788 research outputs found
Individual differences in alpha frequency drive crossmodal illusory perception
Perception routinely integrates inputs from different senses. Stimulus temporal proximity critically determines whether or not these inputs are bound together. Despite the temporal window of integration being a widely accepted notion, its neurophysiological substrate remains unclear. Many types of common audio-visual interactions occur within a time window of -100ms [1-5]. For example, in the sound- induced double-flash illusion, when two beeps are presented within -100ms together with one flash, a second illusory flash is often perceived [2]. Due to their intrinsic rhythmic nature, brain oscillations are one candidate mechanism for gating the temporal window of integration. Interestingly, occipital alpha-band oscillations cycle on average every -100ms with peak frequencies ranging between 8-14Hz (i.e. 120-60ms cycle). Moreover, presenting a brief tone can phase-reset such oscillations in visual cortex [6, 7]. Based on these observations, we hypothesized that the duration of each alpha cycle might provide the temporal unit to bind audio-visual events. Here we first recorded EEG while participants performed the sound-induced double-flash illusion task [4] and found positive correlation between individual alpha-frequency (IAF) peak and the size of the temporal window of the illusion. Participants then performed the same task while receiving occipital transcranial alternating current stimulation (tACS), to modulate oscillatory activity [8] either at their IAF or at off-peak alpha-frequencies (IAF±2Hz). Compared to IAF tACS, IAF-2Hz and IAF+2Hz tACS respectively enlarged and shrunk the temporal window of illusion, suggesting that alpha oscillations might represent the temporal unit of visual processing that cyclically gates perception and the neurophysiological substrate promoting audio-visual interactions
Spectrum of Sizes for Perfect Deletion-Correcting Codes
One peculiarity with deletion-correcting codes is that perfect
-deletion-correcting codes of the same length over the same alphabet can
have different numbers of codewords, because the balls of radius with
respect to the Levenshte\u{\i}n distance may be of different sizes. There is
interest, therefore, in determining all possible sizes of a perfect
-deletion-correcting code, given the length and the alphabet size~.
In this paper, we determine completely the spectrum of possible sizes for
perfect -ary 1-deletion-correcting codes of length three for all , and
perfect -ary 2-deletion-correcting codes of length four for almost all ,
leaving only a small finite number of cases in doubt.Comment: 23 page
Deep forecasting of translational impact in medical research.
The value of biomedical research-a $1.7 trillion annual investment-is ultimately determined by its downstream, real-world impact, whose predictability from simple citation metrics remains unquantified. Here we sought to determine the comparative predictability of future real-world translation-as indexed by inclusion in patents, guidelines, or policy documents-from complex models of title/abstract-level content versus citations and metadata alone. We quantify predictive performance out of sample, ahead of time, across major domains, using the entire corpus of biomedical research captured by Microsoft Academic Graph from 1990-2019, encompassing 43.3 million papers. We show that citations are only moderately predictive of translational impact. In contrast, high-dimensional models of titles, abstracts, and metadata exhibit high fidelity (area under the receiver operating curve [AUROC]Â >Â 0.9), generalize across time and domain, and transfer to recognizing papers of Nobel laureates. We argue that content-based impact models are superior to conventional, citation-based measures and sustain a stronger evidence-based claim to the objective measurement of translational potential
OA01-06 LB. HIV-1 plasma RNA and risk of HIV-1 transmission
Background: Non-sterilizing HIV-1 vaccines may provide public health benefits if they significantly reduce plasma HIV-1 RNA, thus potentially reducing infectiousness. Quantification of reduction in plasma HIV-1 RNA needed to decrease HIV-1 transmission is useful for design of efficacy trials of candidate HIV-1 vaccines. We modeled the relationship between plasma HIV-1 RNA and HIV-1 transmission using data from a prospective study of African heterosexual HIV-1 serodiscordant couples. Methods: 3408 HIV-1-infected participants with CD4 counts ≥250 cells/mm3 enrolled in the Partners in Prevention HSV/HIV Transmission Study and their partners were followed for ≤24 months. HIV-1 transmission events were assessed for viral genetic linkage within the enrolled partnership by determining HIV-1 env and gag sequences from partners. The relationship between plasma HIV-1 RNA over time and risk of genetically linked HIV-1 transmission was evaluated with a Cox model with a natural cubic spline. Results: 84 post-enrollment linked HIV-1 transmissions were observed. HIV-1 incidence increased rapidly and non-linearly with higher plasma HIV-1: from 0.53 transmissions per 100 person-years for plasma HIV-1 RNA 1,000,000 copies/mL (p<0.0001). Baseline HIV-1 RNA in men was, on average, 0.4 log10 higher than in women; no significant difference in risk of transmission for a given HIV-1 level was observed between men and women (p = 0.17). Given the distribution of plasma HIV-1 RNA in this population of stable cohabiting couples, our modeling predicts that a 0.74 log10 reduction in average plasma HIV-1 RNA in the population would be required for a 50% reduction in HIV-1 transmission risk. Conclusion: This analysis provides a detailed description of the relationship between plasma HIV-1 RNA and risk of heterosexual HIV-1 transmission. These findings suggest targets for reduction in HIV-1 RNA for use in evaluating non-sterilizing HIV-1 vaccine candidates in HIV-1 infected persons to reduce risk of heterosexual HIV-1 transmission
Binary Population Synthesis: Methods, Normalization, and Surprises
In this paper we present a brief overview of population synthesis methods
with a discussion of their main advantages and disadvantages. In the second
part, we present some recent results from synthesis models of close binary
compact objects with emphasis on the predicted rates, their uncertainties, and
the model input parameters the rates are most sensitive to. We also report on a
new evolutionary path leading to the formation of close double neutron stars
(NS), with the unique characteristic that none of the two NS ever had the
chance to be recycled by accretion. Their formation rates turn out to be
comparable to or maybe even higher than those of recycled NS-NS binaries (like
the ones observed), but their detection probability as binary pulsars is much
smaller because of their short lifetimes. We discuss the implications of such a
population for gravitational-wave detection of NS-NS inspiral events, and
possibly for gamma-ray bursts and their host galaxies.Comment: 15 pages, 1 figure, to appear in the proceedings ``The influence of
binaries on stellar population studies'', Brussels, August 2000 (Kluwer
Academic Publishers), ed. D.Vanbevere
Adiabatic Evolution of Mass-losing Stars
We have calculated the equilibrium properties of a star in a circular,
equatorial orbit about a Super-Massive Black Hole (SMBH), when the star fills
and overflows its Roche lobe. The mass transfer time scale is anticipated to be
long compared with the dynamical time and short compared with the thermal time
of the star, so that the entropy as a function of the interior mass is
conserved. We have studied how the stellar entropy, pressure, radius, mean
density, and orbital angular momentum vary when the star is evolved
adiabatically, for a representative set of stars. We have shown that the
stellar orbits change with the stellar mean density. Therefore, sun-like stars,
upper main sequence stars and red giants will spiral inward and then outward
with respect to the hole in this stable mass transfer process, while lower main
sequence stars, brown dwarfs and white dwarfs will always spiral outward.Comment: 8 pages, 19 figures, submitted to MNRA
Virological remission after antiretroviral therapy interruption in female African HIV seroconverters.
INTRODUCTION: There are few data on the frequency of virological remission in African individuals after treatment with antiretroviral therapy (ART) in primary HIV infection (PHI). METHODS: We studied participants (n = 82) from South Africa and Uganda in Short Pulse Antiretroviral Treatment at HIV-1 Seroconversion, the first trial of treatment interruption in African individuals with PHI randomized to deferred ART or 48 weeks of immediate ART. All were female and infected with non-B HIV subtypes, mainly C. We measured HIV DNA in CD4 T cells, CD4 cell count, plasma viral load (pVL), cell-associated HIV RNA and T-cell activation and exhaustion. We explored associations with clinical progression and time to pVL rebound after treatment interruption (n = 22). Data were compared with non-African Short Pulse Antiretroviral Treatment at HIV-1 Seroconversion participants. RESULTS: Pretherapy pVL and integrated HIV DNA were lower in Africans compared with non-Africans (median 4.16 vs. 4.72 log10 copies/ml and 3.07 vs. 3.61 log10 copies/million CD4 T cells, respectively; P < 0.001). Pre-ART HIV DNA in Africans was associated with clinical progression (P = 0.001, HR per log10 copies/million CD4 T cells increase (95% CI) 5.38 (1.95-14.79)) and time to pVL rebound (P = 0.034, HR per log10 copies/ml increase 4.33 (1.12-16.84)). After treatment interruption, Africans experienced longer duration of viral remission than non-Africans (P < 0.001; HR 3.90 (1.75-8.71). Five of 22 African participants (22.7%) maintained VL less than 400 copies/ml over a median of 188 weeks following treatment interruption. CONCLUSION: We find evidence of greater probability of virological remission following treatment interruption among African participants, although we are unable to differentiate between sex, ethnicity and viral subtype. The finding warrants further investigation
The inter-relationship of adolescent unhappiness and parental mental distress
Purpose
Substantial evidence supports the hypothesis that parental well-being impacts upon child well-being and that this relationship is bidirectional. Here we explore how, in a large, nationally representative sample, both parents' mental distress relates over time to each other's mental distress and to their adolescent child's unhappiness, and vice versa.
Methods
Analyses were conducted using data from waves one to five (2009/10–2014/15) of Understanding Society, the UK Household Longitudinal Study. Understanding Society collects data on adults' mental distress (General Health Questionnaire), and on youths' (age: 10–15 years) unhappiness in relation to their school work, appearance, family, friends, school, and life as a whole. We use repeated-measures structural equation models to investigate the reciprocal relationships between both parents' distress and their child's unhappiness, using both longitudinal cross-lagged and nonrecursive contemporaneous specifications. The analytic sample is 1,883 triads (adolescent child, mother, and father) with data at two or more consecutive time points. Analyses are stratified by adolescent gender.
Results
Our results show that parental mental distress predicts unhappiness of girls but not that of boys. Reciprocal associations of maternal and paternal mental distress are evident in families with an adolescent daughter. Unhappiness of adolescents does not predict their parents' mental distress. Results are similar whether examined contemporaneously or over time.
Conclusions
Our findings support the suggestion that the family should be considered as a dynamic system, for instance when planning clinical interventions. This is particularly pertinent in families with an adolescent daughter present
Accretion Disks Around Black Holes: Twenty Five Years Later
We study the progress of the theory of accretion disks around black holes in
last twenty five years and explain why advective disks are the best bet in
explaining varied stationary and non-stationary observations from black hole
candidates. We show also that the recently proposed advection dominated flows
are incorrect.Comment: 30 Latex pages including figures. Kluwer Style files included.
Appearing in `Observational Evidence for Black Holes in the Universe', ed.
Sandip K. Chakrabarti, Kluwer Academic Publishers (DORDRECHT: Holland
CPX-351 exhibits hENT-independent uptake and can be potentiated by fludarabine in leukaemic cells lines and primary refractory AML
© 2018 Elsevier Ltd CPX-351, a liposomal formulation co-encapsulating cytarabine and daunorubicin (DNR) in a synergistic 5:1 M ratio, has shown favourable response in newly diagnosed elderly high-risk AML. This study assessed intracellular ara-CTP levels following in vitro exposure of human immortalised leukaemic cell lines and primary AML blasts to CPX-351, and investigated fludarabine potentiation of intracellular ara-CTP formation from CPX-351. Comparison of intracellular handling of CPX-351 to cytarabine in HL-60 cells indicated slower conversion to ara-CTP for CPX-351, but equivalent cytotoxicity to cytarabine and combined DNR/cytarabine (DA) at 48 h, mostly likely reflecting the need for intracellular liposome processing to release encapsulated drugs. Further assessment demonstrated cytotoxicity of CPX-351 to be superior to DA at 48 and 72 h in cytarabine-resistant THP-1 cells (p < 0.001), and this effect could not be inhibited upon blockade of human equilibrative nucleoside transporter (hENT) function with dipyridamole. Assessment of Flu-CPX in primary blasts from presentation AML patients (n = 5) demonstrated a more rapid and pronounced potentiation of ara-CTP from CPX-351 than in immortalised cell lines, with 4/5 patients showing significant increases in ara-CTP, notably for those that went on to fail induction and relapse treatment in vivo (n = 3). This suggests a favourable impact on patient outcome from Flu-CPX
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