Photoemission from the gas phase using soft x-ray fs pulses: An investigation of the space-charge effects

An experimental and computational investigation of the space-charge effects occurring in ultrafast photoelectron spectroscopy from the gas phase is presented. The target sample CF$_3$I is excited by ultrashort (100 fs) far-ultraviolet radiation pulses produced by a free-electron laser. The modification of the energy distribution of the photoelectrons, i.e. the shift and broadening of the spectral structures, is monitored as a function of the pulse intensity. A novel computational approach is presented in which a survey spectrum acquired at low radiation fluence is used to determine the initial energy distribution of the electrons after the photoemission event. The spectrum modified by the space-charge effects is then reproduced by $N$-body calculations that simulate the dynamics of the photoelectrons subject to the mutual Coulomb repulsion and to the attractive force of the positive ions. The employed numerical method allows to reproduce the complete photoelectron spectrum and not just a specific photoemission structure. The simulations also provide information on the time evolution of the space-charge effects on the picosecond scale. Differences with the case of photoemission from solid samples are highlighted and discussed. The presented simulation procedure constitutes an effective tool to predict and account for space-charge effect in time-resolved photoemission experiments with high-intensity pulsed sources.Comment: 18 pages, 4 figures, 1 tabl

Database structure modification of internal exposure management suited for Japanese alimentation behavior

[Purpose] After the Fukushima nuclear accident, the anxieties about radiation exposure by eating food are growing. Management of internal radiation exposure by food is indicated. The authors have examined a modification of the database structure of an internal exposure management tool that is used in Belarus after the Chernobyl accident to be suited for Japanese alimentation behavior. This poster aims to solve the problem left that the method to constitute a dish is complicated. [Methods] 1) The foodstuffs and the amount of the each ingestion of dish are stored in ‘Ingredients’ table to constitute ingesting dish in the old database structure. In the new database structure, the ingestion of foodstuffs and the recipe of the dish are stored to separate table. The amount of ingested natural and artificial radionuclides are estimated by using the ingestion of foodstuffs. 2) To take into consideration of the estimation with detection limit of the radioactivity inspection, the detection limit value is stored.[Results] This database structure modification makes it easy to constitute ingesting dish reflecting Japanese alimentation behavior. Also, the data amount is up to 97% reduced. The estimation of the internal radiation considering the detection limit is enabled.[Conclusion] This modification makes it easy to constitute ingesting dish reflecting Japanese alimentation behavior. Also, the amount of data is drastically reduced. The authors built an internal exposure management tool with higher usability than the original.ECR2015(第27回欧州放射線学会議

Site-level progression of periodontal disease during a follow-up period

<div><p>Periodontal disease is assessed and its progression is determined via observations on a site-by-site basis. Periodontal data are complex and structured in multiple levels; thus, applying a summary statistical approach (i.e., the mean) for site-level evaluations results in loss of information. Previous studies have shown the availability of mixed effects modeling. However, clinically beneficial information on the progression of periodontal disease during the follow-up period is not available.</p><p>We conducted a multicenter prospective cohort study. Using mixed effects modeling, we analyzed 18,834 sites distributed on 3,139 teeth in 124 patients, and data were collected 5 times over a 24-month follow-up period. The change in the clinical attachment level (CAL) was used as the outcome variable. The CAL at baseline was an important determinant of the CAL changes, which varied widely according to the tooth surface. The salivary levels of periodontal pathogens, such as <i>Porphyromonas gingivalis</i> and <i>Aggregatibacter actinomycetemcomitans</i>, were affected by CAL progression. “Linear”- and “burst”-type patterns of CAL progression occurred simultaneously within the same patient. More than half of the teeth that presented burst-type progression sites also presented linear-type progression sites, and most of the progressions were of the linear type. Maxillary premolars and anterior teeth tended to show burst-type progression. The parameters identified in this study may guide practitioners in determining the type and extent of treatment needed at the site and patient levels. In addition, these results show that prior hypotheses concerning "burst" and "linear" theories are not valid.</p></div

Multilevel random intercept model for changes in CAL between the baseline and after 24 months (Model 1).

<p>Multilevel random intercept model for changes in CAL between the baseline and after 24 months (Model 1).</p

Multilevel logistic regression model with repeated measures to distinguish “linear” and “burst” progression during the 24-month follow-up period.

<p>Multilevel logistic regression model with repeated measures to distinguish “linear” and “burst” progression during the 24-month follow-up period.</p

CAL change patterns during the 24-month follow-up period.

<p></p><p></p><p></p><p>(A) Changes of the improved, slightly improved, stable, slightly progressed, progressed and fluctuated categories.</p><p>···▲···: Improved, ··△···: Slightly improved, ─●─: Stable.</p><p>---□---: Slightly progressed, ---■---: progressed, ─■─: Fluctuated</p><p>Differences in the CAL changes over 24 months were classified into six categories: ≤ -3 mm, improved; between -3 mm and -2 mm, slightly improved; between -1 mm to 1 mm, stable; between 1 mm and 2 mm, slightly progressed; 3mm, progressed. In addition, cases with both ≤ -3 mm and ≥ 3mm were classified as fluctuated.</p><p></p><p></p><p>(B) CAL progression patterns of the progressed category</p><p>···▲···: Cluster 1, ···△···: Cluster 2, ─●─: Cluster 3.</p><p>─□─: Cluster 4, —■—: Cluster 5</p><p>A hierarchical cluster analysis was performed for the progressed type portrayed in Fig. 2(A), and 5 clusters were generated. The slope of cluster 1 was moderate, and the slopes of the other clusters were steep. Cluster 1 may correspond to the linear-type progressed sites, and the other clusters may correspond to the burst-type progressed sites.</p><p></p><p></p><p></p> <p>(A) Changes of the improved, slightly improved, stable, slightly progressed, progressed and fluctuated categories.</p> <p>···▲···: Improved, ··△···: Slightly improved, ─●─: Stable.</p> <p>---□---: Slightly progressed, ---■---: progressed, ─■─: Fluctuated</p> <p>Differences in the CAL changes over 24 months were classified into six categories: ≤ -3 mm, improved; between -3 mm and -2 mm, slightly improved; between -1 mm to 1 mm, stable; between 1 mm and 2 mm, slightly progressed; 3mm, progressed. In addition, cases with both ≤ -3 mm and ≥ 3mm were classified as fluctuated.</p> <p>(B) CAL progression patterns of the progressed category</p> <p>···▲···: Cluster 1, ···△···: Cluster 2, ─●─: Cluster 3.</p> <p>─□─: Cluster 4, —■—: Cluster 5</p> <p>A hierarchical cluster analysis was performed for the progressed type portrayed in Fig. 2(A), and 5 clusters were generated. The slope of cluster 1 was moderate, and the slopes of the other clusters were steep. Cluster 1 may correspond to the linear-type progressed sites, and the other clusters may correspond to the burst-type progressed sites.</p