Distinguishing Infections on Different Graph Topologies

The history of infections and epidemics holds famous examples where understanding, containing and ultimately treating an outbreak began with understanding its mode of spread. Influenza, HIV and most computer viruses, spread person to person, device to device, through contact networks; Cholera, Cancer, and seasonal allergies, on the other hand, do not. In this paper we study two fundamental questions of detection: first, given a snapshot view of a (perhaps vanishingly small) fraction of those infected, under what conditions is an epidemic spreading via contact (e.g., Influenza), distinguishable from a "random illness" operating independently of any contact network (e.g., seasonal allergies); second, if we do have an epidemic, under what conditions is it possible to determine which network of interactions is the main cause of the spread -- the causative network -- without any knowledge of the epidemic, other than the identity of a minuscule subsample of infected nodes? The core, therefore, of this paper, is to obtain an understanding of the diagnostic power of network information. We derive sufficient conditions networks must satisfy for these problems to be identifiable, and produce efficient, highly scalable algorithms that solve these problems. We show that the identifiability condition we give is fairly mild, and in particular, is satisfied by two common graph topologies: the grid, and the Erdos-Renyi graphs

VLF, magnetic bay and Pi2 substorm signatures at auroral and midlatitude ground stations

A superposed epoch analysis of 100–300 substorms is performed to determine the median size and shape of the substorm-associated VLF chorus, magnetic bay, and Pi2 pulsation burst observed at the near-auroral Halley research station, Antarctica, and at the midlatitude Faraday station at three different local times (2230, 2330, 0130 MLT). The spatial and temporal properties of the magnetic bay signatures are compared with the University of York implementation of the Kisabeth–Rostoker substorm current wedge (SCW) model and the Weimer pulse model, respectively. These constitute the best analytical models of the substorm to date. It is shown that the polarities and relative amplitudes of the observed magnetic bays in the H, D, and Z components at Halley at midnight MLT and at Faraday in the premidnight sector are consistent with the York model for a SCW 3 hours wide in MLT with its westward electrojet at 67°S magnetic latitude. In particular the little-discussed Z component of the bay agrees with the model and is shown to be the clearest substorm signature of the three components, especially at midlatitude. The midnight and postmidnight bays are similar to the premidnight case but progressively smaller and cannot be fully reconciled with the model. The shape of the H and Z bays at Halley and the D bays at Faraday fit a normalized Weimer pulse well, with Weimer's 2 h−1 recovery rate, but the other components do not. The D component at Halley and H at Faraday do fit the Weimer pulse shape but with a faster recovery rate of 4 h−1. It is proposed that this is due to the effect of a decaying current in the SCW combining with the geometrical effect of changing SCW configuration and position relative to the observing station. The Z component at Faraday recovers more slowly than the 2 h−1 Weimer prediction; we cannot explain this. Secondary bays at Halley and Faraday show a clear tendency to recur after 2 hours. Inflection points just prior to onset at Halley and Faraday are argued to be related to reduced convection associated with northward turning of the IMF. The median substorm signature at Halley in the Pi2 frequency band (7–25 mHz) is well correlated with the bay structure, showing that it is part of a broader band, possibly turbulent, spectrum in the substorm-dependent DP2 current. There is evidence of a minor additional narrow band component occurring at substorm onset. This is the dominant signal at Faraday which shows the classic midlatitude substorm signature, a short Pi2 pulsation burst at onset, that decreases progressively in intensity with increasing local time, implying a source region biased to the evening side or else preferred propagation to the east from a near-midnight source

Implementation and Evaluation of a Checklist in the Postanesthesia Care Transitions

The transition from the operating room to the postoperative care unit is a critical time in the perioperative period for patients. Patients are physically transferred from one location to another and critical information regarding patients’ intraoperative period must be delivered accurately to ensure patient safety. Over the past few years, many healthcare regulating agencies have advocated for a standardized care transitions by suggesting a handoff checklist should be implemented but this has failed to be universally executed. There is not one template universally implemented in post anesthesia standardized handoffs but many different models. Nonetheless, research has shown using a standardized template for this care transition has shown that more information was delivered to the receiving parties and safety events related to miscommunication in postoperative transitions were decreased. The purpose of this project is to refine care transitions through a standardized handoff which will improve communication and decrease safety-related events. Nurses and anesthesiologists were anonymously surveyed about their perception of postanesthesia transitions prior to and after introduction of the intervention. A postanesthesia handoff checklist formatted in a Situation, Background, Assessment, and Recommendation method was implemented at a level one trauma center in the Midwest based on feedback from the organization. The documented handoffs indicated there was a high compliance with using the checklist. The postsurveys presented low participation and neutral feelings regarding the use of a handoff checklist

The electric field response to the growth phase and expansion phase onset of a small isolated substorm

International audienceWe capitalise on the very large field of view of the Halley HF radar to provide a comprehensive description of the electric field response to the substorm growth phase and expansion phase onset of a relatively simple isolated substorm ( |AL| 12 h) of magnetic quiescence, such that prior to the start of the growth phase, the apparent latitudinal motion of the radar backscatter returns is consistent with the variation in latitude of the quiet-time auroral oval with magnetic local time. The growth phase is characterised by an increasing, superimposed equatorward motion of the equatorward edge of the radar backscatter as the auroral oval expands. Within this backscatter region, there is a poleward gradient in the Doppler spectral width, which we believe to correspond to latitudinal structure in auroral emissions and magnetospheric precipitation. During the growth phase the ionospheric convection is dominated by a relatively smooth large-scale flow pattern consistent with the expanding DP2 (convection) auroral electrojets. Immediately prior to substorm onset the ionospheric convection observed by the radar in the midnight sector has a predominantly equatorward flow component. At substorm onset a dramatic change occurs and a poleward flow component prevails. The timing and location are quite remarkable. The timing of the flow change is within one minute of the dispersionless injection observed at geostationary orbit and the Pi2 magnetic signature on the ground. The location shows that this sudden change in flow is due to the effect of the upward field aligned current of the substorm current wedge imposed directly within the Halley radar field of view

Identifying infection processes with incomplete information

textInfections frequently occur on both networks of devices and networks of people, and can model not only viruses, but also information, rumors, and product use. However, in many circumstances, the infection process itself is hidden, and only the effects, e.g. sickness or knowledge, can be observed. In addition, this information is likely incomplete, missing many sick nodes, as well as inaccurate, with false positives. To use this data effectively, it is often essential to identify the infection process causing the sickness, or even whether the cause is an infection. For our purposes, we consider the susceptible-infected (SI) infection model. We seek to distinguish between infections and random sickness, as well as between different infection (or infection-like) processes in a limited information setting. We formulate this as a hypothesis testing problem, where (typically) in the null, the sickness affects nodes at random, and in the alternative, the infection is spread through the network. Similarly, we consider the case where the sickness may be caused by one of two infection (or infection-like) processes, and we wish to find which is the causative process. We do this is a setting with very limited information, given only a single snapshot of the infection. Only a small portion of the infected population reports the sickness. In addition, there are several other limitations we consider. There may be false positives, obfuscating the infection. Similarly, there may be a random sickness and epidemic process occurring simultaneously. Knowledge of the graph topology may be incomplete, with unknown edges over which the infection may spread. The graph may also be weighted, affecting the way the infection spreads over the graph. In all these cases, we develop algorithms to identify the causative process of the infection utilizing the fact that infected nodes will be clustered. We demonstrate that under reasonable conditions, these algorithms detect an infection with asymptotically zero error probability as the graph size increases.Electrical and Computer Engineerin

Leaky Moss in Montana\u27s Grasslands

Grasslands cover more than 40% of Montana[1] and while much is known about the vascular plant community, little attention is paid to the role mosses play. Could these bryophytes be a key part in maintaining proper nutrient cycling and recruiting new plants? In our preliminary study we found that plant biomass is increased in the presence of moss, one explanation involves moss physiology. Mosses are fascinating organisms able to withstand extreme dehydration and can rehydrate within minutes. This rapid rehydration results in nutrient loss through ruptured cell walls, which we hypothesize is then leached into the soil and made available to surrounding organisms. In our current project we are investigating the nature of moss ‘leachate’ and what effect it has on native plants and nonnative plants in competition. Moss has been shown to facilitate plant growth through altering physical structure or water availability; we are focused on how mosses alter the nutrient cycling. Our common garden experiment will treat established grassland plants (C. stoebe, and F. idahoensis) with moss leachate for 4 weeks and measure final biomass. Furthermore, via elemental analysis, we will investigate the nature of moss leachate, quantifying the total organic carbon and nitrogen. Mosses grow in almost every ecosystem on the planet, and linking moss leachate as a key part of the nutrient cycle could yield many management implications. 1. Montana’s Comprehensive Fish and Wildlife Conservation Strategy, Executive Summary, 2005. Montana Fish, Wildlife & Park

Was kennzeichnet "gute" Betreuung bei berufsbegleitenden Studiengängen im Blended-Learning-Format? Tragweite verschiedener Betreuungskomponenten und ihr Transfer auf andere Studiengänge

An der Pädagogischen Hochschule Ludwigsburg wurde im Jahre 2003 ein weiterbildender Masterstudiengang Bildungsmanagement installiert und im Jahr 2011 um einen zweiten Masterstudiengang International Education Management ergänzt. Beide Studiengänge sind als berufsbegleitende Blended-Learning-Studiengänge konzipiert. Ausgehend von diesem Beispiel fokussiert der Beitrag die generelle Diskussion um die Übertragbarkeit von Betreuungskonzepten sowie deren strategischen Ausrichtung. Hierzu werden Ergebnisse einer empirischen Erhebung vorgestellt, die diese Frage aus studentischer Perspektive beleuchten. In beiden Studiengängen wurden die Studierenden hinsichtlich ihrer Einschätzung der einzelnen Betreuungskomponenten befragt. Damit soll ermittelt werden, was eine "gute" Betreuung aus der Sicht von Studierenden auszeichnet und inwieweit ggf. Unterschiede zwischen "nationalen" und "internationalen" Studierenden festzustellen sind. (DIPF/Autor

The importance of contrast sensitivity testing in children

Aim: To discuss the information contrast sensitivity (CS) testing can provide over visual acuity testing, and review the literature relating to CS deficits in children to determine whether there is an optimum test available. Methods: A literature search of databases available through the University of Liverpool library was performed. All searches related to the importance of CS in children, paediatric conditions affecting CS and current clinical tests available for the assessment of CS. Results: Many paediatric conditions exist where CS is defective, often despite ‘normal’ visual acuity (VA): for example, optic pathway gliomas, myopia and primary congenital glaucoma. The finding of a loss of CS has been found to be more prominent and disturbing to an individual than a loss of VA, emphasising the importance of CS assessments in children. Therefore, the clinical assessment of CS in children is valuable in terms of strategies to support the child and establishing the individual’s functional level of vision. Unfortunately, current paediatric clinical tests of CS have failed to demonstrate the same standards and repeatability and reliability as adult tests for the assessment of CS. Conclusions: The range of functional deficits that accompany paediatric ocular disease require more assessments for full evaluation of visual function than standard VA tests. However, reliable assessments for paediatric CS are limited. A new paediatric CS test may be of clinical value