Shock volume: Patient-specific cumulative hypoperfusion predicts organ dysfunction in a prospective cohort of multiply injured patients

BACKGROUND: Multiply injured patients are at risk of developing hemorrhagic shock and organ dysfunction. We determined how cumulative hypoperfusion predicted organ dysfunction by integrating serial Shock Index measurements. METHODS: In this study, we calculated shock volume (SHVL) which is a patient-specific index that quantifies cumulative hypoperfusion by integrating abnormally elevated Shock Index (heart rate/systolic blood pressure ≥ 0.9) values acutely after injury. Shock volume was calculated at three hours (3 hr), six hours (6 hr), and twenty-four hours (24 hr) after injury. Organ dysfunction was quantified using Marshall Organ Dysfunction Scores averaged from days 2 through 5 after injury (aMODSD2–D5). Logistic regression was used to determine correspondence of 3hrSHVL, 6hrSHVL, and 24hrSHVL to organ dysfunction. We compared correspondence of SHVL to organ dysfunction with traditional indices of shock including the initial base deficit (BD) and the lowest pH measurement made in the first 24 hr after injury (minimum pH). RESULTS: SHVL at all three time intervals demonstrated higher correspondence to organ dysfunction (R2 = 0.48 to 0.52) compared to initial BD (R2 = 0.32) and minimum pH (R2 = 0.32). Additionally, we compared predictive capabilities of SHVL, initial BD and minimum pH to identify patients at risk of developing high-magnitude organ dysfunction by constructing receiver operator characteristic curves. SHVL at six hours and 24 hours had higher area under the curve compared to initial BD and minimum pH. CONCLUSION: SHVL is a non-invasive metric that can predict anticipated organ dysfunction and identify patients at risk for high-magnitude organ dysfunction after injury. LEVEL OF EVIDENCE: Prognostic study, level III

Sleep promotes the emergence of lexical competition in visual word recognition

Lexical competition processes are widely viewed as the hallmark of visual word recognition, but little is known about the factors that promote their emergence. This study examined for the first time whether sleep may play a role in inducing these effects. A group of 27 participants learned novel written words, such as banara, at 8 am and were tested on their learning at 8 pm the same day (AM group), while 29 participants learned the words at 8 pm and were tested at 8 am the following day (PM group). Both groups were retested after 24 hours. Using a semantic categorisation task, we showed that lexical competition effects, as indexed by slowed responses to existing neighbor words such as banana, emerged 12 hours later in the PM group who have had slept after learning but not in the AM group. After 24 hours the competition effects were evident in both groups. These findings have important implications for theories of orthographic learning and broader neurobiological models of memory consolidation

The impact of self-reported hearing difficulties on memory collaboration in older adults

Cognitive scientists and philosophers recently have highlighted the value of thinking about people at risk of or living with dementia as intertwined parts of broader cognitive systems that involve their spouse, family, friends, or carers. By this view, we rely on people and things around us to “scaffold” mental processes such as memory. In the current study, we identified 39 long-married, older adult couples who are part of the Australian Imaging Biomarkers and Lifestyle (AIBL) Study of Ageing; all were cognitively healthy but half were subjective memory complainers. During two visits to their homes 1 week apart, we assessed husbands’ and wives’ cognitive performance across a range of everyday memory tasks working alone (Week 1) versus together (Week 2), including a Friends Task where they provided first and last names of their friends and acquaintances. As reported elsewhere, elderly couples recalled many more friends’ names working together compared to alone. Couples who remembered successfully together used well-developed, rich, sensitive, and dynamic communication strategies to boost each other’s recall. However, if one or both spouses self-reported mild-to-moderate or severe hearing difficulties (56% of husbands, 31% of wives), couples received less benefit from collaboration. Our findings imply that hearing loss may disrupt collaborative support structures that couples (and other intimate communicative partners) hone over decades together. We discuss the possibility that, cut off from the social world that scaffolds them, hearing loss may place older adults at greater risk of cognitive decline and dementia

Acceptability and usability of computerized cognitive assessment among Australian Indigenous residents of the Torres Strait Islands

Objectives: This cross-sectional study aimed to investigate the acceptability and usability of the Cogstate Brief Battery (CBB) in a community-based sample of Australian Indigenous people from the Torres Strait region, based on a user experience framework of human-computer interaction. Methods: Two-hundred community participants completed the four subtests of the CBB on an iPad platform, during a free adult health check on two islands in the region, between October and December 2016. Acceptability was defined as completing the learning trial of a task and usability as continuing a task through to completion, determined by examiner acumen and internal Cogstate completion and integrity criteria. These were combined into a single dichotomous completion measure for logistic regression analyses. Performance-measured as reaction times and accuracy of responses-was analyzed using linear regression analyses. Results: CBB completion ranged from 82.0% to 91.5% across the four tasks and the odds of completing decreased with age. After adjusting for age, iPad/tablet familiarity increased the odds of completion for all tasks while level of education and employment increased the odds for some tasks only. These variables accounted for 18.0%-23.8% of the variance in reaction times on speeded tasks. Age and education had the most effect, although semipartial correlations were modest. Conclusions: When administered in a health-screening context, the acceptability and usability of the CBB were greatest in young- to middle-aged participants with some education and iPad/tablet experience. Older and more vulnerable participants may have benefited from additional time and practice on the CBB prior to administration

Calibration Uncertainty for Advanced LIGO's First and Second Observing Runs

Calibration of the Advanced LIGO detectors is the quantification of the detectors' response to gravitational waves. Gravitational waves incident on the detectors cause phase shifts in the interferometer laser light which are read out as intensity fluctuations at the detector output. Understanding this detector response to gravitational waves is crucial to producing accurate and precise gravitational wave strain data. Estimates of binary black hole and neutron star parameters and tests of general relativity require well-calibrated data, as miscalibrations will lead to biased results. We describe the method of producing calibration uncertainty estimates for both LIGO detectors in the first and second observing runs.Comment: 15 pages, 21 figures, LIGO DCC P160013

Upper mantle seismic anisotropy at a strike-slip boundary: South Island, New Zealand

New shear wave splitting measurements made from stations onshore and offshore the South Island of New Zealand show a zone of anisotropy 100–200 km wide. Measurements in central South Island and up to approximately 100 km offshore from the west coast yield orientations of the fast quasi-shear wave nearly parallel to relative plate motion, with increased obliquity to this orientation observed farther from shore. On the eastern side of the island, fast orientations rotate counterclockwise to become nearly perpendicular to the orientation of relative plate motion approximately 200 km off the east coast. Uniform delay times between the fast and slow quasi-shear waves of nearly 2.0 s onshore continue to stations approximately 100 km off the west coast, after which they decrease to ~1 s at 200 km. Stations more than ~300 km from the west coast show little to no splitting. East coast stations have delay times around 1 s. Simple strain fields calculated from a thin viscous sheet model (representing distributed lithospheric deformation) with strain rates decreasing exponentially to both the northwest and southeast with e-folding dimensions of 25–35 km (approximately 75% of the deformation within a zone 100–140 km wide) match orientations and amounts of observed splitting. A model of deformation localized in the lithosphere and then spreading out in the asthenosphere also yields predictions consistent with observed splitting if, at depths of 100–130 km below the lithosphere, typical grain sizes are ~ 6–7 mm.New Zealand. Ministry of Research, Science, and TechnologyNational Science Foundation (U.S.). Continental Dynamics Program (Grant EAR-0409564)National Science Foundation (U.S.). Continental Dynamics Program (Grant EAR-0409609)National Science Foundation (U.S.). Continental Dynamics Program (Grant EAR-0409835

The Effect of Air on Granular Size Separation in a Vibrated Granular Bed

Using high-speed video and magnetic resonance imaging (MRI) we study the motion of a large sphere in a vertically vibrated bed of smaller grains. As previously reported we find a non-monotonic density dependence of the rise and sink time of the large sphere. We find that this density dependence is solely due to air drag. We investigate in detail how the motion of the intruder sphere is influenced by size of the background particles, initial vertical position in the bed, ambient pressure and convection. We explain our results in the framework of a simple model and find quantitative agreement in key aspects with numerical simulations to the model equations.Comment: 14 pages, 16 figures, submitted to PRE, corrected typos, slight change

Adaptive Motor Imagery: A Multimodal Study of Immobilization-Induced Brain Plasticity.

The consequences of losing the ability to move a limb are traumatic. One approach that examines the impact of pathological limb nonuse on the brain involves temporary immobilization of a healthy limb. Here, we investigated immobilization-induced plasticity in the motor imagery (MI) circuitry during hand immobilization. We assessed these changes with a multimodal paradigm, using functional magnetic resonance imaging (fMRI) to measure neural activation, magnetoencephalography (MEG) to track neuronal oscillatory dynamics, and transcranial magnetic stimulation (TMS) to assess corticospinal excitability. fMRI results show a significant decrease in neural activation for MI of the constrained hand, localized to sensorimotor areas contralateral to the immobilized hand. MEG results show a significant decrease in beta desynchronization and faster resynchronization in sensorimotor areas contralateral to the immobilized hand. TMS results show a significant increase in resting motor threshold in motor cortex contralateral to the constrained hand, suggesting a decrease in corticospinal excitability in the projections to the constrained hand. These results demonstrate a direct and rapid effect of immobilization on MI processes of the constrained hand, suggesting that limb nonuse may not only affect motor execution, as evidenced by previous studies, but also MI. These findings have important implications for the effectiveness of therapeutic approaches that use MI as a rehabilitation tool to ameliorate the negative effects of limb nonuse

Genetic algorithm with logistic regression for prediction of progression to Alzheimer\u27s disease

Assessment of risk and early diagnosis of Alzheimer\u27s disease (AD) is a key to its prevention or slowing the progression of the disease. Previous research on risk factors for AD typically utilizes statistical comparison tests or stepwise selection with regression models. Outcomes of these methods tend to emphasize single risk factors rather than a combination of risk factors. However, a combination of factors, rather than any one alone, is likely to affect disease development. Genetic algorithms (GA) can be useful and efficient for searching a combination of variables for the best achievement (eg. accuracy of diagnosis), especially when the search space is large, complex or poorly understood, as in the case in prediction of AD development. This study showed the potential of GA application in the neural science area. It demonstrated that the combination of a small set of variables is superior in performance than the use of all the single significant variables in the model for prediction of progression of disease. Variables more frequently selected by GA might be more important as part of the algorithm for prediction of disease development