Computationally-efficient stochastic cluster dynamics method for modeling damage accumulation in irradiated materials

An improved version of a recently developed stochastic cluster dynamics (SCD) method {[}Marian, J. and Bulatov, V. V., {\it J. Nucl. Mater.} \textbf{415} (2014) 84-95{]} is introduced as an alternative to rate theory (RT) methods for solving coupled ordinary differential equation (ODE) systems for irradiation damage simulations. SCD circumvents by design the curse of dimensionality of the variable space that renders traditional ODE-based RT approaches inefficient when handling complex defect population comprised of multiple (more than two) defect species. Several improvements introduced here enable efficient and accurate simulations of irradiated materials up to realistic (high) damage doses characteristic of next-generation nuclear systems. The first improvement is a procedure for efficiently updating the defect reaction-network and event selection in the context of a dynamically expanding reaction-network. Next is a novel implementation of the $\tau$-leaping method that speeds up SCD simulations by advancing the state of the reaction network in large time increments when appropriate. Lastly, a volume rescaling procedure is introduced to control the computational complexity of the expanding reaction-network through occasional reductions of the defect population while maintaining accurate statistics. The enhanced SCD method is then applied to model defect cluster accumulation in iron thin films subjected to triple ion-beam ($\text{Fe}^{3+}$, $\text{He}^{+}$ and $$\text{H\ensuremath{{}^{+}}}$$) irradiations, for which standard RT or spatially-resolved kinetic Monte Carlo simulations are prohibitively expensive

Physical Layer Security: Detection of Active Eavesdropping Attacks by Support Vector Machines

This article presents a framework for converting wireless signals into structured datasets, which can be fed into machine learning algorithms for the detection of active eavesdropping attacks at the physical layer. More specifically, a wireless communication system, which consists of an access point (AP), K legitimate users and an active eavesdropper, is considered. To detect the eavesdropper who breaks into the system during the authentication phase, we first build structured datasets based on different features and then apply sophisticated support vector machine (SVM) classifiers to those structured datasets. To be more specific, we first process the signals received by the AP and then define a pair of statistical features based on the post-processing of the signals. By arranging for the AP to simulate the entire process of transmission and the process of constructing features, we form the so-called artificial training data (ATD). By training SVM classifiers on the ATD, we classify the received signals associated with eavesdropping attacks and nonattacks, thereby detecting the presence of the eavesdropper. Two SVM classifiers are considered, including a classic twin-class SVM (TC-SVM) and a single-class SVM (SC-SVM). While the TC-SVM is preferred in the case of having perfect channel state information (CSI) of all channels, the SC-SVM is preferred in the realistic scenario when we have only the CSI of legitimate users. We also evaluate the accuracy of the trained models depending on the choice of kernel functions, the choice of features and on the eavesdropper's power. Our numerical results show that careful parameter-tuning is required for exceeding an eavesdropper detection probability of 95%

Preparation and Foliar Application of Oligochitosan - Nanosilica on the Enhancement of Soybean Seed Yield

Oligochitosan with weight average molecu-lar weight (Mw) of 5000 g/mol was prepared by gamma Co-60 radiation degradation of 4% chitosan solution containing 0.5% H2O2 at 21 kGy. Nanosilica with size of 10 – 30 nm was synthesized by calcination of acid treated rice husk at 700o C for 2 h. The mixture of 2% oligo-chitosan-2% nanosilica was prepared by dispersion of nanosilica in oligochitosan solution. Oligochitosan, nanosilica and their mixture were characterized by gel permeation chromatography (GPC), transmission electr-on microscopy (TEM), X-ray diffraction (XRD), energy dispersive x-ray spectroscopy (EDX), Ultraviolet-visible spectroscopy (UV-Vis), and Furrier transform infrared spectroscopy (FT-IR). Effect of foliar application of oli-gochitosan and oligochitosan-nanosilica on soybean seed yield was conducted in experimental field. Results indi-cated that soybean seed yield increased 10.5 and 17.0% for oligochitosan and oligochitosan-nanosilica, respect-tively for the control. Radiation degraded oligo-chitosan and its mixture with nanosilica can be potentially used for cultivation of soybean with enhanced seed yield

Efficacy of Medical Operations and Layout Planning Onboard Nontraditional US Navy Vessels at High Seas

The article of record as published may be found at http://dx.doi.org/10.1093/milmed/usz227Introduction: Attempting to expedite delivery of care to wounded war fighters, this study aimed to quantify the ability of medical and surgical teams to perform lifesaving damage control and resuscitation procedures aboard nontraditional US Navy Vessels on high seas. Specifically, it looked at the ability of the teams to perform procedures in shipboard operating and emergency rooms by analyzing motion of personnel during the procedures. Methods: One hundred and twelve damage control and resuscitation procedures were performed during a voyage of the US Naval Ship Brunswick in transit from Norfolk, Virginia, to San Diego, California. The ability of personnel to perform these procedures was quantified by the use of motion link analysis designed to track the movement of each participant as they completed their assigned tasks. Results: The link analysis showed no significant change in the number of movements of participants from the beginning to the end of the study. However, there was a learning effect observed during the study, with teams completing tasks faster at the end of the study than at the beginning. Conclusion: This shows that the working conditions aboard the US Naval Ship Brunswick were satisfactory for the assigned tasks, indicating that these medical operations may be feasible aboard nontraditional US Navy vessels.This specific study was a part of a major three-phase investigation entitled �Effect of High Deck Accelerations on Surgical Tasks� funded by the following organizations for each phase: Phase I�Office of Naval Research, Phase II�Office of the Chief of Naval Operations (OPNAV) N81, and Phase III�Advanced Medical Development and OPNAV N81.This specific study was a part of a major three-phase investigation entitled �Effect of High Deck Accelerations on Surgical Tasks� funded by the following organizations for each phase: Phase I�Office of Naval Research, Phase II�Office of the Chief of Naval Operations (OPNAV) N81, and Phase III�Advanced Medical Development and OPNAV N81

The impact of environmental and climatic variation on the spatiotemporal trends of hospitalized pediatric diarrhea in Ho Chi Minh City, Vietnam.

It is predicted that the integration of climate-based early warning systems into existing action plans will facilitate the timely provision of interventions to diarrheal disease epidemics in resource-poor settings. Diarrhea remains a considerable public health problem in Ho Chi Minh City (HCMC), Vietnam and we aimed to quantify variation in the impact of environmental conditions on diarrheal disease risk across the city. Using all inpatient diarrheal admissions data from three large hospitals within HCMC, we developed a mixed effects regression model to differentiate district-level variation in risk due to environmental conditions from the overarching seasonality of diarrheal disease hospitalization in HCMC. We identified considerable spatial heterogeneity in the risk of all-cause diarrhea across districts of HCMC with low elevation and differential responses to flooding, air temperature, and humidity driving further spatial heterogeneity in diarrheal disease risk. The incorporation of these results into predictive forecasting algorithms will provide a powerful resource to aid diarrheal disease prevention and control practices in HCMC and other similar settings

Assessing Surgical Task Load and Performance: A Comparison of Simulation and Maritime Operation

The article of record as published may be found at http://dx.doi.org/10.1093/milmed/usz297This study examined the effects of simulated and actual vessel motion at high seas on task load and surgical performance. Methods: This project was performed in phases. Phase I was a feasibility study. Phase II utilized a motion base simulator to replicate vessel motion. Phase III was conducted aboard the U.S. Naval Ship Brunswick. After performing surgical tasks on a surgical simulation mannequin, participants completed the Surgical Task Load Index (TLX) designed to collect workload data. Simulated surgeries were evaluated by subject matter experts. Results: TLX scores were higher in Phase III than Phase II, particularly at higher sea states. Surgical performance was not significantly different between Phase II (84%) and Phase III (89%). Simulated motions were comparable in both phases. Conclusions: Simulated motion was not associated with a significant difference in surgical performance or deck motion, suggesting that this simulator replicates the conditions experienced during surgery at sea on the U.S. Naval Ship Brunswick. However, Surgical TLX scores were dramatically different between the two phases, suggesting increased workload at sea, which may be the result of time at sea, the stress of travel, or other factors. Surgical performance was not affected by sea state in either phase.Bureau of Medicine USN; OPNAV N-81 Assessments Division, Medical Analysis Branch; Navy Advanced Medical Development; Naval Surface Warfare Center, PC.Phase I of this study was sponsored by the Office of Naval Research. Phase II was sponsored by the Office of the Chief of Naval Operations (OPNAV) N-81 Assessments Division, Medical Analysis Branch (N813). Phase III was sponsored by the OPNAV N-81 (N813) and Navy Advanced Medical Development (AMD).Bureau of Medicine USN; OPNAV N-81 Assessments Division, Medical Analysis Branch; Navy Advanced Medical Development; Naval Surface Warfare Center, PC.Phase I of this study was sponsored by the Office of Naval Research. Phase II was sponsored by the Office of the Chief of Naval Operations (OPNAV) N-81 Assessments Division, Medical Analysis Branch (N813). Phase III was sponsored by the OPNAV N-81 (N813) and Navy Advanced Medical Development (AMD)