1,977 research outputs found
Where do we go from here? An assessment of navigation performance using a compass versus a GPS unit
The Global Positioning System (GPS) looks set to replace the traditional map and
compass for navigation tasks in military and civil domains. However, we may ask
whether GPS has a real performance advantage over traditional methods. We present
an exploratory study using a waypoint plotting task to compare the standard magnetic
compass against a military GPS unit, for both expert and non-expert navigators.
Whilst performance times were generally longer in setting up the GPS unit, once
navigation was underway the GPS was more efficient than the compass. For mediumto
long-term missions, this means that GPS could offer significant performance
benefits, although the compass remains superior for shorter missions.
Notwithstanding the performance times, significantly more errors, and more serious
errors, occurred when using the compass. Overall, then, the GPS offers some clear
advantages, especially for non-expert users. Nonetheless, concerns over the
development of cognitive maps remain when using GPS technologies
Post-mortem brain analyses of the Lothian Birth Cohort 1936:Extending lifetime cognitive and brain phenotyping to the level of the synapse
INTRODUCTION: Non-pathological, age-related cognitive decline varies markedly between individuals andplaces significant financial and emotional strain on people, their families and society as a whole.Understanding the differential age-related decline in brain function is critical not only for the development oftherapeutics to prolong cognitive health into old age, but also to gain insight into pathological ageing suchas Alzheimer’s disease. The Lothian Birth Cohort of 1936 (LBC1936) comprises a rare group of people forwhom there are childhood cognitive test scores and longitudinal cognitive data during older age, detailedstructural brain MRI, genome-wide genotyping, and a multitude of other biological, psycho-social, andepidemiological data. Synaptic integrity is a strong indicator of cognitive health in the human brain;however, until recently, it was prohibitively difficult to perform detailed analyses of synaptic and axonalstructure in human tissue sections. We have adapted a novel method of tissue preparation at autopsy toallow the study of human synapses from the LBC1936 cohort in unprecedented morphological andmolecular detail, using the high-resolution imaging techniques of array tomography and electronmicroscopy. This allows us to analyze the brain at sub-micron resolution to assess density, proteincomposition and health of synapses. Here we present data from the first donated LBC1936 brain andcompare our findings to Alzheimer’s diseased tissue to highlight the differences between healthy andpathological brain ageing. RESULTS: Our data indicates that compared to an Alzheimer’s disease patient, the cognitively normalLBC1936 participant had a remarkable degree of preservation of synaptic structures. However,morphological and molecular markers of degeneration in areas of the brain associated with cognition(prefrontal cortex, anterior cingulate cortex, and superior temporal gyrus) were observed. CONCLUSIONS: Our novel post-mortem protocol facilitates high-resolution neuropathological analysis of the well-characterized LBC1936 cohort, extending phenotyping beyond cognition and in vivo imaging to nowinclude neuropathological changes, at the level of single synapses. This approach offers an unprecedentedopportunity to study synaptic and axonal integrity during ageing and how it contributes to differences in agerelatedcognitive change. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40478-015-0232-0) contains supplementary material, which is available to authorized users
Order by disorder and spiral spin liquid in frustrated diamond lattice antiferromagnets
Frustration refers to competition between different interactions that cannot
be simultaneously satisfied, a familiar feature in many magnetic solids. Strong
frustration results in highly degenerate ground states, and a large suppression
of ordering by fluctuations. Key challenges in frustrated magnetism are
characterizing the fluctuating spin-liquid regime and determining the mechanism
of eventual order at lower temperature. Here, we study a model of a diamond
lattice antiferromagnet appropriate for numerous spinel materials. With
sufficiently strong frustration a massive ground state degeneracy develops
amongst spirals whose propagation wavevectors reside on a continuous
two-dimensional ``spiral surface'' in momentum space. We argue that an
important ordering mechanism is entropic splitting of the degenerate ground
states, an elusive phenomena called order-by-disorder. A broad ``spiral
spin-liquid'' regime emerges at higher temperatures, where the underlying
spiral surface can be directly revealed via spin correlations. We discuss the
agreement between these predictions and the well characterized spinel MnSc2S4
The effects of applied water at various fractions of measured evapotranspiration on reproductive growth and water productivity of Thompson Seedless grapevines
The reproductive growth and water productivity (WPb) of Thompson Seedless grapevines were measured as a function of applied water amounts at various fractions of measured grapevine ETc for a total of eight irrigation treatments. Shoots were harvested numerous times during the growing season to calculate water productivity. Berry weight was maximized at the 0.6–0.8 applied water treatments across years. As applied water amounts increased soluble solids decreased. Berry weight measured at veraison and harvest was a linear function of the mean midday leaf water potential measured between anthesis and veraison and anthesis and harvest, respectively. As applied water amounts increased up to the 0.6–0.8 irrigation treatments there was a significant linear increase in yield. Yields at greater applied water amounts either leveled off or decreased. The reduction in yield on either side of the yearly maximum was due to fewer numbers of clusters per vine. Maximum yield occurred at an ETc ranging from 550 to 700 mm. Yield per unit applied water and WPb increased as applied water decreased. The results from this study demonstrated that Thompson Seedless grapevines can be deficit irrigated, increasing water use efficiency while maximizing yields
Can Systemic Interventions Designed to Reduce Reoffending by Youth also Reduce their Victimization?
Previous research indicates considerable overlap between populations of boys who are victimized and boys who victimize others. This study was concerned with whether a systems-focused treatment program designed to address individual and systemic risk factors associated with the perpetration of sexual and violent crimes might also be successful in reducing boys’ victimization by others. Boys adjudicated for sexual offences who received ‘treatment as usual’ (TAU; n = 335) were compared with similarly adjudicated boys who completed the treatment program (n = 200) on their histories of contact with police either as offenders or victims. Despite their higher rates of pre-intervention victimization, the treatment group were victimized less frequently post-intervention than the TAU group. Continued offending was the strongest predictor of victimization post-intervention. These findings suggest that offending and victimization share common risk factors that may be addressed simultaneously within offence-focused treatment
Observation of associated near-side and away-side long-range correlations in √sNN=5.02 TeV proton-lead collisions with the ATLAS detector
Two-particle correlations in relative azimuthal angle (Δϕ) and pseudorapidity (Δη) are measured in √sNN=5.02 TeV p+Pb collisions using the ATLAS detector at the LHC. The measurements are performed using approximately 1 μb-1 of data as a function of transverse momentum (pT) and the transverse energy (ΣETPb) summed over 3.1<η<4.9 in the direction of the Pb beam. The correlation function, constructed from charged particles, exhibits a long-range (2<|Δη|<5) “near-side” (Δϕ∼0) correlation that grows rapidly with increasing ΣETPb. A long-range “away-side” (Δϕ∼π) correlation, obtained by subtracting the expected contributions from recoiling dijets and other sources estimated using events with small ΣETPb, is found to match the near-side correlation in magnitude, shape (in Δη and Δϕ) and ΣETPb dependence. The resultant Δϕ correlation is approximately symmetric about π/2, and is consistent with a dominant cos2Δϕ modulation for all ΣETPb ranges and particle pT
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at s√=8 TeV with the ATLAS detector
The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of 20.1fb−1 of proton–proton collision data at √s = 8 TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via t˜→tχ˜01 or t˜→ bχ˜±1 →bW(∗)χ˜01 , where χ˜01 (χ˜±1 ) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of t˜ → tχ˜01 . For a branching fraction of 100%, top squark masses in the range 270–645 GeV are excluded for χ˜01 masses below 30 GeV. For a branching fraction of 50% to either t˜ → tχ˜01 or t˜ → bχ˜±1 , and assuming the χ˜±1 mass to be twice the χ˜01 mass, top squark masses in the range 250–550 GeV are excluded for χ˜01 masses below 60 GeV
Live Imaging at the Onset of Cortical Neurogenesis Reveals Differential Appearance of the Neuronal Phenotype in Apical versus Basal Progenitor Progeny
The neurons of the mammalian brain are generated by progenitors dividing either at the apical surface of the ventricular zone (neuroepithelial and radial glial cells, collectively referred to as apical progenitors) or at its basal side (basal progenitors, also called intermediate progenitors). For apical progenitors, the orientation of the cleavage plane relative to their apical-basal axis is thought to be of critical importance for the fate of the daughter cells. For basal progenitors, the relationship between cell polarity, cleavage plane orientation and the fate of daughter cells is unknown. Here, we have investigated these issues at the very onset of cortical neurogenesis. To directly observe the generation of neurons from apical and basal progenitors, we established a novel transgenic mouse line in which membrane GFP is expressed from the beta-III-tubulin promoter, an early pan-neuronal marker, and crossed this line with a previously described knock-in line in which nuclear GFP is expressed from the Tis21 promoter, a pan-neurogenic progenitor marker. Mitotic Tis21-positive basal progenitors nearly always divided symmetrically, generating two neurons, but, in contrast to symmetrically dividing apical progenitors, lacked apical-basal polarity and showed a nearly randomized cleavage plane orientation. Moreover, the appearance of beta-III-tubulin–driven GFP fluorescence in basal progenitor-derived neurons, in contrast to that in apical progenitor-derived neurons, was so rapid that it suggested the initiation of the neuronal phenotype already in the progenitor. Our observations imply that (i) the loss of apical-basal polarity restricts neuronal progenitors to the symmetric mode of cell division, and that (ii) basal progenitors initiate the expression of neuronal phenotype already before mitosis, in contrast to apical progenitors
Exercise-based cardiac rehabilitation improves exercise capacity and health-related quality of life in people with atrial fibrillation: A systematic review and meta-analysis of randomised and non-randomised trials
This is the final version. Available on open access from BMJ Publishing Group via the DOI in this recordObjective The aim of this study was to undertake a contemporary review of the impact of exercise-based cardiac rehabilitation (CR) targeted at patients with atrial fibrillation (AF). Methods We conducted searches of PubMED, EMBASE and the Cochrane Library of Controlled Trials (up until 30 November 2017) using key terms related to exercise-based CR and AF. Randomised and non-randomised controlled trials were included if they compared the effects of an exercise-based CR intervention to a no exercise or usual care control group. Meta-analyses of outcomes were conducted where appropriate. Results The nine randomised trials included 959 (483 exercise-based CR vs 476 controls) patients with various types of AF. Compared with control, pooled analysis showed no difference in all-cause mortality (risk ratio (RR) 1.08, 95% CI 0.77 to 1.53, p=0.64) following exercise-based CR. However, there were improvements in health-related quality of life (mean SF-36 mental component score (MCS): 4.00, 95% CI 0.26 to 7.74; p=0.04 and mean SF-36 physical component score: 1.82, 95% CI 0.06 to 3.59; p=0.04) and exercise capacity (mean peak VO2: 1.59 ml/kg/min, 95% CI 0.11 to 3.08; p=0.04; mean 6 min walk test: 46.9 m, 95% CI 26.4 to 67.4; p<0.001) with exercise-based CR. Improvements were also seen in AF symptom burden and markers of cardiac function. Conclusions Exercise capacity, cardiac function, symptom burden and health-related quality of life were improved with exercise-based CR in the short term (up to 6 months) targeted at patients with AF. However, high-quality multicentre randomised trials are needed to clarify the impact of exercise-based CR on key patient and health system outcomes (including health-related quality of life, mortality, hospitalisation and costs) and how these effects may vary across AF subtypes.National Institute for Health Research (NIHR
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