Heterotrophic bacteria exhibit a wide range of rates of extracellular production and decay of hydrogen peroxide

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Bond, R. J., Hansel, C. M., & Voelker, B. M. Heterotrophic bacteria exhibit a wide range of rates of extracellular production and decay of hydrogen peroxide. Frontiers in Marine Science, 7, (2020): 72, doi:10.3389/fmars.2020.00072.Bacteria have been implicated as both a source and sink of hydrogen peroxide (H2O2), a reactive oxygen species which can both impact microbial growth and participate in the geochemical cycling of trace metals and carbon in natural waters. In this study, simultaneous H2O2 production and decay by twelve species of heterotrophic bacteria were evaluated in both batch and flow-through incubations. While wide species-to-species variability of cell-normalized H2O2 decay rate coefficients [2 × 10–8 to 5 × 10–6 hr–1 (cell mL–1)–1] was observed, these rate coefficients were relatively consistent for a given bacterial species. By contrast, observed production rates (below detection limit to 3 × 102 amol cell–1 hr–1) were more variable even for the same species. Variations based on incubation conditions in some bacterial strains suggest that external conditions may impact extracellular H2O2 levels either through increased extracellular production or leakage of intracellular H2O2. Comparison of H2O2 production rates to previously determined superoxide (O2–) production rates suggests that O2– and H2O2 production are not necessarily linked. Rates measured in this study indicate that bacteria could account for a majority of H2O2 decay observed in aqueous systems but likely only make a modest contribution to dark H2O2 production.This research was supported by NSF grant OCE-1131734/1246174 to BV and CH

Quantitative surface inspection methods for metal castings

Inspecting castings to verify the quality of a part is critical for foundries to maintain a high level of customer confidence. Current methods employ qualitative methods, and the manufacturer must correctly interpret the inspection criteria set by the customer in order to meet the design specifications. The interpretation of what is acceptable often differs from the customer to manufacturer and even from inspector to inspector. In this thesis, the visual inspection of cast metal are explored in depth, and improvements to current methods are proposed. First, the risk of Type I and II errors from the inspection process were evaluated based off of varying states of environmental and human factors in the inspection process; however, it was discovered high variation among inspectors still exists due to the subjectivity of the standards. This signals a need for a more quantitative standard to evaluate the surface of a casting. In response a digital standard is proposed, which specifies three parameters to allow the customer to communicate their exact needs in regards to surface finish to the manufacturer. These parameters are calculated based off of a part’s true geometry post shrinkage in absence of surface roughness and abnormalities, or underlying geometry. Since the underlying geometry differs from the part’s intended geometry, methods will be explored to estimate the underlying geometry from a point cloud of the part’s surface. The proposed methods will be compared to identify which approach best estimates the ideal underlying geometry. Once an ideal method is identified, it will be used as a standard method to calculate the underlying geometry in order to create consistency among inspectors at both the customer and manufacturer. The work completed in this thesis will raise awareness of the risk associated with current visual inspection methods for cast metal surfaces. The new, digital standard will reduce the variation in this inspection process allowing greater confidence in the parts leaving the manufacturer. Additionally, the standard will allow the customer to improve communication with the manufacturer in order to achieve the quality of surface required for their specific needs

Evaluation of onset of pain relief from micronized aspirin in a dental pain model

A new formulation of a micronized acetylsalicylic acid swallowable tablet with an effervescent component (FR-aspirin) was evaluated in two independent studies using the dental impaction pain model. These clinical studies were performed to confirm the results of preclinical dissolution studies and human pharmacokinetic studies, which indicated an improved onset of analgesia without compromising duration of effect or safety. Study 1 evaluated a 650-mg dose of aspirin and Study 2 evaluated a 1,000-mg dose of aspirin. Both studies were double-blinded, parallel group and compared to regular aspirin (R-aspirin) and placebo. Speed of onset was measured by the double stopwatch method for time to both first perceptible relief and meaningful relief. In both studies, the FR-aspirin was significantly faster (p < 0.038–0.001) than both R-aspirin and placebo for both onset measures. There were no significant differences between FR-aspirin and R-aspirin for peak or total effects and both treatments were significantly better than placebo. For first perceptible relief, FR-aspirin onset was 19.8 and 16.3 min for 650 mg and 1,000 mg, respectively, compared to 23.7 and 20.0 for R-aspirin. For meaningful relief, FR-aspirin onset was 48.9 and 49.4 min for 650 mg and 1,000 mg, respectively, compared to 119.2 and 99.2 for R-aspirin. These efficacy studies clearly demonstrate that the onset of analgesic efficacy is dramatically improved by adding an effervescent component and micronized active ingredient to the swallowable tablet aspirin formulation. The enhanced onset did not adversely impact either the peak effect or duration of effect or tolerability compared to regular aspirin

Neuro-Dynamic Programming for Radiation Treatment Planning

In many cases a radiotherapy treatment is delivered as a series of smaller dosages over a period of time. Currently, it is difficult to determine the actual dose that has been delivered at each stage, precluding the use of adaptive treatment plans. However, new generations of machines will give more accurate information of actual dose delivered, allowing a planner to compensate for errors in delivery. We formulate a model of the day-to-day planning problem as a stochastic linear program and exhibit the gains that can be achieved by incorporating uncertainty about errors during treatment into the planning process. Due to size and time restrictions, the model becomes intractable for realistic instances. We show how neuro-dynamic programming can be used to approximate the stochastic solution, and derive results from our models for realistic time periods. These results allow us to generate practical rules of thumb that can be immediately implemented in current planning technologies.\ud \ud This material is based on research partially supported by the National Science Foundation Grants ACI-0113051 and CCR-9972372, the Air Force Office of Scientific Research Grant F49620-01-1-0040, Microsoft Corporation and the Guggenheim Foundation

Gastrointestinal Safety of Aspirin for a High-Dose, Multiple-Day Treatment Regimen: A Meta-Analysis of Three Randomized Controlled Trials

Background and Aim: Aspirin is a commonly used over-the-counter (OTC) agent for the symptomatic treatment of acute pain, fever, or the common cold, but data regarding safety in this context are limited. In order to characterize the safety of aspirin beyond single-dose or long-term use data, we conducted a meta-analysis of multiple-dose, multiple-day studies of OTC aspirin at a label-approved dosage. Methods: We conducted a meta-analysis of individual patient data from three Bayer-sponsored studies. The meta-analysis was performed in 2015; the individual studies were conducted between 2008 and 2012 and were of a randomized, parallel-group, placebo-controlled design. Patients received a minimum dosage of aspirin of 2000 mg/day over at least 3 days. The endpoints were patient-reported adverse events (AEs) with an emphasis on the system organ class gastrointestinal system. Event incidences were estimated and an analysis of the odds ratios (ORs) and risk differences (RDs) of aspirin versus placebo were performed. Results: Of the 819 patients included, 433 were treated with aspirin and 386 were treated with placebo. The majority of patients (85.7 %) received a median dose of aspirin of 3000 mg/day for 3 days. The incidence of the overall AEs was low and rates were comparable between the aspirin (10.9 %) and placebo (12.4 %) groups [OR: 0.86 (95 % confidence interval [CI] 0.56, 1.34); RD: -1.49 (95 % CI -6.01, 3.03)]. Gastrointestinal AEs were more common in subjects treated with aspirin (7.4 %) than with placebo (5.4 %), and although this difference did not reach statistical significance, a trend towards increased risk was observed with aspirin use [OR: 1.41 (95 % CI 0.78, 2.54); RD: 2.00 (95 % CI -1.35, 5.35)]. Nausea, upper abdominal pain, dyspepsia, and diarrhea were the most frequently reported gastrointestinal AEs. There were no reports of serious gastrointestinal complications such as bleeding, perforation, or ulceration.: Conclusions: The multiple-dose regimen of aspirin used for several days according to the OTC label is well-tolerated by otherwise healthy non-elderly subjects for short-term and symptomatic treatment of pain, fever, and the common cold. There were no reports of serious gastrointestinal complications in either of the groups

Wigner Glass, Spin-liquids, and the Metal-Insulator Transition

Recent experiments on the two dimensional electron gas in various semiconductor devices have revealed an unexpected metal-insulator transition and have challenged the previously held assumption that there is no such transition in two dimensions. While the experiments are still at the stage of rapid development, it is becoming evident that they cannot be understood from the conventional perspective of weak interactions. In the present paper, we propose the following. (1) The low-density insulating state is the Wigner Glass, a phase with quasi-long-range translational order and competing ferromagnetic and antiferromagnetic spin-exchange interactions. (2) The transition is the melting of this Wigner Glass, disorder being the agent allowing the transition to be second order. (3) Within the Wigner Glass phase, there are at least two, distinct magnetic ground-states, a ferromagnetic state at very low electron density and a spin-liquid state with a spin pseudo-gap at higher densities. (4) The metallic side of the transition is a non-Fermi liquid. These conclusions are encapsulated in Figure 1 which presents the proposed phase diagram as a function of disorder strength and density; we also suggest experimental signatures of the various phases and transitions.Comment: Revised manuscript 6 pages, 1 figure redrawn for clarity; discussion of experiments expande

Detecting and characterizing lateral phishing at scale

We present the first large-scale characterization of lateral phishing attacks, based on a dataset of 113 million employee-sent emails from 92 enterprise organizations. In a lateral phishing attack, adversaries leverage a compromised enterprise account to send phishing emails to other users, benefit-ting from both the implicit trust and the information in the hijacked user's account. We develop a classifier that finds hundreds of real-world lateral phishing emails, while generating under four false positives per every one-million employee-sent emails. Drawing on the attacks we detect, as well as a corpus of user-reported incidents, we quantify the scale of lateral phishing, identify several thematic content and recipient targeting strategies that attackers follow, illuminate two types of sophisticated behaviors that attackers exhibit, and estimate the success rate of these attacks. Collectively, these results expand our mental models of the 'enterprise attacker' and shed light on the current state of enterprise phishing attacks