not previously been investigated in CAP.
To assess the tolerability of IMT in adults discharged from hospital with community-acquired pneumonia.
Patients hospitalised with a diagnosis of CAP between February 2017 and March 2018 were eligible for inclusion and convenience sampling was used for participant selection. Participants received an IMT device (POWERbreath KHP2) following familiarisation. Training frequency (twice daily) and load (50% PImax) were fixed, however training volume was incremental during weeks 1–3 (10, 20, 30 breaths) and constant thereafter (30 breaths.) Participants were followed by combination of telephone and clinic visits for 9 weeks. Outcomes of interest were; utilisation of IMT device per protocol (defined as >94% training adherence), patient-reported IMT acceptability, and number of device-related side effects. Statistical analysis was conducted using Stata (version 15.1.)
Twenty-two participants were recruited; 16 were male (72.7%), mean age was 55.2 years (range 27.9–77.3.) Participants completed IMT per protocol in 72.7% cases. One unrelated, unexpected serious adverse event (death) occurred during follow-up and 3 participants active at this time were stopped from further IMT by research sponsor pending investigation. Two participants were lost to follow-up. Side effects during IMT were reported on 15 occasions across 22 participants over a total 1183 training days. Reported side effects included chest pain (x2), cough (x1), dyspnoea (x4), and dizziness (x8). All side-effects were rated grade 1 and did not prevent participants from continuing training. Participant-reported IMT acceptability, defined by participants rating training as both ‘useful’ and ‘helpful’ at each follow-up contact, was 99.4%.
Inspiratory muscle training appears to be safe, tolerable, and acceptable to patients following CAP. Distinguishing CAP related symptoms and device-related side effects is challenging in patients recovering following an acute infective illness. A clinical trial to determine efficacy is warranted.Nottingham University Hospitals Trus
Intrinsic activity in the fly brain gates visual information during behavioral choices
The small insect brain is often described as an input/output system that executes reflex-like behaviors. It can also initiate neural activity and behaviors intrinsically, seen as spontaneous behaviors, different arousal states and sleep. However, less is known about how intrinsic activity in neural circuits affects sensory information processing in the insect brain and variability in behavior. Here, by simultaneously monitoring Drosophila's behavioral choices and brain activity in a flight simulator system, we identify intrinsic activity that is associated with the act of selecting between visual stimuli. We recorded neural output (multiunit action potentials and local field potentials) in the left and right optic lobes of a tethered flying Drosophila, while its attempts to follow visual motion (yaw torque) were measured by a torque meter. We show that when facing competing motion stimuli on its left and right, Drosophila typically generate large torque responses that flip from side to side. The delayed onset (0.1-1 s) and spontaneous switch-like dynamics of these responses, and the fact that the flies sometimes oppose the stimuli by flying straight, make this behavior different from the classic steering reflexes. Drosophila, thus, seem to choose one stimulus at a time and attempt to rotate toward its direction. With this behavior, the neural output of the optic lobes alternates; being augmented on the side chosen for body rotation and suppressed on the opposite side, even though the visual input to the fly eyes stays the same. Thus, the flow of information from the fly eyes is gated intrinsically. Such modulation can be noise-induced or intentional; with one possibility being that the fly brain highlights chosen information while ignoring the irrelevant, similar to what we know to occur in higher animals
Comparison of sequencing-based methods to profile DNA methylation and identification of monoallelic epigenetic modifications.
Analysis of DNA methylation patterns relies increasingly on sequencing-based profiling methods. The four most frequently used sequencing-based technologies are the bisulfite-based methods MethylC-seq and reduced representation bisulfite sequencing (RRBS), and the enrichment-based techniques methylated DNA immunoprecipitation sequencing (MeDIP-seq) and methylated DNA binding domain sequencing (MBD-seq). We applied all four methods to biological replicates of human embryonic stem cells to assess their genome-wide CpG coverage, resolution, cost, concordance and the influence of CpG density and genomic context. The methylation levels assessed by the two bisulfite methods were concordant (their difference did not exceed a given threshold) for 82% for CpGs and 99% of the non-CpG cytosines. Using binary methylation calls, the two enrichment methods were 99% concordant and regions assessed by all four methods were 97% concordant. We combined MeDIP-seq with methylation-sensitive restriction enzyme (MRE-seq) sequencing for comprehensive methylome coverage at lower cost. This, along with RNA-seq and ChIP-seq of the ES cells enabled us to detect regions with allele-specific epigenetic states, identifying most known imprinted regions and new loci with monoallelic epigenetic marks and monoallelic expression
Autologous microsurgical breast reconstruction and coronary artery bypass grafting: an anatomical study and clinical implications
OBJECTIVE: To identify possible avenues of sparing the internal mammary artery (IMA) for coronary artery bypass grafting (CABG) in women undergoing autologous breast reconstruction with deep inferior epigastric artery perforator (DIEP) flaps. BACKGROUND: Optimal autologous reconstruction of the breast and coronary artery bypass grafting (CABG) are often mutually exclusive as they both require utilisation of the IMA as the preferred arterial conduit. Given the prevalence of both breast cancer and coronary artery disease, this is an important issue for women's health as women with DIEP flap reconstructions and women at increased risk of developing coronary artery disease are potentially restricted from receiving this reconstructive option should the other condition arise. METHODS: The largest clinical and cadaveric anatomical study (n=315) to date was performed, investigating four solutions to this predicament by correlating the precise requirements of breast reconstruction and CABG against the anatomical features of the in situ IMAs. This information was supplemented by a thorough literature review. RESULTS: Minimum lengths of the left and right IMA needed for grafting to the left-anterior descending artery are 160.08 and 177.80 mm, respectively. Based on anatomical findings, the suitable options for anastomosis to each intercostals space are offered. In addition, 87-91% of patients have IMA perforator vessels to which DIEP flaps can be anastomosed in the first- and second-intercostal spaces. CONCLUSION: We outline five methods of preserving the IMA for future CABG: (1) lowering the level of DIEP flaps to the fourth- and fifth-intercostals spaces, (2) using the DIEP pedicle as an intermediary for CABG, (3) using IMA perforators to spare the IMA proper, (4) using and end-to-side anastomosis between the DIEP pedicle and IMA and (5) anastomosis of DIEP flaps using retrograde flow from the distal IMA. With careful patient selection, we hypothesize using the IMA for autologous breast reconstruction need not be an absolute contraindication for future CABG
AutoWS-Bench-101: Benchmarking Automated Weak Supervision with 100 Labels
Weak supervision (WS) is a powerful method to build labeled datasets for
training supervised models in the face of little-to-no labeled data. It
replaces hand-labeling data with aggregating multiple noisy-but-cheap label
estimates expressed by labeling functions (LFs). While it has been used
successfully in many domains, weak supervision's application scope is limited
by the difficulty of constructing labeling functions for domains with complex
or high-dimensional features. To address this, a handful of methods have
proposed automating the LF design process using a small set of ground truth
labels. In this work, we introduce AutoWS-Bench-101: a framework for evaluating
automated WS (AutoWS) techniques in challenging WS settings -- a set of diverse
application domains on which it has been previously difficult or impossible to
apply traditional WS techniques. While AutoWS is a promising direction toward
expanding the application-scope of WS, the emergence of powerful methods such
as zero-shot foundation models reveals the need to understand how AutoWS
techniques compare or cooperate with modern zero-shot or few-shot learners.
This informs the central question of AutoWS-Bench-101: given an initial set of
100 labels for each task, we ask whether a practitioner should use an AutoWS
method to generate additional labels or use some simpler baseline, such as
zero-shot predictions from a foundation model or supervised learning. We
observe that in many settings, it is necessary for AutoWS methods to
incorporate signal from foundation models if they are to outperform simple
few-shot baselines, and AutoWS-Bench-101 promotes future research in this
direction. We conclude with a thorough ablation study of AutoWS methods.Comment: NeurIPS 2022 Datasets and Benchmarks Trac
Regulation of proteasome assembly and activity in health and disease
The proteasome degrades most cellular proteins in a controlled and tightly regulated manner and thereby controls many processes, including cell cycle, transcription, signalling, trafficking and protein quality control. Proteasomal degradation is vital in all cells and organisms, and dysfunction or failure of proteasomal degradation is associated with diverse human diseases, including cancer and neurodegeneration. Target selection is an important and well-established way to control protein degradation. In addition, mounting evidence indicates that cells adjust proteasome-mediated degradation to their needs by regulating proteasome abundance through the coordinated expression of proteasome subunits and assembly chaperones. Central to the regulation of proteasome assembly is TOR complex 1 (TORC1), which is the master regulator of cell growth and stress. This Review discusses how proteasome assembly and the regulation of proteasomal degradation are integrated with cellular physiology, including the interplay between the proteasome and autophagy pathways. Understanding these mechanisms has potential implications for disease therapy, as the misregulation of proteasome function contributes to human diseases such as cancer and neurodegeneration.</p
Collisional and Radiative Processes in Optically Thin Plasmas
Most of our knowledge of the physical processes in distant plasmas is obtained
through measurement of the radiation they produce. Here we provide an overview of the
main collisional and radiative processes and examples of diagnostics relevant to the microphysical
processes in the plasma. Many analyses assume a time-steady plasma with ion
populations in equilibrium with the local temperature and Maxwellian distributions of particle
velocities, but these assumptions are easily violated in many cases. We consider these
departures from equilibrium and possible diagnostics in detail
Unravelling the influence of affective stimulation on functional neurological symptoms: A pilot experiment examining potential mechanisms
Background: Differences in affective processing have previously been shown in functional neurological disorder (FND); however, the mechanistic relevance is uncertain. We tested the hypotheses that highly arousing affective stimulation would result in elevated subjective functional neurological symptoms (FNS), and this would be associated with elevated autonomic reactivity. The possible influence of cognitive detachment was also explored. Method: Individuals diagnosed with FND (motor symptoms/seizures; n=14) and healthy controls (n=14) viewed Positive, Negative and Neutral images in blocks, while passively observing the stimuli ( € Watch') or detaching themselves ( € Distance'). The FND group rated their primary FNS, and all participants rated subjective physical (arousal, pain, fatigue) and psychological states (positive/negative affect, dissociation), immediately after each block. Skin conductance (SC) and heart rate (HR) were monitored continuously. Results: FNS ratings were higher after Negative compared with Positive and Neutral blocks in the FND group (p=0.002, •p2=0.386); however, this effect was diminished in the Distance condition relative to the Watch condition (p=0.018, •p2=0.267). SC and/or HR correlated with FNS ratings in the Negative-Watch and Neutral-Distance conditions (r values=0.527-0.672, p values=0.006-0.035). The groups did not differ in subjective affect or perceived arousal (p values=0.541-0.919, •p2=<0.001-0.015). Conclusions: Emotionally significant events may exert an influence on FNS which is related to autonomic activation rather than altered subjective affect or perceived arousal. This influence may be modulated by cognitive detachment. Further work is needed to determine the relevance and neural bases of these processes in specific FND phenotypes
Active sampling and decision making in Drosophila chemotaxis
The ability to respond to chemical stimuli is fundamental to the survival of motile organisms, but the strategies underlying odour tracking remain poorly understood. Here we show that chemotaxis in Drosophila melanogaster larvae is an active sampling process analogous to sniffing in vertebrates. Combining computer-vision algorithms with reconstructed olfactory environments, we establish that larvae orient in odour gradients through a sequential organization of stereotypical behaviours, including runs, stops, lateral head casts and directed turns. Negative gradients, integrated during runs, control the timing of turns. Positive gradients detected through high-amplitude head casts determine the direction of individual turns. By genetically manipulating the peripheral olfactory circuit, we examine how orientation adapts to losses and gains of function in olfactory input. Our findings suggest that larval chemotaxis represents an intermediate navigation strategy between the biased random walks of Escherichia Coli and the stereo-olfaction observed in rats and humans
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