Mount Mazama Ash Offers Sustainable Solution for ADA Accessibility on Unpaved Trails

National Institute for Transportation and Communities (NITC) researcher Matthew Sleep of Oregon Tech investigated whether Mazama ash could be used in place of portland cement, as a natural pozzolan. Results indicate that it can—and unpaved trail surfaces made with Mazama ash are actually firmer and more durable than those made with portland cement alone. Such trails can provide a reliable surface for wheeled mobility devices

Improving HTc Josephson Junctions (HTc JJ) by annealing: the role of vacancy-interstitial annihilation

We have studied the annealing effect in transport properties of High temperature Josephson Junctions (HTc JJ) made by ion irradiation. Low temperature annealing (80 degrees Celsius) increases the JJ transition temperature (TJ) and the Ic.Rn product, where Ic is the critical current and Rn the normal resistance. We found that the spread in JJ characteristics can be lowered by sufficient long annealing times. Using random walk numerical simulations, we showed that the characteristic annealing time and the evolution of the spread in JJ characteristics can be explained by a vacancy-interstitial annihilation process rather than by an oxygen diffusion one.Comment: 7 pages and 3 figures submitted to Applied Physics Letter

Exploring the parameter space of MagLIF implosions using similarity scaling. III. Rise-time scaling

Magnetized Liner Inertial Fusion (MagLIF) is a z-pinch magneto-inertial-fusion (MIF) concept studied on the Z Machine at Sandia National Laboratories. Two important metrics characterizing current delivery to a z-pinch load are the peak current and the current-rise time, which is roughly the time interval to reach peak current. It is known that, when driving a z-pinch load with a longer current-rise time, the performance of the z-pinch decreases. However, a theory to understand and quantify this effect is still lacking. In this paper, we utilize a framework based on similarity scaling to analytically investigate the variations in performance of MagLIF loads when varying the current-rise time, or equivalently, the implosion timescale. To maintain similarity between the implosions, we provide the scaling prescriptions of the experimental input parameters defining a MagLIF load and derive the scaling laws for the stagnation conditions and for various performance metrics. We compare predictions of the theory to 2D numerical simulations using the radiation, magneto-hydrodynamic code HYDRA. For several metrics, we find acceptable agreement between the theory and simulations. Our results show that the voltage near the MagLIF load follows a weak scaling law $\smash{\varphi_{\rm load} \propto t_\varphi^{-0.12}}$ with respect to the characteristic timescale $t_\varphi$ of the voltage source, instead of the ideal $\smash{\varphi_{\rm load} \propto t_\varphi^{-1}}$ scaling. This occurs because the imploding height of the MagLIF load must increase to preserve end losses. As a consequence of the longer imploding liners, the required total laser preheat energy and delivered electric energy increase. Overall, this study may help understand the trade-offs of the MagLIF design space when considering future pulsed-power generators with shorter and longer current-rise times.Comment: 15 pages, 20 figures, submitted to Phys. Plasmas. arXiv admin note: text overlap with arXiv:2209.1491

A Synthetic Gene Drive System for Local, Reversible Modification and Suppression of Insect Populations

Replacement of wild insect populations with genetically modified individuals unable to transmit disease provides a self-perpetuating method of disease prevention but requires a gene drive mechanism to spread these traits to high frequency. Drive mechanisms requiring that transgenes exceed a threshold frequency in order to spread are attractive because they bring about local but not global replacement, and transgenes can be eliminated through dilution of the population with wild-type individuals and 6]. These features are likely to be important in many social and regulatory contexts. Here we describe the first creation of a synthetic threshold-dependent gene drive system, designated maternal-effect lethal underdominance (UD^(MEL)), in which two maternally expressed toxins, located on separate chromosomes, are each linked with a zygotic antidote able to rescue maternal-effect lethality of the other toxin. We demonstrate threshold-dependent replacement in single- and two-locus configurations in Drosophila. Models suggest that transgene spread can often be limited to local environments. They also show that in a population in which single-locus UDMEL has been carried out, repeated release of wild-type males can result in population suppression, a novel method of genetic population manipulation

The Physics of Fast Z Pinches

The spectacular progress made during the last few years in reaching high energy densities in fast implosions of annular current sheaths (fast Z pinches) opens new possibilities for a broad spectrum of experiments, from x-ray generation to controlled thermonuclear fusion and astrophysics. Presently Z pinches are the most intense laboratory X ray sources (1.8 MJ in 5 ns from a volume 2 mm in diameter and 2 cm tall). Powers in excess of 200 TW have been obtained. This warrants summarizing the present knowledge of physics that governs the behavior of radiating current-carrying plasma in fast Z pinches. This survey covers essentially all aspects of the physics of fast Z pinches: initiation, instabilities of the early stage, magnetic Rayleigh-Taylor instability in the implosion phase, formation of a transient quasi-equilibrium near the stagnation point, and rebound. Considerable attention is paid to the analysis of hydrodynamic instabilities governing the implosion symmetry. Possible ways of mitigating these instabilities are discussed. Non-magnetohydrodynamic effects (anomalous resistivity, generation of particle beams, etc.) are summarized. Various applications of fast Z pinches are briefly described. Scaling laws governing development of more powerful Z pinches are presented. The survey contains 36 figures and more than 300 references

The Effect of Neutral Atoms on Capillary Discharge Z-pinch

We study the effect of neutral atoms on the dynamics of a capillary discharge Z-pinch, in a regime for which a large soft-x-ray amplification has been demonstrated. We extended the commonly used one-fluid magneto-hydrodynamics (MHD) model by separating out the neutral atoms as a second fluid. Numerical calculations using this extended model yield new predictions for the dynamics of the pinch collapse, and better agreement with known measured data.Comment: 4 pages, 4 postscript figures, to be published in Phys. Rev. Let

Assessment of the Impact of Potential Tetracycline Exposure on the Phenotype of Aedes aegypti OX513A: Implications for Field Use

Aedes aegypti is the primary vector of dengue fever, a viral disease which has an estimated incidence of 390 million infections annually. Conventional vector control methods have been unable to curb the transmission of the disease. We have previously reported a novel method of vector control using a tetracycline repressible self-limiting strain of Ae. aegypti OX513A which has achieved >90% suppression of wild populations.We investigated the impact of tetracycline and its analogues on the phenotype of OX513A from the perspective of possible routes and levels of environmental exposure. We determined the minimum concentration of tetracycline and its analogues that will allow an increased survivorship and found these to be greater than the maximum concentration of tetracyclines found in known Ae. aegypti breeding sites and their surrounding areas. Furthermore, we determined that OX513A parents fed tetracycline are unable to pre-load their progeny with sufficient antidote to increase their survivorship. Finally, we studied the changes in concentration of tetracycline in the mass production rearing water of OX513A and the developing insect.Together, these studies demonstrate that potential routes of exposure of OX513A individuals to tetracycline and its analogues in the environment are not expected to increase the survivorship of OX513A

Exploring the parameter space of MagLIF implosions using similarity scaling. II. Current scaling

Magnetized Liner Inertial Fusion (MagLIF) is a magneto-inertial-fusion (MIF) concept, which is presently being studied on the Z Pulsed Power Facility. The MagLIF platform has achieved interesting plasma conditions at stagnation and produced significant fusion yields in the laboratory. Given the relative success of MagLIF, there is a strong interest to scale the platform to higher peak currents. However, scaling MagLIF is not entirely straightforward due to the large dimensionality of the experimental input parameter space and the large number of distinct physical processes involved in MIF implosions. In this work, we propose a novel method to scale MagLIF loads to higher currents. Our method is based on similarity (or similitude) scaling and attempts to preserve much of the physics regimes already known or being studied on today's Z pulsed-power driver. By avoiding significant deviations into unexplored and/or less well-understood regimes, the risk of unexpected outcomes on future scaled-up experiments is reduced. Using arguments based on similarity scaling, we derive the scaling rules for the experimental input parameters characterizing a MagLIF load (as functions of the characteristic current driving the implosion). We then test the estimated scaling laws for various metrics measuring performance against results of 2D radiation--magneto-hydrodynamic HYDRA simulations. Agreement is found between the scaling theory and the simulation results.Comment: 19 pages, submitted to Physics of Plasma

Investigating the Electromechanical Behavior of Unconventionally Ferroelectric Hf0.5Zr0.5O2-Based Capacitors Through Operando Nanobeam X-Ray Diffraction

Understanding various aspects of ferroelectricity in hafnia-based nanomaterials is of vital importance for the development of future nonvolatile memory and logic devices. Here, the unconventional and weak electromechanical response of epitaxial La0.67Sr0.33MnO3/Hf0.5Zr0.5O2/La0.67Sr0.33MnO3 ferroelectric capacitors is investigated, via the sensitivity offered by nanobeam X-ray diffraction experiments during application of electrical bias. It is shown that the pristine rhombohedral phase exhibits a linear piezoelectric effect with piezoelectric coefficient (|d33|) ≈ 0.5–0.8 pmV−1. It is found that the piezoelectric response is suppressed above the coercive voltage. For higher voltages, and with the onset of DC conductivity throughout the capacitor, a second-order effect is observed. The work sheds light into the electromechanical response of rhombohedral Hf0.5Zr0.5O2 and suggests its (un)correlation with ferroelectric switching

Budesonide foam versus budesonide enema in active ulcerative proctitis and proctosigmoiditis

Background: Rectal budesonide is an effective treatment of active ulcerative proctitis or proctosigmoiditis. Aim: To compare the therapeutic efficacy, tolerability and safety, and patient's preference of budesonide foam vs. budesonide enema. Methods: Patients with active ulcerative proctitis or proctosigmoiditis (clinical activity index >4 and endoscopic index ≥4) were eligible for this double-blind, double-dummy, randomized, multicentre study. They received 2 mg/25 mL budesonide foam and placebo enema (n = 265), or 2 mg/100 mL budesonide enema and placebo foam (n = 268) for 4 weeks. Primary endpoint was clinical remission (clinical activity index ≤4) at the final/withdrawal visit (per protocol). Results: A total of 541 patients were randomized - 533 were evaluable for intention-to-treat analysis and 449 for per protocol analysis. Clinical remission rates (per protocol) were 60% for budesonide foam and 66% for budesonide enema (P = 0.02362 for non-inferiority of foam vs. enema within a predefined non-inferiority margin of 15%). Both formulations were safe and no drug-related serious adverse events were observed. Because of better tolerability and easier application most patients preferred foam (84%). Conclusion: Budesonide foam is as effective as budesonide enema in the treatment of active ulcerative proctitis or proctosigmoiditis. Both budesonide formulations are safe, and most patients prefer foam.publishersversionPeer reviewe