5,884 research outputs found
Exploring Outliers in Crowdsourced Ranking for QoE
Outlier detection is a crucial part of robust evaluation for crowdsourceable
assessment of Quality of Experience (QoE) and has attracted much attention in
recent years. In this paper, we propose some simple and fast algorithms for
outlier detection and robust QoE evaluation based on the nonconvex optimization
principle. Several iterative procedures are designed with or without knowing
the number of outliers in samples. Theoretical analysis is given to show that
such procedures can reach statistically good estimates under mild conditions.
Finally, experimental results with simulated and real-world crowdsourcing
datasets show that the proposed algorithms could produce similar performance to
Huber-LASSO approach in robust ranking, yet with nearly 8 or 90 times speed-up,
without or with a prior knowledge on the sparsity size of outliers,
respectively. Therefore the proposed methodology provides us a set of helpful
tools for robust QoE evaluation with crowdsourcing data.Comment: accepted by ACM Multimedia 2017 (Oral presentation). arXiv admin
note: text overlap with arXiv:1407.763
Generalized Log-Normal Chain-Ladder
We propose an asymptotic theory for distribution forecasting from the log
normal chain-ladder model. The theory overcomes the difficulty of convoluting
log normal variables and takes estimation error into account. The results
differ from that of the over-dispersed Poisson model and from the chain-ladder
based bootstrap. We embed the log normal chain-ladder model in a class of
infinitely divisible distributions called the generalized log normal
chain-ladder model. The asymptotic theory uses small asymptotics where
the dimension of the reserving triangle is kept fixed while the standard
deviation is assumed to decrease. The resulting asymptotic forecast
distributions follow t distributions. The theory is supported by simulations
and an empirical application
Sampling bias in systems with structural heterogeneity and limited internal diffusion
Complex systems research is becomingly increasingly data-driven, particularly
in the social and biological domains. Many of the systems from which sample
data are collected feature structural heterogeneity at the mesoscopic scale
(i.e. communities) and limited inter-community diffusion. Here we show that the
interplay between these two features can yield a significant bias in the global
characteristics inferred from the data. We present a general framework to
quantify this bias, and derive an explicit corrective factor for a wide class
of systems. Applying our analysis to a recent high-profile survey of conflict
mortality in Iraq suggests a significant overestimate of deaths
Clinical and social factors associated with involuntary psychiatric hospitalisation in children and adolescents: a systematic review, meta-analysis, and narrative synthesis.
BACKGROUND: Disparities in involuntary psychiatric hospitalisation between population subgroups have been identified in adults, but little is known about the factors associated with involuntary hospitalisation in children or adolescents. We did a systematic review, meta-analysis, and narrative synthesis to investigate the social and clinical factors associated with involuntary psychiatric hospitalisation among children and adolescents. METHODS: We searched MEDLINE, PsycINFO, Embase, and the Cochrane Central Register of Controlled Trials for studies of any type up to July 22, 2020, that compared the characteristics of voluntary and involuntary psychiatric inpatients (mean age of sample ≤18 years). We synthesised results using random effects meta-analysis on unadjusted data and by narrative synthesis. Heterogeneity between studies was calculated using I2. This study is registered on PROSPERO, CRD42020099892. FINDINGS: 23 studies from 11 countries were included in the systematic review and narrative synthesis, of which 19 studies (n=31 212) were included in the meta-analysis. On meta-analysis, involuntary rather than voluntary hospitalisation of minors was associated with a diagnosis of psychosis (eight studies; odds ratio 3·63, 95% CI 2·43-5·44, p<0·0001), substance misuse (five studies; 1·87, 1·05-3·30, p=0·032), or intellectual disability (four studies; 3·33, 1·33-8·34, p=0·010), as well as presenting with a perceived risk of harm to self (eight studies; 2·05, 1·15-3·64, p=0·015) or to others (five studies; 2·37, 1·39-4·03, p=0·0015). Involuntary hospitalisation was also found to be associated with being aged 12 years or older (three studies; 3·57, 1·46-8·73, p=0·0052) and being from a Black rather than a White ethnic group (three studies; 2·72, 1·88-3·95, p<0·0001). There was substantial between-study heterogeneity for most factors included in the meta-analysis (I2 from 51·3% to 92·3%). Narrative synthesis found that more severe illness and poorer global functioning was associated with involuntary hospitalisation. INTERPRETATION: Over-representation of involuntary psychiatric hospitalisation in certain groups might begin in childhood, potentially establishing a cycle of inequality that continues into adulthood. Further research into the systemic factors underlying these health-care inequalities and the barriers to accessing less coercive psychiatric treatment is urgently required, with specific consideration of racial and ethnic factors. FUNDING: UK National Institute for Health Research and Wellcome Trust
Replication-Aware Linearizability
Geo-distributed systems often replicate data at multiple locations to achieve
availability and performance despite network partitions. These systems must
accept updates at any replica and propagate these updates asynchronously to
every other replica. Conflict-Free Replicated Data Types (CRDTs) provide a
principled approach to the problem of ensuring that replicas are eventually
consistent despite the asynchronous delivery of updates.
We address the problem of specifying and verifying CRDTs, introducing a new
correctness criterion called Replication-Aware Linearizability. This criterion
is inspired by linearizability, the de-facto correctness criterion for
(shared-memory) concurrent data structures. We argue that this criterion is
both simple to understand, and it fits most known implementations of CRDTs. We
provide a proof methodology to show that a CRDT satisfies replication-aware
linearizability which we apply on a wide range of implementations. Finally, we
show that our criterion can be leveraged to reason modularly about the
composition of CRDTs
Influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training on the plasma cytokine response to maximum sustainable voluntary ventilation
The influence of oxidative stress, diaphragm fatigue, and inspiratory muscle training (IMT) on the cytokine response to maximum sustainable voluntary ventilation (MSVV) is unknown. Twelve healthy males were divided equally into an IMT or placebo (PLA) group, and before and after a 6-wk intervention they undertook, on separate days, 1h of (1) passive rest and (2) MSVV, whereby participants undertook volitional hyperpnea at rest that mimicked the breathing and respiratory muscle recruitment patterns commensurate with heavy cycling exercise. Plasma cytokines remained unchanged during passive rest. There was a main effect of time (P < 0.01) for plasma interleukin-1 (IL-1) and interleukin-6 (IL-6) concentrations and a strong trend (P = 0.067) for plasma interleukin-1 receptor antagonist concentration during MSVV. Plasma IL-6 concentration was reduced after IMT by 27 + 18% (main effect of intervention, P = 0.029), whereas there was no change after PLA (P = 0.753). There was no increase in a systemic marker of oxidative stress [DNA damage in peripheral blood mononuclear cells (PBMC)], and diaphragm fatigue was not related to the increases in plasma IL-1 and IL-6 concentrations. A dose-response relationship was observed between respiratory muscle work and minute ventilation and increases in plasma IL-6 concentration. In conclusion, increases in plasma IL-1 and IL-6 concentrations during MSVV were not due to diaphragm fatigue or DNA damage in PBMC. Increases in plasma IL-6 concentration during MSVV are attenuated following IMT, and the plasma IL-6 response is dependent upon the level of respiratory muscle work and minute ventilation
The effects of inspiratory muscle training in older adults
Purpose: Declining inspiratory muscle function and structure and systemic low-level inflammation and oxidative stress may contribute to morbidity and mortality during normal ageing. Therefore, we examined the effects of inspiratory muscle training (IMT) in older adults on inspiratory muscle function and structure and systemic inflammation and oxidative stress, and re-examined the reported positive effects of IMT on respiratory muscle strength, inspiratory muscle endurance, spirometry, exercise performance, physical activity levels (PAL) and quality of life (QoL). Methods: Thirty-four healthy older adults (68 ± 3 years) with normal spirometry, respiratory muscle strength and physical fitness were divided equally into a pressure-threshold IMT or sham-hypoxic placebo group. Before and after an 8 week intervention, measurements were taken for dynamic inspiratory muscle function and inspiratory muscle endurance using a weighted plunger pressure-threshold loading device, diaphragm thickness using B-mode ultrasonography, plasma cytokine concentrations using immunoassays, DNA damage levels in peripheral blood mononuclear cells (PBMC) using Comet Assays, spirometry, maximal mouth pressures, exercise performance using a six minute walk test, PAL using a questionnaire and accelerometry, and QoL using a questionnaire
Apoptosis detection in retinal ganglion cells using quantitative changes in multichannel fluorescence colocalization
KcapTR488 is a dual-fluorophore peptide sensor for the real-time reporting of programmed cell death by fluorescence imaging. KcapTR488 contains a nuclear localization sequence (NLS) conjugated with Texas Red, a caspase-cleavable sequence (DEVD), and a C-terminus conjugated to Alexa Fluor 488 (AF488). The synthesis and preliminary evaluation in cellulo of KcapTR488 for monitoring cell death by fluorescence imaging has been previously reported, but its utility in vivo has yet to be tested or validated. Herein, in vitro solution experiments verified the intramolecular fluorescence resonance energy transfer (FRET) between the two fluorophores and enabled a quantitative analysis of enzyme rates and selectivity. The sensor delivery kinetics in live rat models were quantified by ex vivo fluorescence microscopy. Studies in healthy control retinas demonstrated that KcapTR488 concentrated in the nucleus of retinal ganglion cells (RGC), with a strong colocalization of red and green fluorescence signals producing robust FRET signals, indicating an intact reporter. By contrast, using an acute but mild NMDA-induced retinal injury model, dual-color confocal ex vivo microscopy of cleaved KcapTR488 identified sensor activation as early as 2 h after injection. Quantitative changes in fluorescence colocalization were superior to changes in FRET for monitoring injury progression. Longitudinal monitoring revealed that the NLS-Texas Red fragment of the cleaved sensor moved out of the cell body, down the axon, and exited the retina, consistent with anterograde axonal transport. Thus, KcapTR488 may be a powerful tool to study RGC death pathways in live preclinical models of glaucoma
Relativistic quantum model of confinement and the current quark masses
We consider a relativistic quantum model of confined massive spinning quarks
and antiquarks which describes leading Regge trajectories of mesons. The quarks
are described by the Dirac equations and the gluon contribution is approximated
by the Nambu-Goto straight-line string. The string tension and the current
quark masses are the main parameters of the model. Additional parameters are
phenomenological constants which approximate nonstring short-range
contributions. Comparison of the measured meson masses with the model
predictions allows one to determine the current quark masses (in MeV) to be
. The chiral
model[23] makes it possible to estimate from here the - and -quark masses
to be ~ Mev and Mev.Comment: 15 pages, LATEX, 2 tables. (submitted to Phys.Rev.D
Fluctuation induced quantum interactions between compact objects and a plane mirror
The interaction of compact objects with an infinitely extended mirror plane
due to quantum fluctuations of a scalar or electromagnetic field that scatters
off the objects is studied. The mirror plane is assumed to obey either
Dirichlet or Neumann boundary conditions or to be perfectly reflecting. Using
the method of images, we generalize a recently developed approach for compact
objects in unbounded space [1,2] to show that the Casimir interaction between
the objects and the mirror plane can be accurately obtained over a wide range
of separations in terms of charge and current fluctuations of the objects and
their images. Our general result for the interaction depends only on the
scattering matrices of the compact objects. It applies to scalar fields with
arbitrary boundary conditions and to the electromagnetic field coupled to
dielectric objects. For the experimentally important electromagnetic Casimir
interaction between a perfectly conducting sphere and a plane mirror we present
the first results that apply at all separations. We obtain both an asymptotic
large distance expansion and the two lowest order correction terms to the
proximity force approximation. The asymptotic Casimir-Polder potential for an
atom and a mirror is generalized to describe the interaction between a
dielectric sphere and a mirror, involving higher order multipole
polarizabilities that are important at sub-asymptotic distances.Comment: 19 pages, 7 figure
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