Computed Tomography Volumetry of Bone Cement: Retrospective Blinded Validation of Commercially Available Semi-automated Edge Detection Software.

OBJECTIVE: Cement volumes are increasingly linked to orthopedic oncology and neurosurgical outcomes (construct durability, adjacent fracture), but manual cement volumetry remains time prohibitive. The authors aim to report performance of PACS-integrated volumetric software specifically for barium-enhanced polymethylmethacrylate cement. METHODS: Institutional review board-approved single-institution retrospective review of patients from 2019-2022 undergoing kyphoplasty for pathological compression fractures with a quantitative cement infuser providing true cement volume. An operator blinded to true cement volumes retrospectively performed software-assisted volumetry on follow-up computed tomography scans. RESULTS: Included were 91 kyphoplasty levels in 56 patients: mean age, 62 years (range, 34-85 years), 73% female. True cement volume (available for 44 of 66 procedures) was mean 4.5 mL per level (range, 1.2-15.6 mL). Measured cement volume (available for all procedures) yielded a mean of 6.1 mL per level (range, 1.5-27.9 mL). For the 57 levels (39 patients) where both true and measured cement volumes were available, linear regression intercept and slope were 1.46 (95% CI = 0.97-1.95, P < 0.001) and 0.52 (CI = 0.47-0.57, P < 0.001), respectively, suggesting measured volume averaged 1.46 mL greater than true volume, with each additional milliliter of measured volume corresponding to approximately 0.52 mL of true volume. There was no significant difference in the relationship between estimated and actual cement volume in thoracic levels (intercept = -0.24, CI = -1.13 to 0.66, P = 0.61; slope = 0.03, CI = -0.14 to 0.19, P = 0.73) compared with lumbar levels. The goodness-of-fit of the regression model was strong (R2 = 0.81). Discrepancies ranged from 90% underestimation to 52% overestimation; average, 17% overestimation. CONCLUSIONS: Semi-automated volumetry maintained a strong correlation with true volumes across the thoracic and lumbar curvatures, overestimating cement volume by a mean of 17% or 1.46 mL.

Kava-induced dermatitis: A detailed histopathological analysis.

Kava induced dermatitis has been reported in previous case series, however the histology has rarely been described. This case report details an erythematous eruption associated with Kava ingestion and the associated folliculocentric sebaceous inflammation found on histological analysis.

On the origins of spontaneous spherical symmetry-breaking in open-shell atoms through polymer self-consistent field theory.

An alternative approach to density functional theory based on self-consistent field theory for ring polymers is applied to neutral atoms hydrogen to neon in their ground-states. The spontaneous emergence of an atomic shell structure and spherical symmetry-breaking of the total electron density are predicted by the model using the ideas of polymer excluded-volume between pairs of electrons to enforce the Pauli-exclusion principle and an exact electron self-interaction correction. The Pauli potential is approximated by neglecting inter-atomic correlations along with other types of correlations, and comparisons to Hartree-Fock theory are made, which also ignores correlations. The model shows excellent agreement with Hartree-Fock theory to within the standards of orbital-free density functional theory for the atomic binding energies and density profiles of the first six elements, providing exact matches for the elements hydrogen and helium. The predicted shell structure starts to deviate significantly past the element neon, and spherical symmetry-breaking is first predicted to occur at carbon instead of boron. The self-consistent field theory energy functional that describes the model is decomposed into thermodynamic components to trace the origin of spherical symmetry-breaking. It is found to arise from the electron density approaching closer to the nucleus in non-spherical distributions, which lowers the energy despite resulting in frustration between the quantum kinetic energy, electron-electron interaction, and the Pauli exclusion interaction. The symmetry-breaking effect is found to have a minimal impact on the binding energies, which suggests that the spherical-averaging approximation used in previous work is physically reasonable when investigating atomic systems. The pair density contour plots display behavior similar to polymer macro-phase separation, where individual electron pairs occupy single lobe structures that together form a dumbbell shape analogous to the 2p orbital shape. It is further shown that the predicted densities satisfy known constraints and produce the same total electronic density profile that is predicted by other formulations of quantum mechanics.

Molecular Bonding in an Orbital-Free-Related Density Functional Theory.

A density functional theory based on polymer self-consistent field theory is applied to systems of two atoms in order to show that this approach is capable of predicted molecular bonding. Periodic table elements from hydrogen up to neon are examined and homonuclear diatomic molecules are found to form for H2, N2, O2, and F2, in agreement with known results. The heteronuclear molecules CO and HF, which are known to exist under ambient conditions, are also found to be stable. Bond lengths for most of these molecules agree with experimental results to within less than 8%, with the exception of O2 and F2 which deviate more significantly. The bonding energy for H2 is given and is within 16% of the known value, but fundamental vibrational frequencies do not agree well with experiment. The main approximations of the theory are very simple and include a Fermi-Amaldi correction to the electron-electron interaction to account for self-interactions and a basic expression for the Pauli potential to account for the exclusion principle. The self-consistent equations are solved in terms of basis functions that encode the cylindrical symmetry of diatomic molecules. Since orbitals are not used, the approach is related to orbital-free density functional theory.

Intranodal Lymphangiography with Thoracic Duct Embolization for Treatment of Chyle Leak after Thoracic Outlet Decompression Surgery.

From 2015 to 2019, 9 patients underwent ultrasound-guided intranodal lymphangiography for the treatment of a chyle leak following thoracic outlet decompression surgery. Chyle leaks were identified by Lipiodol (Guerbet, Roissy, France) extravasation near the left supraclavicular surgical bed in all patients. The technical success rate of thoracic duct embolization was 67% (6 of 9), including fluoroscopic transabdominal antegrade access (n = 4) and ultrasound-guided retrograde access in the left neck (n = 2). Clinical success was achieved in 89% of patients (8 of 9). The mean interval from lymphangiography to drain removal was 6.6 days (range, 4-18 d). No patients had a chyle leak recurrence during clinical follow-up (mean, 304 d).

An alternative derivation of orbital-free density functional theory.

Polymer self-consistent field theory techniques are used to derive quantum density functional theory without the use of the theorems of density functional theory. Instead, a free energy is obtained from a partition function that is constructed directly from a Hamiltonian so that the results are, in principle, valid at finite temperatures. The main governing equations are found to be a set of modified diffusion equations, and the set of self-consistent equations are essentially identical to those of a ring polymer system. The equations are shown to be equivalent to Kohn-Sham density functional theory and to reduce to classical density functional theory, each under appropriate conditions. The obtained noninteracting kinetic energy functional is, in principle, exact but suffers from the usual orbital-free approximation of the Pauli exclusion principle in addition to the exchange-correlation approximation. The equations are solved using the spectral method of polymer self-consistent field theory, which allows the set of modified diffusion equations to be evaluated for the same computational cost as solving a single diffusion equation. A simple exchange-correlation functional is chosen, together with a shell-structure-based Pauli potential, in order to compare the ensemble average electron densities of several isolated atom systems to known literature results. The agreement is excellent, justifying the alternative formalism and numerical method. Some speculation is provided on considering the timelike parameter in the diffusion equations, which is related to temperature, as having dimensional significance, and thus picturing pointlike quantum particles instead as nonlocal, polymerlike, threads in a higher dimensional thermal-space. A consideration of the double-slit experiment from this point of view is speculated to provide results equivalent to the Copenhagen interpretation. Thus, the present formalism may be considered as a type of "pilot-wave," realist, perspective on density functional theory.

Application of a constant hole volume Sanchez-Lacombe equation of state to mixtures relevant to polymeric foaming.

A variant of the Sanchez-Lacombe equation of state is applied to several polymers, blowing agents, and saturated mixtures of interest to the polymer foaming industry. These are low-density polyethylene-carbon dioxide and polylactide-carbon dioxide saturated mixtures as well as polystyrene-carbon dioxide-dimethyl ether and polystyrene-carbon dioxide-nitrogen ternary saturated mixtures. Good agreement is achieved between theoretically predicted and experimentally determined solubilities, both for binary and ternary mixtures. Acceptable agreement with swelling ratios is found with no free parameters. Up-to-date pure component Sanchez-Lacombe characteristic parameters are provided for carbon dioxide, dimethyl ether, low-density polyethylene, nitrogen, polylactide, linear and branched polypropylene, and polystyrene. Pure fluid low-density polyethylene and nitrogen parameters exhibit more moderate success while still providing acceptable quantitative estimations. Mixture estimations are found to have more moderate success where pure components are not as well represented. The Sanchez-Lacombe equation of state is found to correctly predict the anomalous reversal of solubility temperature dependence for low critical point fluids through the observation of this behaviour in polystyrene nitrogen mixtures.

Communication: Molecular-level insights into asymmetric triblock copolymers: network and phase development.

Molecularly asymmetric triblock copolymers progressively grown from a parent diblock copolymer can be used to elucidate the phase and property transformation from diblock to network-forming triblock copolymer. In this study, we use several theoretical formalisms and simulation methods to examine the molecular-level characteristics accompanying this transformation, and show that reported macroscopic-level transitions correspond to the onset of an equilibrium network. Midblock conformational fractions and copolymer morphologies are provided as functions of copolymer composition and temperature.

Curated and Annotated Dataset of Lung US Images in Zambian Children with Clinical Pneumonia.

See also the commentary by Sitek in this issue. Supplemental material is available for this article.

Hierarchical organization of cognition reflected in distributed frontoparietal activity.

Organization of behavior into a nested hierarchy of tasks and subtasks is characteristic of purposive cognition in humans. While frontoparietal regions have been shown to represent many kinds of task events, their representation of task/subtask structure has not been directly investigated. On each trial of the current study, participants carried out a sequence of four visual target detections organized by task context into subtasks of different structure (three and one or two and two). Through extended regions of frontoparietal cortex, activity elicited by target detections depended upon the hierarchical level of the episode completed. Target detections completing the entire trial elicited greatest activity, followed by targets completing a subtask, and finally targets within one subtask. Results depended on task and subtask completion, rather than the complexity of the next task stage to be established. We suggest that, through large regions of frontoparietal cortex, control representations direct each step of a behavioral program. Completion of a subtask revises control representations related just to this subtask, leaving those related to the overarching task episode intact, while completion of the entire task revises the entire assembly of representations.

Direction-sensitive codes for observed head turns in human superior temporal sulcus.

Humans and other primates are adept at using the direction of another's gaze or head turn to infer where that individual is attending. Research in macaque neurophysiology suggests that anterior superior temporal sulcus (STS) contains a direction-sensitive code for such social attention cues. By contrast, most human functional Magnetic resonance imaging (fMRI) studies report that posterior STS is responsive to social attention cues. It is unclear whether this functional discrepancy is caused by a species difference or by experimental design differences. Furthermore, social attention cues are dynamic in naturalistic social interaction, but most studies to date have been restricted to static displays. In order to address these issues, we used multivariate pattern analysis of fMRI data to test whether response patterns in human right STS distinguish between leftward and rightward dynamic head turns. Such head turn discrimination was observed in right anterior STS/superior temporal gyrus (STG). Response patterns in this region were also significantly more discriminable for head turn direction than for rotation direction in physically matched ellipsoid control stimuli. Our findings suggest a role for right anterior STS/STG in coding the direction of motion in dynamic social attention cues.

Fluid intelligence loss linked to restricted regions of damage within frontal and parietal cortex.

Tests of fluid intelligence predict success in a wide range of cognitive activities. Much uncertainty has surrounded brain lesions producing deficits in these tests, with standard group comparisons delivering no clear result. Based on findings from functional imaging, we propose that the uncertainty of lesion data may arise from the specificity and complexity of the relevant neural circuit. Fluid intelligence tests give a characteristic pattern of activity in posterolateral frontal, dorsomedial frontal, and midparietal cortex. To test the causal role of these regions, we examined fluid intelligence in 80 patients with focal cortical lesions. Damage to each of the proposed regions predicted fluid intelligence loss, whereas damage outside these regions was not predictive. The results suggest that coarse group comparisons (e.g., frontal vs. posterior) cannot show the neural underpinnings of fluid intelligence tests. Instead, deficits reflect the extent of damage to a restricted but complex brain circuit comprising specific regions within both frontal and posterior cortex.

Incorporating global components into ethics education.

Ethics is central to science and engineering. Young engineers need to be grounded in how corporate social responsibility principles can be applied to engineering organizations to better serve the broader community. This is crucial in times of climate change and ecological challenges where the vulnerable can be impacted by engineering activities. Taking a global perspective in ethics education will help ensure that scientists and engineers can make a more substantial contribution to development throughout the world. This paper presents the importance of incorporating the global and cross culture components in the ethic education. The authors bring up a question to educators on ethics education in science and engineering in the globalized world, and its importance, necessity, and impendency. The paper presents several methods for discussion that can be used to identify the differences in ethics standards and practices in different countries; enhance the student's knowledge of ethics in a global arena.

Adaptive coding of task-relevant information in human frontoparietal cortex.

Frontoparietal cortex is thought to be essential for flexible behavior, but the mechanism for control remains elusive. Here, we demonstrate a potentially critical property of this cortex: its dynamic configuration for coding of task-critical information. Using multivoxel pattern analysis of human functional imaging data, we demonstrate an adaptive change in the patterns of activation coding task-relevant stimulus distinctions. When task demands made perceptual information more difficult to discriminate, frontoparietal regions showed increased coding of this information. Visual cortices showed the opposite result: a weaker representation of perceptual information in line with the physical change in the stimulus. On a longer timescale, a rebalancing of coding was also seen after practice, with a diminished representation of task rules as they became familiar. The results suggest a flexible neural system, exerting cognitive control in a wide range of tasks by adaptively representing the task features most challenging for successful goal-directed behavior.

Absence of face-specific cortical activity in the complete absence of awareness: converging evidence from functional magnetic resonance imaging and event-related potentials.

In this study, we explored the neural correlates of perceptual awareness during a masked face detection task. To assess awareness more precisely than in previous studies, participants employed a 4-point scale to rate subjective visibility. An event-related fMRI and a high-density ERP study were carried out. Imaging data showed that conscious face detection was linked to activation of fusiform and occipital face areas. Frontal and parietal regions, including the pre-SMA, inferior frontal sulcus, anterior insula/frontal operculum, and intraparietal sulcus, also responded strongly when faces were consciously perceived. In contrast, no brain area showed face-selective activity when participants reported no impression of a face. ERP results showed that conscious face detection was associated with enhanced N170 and also with the presence of a second negativity around 300 msec and a slow positivity around 415 msec. Again, face-related activity was absent when faces were not consciously perceived. We suggest that, under conditions of backward masking, ventral stream and fronto-parietal regions show similar, strong links of face-related activity to conscious perception and stress the importance of a detailed assessment of awareness to examine activity related to unseen stimulus events.

Lateral prefrontal cortex subregions make dissociable contributions during fluid reasoning.

Reasoning is a key component of adaptable "executive" behavior and is known to depend on a network of frontal and parietal brain regions. However, the mechanisms by which this network supports reasoning and adaptable behavior remain poorly defined. Here, we examine the relationship between reasoning, executive control, and frontoparietal function in a series of nonverbal reasoning experiments. Our results demonstrate that, in accordance with previous studies, a network of frontal and parietal brain regions is recruited during reasoning. Our results also reveal that this network can be fractionated according to how different subregions respond when distinct reasoning demands are manipulated. While increased rule complexity modulates activity within a right lateralized network including the middle frontal gyrus and the superior parietal cortex, analogical reasoning demand-or the requirement to remap rules on to novel features-recruits the left inferior rostrolateral prefrontal cortex and the lateral occipital complex. In contrast, the posterior extent of the inferior frontal gyrus, associated with simpler executive demands, is not differentially sensitive to rule complexity or analogical demand. These findings accord well with the hypothesis that different reasoning demands are supported by different frontal and parietal subregions.

Shape-specific preparatory activity mediates attention to targets in human visual cortex.

The mechanisms of attention prioritize sensory input for efficient perceptual processing. Influential theories suggest that attentional biases are mediated via preparatory activation of task-relevant perceptual representations in visual cortex, but the neural evidence for a preparatory coding model of attention remains incomplete. In this experiment, we tested core assumptions underlying a preparatory coding model for attentional bias. Exploiting multivoxel pattern analysis of functional neuroimaging data obtained during a non-spatial attention task, we examined the locus, time-course, and functional significance of shape-specific preparatory attention in the human brain. Following an attentional cue, yet before the onset of a visual target, we observed selective activation of target-specific neural subpopulations within shape-processing visual cortex (lateral occipital complex). Target-specific modulation of baseline activity was sustained throughout the duration of the attention trial and the degree of target specificity that characterized preparatory activation patterns correlated with perceptual performance. We conclude that top-down attention selectively activates target-specific neural codes, providing a competitive bias favoring task-relevant representations over competing representations distributed within the same subregion of visual cortex.

Assembly and use of new task rules in fronto-parietal cortex.

Severe capacity limits, closely associated with fluid intelligence, arise in learning and use of new task rules. We used fMRI to investigate these limits in a series of multirule tasks involving different stimuli, rules, and response keys. Data were analyzed both during presentation of instructions and during later task execution. Between tasks, we manipulated the number of rules specified in task instructions, and within tasks, we manipulated the number of rules operative in each trial block. Replicating previous results, rule failures were strongly predicted by fluid intelligence and increased with the number of operative rules. In fMRI data, analyses of the instruction period showed that the bilateral inferior frontal sulcus, intraparietal sulcus, and presupplementary motor area were phasically active with presentation of each new rule. In a broader range of frontal and parietal regions, baseline activity gradually increased as successive rules were instructed. During task performance, we observed contrasting fronto-parietal patterns of sustained (block-related) and transient (trial-related) activity. Block, but not trial, activity showed effects of task complexity. We suggest that, as a new task is learned, a fronto-parietal representation of relevant rules and facts is assembled for future control of behavior. Capacity limits in learning and executing new rules, and their association with fluid intelligence, may be mediated by this load-sensitive fronto-parietal network.

Vascular contributions to pattern analysis: comparing gradient and spin echo fMRI at 3T.

Multivariate pattern analysis is often assumed to rely on signals that directly reflect differences in the distribution of particular neural populations. The source of the signal used in these analyses remains unclear however, and an alternative model suggests that signal from larger draining veins may play a significant role. The current study was designed to investigate the vascular contribution to pattern analyses at 3T by comparing the results obtained from gradient and spin echo data. Classification analyses were carried out comparing line orientations in V1, tone frequencies in A1, and responses from different fingers in M1. In all cases, classification accuracy in the spin echo data was not significantly different from chance. In contrast, classification accuracies in the gradient echo data were significantly above chance, and significantly higher than the accuracies observed for the spin echo data. These results suggest that at the field strength and spatial resolution used for the majority of fMRI studies, a considerable proportion of the signal used by pattern analysis originates in the vasculature.

Multi-voxel coding of stimuli, rules, and responses in human frontoparietal cortex.

In human functional magnetic resonance imaging (fMRI), a characteristic pattern of frontal and parietal activity is produced by many different cognitive demands. Although frontoparietal cortex has been shown to represent a variety of task features in different contexts, little is known about detailed representation of different task features within and across different regions. We used multi-voxel pattern analysis (MVPA) of human fMRI data to assess the representational content of frontoparietal cortex in a simple stimulus-response task. Stimulus-response mapping rule was the most strongly represented task feature, significantly coded in a lateral frontal region surrounding the inferior frontal sulcus, a more ventral region including the anterior insula/frontal operculum, and the intraparietal sulcus. Next strongest was coding of the instruction cue (screen color) indicating which rule should be applied. Coding of individual stimuli and responses was weaker, approaching significance in a subset of regions. In line with recent single unit data, the results show a broad representation of task-relevant information across human frontoparietal cortex, with strong representation of a general rule or cognitive context, and weaker coding of individual stimulus/response instances.