926 research outputs found
Rhythms of Consciousness: Binocular Rivalry Reveals Large-Scale Oscillatory Network Dynamics Mediating Visual Perception
Consciousness has been proposed to emerge from functionally integrated large-scale ensembles of gamma-synchronous neural populations that form and dissolve at a frequency in the theta band. We propose that discrete moments of perceptual experience are implemented by transient gamma-band synchronization of relevant cortical regions, and that disintegration and reintegration of these assemblies is time-locked to ongoing theta oscillations. In support of this hypothesis we provide evidence that (1) perceptual switching during binocular rivalry is time-locked to gamma-band synchronizations which recur at a theta rate, indicating that the onset of new conscious percepts coincides with the emergence of a new gamma-synchronous assembly that is locked to an ongoing theta rhythm; (2) localization of the generators of these gamma rhythms reveals recurrent prefrontal and parietal sources; (3) theta modulation of gamma-band synchronization is observed between and within the activated brain regions. These results suggest that ongoing theta-modulated-gamma mechanisms periodically reintegrate a large-scale prefrontal-parietal network critical for perceptual experience. Moreover, activation and network inclusion of inferior temporal cortex and motor cortex uniquely occurs on the cycle immediately preceding responses signaling perceptual switching. This suggests that the essential prefrontal-parietal oscillatory network is expanded to include additional cortical regions relevant to tasks and perceptions furnishing consciousness at that moment, in this case image processing and response initiation, and that these activations occur within a time frame consistent with the notion that conscious processes directly affect behaviour
Epidemiology of antimicrobial-resistant Escherichia coli carriage in sympatric humans and livestock in a rapidly urbanizing city
There are substantial limitations in understanding of the distribution of antimicrobial resistance (AMR) in humans and livestock in developing countries. This papers present the results of an epidemiological study examining patterns of AMR in Escherichia coli isolates circulating in sympatric human (n = 321) and livestock (n = 633) samples from 99 households across Nairobi, Kenya. E. coli isolates were tested for susceptibility to 13 antimicrobial drugs representing nine antibiotic classes. High rates of AMR were detected, with 47.6% and 21.1% of isolates displaying resistance to three or more and five or more antibiotic classes, respectively. Human isolates showed higher levels of resistance to sulfonamides, trimethoprim, aminoglycosides and penicillins compared with livestock (P0.05). These findings revealed a high prevalence of AMR E. coli circulating in healthy humans and livestock in Nairobi, with no evidence to suggest that keeping livestock, when treated as a single risk factor, contributed significantly to the burden of AMR in humans, although the presence of livestock waste was significant. These results provide an understanding of the broader epidemiology of AMR in complex and interconnected urban environments
Incarceration history and risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis
Background
People who inject drugs (PWID) experience a high prevalence of incarceration and might be at high risk of HIV and hepatitis C virus (HCV) infection during or after incarceration. We aimed to assess whether incarceration history elevates HIV or HCV acquisition risk among PWID.
Methods
In this systematic review and meta-analysis, we searched MEDLINE, Embase, and PsycINFO databases for studies in any language published from Jan 1, 2000 until June 13, 2017 assessing HIV or HCV incidence among PWID. We included studies that measured HIV or HCV incidence among community-recruited PWID. We included only studies reporting original results and excluded studies that evaluated incident infections by self-report. We contacted authors of cohort studies that met the inclusion or exclusion criteria, but that did not report on the outcomes of interest, to request data. We extracted and pooled data from the included studies using random-effects meta-analyses to quantify the associations between recent (past 3, 6, or 12 months or since last follow-up) or past incarceration and HIV or HCV acquisition (primary infection or reinfection) risk among PWID. We assessed the risk of bias of included studies using the Newcastle-Ottawa Scale. Between-study heterogeneity was evaluated using the I2 statistic and the P-value for heterogeneity.
Findings
We included published results from 20 studies and unpublished results from 21 studies. These studies originated from Australasia, western and eastern Europe, North and Latin America, and east and southeast Asia. Recent incarceration was associated with an 81% (relative risk [RR] 1·81, 95% CI 1·40–2·34) increase in HIV acquisition risk, with moderate heterogeneity between studies (I2=63·5%; p=0·001), and a 62% (RR 1·62, 95% CI 1·28–2·05) increase in HCV acquisition risk, also with moderate heterogeneity between studies (I2=57·3%; p=0·002). Past incarceration was associated with a 25% increase in HIV (RR 1·25, 95% CI 0·94–1·65) and a 21% increase in HCV (1·21, 1·02–1·43) acquisition risk.
Interpretation
Incarceration is associated with substantial short-term increases in HIV and HCV acquisition risk among PWID and could be a significant driver of HCV and HIV transmission among PWID. These findings support the need for developing novel interventions to minimise the risk of HCV and HIV acquisition, including addressing structural risks associated with drug laws and excessive incarceration of PWID
The exported protein PbCP1 localises to cleft-like structures in the rodent malaria parasite Plasmodium berghei
Protein export into the host red blood cell is one of the key processes in the pathobiology of the malaria parasite Plasmodiumtrl falciparum, which extensively remodels the red blood cell to ensure its virulence and survival. In this study, we aimed to shed further light on the protein export mechanisms in the rodent malaria parasite P. berghei and provide further proof of the conserved nature of host cell remodeling in Plasmodium spp. Based on the presence of an export motif (R/KxLxE/Q/D) termed PEXEL (Plasmodium export element), we have generated transgenic P. berghei parasite lines expressing GFP chimera of putatively exported proteins and analysed one of the newly identified exported proteins in detail. This essential protein, termed PbCP1 (P. berghei Cleft-like Protein 1), harbours an atypical PEXEL motif (RxLxY) and is further characterised by two predicted transmembrane domains (2TMD) in the C-terminal end of the protein. We have functionally validated the unusual PEXEL motif in PbCP1 and analysed the role of the 2TMD region, which is required to recruit PbCP1 to discrete membranous structures in the red blood cell cytosol that have a convoluted, vesico-tubular morphology by electron microscopy. Importantly, this study reveals that rodent malaria species also induce modifications to their host red blood cell
The DEHVILS Survey Overview and Initial Data Release: High-Quality Near-Infrared Type Ia Supernova Light Curves at Low Redshift
While the sample of optical Type Ia Supernova (SN Ia) light curves (LCs)
usable for cosmological parameter measurements surpasses 2000, the sample of
published, cosmologically viable near-infrared (NIR) SN Ia LCs, which have been
shown to be good "standard candles," is still 200. Here, we present
high-quality NIR LCs for 83 SNe Ia ranging from as a part of
the Dark Energy, H, and peculiar Velocities using Infrared Light from
Supernovae (DEHVILS) survey. Observations are taken using UKIRT's WFCAM, where
the median depth of the images is 20.7, 20.1, and 19.3 mag (Vega) for , ,
and -bands, respectively. The median number of epochs per SN Ia is 18 for
all three bands () combined and 6 for each band individually. We fit 47 SN
Ia LCs that pass strict quality cuts using three LC models, SALT3, SNooPy, and
BayeSN and find scatter on the Hubble diagram to be comparable to or better
than scatter from optical-only fits in the literature. Fitting NIR-only LCs, we
obtain standard deviations ranging from 0.128-0.135 mag. Additionally, we
present a refined calibration method for transforming 2MASS magnitudes to WFCAM
magnitudes using HST CALSPEC stars that results in a 0.03 mag shift in the
WFCAM -band magnitudes.Comment: 24 pages, 9 figures. Accepted by MNRA
Cross-National Differences in Victimization : Disentangling the Impact of Composition and Context
Varying rates of criminal victimization across countries are assumed to be the outcome of countrylevel structural constraints that determine the supply ofmotivated o¡enders, as well as the differential composition within countries of suitable targets and capable guardianship. However, previous empirical tests of these ‘compositional’ and ‘contextual’ explanations of cross-national di¡erences
have been performed upon macro-level crime data due to the unavailability of comparable individual-level data across countries. This limitation has had two important consequences for cross-national crime research. First, micro-/meso-level mechanisms underlying cross-national differences cannot be truly inferred from macro-level data. Secondly, the e¡ects of contextual measures (e.g. income inequality) on crime are uncontrolled for compositional heterogeneity. In this
paper, these limitations are overcome by analysing individual-level victimization data across 18 countries from the International CrimeVictims Survey. Results from multi-level analyses on theft and violent victimization indicate that the national level of income inequality is positively related to risk, independent of compositional (i.e. micro- and meso-level) di¡erences. Furthermore, crossnational variation in victimization rates is not only shaped by di¡erences in national context, but
also by varying composition. More speci¢cally, countries had higher crime rates the more they consisted of urban residents and regions with lowaverage social cohesion.
SN 2021hpr and its two siblings in the Cepheid calibrator galaxy NGC 3147: A hierarchical BayeSN analysis of a Type Ia supernova trio, and a Hubble constant constraint
To improve Type Ia supernova (SN Ia) standardisability, the consistency of
distance estimates to siblings -- SNe in the same host galaxy -- should be
investigated. We present Young Supernova Experiment Pan-STARRS-1
photometry of SN 2021hpr, the third spectroscopically confirmed SN Ia in the
high-stellar-mass Cepheid-calibrator galaxy NGC 3147. We analyse NGC 3147's
trio of SN Ia siblings: SNe 1997bq, 2008fv and 2021hpr, using a new version of
the BayeSN model of SN Ia spectral-energy distributions, retrained
simultaneously using optical-NIR (0.35--1.8 m) data. The
distance estimates to each sibling are consistent, with a sample standard
deviation 0.01 mag, much smaller than the total intrinsic scatter in
the training sample: mag. Fitting normal SN Ia siblings
in three additional galaxies, we estimate a 90% probability that the
siblings' intrinsic scatter is smaller than . We build a new
hierarchical model that fits light curves of siblings in a single galaxy
simultaneously; this yields more precise estimates of the common distance and
the dust parameters. Fitting the trio for a common dust law shape yields
. Our work motivates future hierarchical modelling of more
siblings, to tightly constrain their intrinsic scatter, and better understand
SN-host correlations. Finally, we estimate the Hubble constant, using a Cepheid
distance to NGC 3147, the siblings trio, and 109 Hubble flow () SNe Ia; marginalising over the siblings' and population's
intrinsic scatters, and the peculiar velocity dispersion, yields
.Comment: Submitted to MNRAS; 30 pages, 22 figure
Magnetic Domains
Recently a Nahm transform has been discovered for magnetic bags, which are
conjectured to arise in the large n limit of magnetic monopoles with charge n.
We interpret these ideas using string theory and present some partial proofs of
this conjecture. We then extend the notion of bags and their Nahm transform to
higher gauge theories and arbitrary domains. Bags in four dimensions
conjecturally describe the large n limit of n self-dual strings. We show that
the corresponding Basu-Harvey equation is the large n limit of an equation
describing n M2-branes, and that it has a natural interpretation in loop space.
We also formulate our Nahm equations using strong homotopy Lie algebras.Comment: 42 pages, minor improvements, published versio
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