408 research outputs found

    Patients’ Perceptions of Memory Functioning Before and After Surgical Intervention to Treat Medically Refractory Epilepsy.

    Get PDF
    Purpose:One risk associated with epilepsy surgery is memory loss, but perhaps more important is how patients perceive changes in their memories. This longitudinal study evaluated changes in memory self-reports and investigated how self-reports relate to changes on objective memory measures in temporal or extratemporal epilepsy patients who underwent surgery. Methods: Objective memory (Wechsler Memory Scale–Revised) and subjective memory self-reports (Memory Assessment Clinics Self-Rating Scale) were individually assessed for 136 patients ∼6 months before and 6 months after surgery. A measure of depressive affect (Beck Depression Inventory–2nd Edition) was used to control variance attributable to emotional distress. Results: Despite a lack of significant correlational relationships between objective and subjective memory for the entire sample, significant correlations between objective memory scores and self-reports did emerge for a subset of patients who evidenced memory decline. Differences also were found in the subjective memory ratings of temporal lobe versus extratemporal patients. Temporal lobe patients rated their memories more negatively than did extratemporal patients and were more likely to report significant improvements in their memory after surgery. Conclusions: In general, patients were not accurate when rating their memories compared to other adults. However, patients with significant declines in their memories were sensitive to actual changes in their memories over time relative to their own personal baselines

    How contemporary bioclimatic and human controls change global fire regimes

    Get PDF
    Anthropogenically driven declines in tropical savannah burnt area have recently received attention due to their effect on trends in global burnt area. Large-scale trends in ecosystems where vegetation has adapted to infrequent fire, especially in cooler and wetter forested areas, are less well understood. Here, small changes in fire regimes can have a substantial impact on local biogeochemistry. To investigate trends in fire across a wide range of ecosystems, we used Bayesian inference to quantify four primary controls on burnt area: fuel continuity, fuel moisture, ignitions and anthropogenic suppression. We found that fuel continuity and moisture are the dominant limiting factors of burnt area globally. Suppression is most important in cropland areas, whereas savannahs and boreal forests are most sensitive to ignitions. We quantify fire regime shifts in areas with more than one, and often counteracting, trends in these controls. Forests are of particular concern, where we show average shifts in controls of 2.3–2.6% of their potential maximum per year, mainly driven by trends in fuel continuity and moisture. This study gives added importance to understanding long-term future changes in the controls on fire and the effect of fire trends on ecosystem function

    The Nucleus Accumbens: A Switchboard for Goal-Directed Behaviors

    Get PDF
    Reward intake optimization requires a balance between exploiting known sources of rewards and exploring for new sources. The prefrontal cortex (PFC) and associated basal ganglia circuits are likely candidates as neural structures responsible for such balance, while the hippocampus may be responsible for spatial/contextual information. Although studies have assessed interactions between hippocampus and PFC, and between hippocampus and the nucleus accumbens (NA), it is not known whether 3-way interactions among these structures vary under different behavioral conditions. Here, we investigated these interactions with multichannel recordings while rats explored an operant chamber and while they performed a learned lever-pressing task for reward in the same chamber shortly afterward. Neural firing and local field potentials in the NA core synchronized with hippocampal activity during spatial exploration, but during lever pressing they instead synchronized more strongly with the PFC. The latter is likely due to transient drive of NA neurons by bursting prefrontal activation, as in vivo intracellular recordings in anesthetized rats revealed that NA up states can transiently synchronize with spontaneous PFC activity and PFC stimulation with a bursting pattern reliably evoked up states in NA neurons. Thus, the ability to switch synchronization in a task-dependent manner indicates that the NA core can dynamically select its inputs to suit environmental demands, thereby contributing to decision-making, a function that was thought to primarily depend on the PFC

    Neural Correlates of Visual Aesthetics – Beauty as the Coalescence of Stimulus and Internal State

    Get PDF
    How do external stimuli and our internal state coalesce to create the distinctive aesthetic pleasures that give vibrance to human experience? Neuroaesthetics has so far focused on the neural correlates of observing beautiful stimuli compared to neutral or ugly stimuli, or on neural correlates of judging for beauty as opposed to other judgments. Our group questioned whether this approach is sufficient. In our view, a brain region that assesses beauty should show beauty-level-dependent activation during the beauty judgment task, but not during other, unrelated tasks. We therefore performed an fMRI experiment in which subjects judged visual textures for beauty, naturalness and roughness. Our focus was on finding brain activation related to the rated beauty level of the stimuli, which would take place exclusively during the beauty judgment. An initial whole-brain analysis did not reveal such interactions, yet a number of the regions showing main effects of the judgment task or the beauty level of stimuli were selectively sensitive to beauty level during the beauty task. Of the regions that were more active during beauty judgments than roughness judgments, the frontomedian cortex and the amygdala demonstrated the hypothesized interaction effect, while the posterior cingulate cortex did not. The latter region, which only showed a task effect, may play a supporting role in beauty assessments, such as attending to one's internal state rather than the external world. Most of the regions showing interaction effects of judgment and beauty level correspond to regions that have previously been implicated in aesthetics using different stimulus classes, but based on either task or beauty effects alone. The fact that we have now shown that task-stimulus interactions are also present during the aesthetic judgment of visual textures implies that these areas form a network that is specifically devoted to aesthetic assessment, irrespective of the stimulus type

    Epidemiology of severe pediatric adenovirus lower respiratory tract infections in Manitoba, Canada, 1991-2005

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Most pediatric adenovirus respiratory infections are mild and indistinguishable from other viral causes. However, in a few children, the disease can be severe and result in substantial morbidity. We describe the epidemiologic, clinical, radiologic features and outcome of adenovirus lower respiratory tract infections (LRTI) in Aboriginal and Non-Aboriginal children in Manitoba, Canada during the years 1991 and 2005.</p> <p>Methods</p> <p>This was a retrospective study of 193 children who presented to the department of pediatrics at Winnipeg Children's Hospital, Manitoba, Canada with LRTI and had a positive respiratory culture for adenovirus. Patients' demographics, clinical and radiologic features and outcomes were collected. Adenovirus serotype distributions and temporal associations were described. Approximate incidence comparisons (detection rates) of adenovirus LRTI among Aboriginal and Non-Aboriginal children were estimated with 95% confidence intervals.</p> <p>Results</p> <p>Adenovirus infections occurred throughout the year with clusters in the fall and winter. Serotypes 1 to 3 were the predominant isolates (two thirds of the cases). The infection was more frequent among Canadian Aboriginals, as illustrated in 2004, where its incidence in children 0-4 years old was 5.6 fold higher in Aboriginals (13.51 vs. 2.39 per 10,000, <it>p </it>< 0.000). There were no significant differences in length of hospitalization and use of ventilator assistance between the two groups (<it>p </it>> 0.185 and <it>p </it>> 0.624, respectively) nor across serotypes (<it>p </it>> 0.10 and <it>p </it>> 0.05, respectively). The disease primarily affected infants (median age, 9.5 months). Most children presented with bronchiolitis or pneumonia, with multi-lobar consolidations on the chest x-ray. Chronic (residual) changes were documented in 16 patients, with eight patients showing bronchiectasis on the chest computerized tomography scan.</p> <p>Conclusions</p> <p>Adenovirus infection is associated with significant respiratory morbidities, especially in young infants. The infection appears to be more frequent in Aboriginal children. These results justify a careful follow-up for children with adenovirus LRTI.</p

    Search for Kaluza-Klein Graviton Emission in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy Signature

    Get PDF
    We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb1{pb}^{-1} of \ppb collisions at s\sqrt{s} = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a 3+1+n3+1+n-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for nn=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure

    Double Non-Global Logarithms In-N-Out of Jets

    Full text link
    We derive the leading non-global logarithms (NGLs) of ratios of jet masses m_{1,2} and a jet energy veto \Lambda due to soft gluons splitting into regions in and out of jets. Such NGLs appear in any exclusive jet cross section with multiple jet measurements or with a veto imposed on additional jets. Here, we consider back-to-back jets of radius R produced in e^+e^- collisions, found with a cone or recombination algorithm. The leading NGLs are of the form \alpha_s^2 \ln^2(\Lambda/m_{1,2}) or \alpha_s^2\ln^2(m_1/m_2). Their coefficients depend both on the algorithm and on R. We consider cone, \kt, anti-\kt, and Cambridge-Aachen algorithms. In addition to determining the full algorithmic and R dependence of the leading NGLs, we derive new relations among their coefficients. We also derive to all orders in \alpha_s a factorized form for the soft function S(k_L,k_R,\Lambda) in the cross section \sigma(m_1,m_2,\Lambda) in which dependence on each of the global logs of \mu/k_L, \mu/k_R and \mu/\Lambda determined by the renormalization group are separated from one another and from the non-global logs. The same kind of soft function, its associated non-global structure, and the algorithmic dependence we derive here will also arise in exclusive jet cross sections at hadron colliders, and must be understood and brought under control to achieve precise theoretical predictions.Comment: 19 pages, 10 figures. v2: minor edits, additional discussion in Introduction. v3: version published in JHE

    Mitochondrial phylogeography of baboons (Papio spp.) – Indication for introgressive hybridization?

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Baboons of the genus <it>Papio </it>are distributed over wide ranges of Africa and even colonized parts of the Arabian Peninsula. Traditionally, five phenotypically distinct species are recognized, but recent molecular studies were not able to resolve their phylogenetic relationships. Moreover, these studies revealed para- and polyphyletic (hereafter paraphyletic) mitochondrial clades for baboons from eastern Africa, and it was hypothesized that introgressive hybridization might have contributed substantially to their evolutionary history. To further elucidate the phylogenetic relationships among baboons, we extended earlier studies by analysing the complete mitochondrial cytochrome <it>b </it>gene and the 'Brown region' from 67 specimens collected at 53 sites, which represent all species and which cover most of the baboons' range.</p> <p>Results</p> <p>Based on phylogenetic tree reconstructions seven well supported major haplogroups were detected, which reflect geographic populations and discordance between mitochondrial phylogeny and baboon morphology. Our divergence age estimates indicate an initial separation into southern and northern baboon clades 2.09 (1.54–2.71) million years ago (mya). We found deep divergences between haplogroups within several species (~2 mya, northern and southern yellow baboons, western and eastern olive baboons and northern and southern chacma baboons), but also recent divergence ages among species (< 0.7 mya, yellow, olive and hamadryas baboons in eastern Africa).</p> <p>Conclusion</p> <p>Our study confirms earlier findings for eastern Africa, but shows that baboon species from other parts of the continent are also mitochondrially paraphyletic. The phylogenetic patterns suggest a complex evolutionary history with multiple phases of isolation and reconnection of populations. Most likely all these biogeographic events were triggered by multiple cycles of expansion and retreat of savannah biomes during Pleistocene glacial and inter-glacial periods. During contact phases of populations reticulate events (i.e. introgressive hybridization) were highly likely, similar to ongoing hybridization, which is observed between East African baboon populations. Defining the extent of the introgressive hybridization will require further molecular studies that incorporate additional sampling sites and nuclear loci.</p

    External Learning Opportunities and the Diffusion of Process Innovations to Small Firms: The Case of Programmable Automation

    Get PDF
    In this chapter, we are concerned with explaining which types of firms have failed to adopt well-known improvements in process technology. This problem has, of course, been the underlying concern of all studies of diffusion “to rationalize why, if a new technology is superior, it is not taken up by all potential adopters” (Stoneman, 1983). Drawing on various theoretical perspectives, we identify a number of different barriers to adoption. With data collected from a 1987 nationally representative sample of US establishments in 21 metal-working and machinery manufacturing industries, we then construct a multivariate logistic regression model to empirically test for the effects of these factors on the likelihood of adoption of a particular process innovation, namely programmable automation (PA) machine tools
    corecore