Compression tests measured the mechanical properties of AlSi10MnMg matrix syntactic foams filled with lightweight expanded clay particles (LECAPs). The metal matrix syntactic foams were produced by ...low-pressure liquid state infiltration method. Two types of LECAPs were used during production. One with ∼3 mm diameter and the other type with ∼9 mm diameter. The samples were machined and heat treated. The T6 heat treatment caused a significant increase in the properties in terms of plateau strength and absorbed energy. Also, the heat treatment caused a different failure mode in the case of the LECAP-9, which is why the absorbed energy increased by ∼50% compared to the as-cast sample.
To study the nature of the quark-hadron phase transition, it is important to investigate the space-time structure of the hadron-emitting source in heavy-ion collisions. Measurements of HBT ...correlations have proven to be a powerful tool to gain information about the source. In these proceedings, we report the current status of the analysis of source parameters obtained from Lévy fits to the measured one-dimensional two-pion correlation functions in Au + Au collisions at
= 200 GeV.
Phys. Rev. C 102, 064912 (2020) We present detailed calculations about the expected shape of two-pion
Bose-Einstein (or HBT) correlations in high energy heavy ion collisions that
include a realistic ...treatment of final state Coulomb interaction as well as
strong interactions (dominated by s-wave scattering). We assume L\'evy type
source functions, a generalization that goes beyond the Gaussian approximation.
Various recent experimental results found the use of such source types
necessary to properly describe the shape of the measured correlation functions.
We find that strong final state interactions may play an important role in the
shape of the two-pion correlation functions, especially if one considers source
parameters beyond the Gaussian HBT radii. Precise experimental determination of
these source parameters (such as L\'evy stability exponent, correlation
strength, etc.) seems to require the inclusion of the treatment of strong
interaction not just for heavier particles (e.g. protons, lambdas) but also in
case of two-pion measurements.
We present detailed calculations about the expected shape of two-pion Bose-Einstein (or HBT) correlations in high energy heavy ion collisions that include a realistic treatment of final state Coulomb ...interaction as well as strong interactions (dominated by s-wave scattering). We assume Lévy type source functions, a generalization that goes beyond the Gaussian approximation. Various recent experimental results found the use of such source types necessary to properly describe the shape of the measured correlation functions. We find that strong final state interactions may play an important role in the shape of the two-pion correlation functions, especially if one considers source parameters beyond the Gaussian HBT radii. Precise experimental determination of these source parameters (such as Lévy stability exponent, correlation strength, etc.) seems to require the inclusion of the treatment of strong interaction not just for heavier particles (e.g. protons, lambdas) but also in case of two-pion measurements.
Transorbital sonography (TOS) could be a swift and convenient method to detect the atrophy of the optic nerve, possibly providing a marker that might reflect other quantitative structural markers of ...multiple sclerosis (MS). Here we evaluate the utility of TOS as a complementary tool for assessing optic nerve atrophy, and investigate how TOS-derived measures correspond to volumetric brain markers in MS. We recruited 25 healthy controls (HC) and 45 patients with relapsing-remitting MS and performed B-mode ultrasonographic examination of the optic nerve. Patients additionally underwent MRI scans to obtain T1-weighted, FLAIR and STIR images. Optic nerve diameters (OND) were compared between HC, MS patients with and without history of optic neuritis (non-ON) using a mixed-effects ANOVA model. The relationship between within-subject-average OND and global and regional brain volumetric measures was investigated using FSL SIENAX, voxel-based morphometry and FSL FIRST. OND was significantly different between HC-MS (HC = 3.2 ± 0.4 mm, MS = 3 ± 0.4 mm; p < 0.019) and we found significant correlation between average OND and normalised whole brain (β = 0.42, p < 0.005), grey matter (β = 0.33, p < 0.035), white matter (β = 0.38, p < 0.012) and ventricular cerebrospinal fluid volume (β = - 0.36, p < 0.021) in the MS group. History of ON had no impact on the association between OND and volumetric data. In conclusion, OND is a promising surrogate marker in MS, that can be simply and reliably measured using TOS, and its derived measures correspond to brain volumetric measures. It should be further explored in larger and longitudinal studies.
▸ Transcranial direct current stimulation (tDCS) modulates explicit sequence learning. ▸ Anodal tDCS applied during the task speeds motor learning. ▸ Anodal tDCS applied before the task slows motor ...learning. ▸ Cathodal tDCS slows the rate of learning in both cases.
Transcranial direct current stimulation (tDCS) is attracting increasing interest as a therapeutic tool for neurorehabilitation, particularly after stroke, because of its potential to modulate local excitability and therefore promote functional plasticity. Previous studies suggest that timing is important in determining the behavioural effects of brain stimulation. Regulatory metaplastic mechanisms exist to modulate the effects of a stimulation intervention in a manner dependent on prior cortical excitability, thereby preventing destabilization of existing cortical networks. The importance of such timing dependence has not yet been fully explored for tDCS. Here, we describe the results of a series of behavioural experiments in healthy controls to determine the importance of the relative timing of tDCS for motor performance. Application of tDCS during an explicit sequence-learning task led to modulation of behaviour in a polarity specific manner: relative to sham stimulation, anodal tDCS was associated with faster learning and cathodal tDCS with slower learning. Application of tDCS prior to performance of the sequence-learning task led to slower learning after both anodal and cathodal tDCS. By contrast, regardless of the polarity of stimulation, tDCS had no significant effect on performance of a simple reaction time task. These results are consistent with the idea that anodal tDCS interacts with subsequent motor learning in a metaplastic manner and suggest that anodal stimulation modulates cortical excitability in a manner similar to motor learning.
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