Discovery and mapping of the Triton seep site, Redondo Knoll: fluid flow and microbial colonization within an oxygen minimum zone

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Wagner, J. K. S., Smart, C., & German, C. R. Discovery and mapping of the Triton seep site, Redondo Knoll: fluid flow and microbial colonization within an oxygen minimum zone. Frontiers in Marine Science, 7, (2020): 108, doi:10.3389/fmars.2020.00108.This paper examines a deep-water (∼900 m) cold-seep discovered in a low oxygen environment ∼30 km off the California coast in 2015 during an E/V Nautilus telepresence-enabled cruise. This Triton site was initially detected from bubble flares identified via shipboard multibeam sonar and was then confirmed visually using the remotely operated vehicle (ROV) Hercules. High resolution mapping (to 1 cm resolution) and co-registered imaging has provided us with a comprehensive site overview – both of the geologic setting and the extent of the associated microbial colonization. The Triton site represents an active cold-seep where microorganisms can act as primary producers at the base of a chemosynthesis-driven food chain. But it is also located near the core of a local oxygen minimum zone (OMZ), averaging 100 m across the seafloor, dominate the site, while typical seep-endemic macro-fauna were noticeably absent from our co-registered photographic and high-resolution mapping surveys – especially when compared to all adjacent seep sites within the same California Borderlands region. While such absences of abundant macro-fauna could be attributable to variations in the availability of dissolved oxygen in the overlying water column this need not necessarily be the case. An alternate possibility is that the zonation in microbial activity that is readily observable at the seafloor at Triton reflects, instead, a concentric pattern of radially diminishing fluxes of reductants from the underlying seafloor. This unusual but readily accessible discovery, in close proximity to Los Angeles harbor, provides an intriguing new natural laboratory at which to examine biogeochemical and microbiological interactions associated with the functioning of cold seep ecosystems within an OMZ.Ship time was funded by NOAA – Office of Exploration and Research and the Ocean Exploration Trust. This material is based upon work supported by a National Science Foundation Graduate Research Fellowship (to JW), the Office of Naval Research (to CS), and NASA’s Astrobiology program (to CG)

Microbial Evaluation of the Calamus Heated Gutta-Percha Delivery System

If gutta-percha cartridges are contaminated with bacteria prior to obturation then contamination of the root canal system may result. Successful treatment not only depends on bacterial elimination but also depends on prevention of recontamination. This study was motivated by the observation that endodontists frequently use single use gutta-percha cartridges on multiple patients. The goal of this study was to determine if cross contamination occurred when a single gutta-percha cartridge in the Calamus™ Flow System was used on multiple patients. An effective recovery method was established during a pilot study using Enterococcus faecalis as a sample bacterium. Microbial recovery was obtained using standard media. The Calamus™ heated gutta-percha delivery system was evaluated to determine the percentage of cartridges with recoverable microorganism under four conditions. Results showed that for cartridges tested immediately after removal from manufacturer’s packaging, the observed negative outcome was 0/10 (0%). For cartridges used on a single patient with an alcohol wipe after use, the negative outcome was 0/20 (0%). For cartridges used on a single patient with no alcohol wipe after use, the negative outcome was 1/20 (5%). For cartridges used on three patients with an alcohol wipe after each use, the number of observed negative outcomes was 0/20 (0%). Using 95% score confidence intervals, the results indicate that the percentage of cartridges with recoverable microorganism under the four conditions is below 27.8% for cartridges sampled from manufacturer’s packaging, 16.1% for cartridges used on a single patient with a alcohol wipe after use, 23.6% for cartridges used on a single patient with no alcohol wipe after use, and 16.1% for cartridges used on three patients with an alcohol wipe after each use. Evidence from this study indicates using Calamus™ flow cartridges on multiple patients vs. single patient does not lead to an increased contamination risk

Teacher Motivation and Learning: Reflective Participation in Professional Learning Communities

As part of the ongoing search for meaningful school reform, many schools have organized themselves into professional learning communities to improve student learning and support teacher learning. Most of the studies on PLCs have focused on their impact on student learning and not on why and how teachers are involved individually and collectively in a meaningful way to support student learning and improved instructional practices through their own professional growth. This qualitative study addresses the motivation of secondary school teachers to engage in their professional learning through their participation in PLCs. The study also sought to explore whether this participation affected teacher learning and their instructional practices. Three research questions guided the study: (a) what motivates teachers to get and remain involved in PLCs; (b) how did teachers believe their participation in PLCs affected teacher learning; (c) did the teachers perceive their participation in PLCs impacted instructional practices. Through one-on-one interviews with teachers, observations of PLCs, artifact collection, and survey responses, data were gathered to learn about how self-motivation influenced teacher involvement in PLC activities. Data collection and analysis were guided and viewed through the lens of Self-Determination Theory, a theory of motivation which focuses on the intrinsic tendencies of people to behave in healthy ways, through their fulfilment of the basic psychological needs of autonomy, competence, and relatedness (Deci & Ryan, 1985; Ryan & Deci, 2000). The major findings of this study identified that while teachers are actively involved in regular PLC activities and are able to demonstrate the essential motivational needs of autonomy, competence, and relatedness, the fact that they are not able to choose their own PLCs nor share a common definition of what a PLC is limits the effectiveness of this process. Autonomy, actualized through the choices that teachers have to influence the activities of their PLC activities, and relatedness, actualized through collaboration and shared work, are present but are dependent upon tenure, department membership, and teacher’s educational philosophy. Also, the lack of a clear sense of how PLCs can support collective inquiry and action research suggests that there will be an inconsistent experience of the benefits of PLCs

Mining topological relations from the web

Topological relations between geographic regions are of interest in many applications. When the exact boundaries of regions are not available, such relations can be established by analysing natural language information from web documents. In particular we demonstrate how redundancy-based techniques can be used to acquire containment and adjacency relations, and how fuzzy spatial reasoning can be employed to maintain the consistency of the resulting knowledge base

Trace Fossils in the Permian Rocks of English Riviera UNESCO Global Geopark

The Permian breccias, conglomerates and sandstones of the English Riviera UNESCO Global Geopark were deposited in quite harsh, desert environments just north of the Permian Equator. Body fossil evidence is completely lacking but rare trace fossils provide evidence of a land-based community. There is a variety of traces present, probably indicative of the presence of a range of unknown animals. Though these animals cannot be identified, their occurrence is important in the understanding of the biodiversity of these Permian environments

Scheduling Design with Unknown Execution Time Distributions or Modes

Open soft real-time systems, such as mobile robots, experience unpredictable interactions with their environments and yet must respond both adaptively and with reasonable temporal predictability. Because of the uncertainty inherent in such interactions, many of the assumptions of the real-time scheduling techniques traditionally used to ensure predictable timing of system actions do not hold in those environments. In previous work we have developed novel techniques for scheduling policy design where up-front knowledge of execution time distributions can be used to produce both compact representations of resource utilization state spaces and efficient optimal scheduling policies over those state spaces. This paper makes two main contributions beyond our previous work, to the state of the art in scheduling open soft real-time systems: (1) it shows how to relax the assumption that the entire distribution of execution times is known up front, to allow online learning of an execution time distribution during system run-time; and (2) it shows how to relax the assumption that the execution time of a system action can be characterized by a single distribution, to accommodate different execution time distributions for an action being taken in one of multiple modes. Each of these contributions allows a wider range of system actions to be scheduled adaptively and with temporal predictability, which increases the applicability of our approach to even more general classes of open soft real-time systems

Optimal Time Utility Based Scheduling Policy Design for Cyber-Physical Systems

Classical scheduling abstractions such as deadlines and priorities do not readily capture the complex timing semantics found in many real-time cyber-physical systems. Time utility functions provide a necessarily richer description of timing semantics, but designing utility-aware scheduling policies using them is an open research problem. In particular, optimal utility accrual scheduling design is needed for real-time cyber-physical domains. In this paper we design optimal utility accrual scheduling policies for cyber-physical systems with periodic, non-preemptable tasks that run with stochastic duration. These policies are derived by solving a Markov Decision Process formulation of the scheduling problem. We use this formulation to demonstrate that our technique improves on existing heuristic utility accrual scheduling policies

Subverting National Internet Censorship - An Investigation into existing Tools and Techniques

The announcement of a trial of a National level internet filter in Australia has caused renewed interest in the arena of internet censorship. Whilst details on the schemes being tested have been fairly sparse the announcement of the trial itself, has drawn wide condemnation from privacy advocates throughout the world. Given this announcement it was decided to test and compare three of the most popular free tools available that allow for the bypassing of internet censorship devices such as those used within China. Tests were conducted using three software packages, Freegate, GPass and GTunnel which were analysed through packet capture to determine their likely effectiveness against the speculated methods to be employed by the Australian trials. The tests clearly showed that all three applications provide an easy means of subverting any likely filtering method with GPass and GTunnel the more suitable candidates as Freegate still allowed for plain-text DNS requests