Temporal and spatial evolution of a waxing then waning catastrophic density current revealed by chemical mapping

We reconstruct the behavior of a catastrophic sustained radial pyroclastic density current as it waxed then waned during its brief lifespan. By subdividing the deposit into 8 time slices using a chemical tracer, we show that the sustained current initially was topographically restricted, but that its leading edge advanced in all directions, encroaching upon and gradually ascending hills. During peak flow the current reached its maximum extent and overtopped all topographic highs. After this, and while the current direction from source was maintained, the leading edge gradually retreated sourceward. High-resolution analysis of the depositional architecture reveals how the flow dynamics evolved and runout distance of the sustained density current rapidly increased then decreased, reflecting the dominant influence of changing mass flux, as demonstrated in numerical models but not previously distinguished in a natural deposit

TETRA Observation of Gamma Rays at Ground Level Associated with Nearby Thunderstorms

Terrestrial Gamma ray Flashes (TGFs) -- very short, intense bursts of electrons, positrons, and energetic photons originating from terrestrial thunderstorms -- have been detected with satellite instruments. TETRA, an array of NaI(Tl) scintillators at Louisiana State University, has now been used to detect similar bursts of 50 keV to over 2 MeV gamma rays at ground level. After 2.6 years of observation, twenty-four events with durations 0.02- 4.2 msec have been detected associated with nearby lightning, three of them coincident events observed by detectors separated by ~1000 m. Nine of the events occurred within 6 msec and 3 miles of negative polarity cloud-to-ground lightning strokes with measured currents in excess of 20 kA. The events reported here constitute the first catalog of TGFs observed at ground level in close proximity to the acceleration site.Comment: To be published in Journal of Geophysical Research: Space Phys. 118,

Implications of single-neuron gain scaling for information transmission in networks

Summary: 

Many neural systems are equipped with mechanisms to efficiently encode sensory information. To represent natural stimuli with time-varying statistical properties, neural systems should adjust their gain to the inputs' statistical distribution. Such matching of dynamic range to input statistics has been shown to maximize the information transmitted by the output spike trains (Brenner et al., 2000, Fairhall et al., 2001). Gain scaling has not only been observed as a system response property, but also in single neurons in developing somatosensory cortex stimulated with currents of different amplitude (Mease et al., 2010). While gain scaling holds for cortical neurons at the end of the first post-natal week, at birth these neurons lack this property. The observed improvement in gain scaling coincides with the disappearance of spontaneous waves of activity in cortex (Conheim et al., 2010).

We studied how single-neuron gain scaling affects the dynamics of signal transmission in networks, using the developing cortex as a model. In a one-layer feedforward network, we showed that the absence of gain control made the network relatively insensitive to uncorrelated local input fluctuations. As a result, these neurons selectively and synchronously responded to large slowly-varying correlated input--the slow build up of synaptic noise generated in pacemaker circuits which most likely triggers waves. Neurons in gain scaling networks were more sensitive to the small-scale input fluctuations, and responded asynchronously to the slow envelope. Thus, gain scaling both increases information in individual neurons about private inputs and allows the population average to encode the slow fluctuations in the input. Paradoxically, the synchronous firing that corresponds to wave propagation is associated with low information transfer. We therefore suggest that the emergence of gain scaling may help the system to increase information transmission on multiple timescales as sensory stimuli become important later in development. 

Methods:

Networks with one and two layers consisting of hundreds of model neurons were constructed. The ability of single neurons to gain scale was controlled by changing the ratio of sodium to potassium conductances in Hodgkin-Huxley neurons (Mainen et al., 1995). The response of single layer networks was studied with ramp-like stimuli with slopes that varied over several hundreds of milliseconds. Fast fluctuations were superimposed on this slowly-varying mean. Then the response to these networks was tested with continuous stimuli. Gain scaling networks captured the slow fluctuations in the inputs, while non-scaling networks simply thresholded the input. Quantifying information transmission confirmed that gain scaling neurons transmit more information about the stimulus. With the two-layer networks we simulated a cortical network where waves could spontaneously emerge, propagate and degrade, based on the gain scaling properties of the neurons in the network

Grief, depressive symptoms, and physical health among recently bereaved spouses

pre-printPurpose of Study: Widowhood is among the most distressing of all life events, resulting in both mental and physical health declines. This paper explores the dynamic relationship between physical health and psychological well-being among recently bereaved spouses. Design and Method: Using a sample of 328 bereaved persons who participated in the Living After Loss study, we modeled trends in physical health, somatic symptoms, and psychological well-being over the first year and a half of widowhood. The primary focus is whether physical health at the time of widowhood modifies psychological well-being over time. Results: There were considerable somatic symptoms during the earliest months of bereavement, but no major health declines over the first year and half of bereavement. Those in poor health had initially higher levels of grief and depressive symptoms, but the trajectories or changes over time were similar regardless of health status. Those with poor health at the time of widowhood had significantly higher risks of complicated grief and major depression disorder. Implications: Bereavement requires physical and emotional adjustment, but the psychological trajectory of bereavement may be somewhat universal. Bereavement support ought to include a focus on self-care and health promotion in addition to emotional support, especially since those with poor health initially may be most susceptible to prolonged and intense clinical distress

Nutrients, Eutrophic Response, and Fish Anomalies in the Little Miami River, Ohio

Author Institution: Dept of Biological Sciences, Northern Kentucky University, Highland Heights, KYAuthor Institution: University of Cincinnati, Dept of Biological Sciences, Cincinnati, OHWe documented the eutrophic and chemical environment in the Little Miami River (LMR) to better understand the interaction between eutrophication, eutrophic response variables, and the health of aquatic organisms. Total phosphorus (TP) and soluble reactive phosphorus (SRP), nitrogen, dissolved oxygen (DO), benthic and sestonic algal biomass, benthic phosphorus storage, aqueous trace metals (Cd, Cr, Cu, Se, Zn), heavy metals (Al, Fe, Mn) and major cations (Ca, K, Mg, Na, Si) were analyzed at twelve sites over two summers. Results showed excess TP (>70 ug/L, p <0.05) and SRP (≥62.5 ug/L, p <0.05), borderline nuisance benthic algal biomass (mg/L chlorophyll a/m2) (periphyton: mean = 73.8 +/- 74.2, n = 125; Cladophora: mean = 216.7 +/- 380.7, n = 54), excess benthic phosphorus storage (mg P/m2) (periphyton: mean = 45.5 +/- 23.2, n = 64; Cladophora: mean = 129.3 +/- 224, n = 52), and high daytime DO (mean = 9.1 +/- 1.5 mg/L, n = 132). Previous studies showed aqueous phosphorus concentration and diurnal DO swings were positively correlated with fish anomalies (OEPA 1995, 2000). In this study, however, periphyton phosphorus (P) was the only eutrophic response variable to correlate with the distribution of fish anomalies reported by OEPA in 1995 and 2000, and the association was negative (R2 = 0.143, p = 0.002, m = -1.634, df = 1, 62). We concluded that aqueous nutrients, eutrophic response variables, and/or water chemistry alone did not explain the occurrence of fish anomalies in the LMR

Neonatal bacterial colonization of the intestine—Implications for the practitioner

Background: Neonatal intestinal bacterial colony balance has correlations with positive and negative health situations. The understanding of how neonate colonization occurs is therefore extremely important in providing life-extending and holistic care for infants. Certain medical interventions can impede optimal intestinal colonization. However, with proper screening and identification, side effects can be limited and compensated for, and complications can be minimized in an already compromised population. This study aims to identify influences on neonate microbiomes to create best practices for increased health outcomes.&nbsp; Develop mitigations for factors leading to intestinal microbiome conditions linked to negative neonate outcomes and increase opportunities for healthy colonization. Methods: The research team conducted a literature review via PubMed, Cumulative Index of Nursing and Allied Health Literature, and Academic Search Ultimate to collect data regarding neonatal bacterial colonization of the intestine.&nbsp; Results: Normal colonization is affected by birth age, birthing method, time spent in direct skin to skin contact with mother and feeding type. Iatrogenic influences include the use of oral and topical antibiotics, proton blockers, and practices that limit direct contact. Conclusion: The nursing process and policy adaptations can have a positive effect on developing a protective neonate intestinal microbiome. Awareness of risks and early clinical signs can improve positive interventions that may prevent life-threatening complications in susceptible neonates. &nbsp