Since the inception of high explosives as an industrial tool, significant efforts have been made to understand the flow of energy from an explosive into its surroundings to maximize work produced while minimizing damaging effects. Many tools have been developed over the past century, such as the Hopkinson–Cranz (H-C) Scaling Formula, to define blast wave behavior in open air. Despite these efforts, the complexity of wave dynamics has rendered blast wave prediction difficult under confinement, where the wave interacts with reflective surfaces producing complex time-pressure waveforms. This paper implements two methods to better understand blast overpressure propagation in a confined tunnel environment and establish whether scaled tests can be performed comparatively to costly full-scale experiments. Time–pressure waveforms were predicted using both a 1:10 scaled model and three-dimensional air blast simulations conducted in Ansys Autodyn. A comparison of the reduced scale model simulation with a full-scale blast simulation resulted in self-similar overpressure waveforms when employing the H-C scaling model. Experimental overpressure waveforms showed a high level of correlation between the reduced scale model and simulations. Additionally, peak overpressure, duration, and impulse values were found to match within tolerances that are highly promising for applying this methodology in future applications. Using this validated relationship, the simulated model and reduced scale tests were used to predict an overpressure waveform in a full-scale underground mine opening to within 2.12%, 2.91%, and 7.84% for peak overpressure, time of arrival, and impulse, respectively. This paper demonstrates the effectiveness of scaled, blast models when predicting blast wave parameters in a confined environment.

The aims of the present ERP study were twofold. First, to determine whether a previous study on creative cognition could be replicated, and second, to extend these findings by examining individual differences in creativity. Conceptual expansion, a capacity that is central to creativity, was induced via the processing of novel metaphors. Brain activity patterns in relation to these were compared to the processing of literal and nonsense phrases. The previous findings were replicated in that the N400, known for its sensitivity to semantic anomalies, indexed the originality of the phrases, while a post-N400 late component (LC), which is linked to semantic integration processes, indexed the appropriateness of the phrases. Moreover, only the LC was significantly sensitive to individual differences in creativity in the processing of these phrases. Differences at the level of semantic integration processes as well as the structure of knowledge organization are thereby implicated in individual differences in creativity.

INTRODUCTIONBlast overpressure exposure, an important cause of traumatic brain injury (TBI), may occur during combat or military training. TBI, most commonly mild TBI, is considered a signature injury of recent combat in Iraq and Afghanistan. Low intensity primary blast-induced TBI (bTBI), caused by exposure to an explosive shock wave, commonly leaves no obvious physical external signs. Numerous studies have been conducted to understand its biological effects; however, the role of shock wave energy as related to bTBI remains poorly understood. This report combines shock wave analysis with established biological effects on the mouse brain to provide insights into the effects of shock wave physics as related to low intensity bTBI outcomes from both open-air and shock tube environments.METHODSShock wave peak pressure, rise time, positive phase duration, impulse, shock velocity, and particle velocity were measured using the Missouri open-air blast model from 16 blast experiments totaling 122 mice to quantify physical shock wave properties. Open-air shock waves were generated by detonating 350-g 1-m suspended Composition C-4 charges with targets on 1-m elevated stands at 2.15, 3, 4, and 7 m from the source.RESULTSAll mice sustained brain injury with no observable head movement, because of mice experiencing lower dynamic pressures than calculated in shock tubes. Impulse, pressure loading over time, was found to be directly related to bTBI severity and is a primary shock physics variable that relates to bTBI.DISCUSSIONThe physical blast properties including shock wave peak pressure, rise time, positive phase duration, impulse, shock velocity, and particle velocity were examined using the Missouri open-air blast model in mice with associated neurobehavioral deficits. The blast-exposed mice sustained ultrastructural abnormalities in mitochondria, myelinated axons, and synapses, implicating that primary low intensity blast leads to nanoscale brain damage by providing the link to its pathogenesis. The velocity of the shock wave reflected back from the target stand was calculated from high-speed video and compared with that of the incident shock wave velocity. Peak incident pressure measured from high sample rate sensors was found to be within 1% of the velocity recorded by the high-speed camera, concluding that using sensors in or close to an animal brain can provide useful information regarding shock velocity within the brain, leading to more advanced knowledge between shock wave physics and tissue damage that leads to bTBIs.

Abstract Coal dust explosions are a lethal threat to anyone working in an underground coal mine. Many coal mining countries including Australia and much of Europe already utilize passive barrier explosion suppressant systems but due to differences in ventilation patterns in the United States, simple passive systems such as the bagged barrier are not as cost effective. Active systems are triggered by properties of an explosion, such as pressure, heat, or light, and release or project a suppressant into the environment to suppress an explosion. To deploy an active system, the best sensor and suppressant release location and spacing must be determined; this must account for total system latency and explosive propagation speed. A 10:1 model of a longwall entry system has been developed to study the pressure wave propagation of coal dust explosions and consequent triggering of different suppressants. The scaled model, with its removable stoppings, allows multiple potential propagation pathways for an explosion to be repeatedly tested, different from typical straight shock tunnel tests. The layout also facilitates the placement of sensors and cameras to fully observe and document the tests. The pressure wave characteristics found at crosscuts and corners will aid in the development of active barrier trigger systems and spacing of suppressant release locations.

The aims of this fMRI study were two-fold. The first objective of the study was to verify whether the findings associated with a previous fMRI study could be replicated in which a novel event-related experimental design was developed which rendered it possible to investigate the brain basis of creative conceptual expansion. The ability to widen the boundaries of conceptual structures is integral to creative idea generation, which makes conceptual expansion a core component of creative cognition. Creative conceptual expansion led to the engagement of brain regions that are known to be involved in the access, storage and relational integration of conceptual knowledge in the original study. These included the anterior inferior frontal gyrus, the temporal poles and the lateral frontal pole. These findings in relation to the brain basis of creative conceptual expansion were replicated in the current study. The second objective of this study was to evaluate the brain basis of individual differences in creative conceptual expansion. The high creative group relative to the low creative group was shown to exhibit greater activity in regions of the semantic cognition network as well as the salience network during creative conceptual expansion. The findings are discussed from the point of view of classical hypotheses about information processing biases that explain individual differences in creativity including flat associative hierarchies, defocused attention and cognitive disinhibition.

Social Value Orientation (SVO) refers to an individual’s preference for the division of resources between the self and another person. Since evidence suggests that hormones influence several facets of human social behavior, we asked whether SVO might fluctuate across the female menstrual cycle. Using self-report data obtained in two independent online studies, we show that cooperative preferences, as indexed by SVO, are indeed significantly more prosocial in the early follicular compared to the midluteal phase in naturally ovulating women. Furthermore, when estimating hormonal variations from norm data, we found estradiol, but not progesterone or testosterone, to be a significant predictor of SVO across the menstrual cycle in both studies, with a negative correlation. Our findings provide evidence that the willingness to cooperate varies across the natural female menstrual cycle and highlight the potential of investigating psychological effects of ovarian sex hormones.

A novel ERP paradigm was employed to investigate conceptual expansion, a central component of creative thinking. Participants were presented with word pairs, consisting of everyday objects and uses for these objects, which had to be judged based on the two defining criteria of creative products: unusualness and appropriateness. Three subject-determined trial types resulted from this judgement: high unusual and low appropriate (nonsensical uses), low unusual and high appropriate (common uses), and high unusual and high appropriate (creative uses). Word pairs of the creative uses type are held to passively induce conceptual expansion. The N400 component was not specifically modulated by conceptual expansion but was, instead, generally responsive as a function of unusualness or novelty of the stimuli (nonsense=creative>common). Explorative analyses in a later time window (500-900 ms) revealed that ERP activity in this phase indexes appropriateness (nonsense>creative=common). In the discussion of these findings with reference to the literature on semantic cognition, both components are proposed as indexing processes relevant to conceptual expansion as they are selectively involved in the encoding and integration of a newly established semantic connection between two previously unrelated concepts.

Conceptual expansion is a key process that underlies our ability to think creatively. In the present event-related fMRI study, a modified Alternate Uses Task was used to identify brain regions involved during passive conceptual expansion and thereby separately assess the effects of the two defining elements of creative output: Originality (unusualness) and Relevance (appropriateness). Participants viewed word pairs consisting of an object and a use and indicated whether the given use was unusual and/or appropriate for the given object. Trials with object-use combinations judged as unusual and appropriate (HUHA) were contrasted against trials judged as just unusual but inappropriate (HULA) or just appropriate but not unusual (LUHA). As hypothesized, conceptual expansion related activation (HUHA) was found in the bilateral inferior frontal gyrus (BA 45, 47), left temporal pole (BA 38) and left frontopolar cortex (BA 10). We discuss the specific contributions of these regions with reference to semantic cognition.

Neurophysiological studies of creativity thus far have not allowed for clear conclusions to be made regarding the specific neural underpinnings of such complex cognition due to overgeneralizations concerning the creativity construct, heterogeneity in the type of creativity tasks used, and the questionable efficacy of the employed comparison tasks. A novel experimental design was developed in the present fMRI study which rendered it possible to investigate a critical facet of creative cognition – that of conceptual expansion – as distinct from general divergent thinking, working memory, or cognitive load. Brain regions involved in the retention, retrieval and integration of conceptual knowledge such as the anterior inferior frontal gyrus, the temporal poles and the lateral frontopolar cortex were found to be selectively involved during conceptual expansion. The findings go against generic ideas that argue for the dominance of the right hemisphere during creative thinking and indicate the necessity to reconsider the functions of regions such as the anterior cingulate cortex to include more abstract facets of cognitive control. This study represents a new direction in the investigation of creativity in that it highlights the necessity to adopt a process based perspective in which the multifaceted nature of creativity can be truly grasped.

Conceptual expansion, one of the core operations in creative cognition, was investigated in the present ERP study. An experimental paradigm using novel metaphoric, nonsensical and literal phrases was employed where individual differences in conceptual knowledge organization were accounted for by using participants' responses to categorize the stimuli to each condition. The categorization was determined by their judgment of the stimuli on the two defining criteria of creativity: unusualness and appropriateness. Phrases judged as unusual and appropriate were of special interest as they are novel and unfamiliar phrases thought to passively induce conceptual expansion. The results showed a graded N400 modulation for phrases judged to be unusual and inappropriate (nonsense) or unusual and appropriate (conceptual expansion, novel metaphorical) relative to usual and appropriate (literal) phrases. The N400 is interpreted as indexing greater effort to retrieve semantic information and integrate the novel concepts presented through the phrases. Analyses of the later time-window showed an ongoing negativity that was graded in the same manner as the N400. The findings attest to the usefulness of investigating creative cognition using event-related electrophysiology.

Creativity has emerged in the focus of neurocognitive research in the past decade. However, a heterogeneous pattern of brain areas has been implicated as underpinning the neural correlates of creativity. One explanation for these divergent findings lies in the fact that creativity is not usually investigated in terms of its many underlying cognitive processes. The present fMRI study focuses on the neural correlates of conceptual expansion, a central component of all creative processes. The study aims to avoid pitfalls of previous fMRI studies on creativity by employing a novel paradigm. Participants were presented with phrases and made judgments regarding both the unusualness and the appropriateness of the stimuli, corresponding to the two defining criteria of creativity. According to their respective evaluation, three subject-determined experimental conditions were obtained. Phrases judged as both unusual and appropriate were classified as indicating conceptual expansion in participants. The findings reveal the involvement of frontal and temporal regions when engaging in passive conceptual expansion as opposed to the information processing of mere unusualness (novelty) or appropriateness (relevance). Taking this new experimental approach to uncover specific processes involved in creative cognition revealed that frontal and temporal regions known to be involved in semantic cognition and relational reasoning play a role in passive conceptual expansion. Adopting a different vantage point on the investigation of creativity would allow for critical advances in future research on this topic.