330 research outputs found
A three domain covariance framework for EEG/MEG data
In this paper we introduce a covariance framework for the analysis of EEG and
MEG data that takes into account observed temporal stationarity on small time
scales and trial-to-trial variations. We formulate a model for the covariance
matrix, which is a Kronecker product of three components that correspond to
space, time and epochs/trials, and consider maximum likelihood estimation of
the unknown parameter values. An iterative algorithm that finds approximations
of the maximum likelihood estimates is proposed. We perform a simulation study
to assess the performance of the estimator and investigate the influence of
different assumptions about the covariance factors on the estimated covariance
matrix and on its components. Apart from that, we illustrate our method on real
EEG and MEG data sets.
The proposed covariance model is applicable in a variety of cases where
spontaneous EEG or MEG acts as source of noise and realistic noise covariance
estimates are needed for accurate dipole localization, such as in evoked
activity studies, or where the properties of spontaneous EEG or MEG are
themselves the topic of interest, such as in combined EEG/fMRI experiments in
which the correlation between EEG and fMRI signals is investigated.Comment: 25 pages, 8 figures, 1 tabl
Long-term bonding to eroded dentin requires superficial bur preparation
Objectives: This study aims to evaluate the influence of different surface preparation techniques on long-term bonding effectiveness to eroded dentin. Materials and methods: Dentin specimens were eroded by pH cycling or were left untreated as control, respectively. Five different "preparation” techniques were applied: (1) cleaning with pumice, (2) air abrasion, (3) silicon polisher, (4) proxo-shape, and (5) diamond bur. The three-step etch-and-rinse adhesive OptiBond FL (O-FL; Kerr) and the mild two-step self-etch adhesive Clearfil SE Bond (C-SE; Kuraray) were evaluated. Micro-tensile bond strength was measured after water storage for 24h and 1year. Fracture analysis was performed by stereomicroscopy and SEM. Interfaces were characterized by TEM. Differences were statistically analyzed with a linear mixed effects model (α = 0.05). Results: Erosion reduced bond strength in all groups, but this effect was less prominent when eroded dentin was prepared by diamond bur. Storage lowered bond strength in almost all groups significantly, but this ageing effect was more prominent for the eroded surfaces than for non-eroded controls. Whereas after 1-year control specimens revealed superior bond strength with the three-step etch-and-rinse adhesive (O-FL), the mild two-step self-etch adhesive (C-SE) revealed a better 1-year bond strength to eroded dentin. The interface at eroded dentin appeared very prone to degradation as was shown by the increased amount of adhesive failures and by the silver infiltration detected by TEM. Conclusions and clinical relevance: Although a minimally invasive approach should clinically always be strived for, superficial preparation (or minimal roughening) with a diamond bur is recommendable for long-term bonding to eroded denti
Sensing of endogenous nucleic acids by ZBP1 induces keratinocyte necroptosis and skin inflammation
Aberrant detection of endogenous nucleic acids by the immune system can cause inflammatory disease. The scaffold function of the signaling kinase RIPK1 limits spontaneous activation of the nucleic acid sensor ZBP1. Consequently, loss of RIPK1 in keratinocytes induces ZBP1-dependent necroptosis and skin inflammation. Whether nucleic acid sensing is required to activate ZBP1 in RIPK1-deficient conditions and which immune pathways are associated with skin disease remained open questions. Using knock-in mice with disrupted ZBP1 nucleic acid–binding activity, we report that sensing of endogenous nucleic acids by ZBP1 is critical in driving skin pathology characterized by antiviral and IL-17 immune responses. Inducing ZBP1 expression by interferons triggers necroptosis in RIPK1-deficient keratinocytes, and epidermis-specific deletion of MLKL prevents disease, demonstrating that cell-intrinsic events cause inflammation. These findings indicate that dysregulated sensing of endogenous nucleic acid by ZBP1 can drive inflammation and may contribute to the pathogenesis of IL-17–driven inflammatory skin conditions such as psoriasis
Prolonged screening interval due to the COVID-19 pandemic and its association with tumor characteristics and treatment; a register-based study from BreastScreen Norway
Objective: During the COVID-19 pandemic Norway had to suspend its national breast cancer screening program.
We aimed to investigate the effect of the pandemic-induced suspension on the screening interval, and its subsequent association with the tumor characteristics and treatment of screen-detected (SDC) and interval breast
cancer (IC).
Methods: Information about women aged 50–69, participating in BreastScreen Norway, and diagnosed with a
SDC (N = 3799) or IC (N = 1806) between 2018 and 2021 was extracted from the Cancer Registry of Norway.
Logistic regression was used to investigate the association between COVID-19 induced prolonged screening intervals and tumor characteristics and treatment.
Results: Women with a SDC and their last screening exam before the pandemic had a median screening interval of
24.0 months (interquartile range: 23.8–24.5), compared to 27.0 months (interquartile range: 25.8–28.5) for
those with their last screening during the pandemic. The tumor characteristics and treatment of women with a
SDC, last screening during the pandemic, and a screening interval of 29–31 months, did not differ from those of
women with a SDC, last screening before the pandemic, and a screening interval of 23–25 months. ICs detected
24–31 months after screening, were more likely to be histological grade 3 compared to ICs detected 0–23 months
after screening (odds ratio: 1.40, 95% confidence interval: 1.06–1.84).
Conclusions: Pandemic-induced prolonged screening intervals were not associated with the tumor characteristics
and treatment of SDCs, but did increase the risk of a histopathological grade 3 IC. This study provides insights
into the possible effects of extending the screening interval
The development of hemispheric asymmetry in human motion VEPs
AbstractIn six healthy adults we examined the sources underlying P1 and N2 of the motion VEP. For this purpose we acquired, in addition to the VEP, MRI images and patterns of regional cerebral blood flow with SPECT for three of the subjects. With the same motion stimulus we also examined the spatial distribution of N2 in children. In both adults and children left and right half-field responses were compared. It was found that N2 is generated by extrastriate activity and that motion stimuli are not equivalently processed in the two cerebral hemispheres. In adults, N2 dominates in one hemisphere irrespective of the visual half-field used for stimulation whereas children show an ipsilateral maximum for N2 upon half-field presentation
Topographical Organization of Mu and Beta Band Activity Associated with Hand and Foot Movements in Patients with Perirolandic Lesions
To study the topographical organization of mu and beta band event-related desynchronization (ERD) associated with voluntary hand and foot movements, we used magnetoencephalographic (MEG) recordings from 19 patients with perirolandic lesions. Synthetic aperture magnetometry (SAM) was used to detect and localize changes in the mu (7 - 11 Hz) and beta (13 - 30 Hz) frequency bands associated with repetitive movements of the hand and foot and overlaid on individual coregistered magnetic resonance (MR) images. Hand movements showed homotopic and contralateral ERD at the sensorimotor (S/M) cortex in the majority of cases for mu and to a lesser extent for beta rhythms. Foot movements showed an increased heterotopic distribution with bilateral and ipsilateral ERD compared to hand movements. No systematic topographical segregation between mu and beta ERD could be observed. In patients with perirolandic lesions, the mu and beta band spatial characteristics associated with hand movements retain the expected functional-anatomical boundaries to a large extent. Foot movements have altered patterns of mu and beta band ERD, which may give more insight into the differential functional role of oscillatory activity in different voluntary movements
Cold performance tests of blocked-impurity-band Si:As detectors developed for DARWIN
We report first results of laboratory tests of Si:As blocked-impurity-band
(BIB) mid-infrared (4 to 28 um) detectors developed by IMEC. These prototypes
feature 88 pixels hybridized on an integrated cryogenic readout electronics
(CRE). They were developed as part of a technology demonstration program for
the future DARWIN mission. In order to be able to separate detector and readout
effects, a custom build TIA circuitry was used to characterize additional
single pixel detectors. We used a newly designed test setup at the MPIA to
determine the relative spectral response, the quantum efficiency, and the dark
current. All these properties were measured as a function of operating
temperature and detector bias. In addition the effects of ionizing radiation on
the detector were studied. For determining the relative spectral response we
used a dual-grating monochromator and a bolometer with known response that was
operated in parallel to the Si:As detectors. The quantum efficiency was
measured by using a custom-build high-precision vacuum black body together with
cold (T ~ 4 K) filters of known (measured) transmission.Comment: 11 pages, 8 figures, to appear in "High Energy, Optical, and Infrared
Detectors for Astronomy" SPIE conference Proc. 7021, Marseille, 23-28 June
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