886 research outputs found

    Sleep Analytics and Online Selective Anomaly Detection

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    We introduce a new problem, the Online Selective Anomaly Detection (OSAD), to model a specific scenario emerging from research in sleep science. Scientists have segmented sleep into several stages and stage two is characterized by two patterns (or anomalies) in the EEG time series recorded on sleep subjects. These two patterns are sleep spindle (SS) and K-complex. The OSAD problem was introduced to design a residual system, where all anomalies (known and unknown) are detected but the system only triggers an alarm when non-SS anomalies appear. The solution of the OSAD problem required us to combine techniques from both machine learning and control theory. Experiments on data from real subjects attest to the effectiveness of our approach.Comment: Submitted to 20th ACM SIGKDD Conference on Knowledge Discovery and Data Mining 201

    Teegi: Tangible EEG Interface

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    We introduce Teegi, a Tangible ElectroEncephaloGraphy (EEG) Interface that enables novice users to get to know more about something as complex as brain signals, in an easy, en- gaging and informative way. To this end, we have designed a new system based on a unique combination of spatial aug- mented reality, tangible interaction and real-time neurotech- nologies. With Teegi, a user can visualize and analyze his or her own brain activity in real-time, on a tangible character that can be easily manipulated, and with which it is possible to interact. An exploration study has shown that interacting with Teegi seems to be easy, motivating, reliable and infor- mative. Overall, this suggests that Teegi is a promising and relevant training and mediation tool for the general public.Comment: to appear in UIST-ACM User Interface Software and Technology Symposium, Oct 2014, Honolulu, United State

    Multi-Q mesoscale magnetism in CeAuSb2_2

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    We report the discovery of a field driven transition from a striped to woven Spin Density Wave (SDW) in the tetragonal heavy fermion compound CeAuSb2_2. Polarized along c\bf c, the sinusoidal SDW amplitude is 1.8(2) ÎŒB\mu_B/Ce for Tâ‰ȘTNT \ll T_N=6.25(10) K with wavevector q1=(η,η,12){\bf q}_{1}=( \eta, \eta, \frac{1}{2} ) (η=0.136(2)\eta=0.136(2)). For H∄c{\bf H}\parallel{\bf c}, harmonics appearing at 2q12{\bf q}_{1} evidence a striped magnetic texture below Ό∘Hc1=2.78(1)\mu_\circ H_{c1}=2.78(1) T. Above Hc1H_{c1}, these are replaced by woven harmonics at q1+q2=(2η,0,0)+c∗{\bf q}_{1}+{\bf q}_2=(2\eta, 0, 0)+{\bf c}^* until Ό∘Hc2=5.42(5)\mu_\circ H_{c2}=5.42(5) T, where satellites vanish and magnetization non-linearly approaches saturation at 1.64(2) ÎŒB\mu_B/Ce for Ό∘H≈7\mu_\circ H\approx 7 T.Comment: 5 pages, 4 figure

    Diagnosis by Documentary: Professional Responsibilities in Informal Encounters

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    Most work addressing clinical workers' professional responsibilities concerns the norms of conduct within established professional-patient relationships, but such responsibilities may extend beyond the clinical context. We explore health workers' professional responsibilities in such "informal" encounters through the example of a doctor witnessing the misdiagnosis and mistreatment of a serious long-term condition in a television documentary, arguing that neither internalist approaches to professional responsibility (such as virtue ethics or care ethics) nor externalist ones (such as the "social contract" model) provide sufficiently clear guidance in such situations. We propose that a mix of both approaches, emphasizing the noncomplacency and practical wisdom of virtue ethics, but grounding the normative authority of virtue in an external source, is able to engage with the health worker's responsibilities in such situations to the individual, the health care system, and the population at large

    The transformation of the forest steppe in the lower Danube Plain of south-eastern Europe : 6000 years of vegetation and land use dynamics

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    Forest steppes are dynamic ecosystems, highly susceptible to changes in climate and land use. Here we examine the Holocene history of the European forest steppe ecotone in the Lower Danube Plain to better understand its sensitivity to climate fluctuations and human impact, and the timing of its transition into a cultural forest steppe. We used multi-proxy analyses (pollen, n-alkane, coprophilous fungi, charcoal, and geochemistry) of a 6000-year sequence from Lake Oltina (SE Romania), combined with a REVEALS model of quantitative vegetation cover. We found the greatest tree cover, composed of xerothermic (Carpinus orientalis and Quercus) and temperate (Carpinus betulus, Tilia, Ulmus and Fraxinus) tree taxa between 6000 and 2500 cal yr BP. Maximum tree cover (~ 50 %) occurred between 4200 and 2500 cal yr BP at a time of wetter climatic conditions. Compared to other European forest steppe areas, the dominance of Carpinus orientalis represents the most distinct feature of the woodland's composition during that time. Forest loss was under way by 2500 yr BP (Iron Age) with REVEALS estimates indicating a fall to ~ 20 % tree cover from the mid-Holocene forest maximum linked to clearance for agriculture, while climate conditions remained wet. Biomass burning increased markedly at 2500 cal yr BP suggesting that fire was regularly used as a management tool until 1000 cal yr BP when woody vegetation became scarce. A sparse tree cover, with only weak signs of forest recovery, then became a permanent characteristic of the Lower Danube Plain, highlighting recurring anthropogenic pressure. The timing of anthropogenic ecosystem transformation here (2500 cal yr BP) was in between that in central eastern (between 3700 and 3000 cal yr BP) and eastern (after 2000 cal yr BP) Europe. Our study is the first quantitative land cover estimate at the forest steppe ecotone in south eastern Europe spanning 6000 years and provides critical empirical evidence that the present-day forest steppe/woodlands reflects the potential natural vegetation in this region under current climate conditions. This study also highlights the potential of n-alkane indices for vegetation reconstruction, particularly in dry regions where pollen is poorly preserved

    Cluster Spin Glass Distribution Functions in La2−x_{2-x}Srx_xCuO4_4

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    Signatures of the cluster spin glass have been found in a variety of experiments, with an effective onset temperature TonT_{on} that is frequency dependent. We reanalyze the experimental results and find that they are characterized by a distribution of activation energies, with a nonzero glass transition temperature Tg(x)<TonT_g(x)<T_{on}. While the distribution of activation energies is the same, the distribution of weights depends on the process. Remarkably, the weights are essentially doping independent.Comment: 5 pages, 5 ps figure

    Webteaching: sequencing of subject matter in relation to prior knowledge of pupils

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    Two experiments are discussed in which the sequencing procedure of webteaching is compared with a linear sequence for the presentation of text material.\ud \ud In the first experiment variations in the level of prior knowledge of pupils were studied for their influence on the sequencing mode of text presentation. Prior knowledge greatly reduced the effect of the size of sequencing procedures.\ud \ud In the second experiment pupils with a low level of prior knowledge studied a text, following either a websequence or a linear sequence. Webteaching was superior to linear teaching on a number of dependent variables. It is concluded that webteaching is an effective sequencing procedure in those cases where substantial new learning is required

    More than just an eagle killer: The freshwater cyanobacterium Aetokthonos hydrillicola produces highly toxic dolastatin derivatives

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    Cyanobacteria are infamous producers of toxins. While the toxic potential of planktonic cyanobacterial blooms is well documented, the ecosystem level effects of toxigenic benthic and epiphytic cyanobacteria are an understudied threat. The freshwater epiphytic cyanobacterium Aetokthonos hydrillicola has recently been shown to produce the “eagle killer” neurotoxin aetokthonotoxin (AETX) causing the fatal neurological disease vacuolar myelinopathy. The disease affects a wide array of wildlife in the southeastern United States, most notably waterfowl and birds of prey, including the bald eagle. In an assay for cytotoxicity, we found the crude extract of the cyanobacterium to be much more potent than pure AETX, prompting further investigation. Here, we describe the isolation and structure elucidation of the aetokthonostatins (AESTs), linear peptides belonging to the dolastatin compound family, featuring a unique modification of the C-terminal phenylalanine-derived moiety. Using immunofluorescence microscopy and molecular modeling, we confirmed that AEST potently impacts microtubule dynamics and can bind to tubulin in a similar matter as dolastatin 10. We also show that AEST inhibits reproduction of the nematode Caenorhabditis elegans. Bioinformatic analysis revealed the AEST biosynthetic gene cluster encoding a nonribosomal peptide synthetase/polyketide synthase accompanied by a unique tailoring machinery. The biosynthetic activity of a specific N-terminal methyltransferase was confirmed by in vitro biochemical studies, establishing a mechanistic link between the gene cluster and its product
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