The Unequal Twins - Probability Distributions Aren't Everything

It is the common lore to assume that knowing the equation for the probability distribution function (PDF) of a stochastic model as a function of time tells the whole picture defining all other characteristics of the model. We show that this is not the case by comparing two exactly solvable models of anomalous diffusion due to geometric constraints: The comb model and the random walk on a random walk (RWRW). We show that though the two models have exactly the same PDFs, they differ in other respects, like their first passage time (FPT) distributions, their autocorrelation functions and their aging properties

Tolerance of endolithic algae to elevated temperature and light in the coral Montipora monasteriata from the southern Great Barrier Reef

Photosynthetic endolithic algae and cyanobacteria live within the skeletons of many scleractinians. Under normal conditions, less than 5% of the photosynthetically active radiation (PAR) reaches the green endolithic algae because of the absorbance of light by the endosymbiotic dinoflagellates and the carbonate skeleton. When corals bleach (loose dinoflagellate symbionts), however, the tissue of the corals become highly transparent and photosynthetic microendoliths may be exposed to high levels of both thermal and solar stress. This study explores the consequence of these combined stresses on the phototrophic endoliths inhabiting the skeleton of Montipora monasteriata, growing at Heron Island, on the southern Great Barrier Reef. Endoliths that were exposed to sun after tissue removal were by far more susceptible to thermal photoinhibition and photo-damage than endoliths under coral tissue that contained high concentrations of brown dinoflagellate symbionts. While temperature or light alone did not result in decreased photosynthetic efficiency of the endoliths, combined thermal and solar stress caused a major decrease and delayed recovery. Endoliths protected under intact tissue recovered rapidly and photoacclimated soon after exposure to elevated sea temperatures. Endoliths under naturally occurring bleached tissue of M. monasteriata colonies (bleaching event in March 2004 at Heron Island) acclimated to increased irradiance as the brown symbionts disappeared. We suggest that two major factors determine the outcome of thermal bleaching to the endolith community. The first is the microhabitat and light levels under which a coral grows, and the second is the susceptibility of the coral-dinoflagellates symbiosis to thermal stress. More resistant corals may take longer to bleach allowing endoliths time to acclimate to a new light environment. This in turn may have implications for coral survival

Some Like It Fat: Comparative Ultrastructure of the Embryo in Two Demosponges of the Genus Mycale (Order Poecilosclerida) from Antarctica and the Caribbean

0000-0002-7993-1523© 2015 Riesgo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License [4.0], which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The attached file is the published version of the article

Preparedness for maternal and neonatal emergencies in UK midwifery units: a national survey using the UK Midwifery Study System (UKMidSS)

Objective We aimed to document and describe variation in a range of factors impacting on preparedness for and the management of emergencies in midwifery units in the UK. Design, setting and participants National cross-sectional survey administered online through the UK Midwifery Study System (UKMidSS) to midwife ‘reporters’ in all 206 alongside and freestanding midwifery units in the UK, January-April 2020. Topics investigated included communication with the ambulance service in freestanding units, staff support for emergencies, training and equipment held. Findings In total, 137 (67%) midwifery units responded, representing 75% of eligible UK maternity services. There was no evidence of differences between responding and non-responding units in terms of type of unit, annual number of births, or country/region of the UK. Overall, 10 freestanding units (20%) reported using an ordered categorical system (e.g. ‘category 1’ or ‘code red’) to communicate an emergency to the ambulance service, 17 (35%) reported using other words describing urgency (e.g. ‘obstetric emergency’), and 15 (31%) reported having no agreed word or phrase. Almost all alongside units reported that a senior midwife, paediatrician/neonatologist and obstetrician might attend in an emergency, whereas most freestanding units reported the attendance of paramedics and/or a senior midwife. The type and frequency of staff training varied, with 77% of units reporting annual skills and drills training, and lower proportions reporting annual multi-disciplinary simulation (55%), in-situ simulation (50%) and neonatal life support training (59%). The equipment kept in midwifery units varied between different types of unit. For example, 28 alongside units (32%) reported keeping ventouse in the unit and 21 (24%) kept forceps, compared with 4 (8%) and 2 (4%) freestanding units respectively. Almost half of freestanding units (47%) and around a quarter of alongside units (24%) reported having a cardiotocograph (CTG) in the unit. Conclusions The study found wide variation in factors that impact on preparedness for and management of emergencies in UK midwifery units. Although some variation is inevitable given the varying size and location of units, this study has identified some areas where greater consistency might improve outcomes

Memory effects in the electron glass

We investigate theoretically the slow nonexponential relaxation dynamics and associated memory effects of glasses far from equilibrium, which are arguably the most important characteristics of the glass phase. We focus on the electron glass which offers an advantageous starting point compared to other glassy systems both theoretically and experimentally: the model used here is discrete, and experimentally it offers new ways to address these effects by changing a simple experimental parameter —the gate voltage. The full nonlinearized self-consistent model of the dynamics of the occupation numbers in the system successfully recovers the general behavior found in experiments. Our numerical analysis is consistent with both the expected logarithmic relaxation and our understanding of how increasing disorder or interaction slows down the relaxation process, thus yielding a consistent picture of the electron glass, and shedding light on the understanding of glassy behavior in general. We also present a novel finite-size domino effect where the connection to the leads affects the relaxation process of the electron glass in mesoscopic systems. This effect speeds up the relaxation process, and may even reverse the expected effect of interaction; stronger interaction then leading to a faster relaxation

Universal frequency-dependent conduction of electron glasses

Characterizing the frequency-dependent response of amorphous systems and glasses can provide important insights into their physics. Here, we study the response of an electron glass, where Coulomb interactions are important and have previously been shown to significantly modify the conductance and lead to memory effects and aging. We propose a model which allows us to take the interactions into account in a self-consistent way, and explore the frequency-dependent conduction at all frequencies. At low frequencies conduction occurs on the percolation backbone, and the model captures the variable-range-hopping behavior. At high frequencies conduction is dominated by localized clusters. Despite the difference in physical mechanisms at low and high frequency, we are able to scale all numerical data onto a single curve, using two parameters: the DC conduction and dielectric constant. The behavior follows the universal scaling that is experimentally observed for a large class of amorphous solids