Charting human brain maturation between childhood and adulthood is a fundamental prerequisite for understanding the rapid biological and psychological changes during human development. Two barriers ...have precluded the quantification of maturational trajectories: demands on data and demands on estimation. Using high-temporal resolution neuroimaging data of up to 12-waves in the HUBU cohort (N = 90, aged 7-21 years) we investigate changes in apparent cortical thickness across childhood and adolescence. Fitting a four-parameter logistic nonlinear random effects mixed model, we quantified the characteristic, s-shaped, trajectory of cortical thinning in adolescence. This approach yields biologically meaningful parameters, including the midpoint of cortical thinning (MCT), which corresponds to the age at which the cortex shows most rapid thinning - in our sample occurring, on average, at 14 years of age. These results show that, given suitable data and models, cortical maturation can be quantified with precision for each individual and brain region.
The purpose of this study was to evaluate the properties (fracture toughness, surface hardness) of newer conventional glass-ionomer restorative materials that are marketed for posterior ...stress-bearing areas compared with more traditional glass-ionomer restorative materials marketed for non-load-bearing areas and composite-resin restorative materials.
Notched-beam fracture toughness specimens were created in a mold with each tested material (Equia Forte, GC America, with and without a surface coating of Equia Forte Coat; Ketac Universal, 3M/ESPE; ChemFil Rock, Dentsply; Fuji IX GP Extra, GC; Ionostar Molar, VOCO; Filtek Z250, 3M/ESPE; Filtek Supreme Ultra, 3M/ESPE) and fractured using a universal testing machine after 24 hours of storage. Hardness values were determined on the surface of the fracture toughness specimens using a hardness tester. Data were analyzed with a one-way ANOVA and Tukey's post hoc test per property (alpha=0.05).
The composite-resin restorative materials had significantly greater fracture toughness than the glass-ionomer materials. There was no significant difference in fracture toughness between the glass-ionomer materials. The use of a resin coating significantly increased the surface hardness of the newer glass ionomer marketed for stress-bearing areas.
Fracture toughness was not improved with the newer glass-ionomer restorative materials marketed for stress-bearing areas compared to the conventional glass-ionomer materials, however a resin coating provided greater surface hardness.
Despite the high density of threading dislocations generally found in (AlGaIn)N heterostructures, the light emission efficiency of such structures is exceptionally high. It has become common to ...attribute the high efficiency to compositional fluctuations or even phase separation in the active GaInN quantum well region. The resulting localization of charge carriers is thought to keep them from recombining nonradiatively at the defects. Here, we show that random disorder is not the key but that under suitable growth conditions hexagonal V-shaped pits decorating the defects exhibit narrow sidewall quantum wells with an effective band gap significantly larger than that of the regular c-plane quantum wells. Thereby nature provides a unique, hitherto unrecognized mechanism generating a potential landscape which effectively screens the defects themselves by providing an energy barrier around every defect.
The ‘KASCADE Cosmic ray Data Centre’ is a web portal (
https://kcdc.ikp.kit.edu
), where the data of the astroparticle physics experiment KASCADE-Grande are made available for the interested public. ...The KASCADE experiment was a large-area detector for the measurement of high-energy cosmic rays via the detection of extensive air showers. The multi-detector installations KASCADE and its extension KASCADE-Grande stopped the active data acquisition in 2013 after more than 20 years of data taking. In several updates since our first release in 2013 with KCDC we provide the public measured and reconstructed parameters of more than 433 million air showers. In addition, KCDC provides meta data information and documentation to enable a user outside the community of experts to perform their own data analysis. Simulation data from three different high energy interaction models have been made available as well as a compilation of measured and published spectra from various experiments. In addition, detailed educational examples shall encourage high-school students and early stage researchers to learn about astroparticle physics, cosmic radiation as well as the handling of Big Data and about the sustainable and public provision of scientific data.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
KASCADE and KASCADE-Grande were multi-detector installations to measure individual air showers of cosmic rays at ultra-high energy. Based on data sets measured by KASCADE and KASCADE-Grande, 90% C.L. ...upper limits to the flux of gamma-rays in the primary cosmic ray flux are determined in an energy range of eV. The analysis is performed by selecting air showers with a low muon content as expected for gamma-ray-induced showers compared to air showers induced by energetic nuclei. The best upper limit of the fraction of gamma-rays to the total cosmic ray flux is obtained at eV with . Translated to an absolute gamma-ray flux this sets constraints on some fundamental astrophysical models, such as the distance of sources for at least one of the IceCube neutrino excess models.
Most studies on the development of face cognition abilities have focussed on childhood, with early maturation accounts contending that face cognition abilities are mature by 3-5 years. Late ...maturation accounts, in contrast, propose that some aspects of face cognition are not mature until at least 10 years. Here, we measured face memory and face perception, two core face cognition abilities, in 661 participants (397 females) in four age groups (younger adolescents (11.27-13.38 years); mid-adolescents (13.39-15.89 years); older adolescents (15.90-18.00 years); and adults (18.01-33.15 years)) while controlling for differences in general cognitive ability. We showed that both face cognition abilities mature relatively late, at around 16 years, with a female advantage in face memory, but not in face perception, both in adolescence and adulthood. Late maturation in the face perception task was driven mainly by protracted development in identity perception, while gaze perception abilities were already comparatively mature in early adolescence. These improvements in the ability to memorize, recognize and perceive faces during adolescence may be related to increasing exploratory behaviour and exposure to novel faces during this period of life.
MIMO Radar Ambiguity Functions San Antonio, G.; Fuhrmann, D.R.; Robey, F.C.
IEEE journal of selected topics in signal processing,
06/2007, Letnik:
1, Številka:
1
Journal Article
Recenzirano
Multiple-Input Multiple-Output (MIMO) radar has been shown to provide enhanced performance in theory and in practice. MIMO radars are equipped with the ability to choose freely their transmitted ...waveforms at each aperture. In conventional radar systems Woodward's ambiguity function is used to characterize waveform resolution performance. In this paper we extend the idea of waveform ambiguity functions to MIMO radars. MIMO ambiguity functions are developed that simultaneously characterize the effects of array geometry and transmitted waveforms on resolution performance. Overall resolution performance is shown to be governed by a space-time covariance function that can be controlled by the system on transmit using waveform diversity. Visual examples are provided to illustrate the resolution enhancement possible using MIMO technology
The KASCADE experiment measures extensive air showers induced by cosmic rays in the energy range around the so-called knee. The data of KASCADE have been used in a composition analysis showing the ...knee at 3–5
PeV to be caused by a steepening in the light-element spectra T. Antoni et al., (KASCADE Coll.), Astropart. Phys. 24 (2005) 1–25. Since the applied unfolding analysis depends crucially on simulations of air showers, different high-energy hadronic interaction models (QGSJet and SIBYLL) were used. The results have shown a strong dependence of the relative abundance of the individual mass groups on the underlying model. In this update of the analysis we apply the unfolding method with a different low energy interaction model (FLUKA instead of GHEISHA) in the simulations. While the resulting individual mass group spectra do not change significantly, the overall description of the measured data improves by using the FLUKA model. In addition data in a larger range of zenith angle are analysed. The new results are completely consistent, i.e. there is no hint to any severe problem in applying the unfolding analysis method to KASCADE data.
A CFAR adaptive matched filter detector Robey, F.C.; Fuhrmann, D.R.; Kelly, E.J. ...
IEEE transactions on aerospace and electronic systems,
1992-Jan., 1992, 1992-01-00, 19920101, Letnik:
28, Številka:
1
Journal Article
Recenzirano
An adaptive algorithm for radar target detection using an antenna array is proposed. The detector is derived in a manner similar to that of the generalized likelihood-ratio test (GLRT) but contains a ...simplified test statistic that is a limiting case of the GLRT detector. This simplified detector is analyzed for performance to signals on boresight, as well as when the signal direction is misaligned with the look direction.< >
We examine the problem of source localization and spatial spectrum estimation using sensor arrays that are noncoherent collections of small, coherent subarrays. The covariance of the signal snapshots ...at each of the coherent subarrays are functions of, among other things, the signal source locations (or the spatial spectrum). Our approach is to derive functions of the subarray covariance matrices that are close approximations of the signal source locations (or the spatial spectrum). We also show how these functions may be considered generalizations of the multiple signal classification (MUSIC) algorithm and the minimum variance distortionless response (MVDR) criterion, respectively. We demonstrate via simulation that, using this approach and array architecture, it is possible to resolve directional ambiguities.
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