Nonnormal amplification in random balanced neuronal networks

In dynamical models of cortical networks, the recurrent connectivity can amplify the input given to the network in two distinct ways. One is induced by the presence of near-critical eigenvalues in the connectivity matrix W, producing large but slow activity fluctuations along the corresponding eigenvectors (dynamical slowing). The other relies on W being nonnormal, which allows the network activity to make large but fast excursions along specific directions. Here we investigate the tradeoff between nonnormal amplification and dynamical slowing in the spontaneous activity of large random neuronal networks composed of excitatory and inhibitory neurons. We use a Schur decomposition of W to separate the two amplification mechanisms. Assuming linear stochastic dynamics, we derive an exact expression for the expected amount of purely nonnormal amplification. We find that amplification is very limited if dynamical slowing must be kept weak. We conclude that, to achieve strong transient amplification with little slowing, the connectivity must be structured. We show that unidirectional connections between neurons of the same type together with reciprocal connections between neurons of different types, allow for amplification already in the fast dynamical regime. Finally, our results also shed light on the differences between balanced networks in which inhibition exactly cancels excitation, and those where inhibition dominates.Comment: 13 pages, 7 figure

Examining evidence based resistance plus balance training in community-dwelling older adults with complex health care needs: Trial protocol for the Muscling Up Against Disability project

Available online 6 October 2016Abstract not availableJustin W.L. Keogh, Tim Henwood, Paul Gardiner, Anthony Tuckett, Brent Hodgkinson, Kevin Rous

Secular change in TTG compositions: Implications for the evolution of Archaean geodynamics

It is estimated that around three quarters of Earth's first generation continental crust had been produced by the end of the Archaean Eon, 2.5 billion years ago. This ancient continental crust is mostly composed of variably deformed and metamorphosed magmatic rocks of the tonalite–trondhjemite–granodiorite (TTG) suite that formed by partial melting of hydrated mafic rocks. However, the geodynamic regime under which TTG magmas formed is a matter of ongoing debate. Using a filtered global geochemical dataset of 563 samples with ages ranging from the Eoarchaean to Neoarchaean (4.0–2.5 Ga), we interrogate the bulk rock major oxide and trace element composition of TTGs to assess evidence for secular change. Despite a high degree of scatter in the data, the concentrations or ratios of several key major oxides and trace elements show statistically significant trends that indicate maxima, minima and/or transitions in the interval 3.3–3.0 Ga. Importantly, a change point analysis of K2O/Na2O, Sr/Y and LaN/YbN demonstrates a statistically significant (>99% confidence) change during this 300 Ma period. These shifts may be linked to a fundamental change in geodynamic regime around the peak in upper mantle temperatures from one dominated by non-uniformitarian, deformable stagnant lid processes to another dominated by the emergence of global mobile lid or plate tectonic processes by the end of the Archaean. A notable change is also evident at 2.8–2.7 Ga that coincides with a major jump in the rate of survival of metamorphic rocks with contrasting thermal gradients, which may relate to the emergence of more potassic continental arc magmas and an increased preservation potential during collisional orogenesis. In many cases, the chemical composition of TTGs shows an increasing spread through the Archaean, reflecting the irreversible differentiation of the lithosphere

Perfect mirror transport protocol with higher dimensional quantum chains

A globally controlled scheme for quantum transport is proposed. The scheme works on a 1D chain of nearest neighbor coupled systems of qudits (finite dimension), or qunats (continuous variable), taking any arbitrary initial quantum state of the chain and producing a final quantum state which is perfectly spatially mirrored about the mid-point of the chain. As a particular novel application, the method can be used to transport continuous variable (CV) quantum states. A physical realization is proposed where it is shown how the quantum states of the microwave fields held in a chain of driven superconducting coplanar waveguides can experience quantum mirror transport when coupled by switchable Cooper Pair Boxes.Comment: Published version; 4 pages, 4 Figure

N-body simulations of the Magellanic Stream

A suite of high-resolution N-body simulations of the Magellanic Clouds -- Milky Way system are presented and compared directly with newly available data from the HI Parkes All-Sky Survey (HIPASS). We show that the interaction between Small and Large Magellanic Clouds results in both a spatial and kinematical bifurcation of both the Stream and the Leading Arm. The spatial bifurcation of the Stream is readily apparent in the HIPASS data, and the kinematical bifurcation is also tentatively identified. This bifurcation provides strong support for the tidal disruption origin for the Magellanic Stream. A fiducial model for the Magellanic Clouds is presented upon completion of an extensive parameter survey of the potential orbital configurations of the Magellanic Clouds and the viable initial boundary conditions for the disc of the Small Magellanic Cloud. The impact of the choice of these critical parameters upon the final configurations of the Stream and Leading Arm is detailed.Comment: Accepted by MNRAS, 07 Jun 2006. 14 pages, 14 figures, 3 tables. LaTeX (mn2e.sty). File with decent resolution images (strongly recommended) available at http://astronomy.swin.edu.au/~tconnors/publications/ . References added; distance and HI-LOres difference figures added; clearer figures; discussion added to, but conclusions unchange

National Trends in Preterm Infant Mortality in the United States by Race and Socioeconomic Status, 1995-2020

Importance: Inequalities in preterm infant mortality exist between population subgroups within the United States. // Objective: To characterize trends in preterm infant mortality by maternal race and socioeconomic status to assess how inequalities in preterm mortality rates have changed over time. // Design, Setting, and Participants: This was a retrospective longitudinal descriptive study using the US National Center for Health Statistics birth infant/death data set for 12 256 303 preterm infant births over 26 years, between 1995 and 2020. Data were analyzed from December 2022 to March 2023. // Exposures: Maternal characteristics including race, smoking status, educational attainment, antenatal care, and insurance status were used as reported on an infant’s US birth certificate. // Main Outcomes and Measures: Preterm infant mortality rate was calculated for each year from 1995 to 2020 for all subgroups, with a trend regression coefficient calculated to describe the rate of change in preterm mortality. // Results: The average US preterm infant mortality rate (IMR) decreased from 33.71 (95% CI, 33.71 to 34.04) per 1000 preterm births per year between 1995-1997, to 23.32 (95% CI, 23.05 to 23.58) between 2018-2020. Black non-Hispanic infants were more likely to die following preterm births than White non-Hispanic infants (IMR, 31.09; 95% CI, 30.44 to 31.74, vs 21.81; 95% CI, 21.43 to 22.18, in 2018-2020); however, once born, extremely prematurely Black and Hispanic infants had a narrow survival advantage (IMR rate ratio, 0.87; 95% CI, 0.84 to 0.91, in 2018-2020). The rate of decrease in preterm IMR was higher in Black infants (−0.015) than in White (−0.013) and Hispanic infants (−0.010); however, the relative risk of preterm IMR among Black infants compared with White infants remained the same between 1995-1997 vs 2018-2020 (relative risk, 1.40; 95% CI, 1.38 to 1.44, vs 1.43; 95% CI, 1.39 to 1.46). The rate of decrease in preterm IMR was higher in nonsmokers compared with smokers (−0.015 vs −0.010, respectively), in those with high levels of education compared with those with intermediate or low (−0.016 vs – 0.010 or −0.011, respectively), and in those who had received adequate antenatal care compared with those who did not (−0.014 vs −0.012 for intermediate and −0.013 for inadequate antenatal care). Over time, the relative risk of preterm mortality widened within each of these subgroups. // Conclusions and Relevance: This study found that between 1995 and 2020, US preterm infant mortality improved among all categories of prematurity. Inequalities in preterm infant mortality based on maternal race and ethnicity have remained constant while socioeconomic disparities have widened over time

Developing a business case for greening hard coastal and estuarine infrastructure: preliminary results

This paper presents a new framework of critical success factors (CSF) that is being developed to aid approval of ecological enhancements and green engineering options in cities, historic conservation areas, estuaries and at the coast. This is intended to support asset managers, engineers, conservation and biodiversity teams, decision-makers, and other end-users. The CSF framework is outlined and demonstrated by assessing the engineering performance and ecosystem services benefits of ecological enhancements used in specific operational scale case studies. Where data availability permits, the costs and benefits of different greening approaches compared to ‘business as usual’ are assessed. Three coastal and estuarine case studies are presented to demonstrate how the framework can be applied to compare traditional engineering solutions to green-grey options. Results show that simple, inexpensive ecological enhancement and green engineering solutions can deliver more multifunctional benefits than business as usual solutions for similar or reduced costs. They also demonstrate that the CSF framework will be a powerful tool that can aid practitioners in evaluating green engineering solutions compared with business as usual

Growth-induced breaking and unbreaking of ergodicity in fully-connected spin systems

Two canonical models of statistical mechanics, the fully-connected voter and Glauber-Ising models, are modified to incorporate growth via the addition or replication of spins. The resulting behaviour is examined in a regime where the timescale of expansion cannot be separated from that of the internal dynamics. Depending on the model specification, growth radically alters the long-time dynamical behaviour by breaking or unbreaking ergodicity.Comment: 10 pages, 3 figures, 1 tabl

Progressive resistance plus balance training for older Australians receiving in-home care services: cost-effectiveness analyses alongside the muscling up against disability stepped-wedge randomized control trial.

In this article, the authors assessed the cost-effectiveness of center-based exercise training for older Australians. The participants were recipients of in-home care services, and they completed 24 weeks of progressive resistance plus balance training. Transport was offered to all participants. A stepped-wedge randomized control trial produced pre-, post-, and follow-up outcomes and cost data, which were used to calculate incremental cost-effectiveness ratios per quality-adjusted life year gained. Analyses were conducted from a health provider perspective and from a government perspective. From a health-service provider perspective, the direct cost of program provision was $303 per person, with transport adding an additional$1,920 per person. The incremental cost–utility ratio of the program relative to usual care was $70,540 per quality-adjusted life year over 6 months, decreasing to$37,816 per quality-adjusted life year over 12 months. The findings suggest that Muscling Up Against Disability offers good value for the money within commonly accepted threshold values

Sarc-F and muscle function in community dwelling adults with aged care service needs: baseline and post-training relationship.

Background. This study sought to better understand the psychometric properties of the SARC-F, by examining the baseline and training-related relationships between the five SARC-F items and objective measures of muscle function. Each of the five items of the SARC-F are scored from 0 to 2, with total score of four or more indicative of likely sarcopenia. Methods. This manuscript describes a sub-study of a larger step-wedge, randomised controlled 24-week progressive resistance and balance training (PRBT) program trial for Australian community dwelling older adults accessing government supported aged care. Muscle function was assessed using handgrip strength, isometric knee extension, 5-time repeated chair stand and walking speed over 4 m. Associations within and between SARC-F categories and muscle function were assessed using multiple correspondence analysis (MCA) and multinomial regression, respectively. Results. Significant associations were identified at baseline between SARC-F total score and measures of lower-body muscle function (r = −0.62 to 0.57; p ≤ 0.002) in 245 older adults. MCA analysis indicated the first three dimensions of the SARC-F data explained 48.5% of the cumulative variance. The initial dimension represented overall sarcopenia diagnosis, Dimension 2 the ability to displace the body vertically, and Dimension 3 walking ability and falls status. The majority of the 168 older adults who completed the PRBT program reported no change in their SARC-F diagnosis or individual item scores (56.5–79.2%). However, significant associations were obtained between training-related changes in SARC-F total and item scores and changes in walking speed and chair stand test performance (r = −0.30 to 0.33; p < 0.001 and relative risk ratio = 0.40–2.24; p < 0.05, respectively). MCA analysis of the change score data indicated that the first two dimensions explained 32.2% of the cumulative variance, with these dimensions representing whether a change occurred and the direction of change, respectively. Discussion. The results advance our comprehension of the psychometric properties on the SARC-F, particularly its potential use in assessing changes in muscle function. Older adults’ perception of their baseline and training-related changes in their function, as self-reported by the SARC-F, closely matched objectively measured muscle function tests. This is important as there may be a lack of concordance between self-reported and clinician-measured assessments of older adults’ muscle function. However, the SARC-F has a relative lack of sensitivity to detecting training-related changes, even over a period of 24 weeks. Conclusions. Results of this study may provide clinicians and researchers a greater understanding of how they may use the SARC-F and its potential limitations. Future studies may wish to further examine the SARC-F’s sensitivity of change, perhaps by adding a few additional items or an additional category of performance to each item