scholarly journals Real-Time Identification of Oxygen Vacancy Centers in LiNbO3 and SrTiO3 during Irradiation with High Energy Particles

Crystals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 315 ◽  
Author(s):  
Miguel L. Crespillo ◽  
Joseph T. Graham ◽  
Fernando Agulló-López ◽  
Yanwen Zhang ◽  
William J. Weber
Keyword(s):  
Oxygen Vacancy ◽  
Real Time ◽  
Oxygen Vacancies ◽  
Emission Spectra ◽  
Alkali Halides ◽  
High Energy ◽  
Color Centers ◽  
Precise Control ◽  
Real Time Identification ◽  
High Energy Particles

Oxygen vacancies are known to play a central role in the optoelectronic properties of oxide perovskites. A detailed description of the exact mechanisms by which oxygen vacancies govern such properties, however, is still quite incomplete. The unambiguous identification of oxygen vacancies has been a subject of intense discussion. Interest in oxygen vacancies is not purely academic. Precise control of oxygen vacancies has potential technological benefits in optoelectronic devices. In this review paper, we focus our attention on the generation of oxygen vacancies by irradiation with high energy particles. Irradiation constitutes an efficient and reliable strategy to introduce, monitor, and characterize oxygen vacancies. Unfortunately, this technique has been underexploited despite its demonstrated advantages. This review revisits the main experimental results that have been obtained for oxygen vacancy centers (a) under high energy electron irradiation (100 keV–1 MeV) in LiNbO3, and (b) during irradiation with high-energy heavy (1–20 MeV) ions in SrTiO3. In both cases, the experiments have used real-time and in situ optical detection. Moreover, the present paper discusses the obtained results in relation to present knowledge from both the experimental and theoretical perspectives. Our view is that a consistent picture is now emerging on the structure and relevant optical features (absorption and emission spectra) of these centers. One key aspect of the topic pertains to the generation of self-trapped electrons as small polarons by irradiation of the crystal lattice and their stabilization by oxygen vacancies. What has been learned by observing the interplay between polarons and vacancies has inspired new models for color centers in dielectric crystals, models which represent an advancement from the early models of color centers in alkali halides and simple oxides. The topic discussed in this review is particularly useful to better understand the complex effects of different types of radiation on the defect structure of those materials, therefore providing relevant clues for nuclear engineering applications.

Local high-energy particles measurements for detecting primary cosmic-ray variations: application for soil moisture estimation

2020 ◽  
Author(s):  
Luca Stevanato ◽  
Gabriele Baroni ◽  
Cristiano Fontana ◽  
Marcello Lunardon ◽  
Sandra Moretto ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Real Time ◽  
Land Surface ◽  
Spatial Scales ◽  
Cosmic Ray ◽  
High Energy ◽  
Canopy Interception ◽  
Local Conditions ◽  
Proportional Counters ◽  
High Energy Particles

<p>In the last decade the measurement of secondary cosmic ray neutrons has been established as a unique approach for intermediate scale observation of land surface hydrogen pools. Originally developed for soil moisture measurements, it has shown also promising applications for snow, biomass and canopy interception. The approach relies on the correlation between natural neutron background as created by cosmic-ray fluxes and local hydrogen pools. Due to the specific capabilities of the neutrons to move in air, the signal detected by the sensor installed above-ground is sensitive to an area of hundreds of meters providing a new perspective for proximal land-surface observations. The measurements are generally performed based on moderated proportional counters filled with Helium-3 or Boron and the moderation is created by adding shielding material (mostly polyethylene) around the counter.</p><p>The signal is affected by the temporal variability of the incoming neutron fluxes. At first, the variability of neutron fluxes is due to solar activities. The neutrons are further attenuated by the mass of the air and air humidity.</p><p>Specific corrections have been proposed to account for these effects. Air pressure and humidity corrections rely on local measurements that could be easily collected. Incoming correction due to solar cosmic-ray fluctuation is based on a worldwide network monitoring station (NMDB). This network provides online access to their data in real-time. However, this approach showed some limitations in region where incoming fluxes could be not representative of local conditions introducing errors that could be relevant for the estimation of the targeted variable. In addition, it requires the need of post-processing of the data resulting in some difficulties to provide, e.g., soil moisture observations in real-time.</p><p>In the present contribution, we show the results of tests conducted on an alternative commercial sensor based on scintillators. The new probe has the capability to identify different neutron energies ranges and gamma-rays providing new opportunities for hydrological observations at different spatial scales. In addition, the probe is sensitive to high energy particles that can be used for correcting the neutron signal by the variations of primary cosmic-ray flux. We present results from the comparison of the new probe with standard proportional counters and neutron monitor database in a long-term outdoor case study. We show how the use of local high energy particles is a practical alternative to account atmospheric corrections and overcome the limitation of using data from NMDB.</p>

scholarly journals Role of oxygen vacancies on light emission mechanisms in SrTiO3induced by high-energy particles

2017 ◽  
Vol 50 (15) ◽  
pp. 155303 ◽  
Author(s):  
M L Crespillo ◽  
J T Graham ◽  
F Agulló-López ◽  
Y Zhang ◽  
W J Weber
Keyword(s):  
Oxygen Vacancies ◽  
Light Emission ◽  
High Energy ◽  
High Energy Particles

Observation of High-Energy Particles in the Inner Radiation Belt by the HEP Instrument of the Arase Satellite

2020 ◽  
Vol 18 (6) ◽  
pp. 398-403
Author(s):  
Honoka TODA ◽  
Wataru MIYAKE ◽  
Takefumi MITANI ◽  
Takeshi TAKASHIMA ◽  
Yoshizumi MIYOSHI ◽  
...  
Keyword(s):  
Radiation Belt ◽  
High Energy ◽  
High Energy Particles

scholarly journals Real-Time Identification of Patients Included in the CMS Bundled Payment Care Improvement (BPCI) Program

2020 ◽  
Vol 41 (S1) ◽  
pp. s367-s368
Author(s):  
Michael Korvink ◽  
John Martin ◽  
Michael Long
Keyword(s):  
Performance Evaluation ◽  
Real Time ◽  
Naive Bayes ◽  
Naïve Bayes ◽  
Care Providers ◽  
Meta Model ◽  
Bundled Payment ◽  
Clinical Cohort ◽  
Real Time Identification ◽  
Care Improvement

Background: The Bundled Payment Care Improvement Program is a CMS initiative designed to encourage greater collaboration across settings of care, especially as it relates to an initial set of targeted clinical episodes, which include sepsis and pneumonia. As with many CMS incentive programs, performance evaluation is retrospective in nature, resulting in after-the-fact changes in operational processes to improve both efficiency and quality. Although retrospective performance evaluation is informative, care providers would ideally identify a patient’s potential clinical cohort during the index stay and implement care management procedures as necessary to prevent or reduce the severity of the condition. The primary challenges for real-time identification of a patient’s clinical cohort are CMS-targeted cohorts are based on either MS-DRG (grouping of ICD-10 codes) or HCPCS coding—coding that occurs after discharge by clinical abstractors. Additionally, many informative data elements in the EHR lack standardization and no simple and reliable heuristic rules can be employed to meaningfully identify those cohorts without human review. Objective: To share the results of an ensemble statistical model to predict patient risks of sepsis and pneumonia during their hospital (ie, index) stay. Methods: The predictive model uses a combination of Bernoulli Naïve Bayes natural language processing (NLP) classifiers, to reduce text dimensionality into a single probability value, and an eXtreme Gradient Boosting (XGBoost) algorithm as a meta-model to collectively evaluate both standardized clinical elements alongside the NLP-based text probabilities. Results: Bernoulli Naïve Bayes classifiers have proven to perform well on short text strings and allow for highly explanatory unstructured or semistructured text fields (eg, reason for visit, culture results), to be used in a both comparative and generalizable way within the larger XGBoost model. Conclusions: The choice of XGBoost as the meta-model has the benefits of mitigating concerns of nonlinearity among clinical features, reducing potential of overfitting, while allowing missing values to exist within the data. Both the Bayesian classifier and meta-model were trained using a patient-level integrated dataset extracted from both a patient-billing and EHR data warehouse maintained by Premier. The data set, joined by patient admission-date, medical record number, date of birth, and hospital entity code, allows the presence of both the coded clinical cohort (derived from the MS-DRG) and the explanatory features in the EHR to exist within a single patient encounter record. The resulting model produced F1 performance scores of .65 for the sepsis population and .61 for the pneumonia population.Funding: NoneDisclosures: None

scholarly journals Gamma-Ray and Neutrino Signals from Accretion Disk Coronae of Active Galactic Nuclei

Galaxies ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 36
Author(s):  
Yoshiyuki Inoue ◽  
Dmitry Khangulyan ◽  
Akihiro Doi
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Thermal Activity ◽  
X Ray ◽  
Cascade Models ◽  
Coronal Activity ◽  
Ngc 1068 ◽  
High Energy Particles

To explain the X-ray spectra of active galactic nuclei (AGN), non-thermal activity in AGN coronae such as pair cascade models has been extensively discussed in the past literature. Although X-ray and gamma-ray observations in the 1990s disfavored such pair cascade models, recent millimeter-wave observations of nearby Seyferts have established the existence of weak non-thermal coronal activity. In addition, the IceCube collaboration reported NGC 1068, a nearby Seyfert, as the hottest spot in their 10 yr survey. These pieces of evidence are enough to investigate the non-thermal perspective of AGN coronae in depth again. This article summarizes our current observational understanding of AGN coronae and describes how AGN coronae generate high-energy particles. We also provide ways to test the AGN corona model with radio, X-ray, MeV gamma ray, and high-energy neutrino observations.

scholarly journals Multi-Modal Multi-Spectral Intravital Microscopic Imaging of Signaling Dynamics in Real-Time during Tumor–Immune Interactions

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 499
Author(s):  
Tracy W. Liu ◽  
Seth T. Gammon ◽  
David Piwnica-Worms
Keyword(s):  
Molecular Imaging ◽  
Single Cell ◽  
Real Time ◽  
Bioluminescence Imaging ◽  
Emission Spectra ◽  
Ccd Camera ◽  
Microscopic Imaging ◽  
Signaling Dynamics ◽  
Window Chamber

Intravital microscopic imaging (IVM) allows for the study of interactions between immune cells and tumor cells in a dynamic, physiologically relevant system in vivo. Current IVM strategies primarily use fluorescence imaging; however, with the advances in bioluminescence imaging and the development of new bioluminescent reporters with expanded emission spectra, the applications for bioluminescence are extending to single cell imaging. Herein, we describe a molecular imaging window chamber platform that uniquely combines both bioluminescent and fluorescent genetically encoded reporters, as well as exogenous reporters, providing a powerful multi-plex strategy to study molecular and cellular processes in real-time in intact living systems at single cell resolution all in one system. We demonstrate that our molecular imaging window chamber platform is capable of imaging signaling dynamics in real-time at cellular resolution during tumor progression. Importantly, we expand the utility of IVM by modifying an off-the-shelf commercial system with the addition of bioluminescence imaging achieved by the addition of a CCD camera and demonstrate high quality imaging within the reaches of any biology laboratory.

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