1,982 research outputs found
Event-related Potentials reveal differential Brain Regions implicated in Discounting in Two Tasks
The way people make decisions about future benefits – termed discounting - has important implications for both financial planning and health behaviour. Several theories assume that, when delaying gratification, the lower weight given to future benefits (the discount rate) declines exponentially. However there is considerable evidence that it declines hyperbolically with the rate of discount being proportionate to the delay distance. There is relatively little evidence as to whether neural areas mediating time- dependent discounting processes differ according to the nature of the task. The present study investigates the potential neurological mechanisms underpinning domain-specific discounting processes. We present high-density event-related potentials (ERPs) data from a task in which participants were asked to make decisions about financial rewards or their health over short and long time-horizons. Participants (n=17) made a button-press response to their preference for an immediate or delayed gain (in the case of finance) or loss (in the case of health), with the discrepancy in the size of benefits/losses varying between alternatives. Waveform components elicited during the task were similar for both domains and included posterior N1, frontal P2 and posterior P3 components. We provide source dipole evidence that differential brain activation does occur across domains with results suggesting the possible involvement of the right cingulate gyrus and left claustrum for the health domain and the left medial and right superior frontal gyri for the finance domain. However, little evidence for differential activation across time horizons is found.Decision Making, Domain-Specific Discounting, Event-Related Potentials
The experience of long-term opiate maintenance treatment and reported barriers to recovery: A qualitative systematic review
Background/Aim: To inform understanding of the experience of long-term opiate maintenance and identify barriers to recovery. Methods: A qualitative systematic review. Results: 14 studies in 17 papers, mainly from the USA (65%), met inclusion criteria, involving 1,088 participants. Studies focused on methadone prescribing. Participants reported stability; however, many disliked methadone. Barriers to full recovery were primarily ‘inward focused'. Conclusion: This is the first review of qualitative literature on long-term maintenance, finding that universal service improvements could be made to address reported barriers to recovery, including involving ex-users as positive role models, and increasing access to psychological support. Treatment policies combining harm minimisation and abstinence-orientated approaches may best support individualised recovery
Projective simulation for artificial intelligence
We propose a model of a learning agent whose interaction with the environment
is governed by a simulation-based projection, which allows the agent to project
itself into future situations before it takes real action. Projective
simulation is based on a random walk through a network of clips, which are
elementary patches of episodic memory. The network of clips changes
dynamically, both due to new perceptual input and due to certain compositional
principles of the simulation process. During simulation, the clips are screened
for specific features which trigger factual action of the agent. The scheme is
different from other, computational, notions of simulation, and it provides a
new element in an embodied cognitive science approach to intelligent action and
learning. Our model provides a natural route for generalization to
quantum-mechanical operation and connects the fields of reinforcement learning
and quantum computation.Comment: 22 pages, 18 figures. Close to published version, with footnotes
retaine
Identification of hip fracture patients from radiographs using Fourier analysis of the trabecular structure: a cross-sectional study
Peer reviewedPublisher PD
Increased insolation threshold for runaway greenhouse processes on Earth like planets
Because the solar luminosity increases over geological timescales, Earth
climate is expected to warm, increasing water evaporation which, in turn,
enhances the atmospheric greenhouse effect. Above a certain critical
insolation, this destabilizing greenhouse feedback can "runaway" until all the
oceans are evaporated. Through increases in stratospheric humidity, warming may
also cause oceans to escape to space before the runaway greenhouse occurs. The
critical insolation thresholds for these processes, however, remain uncertain
because they have so far been evaluated with unidimensional models that cannot
account for the dynamical and cloud feedback effects that are key stabilizing
features of Earth's climate. Here we use a 3D global climate model to show that
the threshold for the runaway greenhouse is about 375 W/m, significantly
higher than previously thought. Our model is specifically developed to quantify
the climate response of Earth-like planets to increased insolation in hot and
extremely moist atmospheres. In contrast with previous studies, we find that
clouds have a destabilizing feedback on the long term warming. However,
subsident, unsaturated regions created by the Hadley circulation have a
stabilizing effect that is strong enough to defer the runaway greenhouse limit
to higher insolation than inferred from 1D models. Furthermore, because of
wavelength-dependent radiative effects, the stratosphere remains cold and dry
enough to hamper atmospheric water escape, even at large fluxes. This has
strong implications for Venus early water history and extends the size of the
habitable zone around other stars.Comment: Published in Nature. Online publication date: December 12, 2013.
Accepted version before journal editing and with Supplementary Informatio
Control of hyperglycaemia in paediatric intensive care (CHiP): study protocol.
BACKGROUND: There is increasing evidence that tight blood glucose (BG) control improves outcomes in critically ill adults. Children show similar hyperglycaemic responses to surgery or critical illness. However it is not known whether tight control will benefit children given maturational differences and different disease spectrum. METHODS/DESIGN: The study is an randomised open trial with two parallel groups to assess whether, for children undergoing intensive care in the UK aged <or= 16 years who are ventilated, have an arterial line in-situ and are receiving vasoactive support following injury, major surgery or in association with critical illness in whom it is anticipated such treatment will be required to continue for at least 12 hours, tight control will increase the numbers of days alive and free of mechanical ventilation at 30 days, and lead to improvement in a range of complications associated with intensive care treatment and be cost effective. Children in the tight control group will receive insulin by intravenous infusion titrated to maintain BG between 4 and 7.0 mmol/l. Children in the control group will be treated according to a standard current approach to BG management. Children will be followed up to determine vital status and healthcare resources usage between discharge and 12 months post-randomisation. Information regarding overall health status, global neurological outcome, attention and behavioural status will be sought from a subgroup with traumatic brain injury (TBI). A difference of 2 days in the number of ventilator-free days within the first 30 days post-randomisation is considered clinically important. Conservatively assuming a standard deviation of a week across both trial arms, a type I error of 1% (2-sided test), and allowing for non-compliance, a total sample size of 1000 patients would have 90% power to detect this difference. To detect effect differences between cardiac and non-cardiac patients, a target sample size of 1500 is required. An economic evaluation will assess whether the costs of achieving tight BG control are justified by subsequent reductions in hospitalisation costs. DISCUSSION: The relevance of tight glycaemic control in this population needs to be assessed formally before being accepted into standard practice
Imaging Atherosclerosis.
Advances in atherosclerosis imaging technology and research have provided a range of diagnostic tools to characterize high-risk plaque in vivo; however, these important vascular imaging methods additionally promise great scientific and translational applications beyond this quest. When combined with conventional anatomic- and hemodynamic-based assessments of disease severity, cross-sectional multimodal imaging incorporating molecular probes and other novel noninvasive techniques can add detailed interrogation of plaque composition, activity, and overall disease burden. In the catheterization laboratory, intravascular imaging provides unparalleled access to the world beneath the plaque surface, allowing tissue characterization and measurement of cap thickness with micrometer spatial resolution. Atherosclerosis imaging captures key data that reveal snapshots into underlying biology, which can test our understanding of fundamental research questions and shape our approach toward patient management. Imaging can also be used to quantify response to therapeutic interventions and ultimately help predict cardiovascular risk. Although there are undeniable barriers to clinical translation, many of these hold-ups might soon be surpassed by rapidly evolving innovations to improve image acquisition, coregistration, motion correction, and reduce radiation exposure. This article provides a comprehensive review of current and experimental atherosclerosis imaging methods and their uses in research and potential for translation to the clinic.J.M.T. is supported by a Wellcome Trust research training fellowship (104492/Z/14/Z). M.D is supported by the British Heart Foundation (FS/14/78/31020). N.R.E. is supported by a research training fellowship from the Dunhill Medical Trust (RTF44/0114). A.J.B. is supported by the British Heart Foundation. J.H.F.R. is part-supported by the HEFCE, the NIHR Cambridge Biomedical Research Centre, the British Heart Foundation, and the Wellcome Trust.This is the final version of the article. It first appeared from the American Heart Association via http://dx.doi.org/10.1161/CIRCRESAHA.115.30624
Refractory chronic GVHD emerging after splenectomy in a marrow transplant recipient with accelerated phase CML
We report a 39-year-old female patient who underwent HLA-identical sibling allogeneic BMT for CML in accelerated phase. Severe pancytopenia refractory to G-CSF associated with progressive splenomegaly and RBC/ platelet transfusion dependency were present from day + 60 after BMT. MRD assessed by FISH and RT-PCR multiplex for BCR-ABL rearrangement was negative, and complete chimerism was documented by VNTR on days + 100, + 180, + 360 and 2 years after BMT. Splenectomy was performed on day + 225 and pancytopenia resolved but chronic extensive graft-versus-host disease developed, with hepatic cholestasis, diffuse scleroderma and sicca-like syndrome. She was sequentially and progressively treated with different immunosuppressive therapy combinations with no clear benefit. On day + 940, she presented with infection over the previously present ulcers on both limbs, which culminated in septic shock and death on day + 1041. We conclude that, although splenectomy may reverse poor graft function after allogeneic BMT, hyposplenism may trigger or worsen chronic extensive GVHD leading to increased morbidity and mortality.Hosp São Paulo, São Paulo, BrazilHosp São Paulo, São Paulo, BrazilWeb of Scienc
Ambient vibration tests of a cross-laminated timber building
Cross-laminated timber has, in the last 6 years, been used for the first time to form shear walls and cores in multi-storey buildings of seven storeys or more. Such buildings can have low mass in comparison to conventional structural forms. This low mass means that, as cross-laminated timber is used for taller buildings still, their dynamic movement under wind load is likely to be a key design parameter. An understanding of dynamic lateral stiffness and damping, which has so far been insufficiently researched, will be vital to the effective design for wind-induced vibration. In this study, an ambient vibration method is used to identify the dynamic properties of a seven-storey cross-laminated timber building in situ. The random decrement method is used, along with the Ibrahim time domain method, to extract the modal properties of the structure from the acceleration measured under ambient conditions. The results show that this output-only modal analysis method can be used to extract modal information from such a building, and that information is compared with a simple structural model. Measurements on two occasions during construction show the effect of non-structural elements on the modal properties of the structure
- …
