Leveraging HPC Profiling & Tracing Tools to Understand the Performance of Particle-in-Cell Monte Carlo Simulations

Large-scale plasma simulations are critical for designing and developing next-generation fusion energy devices and modeling industrial plasmas. BIT1 is a massively parallel Particle-in-Cell code designed for specifically studying plasma material interaction in fusion devices. Its most salient characteristic is the inclusion of collision Monte Carlo models for different plasma species. In this work, we characterize single node, multiple nodes, and I/O performances of the BIT1 code in two realistic cases by using several HPC profilers, such as perf, IPM, Extrae/Paraver, and Darshan tools. We find that the BIT1 sorting function on-node performance is the main performance bottleneck. Strong scaling tests show a parallel performance of 77% and 96% on 2,560 MPI ranks for the two test cases. We demonstrate that communication, load imbalance and self-synchronization are important factors impacting the performance of the BIT1 on large-scale runs.Comment: Accepted by the Euro-Par 2023 workshops (TDLPP 2023), prepared in the standardized Springer LNCS format and consists of 12 pages, which includes the main text, references, and figure

Tritiation of amorphous and crystalline silicon using T <inf>2</inf> gas

Incorporation of tritium in hydrogenated amorphous silicon (a-Si:H) and crystalline silicon (c-Si) at 250 °C using tritium (T 2) gas at pressures of up to 120 atm is reported. The tritium is stored in a surface layer which is approximately 150 and 10 nm for a-Si:H and c-Si, respectively. The concentration of tritium occluded in planar and textured c-Si is linearly dependent on the total surface area. The tritium is stable and the dominant tritium evolution occurs at temperatures above 300 °C. The concentration of tritium locked in a-Si:H and c-Si was 20 and 4 at. %, respectively. Self-catalysis appears to be important in the tritiation process. © 2006 American Institute of Physics

Plasma potential probes for hot plasmas: A review and some news

Plasma probes are well established diagnostic tools. They are not complicated, relatively easy to construct and to handle. The easiest and fastest accessible parameter is their floating potential. However, the floating potential of a cold probe is not very significant. Much more important and relevant is the plasma potential. But in most types of plasmas, consisting mainly of electrons and only positive ions, the floating potential is more negative than the plasma potential by a factor proportional to the electron temperature. Obviously this is due to the much higher mobility of the electrons. We present a review on probes whose floating potential is close to or ideally equal to the plasma potential. Such probes we name Plasma Potential Probes (PPP) and they can either be Electron Emissive Probes (EEP) or so-called Electron Screening Probes (EPS). These probes make it possible to measure the plasma potential directly and thus with high temporal resolution. An EEP compensates the plasma electron current by an electron emission current from the probe into the plasma, thereby rendering the current-voltage characteristic symmetric with respect to the plasma potential and shifting the floating potential towards the plasma potential. Only the simplest case of an EEP floating exactly on the plasma potential is discussed here in which case no sheath is present around the probe. An ESP, principally operable only in strong magnetic fields, screens off most of the plasma electron current from the probe collector, taking advantage of the fact that the gyro radius of electrons is usually much smaller than that of the ions. Also in this case we obtain a symmetric current-voltage characteristic and a shift of the probe’s floating potential towards the plasma potential. We have developed strong and robust EEPs and two types of ESPs, called BUnker Probes (BUP), for the use in the Scrape-Off Layer (SOL) of Medium-Size Tokamaks (MST), and other types of strongly magnetized hot plasmas. These probes are presented in detail

Sex difference and intra-operative tidal volume: Insights from the LAS VEGAS study

BACKGROUND: One key element of lung-protective ventilation is the use of a low tidal volume (VT). A sex difference in use of low tidal volume ventilation (LTVV) has been described in critically ill ICU patients.OBJECTIVES: The aim of this study was to determine whether a sex difference in use of LTVV also exists in operating room patients, and if present what factors drive this difference.DESIGN, PATIENTS AND SETTING: This is a posthoc analysis of LAS VEGAS, a 1-week worldwide observational study in adults requiring intra-operative ventilation during general anaesthesia for surgery in 146 hospitals in 29 countries.MAIN OUTCOME MEASURES: Women and men were compared with respect to use of LTVV, defined as VT of 8 ml kg-1 or less predicted bodyweight (PBW). A VT was deemed 'default' if the set VT was a round number. A mediation analysis assessed which factors may explain the sex difference in use of LTVV during intra-operative ventilation.RESULTS: This analysis includes 9864 patients, of whom 5425 (55%) were women. A default VT was often set, both in women and men; mode VT was 500 ml. Median [IQR] VT was higher in women than in men (8.6 [7.7 to 9.6] vs. 7.6 [6.8 to 8.4] ml kg-1 PBW, P &lt; 0.001). Compared with men, women were twice as likely not to receive LTVV [68.8 vs. 36.0%; relative risk ratio 2.1 (95% CI 1.9 to 2.1), P &lt; 0.001]. In the mediation analysis, patients' height and actual body weight (ABW) explained 81 and 18% of the sex difference in use of LTVV, respectively; it was not explained by the use of a default VT.CONCLUSION: In this worldwide cohort of patients receiving intra-operative ventilation during general anaesthesia for surgery, women received a higher VT than men during intra-operative ventilation. The risk for a female not to receive LTVV during surgery was double that of males. Height and ABW were the two mediators of the sex difference in use of LTVV.TRIAL REGISTRATION: The study was registered at Clinicaltrials.gov, NCT01601223

Modeling of beta conductivity in tritiated amorphous silicon

grantor: University of TorontoFor the first time a model was developed to explain the time evolution of the electrical conductivity in tritiated amorphous silicon samples using data obtained earlier by Mr. Tome Kosteski and Dr. Franco Gaspari. The model takes into account thermally activated conductivity in the extended states, hopping conductivity in the conduction band tail localized states and beta conductivity in the extended states. The variable parameters are neutral and positively charged dangling bond concentrations, the quasi-Fermi energy for electrons and the hopping distance. Results show that the main factor affecting the conductivity is the concentration of neutral dangling bonds. The time evolution of the total dangling bond concentration is in agreement with the tritium nuclear decay process. The values found for the Fermi energy and for the hopping distance are in agreement with the literature and support the time evolution of the dangling bond concentration.M.A.Sc

InN Based Water Condensation Sensors on Glass and Flexible Plastic Substrates

In this paper, we report the realization and characterization of a condensation sensor based on indium nitride (InN) layers deposited by magnetron sputtering on glass and flexible plastic substrates, having fast response and using potentially low cost fabrication technology. The InN devices work as open gate thin film sensitive transistors. Condensed water droplets, formed on the open gate region of the sensors, deplete the electron accumulation layer on the surface of InN film, thus decreasing the current of the sensor. The current increases back to its initial value when water droplets evaporate from the exposed InN film surface. The response time is as low as 2 s

THEORETICAL AND PRACTICAL ASPECTS IN THE MAINTENANCE PROCESSES OF CEMENT RETAINED IMPLANT SUPPORTED FIXED RESTORATIONS

The lifespan of a fixed implant supported restoration is influenced by several factors: the medical team's experience, the superior technical and material endowment, the experience of the dental laboratory, but also maintaining a proper hygiene by the patient. Purpose. In this study, we insisted on the responsibility that rehabilitated patients through implant supported restorations should assume. Material and method. The study was conducted between March 2016 and March 2018 on a group of 73 patients rehabilitated by fixed implant supported restorations using a questionnaire consisting of 7 questions. Results and discussions. Maintaining a high degree of hygiene by regular or professional means of implant-prosthetic restorations leads to prolonging their life span. For this, it is necessary on the one hand for the medical team to make pertinent, logical, sufficient and easy to understand recommendations for all patients and on the other hand for the patients to implement the part of the recommendation that directly targets them. Conclusions. The recommendations of the medical team on oral hygiene after fixed implant supported restorations should be done in a language that is appropriate and easy to understand by patients. To the same extent, the recommendations must be assimilated and respected by patients, as a significant component in maintaining good hygiene in fixed implant supported restorations is the patient

PRELIMINARY STUDY ON ANTIMICROBIAL EFFICIENCY OF SOME COMMON CHEMICAL SUBSTANCES WITH A DISINFECTING CHARACTER ON IMPRESSION MATERIALS USED IN IMPLANT-PROSTHETIC REHABILITATION

Purpose. Starting from a very recent event on the market of disinfectants, where for many years very diluted disinfectant products were marketed in Romania, the antimicrobial activity being non-existent, we tried, on the basis of simple experiments, to study the antimicrobial efficiency of the active substances of some common products used on impression materials in implant-prosthetic rehabilitation, but also in classical dental prosthetics and in orthodontics and dentofacial orthopedics, products approved and used in the European Union. Material and method. 7 decontamination and/or disinfectant products were tested for qualitative screening for the sensitivity to different microbial strains as well as for quantitative testing of antimicrobial activity. Results and discussions. The study results for the two objectives are influenced by the active substances of the tested products. Conclusions. Decontamination of dental impressions must also become a certainty in implant-prosthetic rehabilitation, in classical dental prosthetics and in orthodontics and dentofacial orthopedics even if this work is disregarded and ignored by many practitioners