Video-based quantification of movement biomarkers for early detection of cerebral palsy in high-risk infants

Objective: The recent development of motion tracking systems offers new possibilities to automate and quantify the assessment of general movements exhibited by infants, which could contribute to early detection and treatment of cerebral palsy (CP) in high-risk infants. The primary aim of this study was to determine how accurately multiple quantified Motor Optimality Score (MOS) items are differentiating between CP and non-CP outcomes. The secondary aim of this study was to determine how the quantified MOS-items correspond with what is scored as “observed” or “not observed” by the clinician or General Movement Assessment (GMA) expert. Participants & method: video recordings of 557 infants (CP = 84, non-CP = 473) who were enrolled in previous studies and were all at high risk for developing a perinatal brain injury were included. Using MATLAB (version R2021b), a skeleton representation of the infants was constructed, and several variables and features were calculated. A total of nine MOS-items were selected for quantification based on several exclusion criteria. A grid search was performed for each variable in order to find the threshold with the best discriminative performance, based on: 1) the Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) curve, 2) specificity, 3) sensitivity, and 4) balanced accuracy was used. The performance of each quantified MOS-item was assessed for all features individually, for a clustering within the items, and for a clustering between the items. The AUC of the ROC curve as well as the distribution differences of the features between CP and non-CP were analyzed to assess the performance of the model. Lastly, the prevalence of each item was determined, split for the CP and non-CP group. Results: AUC for the within-item feature clusters ranged from 0.5188 (95% CI = 0.3811 - 0.6419) to 0.7623 (95% CI = 0.6557 - 0.8620) and the between-item clustering of all features across the items resulted in an AUC of 0.6207 (95% CI = 0.4918 - 0.7453). Feature importance across the different clusters revealed a high relative weight of body symmetry total time (17.5%), body symmetry frequency (13.4%), and legs lift total time (12.6%). When separated for the different features, the head-centered item had the highest relative weight (50.2%, 60.6%, 62.8% and 54% for respectively the features total time, average time, percentage, and frequency). Deviation in prevalence compared to previous observational research mainly concerned items including joint-angle calculations or movements along the line of gravity, suggesting insufficient quantification of these items. Conclusion: This study found that individual features and between-item clustering of features had limited to no predictive capability. On the other hand, a within-item clustering of features showed that seven out of nine quantified MOS-items were performing better than a random classifier for the prediction of CP. This suggests that the developed quantification method based on within-item clustering, is a feasible method to differentiate between CP and non-CP outcomes in high-risk infants

High Pressure X-Ray Diffraction Study of UMn2Ge2

Uranium manganese germanide, UMn2Ge2, crystallizes in body-centered tetragonal ThCr2Si2 structure with space group I4/mmm, a = 3.993A and c = 10.809A under ambient conditions. Energy dispersive X-ray diffraction was used to study the compression behaviour of UMn2Ge2 in a diamond anvil cell. The sample was studied up to static pressure of 26 GPa and a reversible structural phase transition was observed at a pressure of ~ 16.1 GPa. Unit cell parameters were determined up to 12.4 GPa and the calculated cell volumes were found to be well reproduced by a Murnaghan equation of state with K0 = 73.5 GPa and K' = 11.4. The structure of the high pressure phase above 16.0 GPa is quite complicated with very broad lines and could not be unambiguously determined with the available instrument resolution

The effect of uniaxial pressure on the magnetic anomalies of the heavy-fermion metamagnet CeRu2Si2

The effect of uniaxial pressure (P_u) on the magnetic susceptibility (X), magnetization (M), and magnetoresistance (MR) of the heavy-fermion metamagnet CeRu2Si2 has been investigated. For the magnetic field along the tetragonal c axis, it is found that characteristic physical quantities, i.e., the temperature of the susceptibility maximum (T_max), the pagamagnetic Weiss temperature (Q_p), 1/X at 2 K, and the magnetic field of the metamagnetic anomaly (H_M), scale approximately linearly with P_u, indicating that all the quantities are related to the same energy scale, probably of the Kondo temperature. The increase (decrease) of the quantities for P_u || c axis (P_u || a axis) can be attributed to a decrease (increase) in the nearest Ce-Ru distance. Consistently in MR and X, we observed a sign that the anisotropic nature of the hybridization, which is believed to play an important role in the metamagnetic anomaly, can be controlled by applying the uniaxial pressure. PACS numbers: 75.20.Hr, 71.27.+a, 74.62.FjComment: 7 pages, ReVTeX, 6 EPS figures : Will appear in Phys. Rev.

Spin glass behavior in URh_2Ge_2

URh_2Ge_2 occupies an extraordinary position among the heavy-electron 122-compounds, by exhibiting a previously unidentified form of magnetic correlations at low temperatures, instead of the usual antiferromagnetism. Here we present new results of ac and dc susceptibilities, specific heat and neutron diffraction on single-crystalline as-grown URh_2Ge_2. These data clearly indicate that crystallographic disorder on a local scale produces spin glass behavior in the sample. We therefore conclude that URh_2Ge_2 is a 3D Ising-like, random-bond, heavy-fermion spin glass.Comment: 10 pages, RevTeX, with 4 postscript figures, accepted by Physical Review Letters Nov 15, 199

Superconductivity in the YIr2Si2 and LaIr2Si2 Polymorphs

We report on existence of superconductivity in YIr2Si2 and LaIr2Si2 compounds in relation to crystal structure. The two compounds crystallize in two structural polymorphs, both tetragonal. The high temperature polymorph (HTP) adopts the CaBe2Ge2-structure type (space group P4/nmm) while the low temperature polymorph (LTP) is of the ThCr2Si2 type (I4/mmm). By studying polycrystals prepared by arc melting we have observed that the rapidly cooled samples retain the HTP even at room temperature (RT) and below. Annealing such samples at 900C followed by slow cooling to RT provides the LTP. Both, the HTP and LTP were subsequently studied with respect to magnetism and superconductivity by electrical resistivity, magnetization, AC susceptibility and specific heat measurements. The HTP and LTP of both compounds respectively, behave as Pauli paramagnets. Superconductivity has been found exclusively in the HTP of both compounds below Tsc (= 2.52 K in YIr2Si2 and 1.24 K in LaIr2Si2). The relations of magnetism and superconductivity with the electronic and crystal structure are discussed with comparing experimental data with the results of first principles electronic structure calculations