183 research outputs found
Optical characterisation of polymeric nanocomposites using tomographic, spectroscopic and Fraunhofer wavefront assessment
Polymers are often embedded with specific nanofillers such that the functional characteristics and properties of the
resulting polymeric nanocomposite (PNC) are enhanced. The degree to which these enhancements can be achieved
depends not only on the level of particle loading of nanofillers, but most importantly on the resulting dispersion profile
achieved within the matrix. Agglomeration (often referred to as clustering) is a result of the mixing process and very
much depends on the chemistry between the polymer and nanofiller. Depending on the PNC type, different mixing
processes can be applied but the general consensus is that such processes are not repeatable themselves. Not only it is
quite difficult to achieve the desired level of dispersion, but in addition there is a limited number of characterization tools
that can be employed to routinely check the homogeneity achieved within a produced sample. Transmission electron
microscopy (TEM) and X-ray diffraction (XRD) techniques are usually employed, but they are very time consuming,
expensive, require special sample preparation and treatment, often produce results that are difficult to interpret and can
only analyse very small areas of sample. This work reports on the adaptation and development and three optical
techniques that are non-destructive, can accurately characterize the dispersion achieved as a result of the mixing process
and can analyse larger material areas. The techniques reported are based on static and dynamic visible and infra-red light
scattering
Quantum advantage in learning from experiments
Quantum technology has the potential to revolutionize how we acquire and
process experimental data to learn about the physical world. An experimental
setup that transduces data from a physical system to a stable quantum memory,
and processes that data using a quantum computer, could have significant
advantages over conventional experiments in which the physical system is
measured and the outcomes are processed using a classical computer. We prove
that, in various tasks, quantum machines can learn from exponentially fewer
experiments than those required in conventional experiments. The exponential
advantage holds in predicting properties of physical systems, performing
quantum principal component analysis on noisy states, and learning approximate
models of physical dynamics. In some tasks, the quantum processing needed to
achieve the exponential advantage can be modest; for example, one can
simultaneously learn about many noncommuting observables by processing only two
copies of the system. Conducting experiments with up to 40 superconducting
qubits and 1300 quantum gates, we demonstrate that a substantial quantum
advantage can be realized using today's relatively noisy quantum processors.
Our results highlight how quantum technology can enable powerful new strategies
to learn about nature.Comment: 6 pages, 17 figures + 46 page appendix; open-source code available at
https://github.com/quantumlib/ReCirq/tree/master/recirq/qml_lf
Effects of habitat composition and landscape structure on worker foraging distances of five bumblebee species
Bumblebees (Bombus spp.) are important pollinators of both crops and wild flowers. Their contribution to this essential ecosystem service has been threatened over recent decades by changes in land use, which have led to declines in their populations. In order to design effective conservation measures it is important to understand the effects of variation in landscape composition and structure on the foraging activities of worker bumblebees. This is because the viability of individual colonies is likely to be affected by the trade-off between the energetic costs of foraging over greater distances and the potential gains from access to additional resources. We used field surveys, molecular genetics and fine resolution remote sensing to estimate the locations of wild bumblebee nests and to infer foraging distances across a 20 km2 agricultural landscape in southern England. We investigated five species, including the rare B. ruderatus and ecologically similar but widespread B. hortorum. We compared worker foraging distances between species and examined how variation in landscape composition and structure affected foraging distances at the colony level. Mean worker foraging distances differed significantly between species. Bombus terrestris, B. lapidarius and B. ruderatus exhibited significantly greater mean foraging distances (551 m, 536 m, 501 m, respectively) than B. hortorum and B. pascuorum (336 m, 272 m, respectively). There was wide variation in worker foraging distances between colonies of the same species, which was in turn strongly influenced by the amount and spatial configuration of available foraging habitats. Shorter foraging distances were found for colonies where the local landscape had high coverage and low fragmentation of semi-natural vegetation, including managed agri-environmental field margins. The strength of relationships between different landscape variables and foraging distance varied between species, for example the strongest relationship for B. ruderatus being with floral cover of preferred forage plants. Our findings suggest that favourable landscape composition and configuration has the potential to minimise foraging distances across a range of bumblebee species. There is thus potential for improvements in the design and implementation of landscape management options, such as agri-environment schemes, aimed at providing foraging habitat for bumblebees and enhancing crop pollination services
Informing National Health Service patients about participation in clinical research: A comparison of opt-in and opt-out approaches across the United Kingdom
Objective: Recruitment to clinical research in the NHS remains challenging. One barrier is accessing patients to discuss research participation. Two general approaches are used in the UK to facilitate this: an ‘opt-in’ approach (when clinicians communicate research opportunities to patients) and an ‘opt-out’ approach (all patients have the right to be informed of relevant research opportunities). No evidence-based data are available, however, to inform the decision about which approach is preferable. This study aimed to collect information from ‘opt-in’ and ‘opt-out’ Trusts and identify which of the two approaches is optimal for ensuring NHS patients are given opportunities to discuss research participation.
Method: This sequential mixed methods study comprised three phases: (1) an Appreciative Inquiry across UK Trusts, and (2) online surveys and (3) focus groups with NHS staff and patients at a representative mental health Trust.
Results: The study was conducted between June and October 2019. Out of seven NHS Mental Health Trusts contacted (three ‘opt-out’ and four ‘opt-in’), only four took part in phase 1 of the study and three of them were ‘opt-out’ Trusts. Benefits of an ‘opt-out’ approach included greater inclusivity of patients and the removal of research gatekeepers, whilst the involvement of research-active clinicians and established patient-clinician relationships were cited as important to ‘opt-in’ success. Phase 2 and 3 were conducted at a different Trust (Oxford Health NHS Foundation Trust, OHNHSFT) which was using an ‘opt-in’ approach. Of 333 staff and member survey responders, 267 (80.2%) favoured moving to an ‘opt-out’ approach (phase 2). Nineteen staff and 16 patients and carers participated in focus groups (phase 3). Concern was raised by staff regarding the lack of time for clinical research, with clinical work taking precedence over research; patients were concerned about a lack of research activity; all considered research to be beneficial and were supportive of a move to ‘opt-out’.
Conclusion:
Findings suggest that ‘opt-out’ is more beneficial than ‘opt-in’, with the potential to vastly increase patient access to research opportunities and to enable greater equality of information provision for currently marginalised groups. This should ensure that healthcare research is more representative of the entire population, including those with a mental health diagnosis
Inhibition of Nox2 Oxidase Activity Ameliorates Influenza A Virus-Induced Lung Inflammation
Influenza A virus pandemics and emerging anti-viral resistance highlight the urgent need for novel generic pharmacological strategies that reduce both viral replication and lung inflammation. We investigated whether the primary enzymatic source of inflammatory cell ROS (reactive oxygen species), Nox2-containing NADPH oxidase, is a novel pharmacological target against the lung inflammation caused by influenza A viruses. Male WT (C57BL/6) and Nox2−/y mice were infected intranasally with low pathogenicity (X-31, H3N2) or higher pathogenicity (PR8, H1N1) influenza A virus. Viral titer, airways inflammation, superoxide and peroxynitrite production, lung histopathology, pro-inflammatory (MCP-1) and antiviral (IL-1β) cytokines/chemokines, CD8+ T cell effector function and alveolar epithelial cell apoptosis were assessed. Infection of Nox2−/y mice with X-31 virus resulted in a significant reduction in viral titers, BALF macrophages, peri-bronchial inflammation, BALF inflammatory cell superoxide and lung tissue peroxynitrite production, MCP-1 levels and alveolar epithelial cell apoptosis when compared to WT control mice. Lung levels of IL-1β were ∼3-fold higher in Nox2−/y mice. The numbers of influenza-specific CD8+DbNP366+ and DbPA224+ T cells in the BALF and spleen were comparable in WT and Nox2−/y mice. In vivo administration of the Nox2 inhibitor apocynin significantly suppressed viral titer, airways inflammation and inflammatory cell superoxide production following infection with X-31 or PR8. In conclusion, these findings indicate that Nox2 inhibitors have therapeutic potential for control of lung inflammation and damage in an influenza strain-independent manner
The chemical basis of serine palmitoyltransferase inhibition by myriocin
Sphingolipids (SLs) are essential components of cellular membranes formed from the condensation of L-serine and a long-chain acyl thioester. This first step is catalyzed by the pyridoxal-5'-phosphate (PLP)-dependent, enzyme serine palmitoyltransferase (SPT) which is a promising therapeutic target. The fungal natural product myriocin is a potent inhibitor of SPT and is widely used to block SL biosynthesis despite a lack of a detailed understanding of its molecular-mechanism. By combining spectroscopy, mass spectrometry, X-ray crystallography, and kinetics, we have characterized the molecular details of SPT inhibition by myriocin. Myriocin initially forms an external aldimine with PLP at the active site, and a structure of the resulting co-complex explains its nanomolar affinity for the enzyme. This co-complex then catalytically degrades via an unexpected 'retro-aldol-like' cleavage mechanism to a C18 aldehyde which in turn acts as a suicide inhibitor of SPT by covalent modification of the essential catalytic lysine. This surprising dual mechanism of inhibition rationalizes the extraordinary potency and longevity of myriocin inhibition.</p
Optimizing microsurgical skills with EEG neurofeedback
Background
By enabling individuals to self-regulate their brainwave activity in the field of optimal performance in healthy individuals, neurofeedback has been found to improve cognitive and artistic performance. Here we assessed whether two distinct EEG neurofeedback protocols could develop surgical skill, given the important role this skill plays in medicine.
Results
National Health Service trainee ophthalmic microsurgeons (N = 20) were randomly assigned to either Sensory Motor Rhythm-Theta (SMR) or Alpha-Theta (AT) groups, a randomized subset of which were also part of a wait-list 'no-treatment' control group (N = 8). Neurofeedback groups received eight 30-minute sessions of EEG training. Pre-post assessment included a skills lab surgical procedure with timed measures and expert ratings from video-recordings by consultant surgeons, together with state/trait anxiety self-reports. SMR training demonstrated advantages absent in the control group, with improvements in surgical skill according to 1) the expert ratings: overall technique (d = 0.6, p < 0.03) and suture task (d = 0.9, p < 0.02) (judges' intraclass correlation coefficient = 0.85); and 2) with overall time on task (d = 0.5, p = 0.02), while everyday anxiety (trait) decreased (d = 0.5, p < 0.02). Importantly the decrease in surgical task time was strongly associated with SMR EEG training changes (p < 0.01), especially with continued reduction of theta (4–7 Hz) power. AT training produced marginal improvements in technique and overall performance time, which were accompanied by a standard error indicative of large individual differences. Notwithstanding, successful within session elevation of the theta-alpha ratio correlated positively with improvements in overall technique (r = 0.64, p = 0.047).
Conclusion
SMR-Theta neurofeedback training provided significant improvement in surgical technique whilst considerably reducing time on task by 26%. There was also evidence that AT training marginally reduced total surgery time, despite suboptimal training efficacies. Overall, the data set provides encouraging evidence of optimised learning of a complex medical specialty via neurofeedback training
Liver-Derived IGF-I Regulates Mean Life Span in Mice
Background: Transgenic mice with low levels of global insulin-like growth factor-I (IGF-I) throughout their life span, including pre- and postnatal development, have increased longevity. This study investigated whether specific deficiency of liver-derived, endocrine IGF-I is of importance for life span. Methods and Findings: Serum IGF-I was reduced by approximately 80 % in mice with adult, liver-specific IGF-I inactivation (LI-IGF-I-/- mice), and body weight decreased due to reduced body fat. The mean life span of LI-IGF-I-/- mice (n = 84) increased 10 % vs. control mice (n = 137) (Cox’s test, p,0.01), mainly due to increased life span (16%) of female mice [LI-IGF-I-/- mice (n = 31): 26.761.1 vs. control (n = 67): 23.060.7 months, p,0.001]. Male LI-IGF-I-/- mice showed only a tendency for increased longevity (p = 0.10). Energy expenditure, measured as oxygen consumption during and after submaximal exercise, was increased in the LI-IGF-I-/- mice. Moreover, microarray and RT-PCR analyses showed consistent regulation of three genes (heat shock protein 1A and 1B and connective tissue growth factor) in several body organs in the LI-IGF-I-/- mice. Conclusions: Adult inactivation of liver-derived, endocrine IGF-I resulted in moderately increased mean life span. Body weight and body fat decreased in LI-IGF-I-/- mice, possibly due to increased energy expenditure during exercise. Genes earlier reported to modulate stress response and collagen aging showed consistent regulation, providing mechanisms tha
Bostonia: v. 61, no. 1-2, 4
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
An RGS-Containing Sorting Nexin Controls Drosophila Lifespan
The pursuit of eternal youth has existed for centuries and recent data indicate that fat-storing tissues control lifespan. In a D. melanogaster fat body insertional mutagenic enhancer trap screen designed to isolate genes that control longevity, we identified a regulator of G protein signaling (RGS) domain containing sorting nexin, termed snazarus (sorting nexin lazarus, snz). Flies with insertions into the 5′ UTR of snz live up to twice as long as controls. Transgenic expression of UAS-Snz from the snz Gal4 enhancer trap insertion, active in fat metabolic tissues, rescued lifespan extension. Further, the lifespan extension of snz mutants was independent of endosymbiont, e.g., Wolbachia, effects. Notably, old snz mutant flies remain active and fertile indicating that snz mutants have prolonged youthfulness, a goal of aging research. Since mammals have snz-related genes, it is possible that the functions of the snz family may be conserved to humans
- …