Purpose
Liquid water being the major constituent of the human body, is of fundamental importance in radiobiological research. Hence, the knowledge of electron‐water interaction physics and particularly the secondary electron yield is essential. However, to date, only very little is known experimentally on the low energy electron interaction with liquid water because of certain practical limitations. The purpose of this study was to gain some useful information about electron emission from water using a Monte Carlo (MC) simulation technique that can numerically model electron transport trajectories in water.
Methods
In this study, we have performed MC simulations of electron emission from liquid water in the primary energy range of 50 eV–30 keV by using two different codes, i.e., a classical trajectory MC (CMC) code developed in our laboratory and the Geant4‐DNA (G4DNA) code. The calculated secondary electron yield and electron backscattering coefficient are compared with experimental results wherever applicable to verify the validity of physical models for the electron‐water interaction.
Results
The secondary electron yield vs. primary energy curves calculated using the two codes present the same generic curve shape as that of metals but in rather different absolute values. G4DNA underestimates the secondary electron yield due to the application of one step thermalization model by setting a cutoff energy at 10 eV so that the low energy losses due to phonon excitations are omitted. Our CMC code, using a full energy loss spectrum to model electron inelastic scattering, allows the simulation of individual phonon scattering events for very low energy losses down to 10 meV, which then enables the calculated secondary electron yields much closer to the experimental data and also gives quite reasonable energy distribution curve of secondary electrons.
Conclusions
It is concluded that full dielectric function data at low energy loss values below 10 eV are recommended for modeling of low energy electrons in liquid water.
This paper is concerned with the numerical solution of timefractional partial differential equations (PDEs) via local meshless differential quadrature collocation method (LMM) using radial basis functions (RBFs). For the sake of comparison, global version of the meshless method is also considered. The meshless methods do not need mesh and approximate solution on scattered and uniform nodes in the domain. The local and global meshless procedures are used for spatial discretization. Caputo derivative is used in the temporal direction for both the values of α ∈ (0, 1) and α ∈ (1, 2). To circumvent spurious oscillation casued by convection, an upwind technique is coupled with the LMM. Numerical analysis is given to asses accuracy of the proposed meshless method for one-and two-dimensional problems on rectangular and non-rectangular domains.
With a small database of electron SPs and basic material properties, the ensemble ML technique enabled to predict SPs for the elements for which no data exist as well as to extrapolate SPs to lower energies where other theoretical approaches failed.
Objective: To assess impact of stringent Internal Quality Control (IQC) checks on performance of proficiency testing
Material and methods: This was a Prospective study conducted between September 2020 and April 2021 at Chemical pathology lab of Fauji Foundation Hospital Rawalpindi. External quality control data (EQC) from the month of September was evaluated. As part of corrective action plan IQC checks were enforced, internal quality control (IQC) data of the month of September 2020 and April 2022 were assessed. Performance characteristics of routine chemistry analytes coefficient of variance (CV), standard deviations (SD)and Bias were calculated and compared using paired –T- test.
Results: Proficiency testing report (NEQAPP) of cycle 10 round 1 showed 11% External Quality Control (EQC) failure among 18 biochemical parameters. Serum Creatinine and Total Protein failed acceptability criteria with Z-score of greater than 2. As part of corrective action IQC checks were done, which led to improvement in CV (SD) of these parameters. The next EQC lab report for routine chemistry analytes met the acceptability criteria with z-scores of all anaytes being less than 2.
Conclusion: Precise & accurate IQC results lead to better performance in EQC results
Knowledge of absolute secondary electron yield () is important for various applications of electron emission materials. Besides, it is also crucial to know the dependence of on primary electron energy...
Objective: To assess and correlate changes in vitamin D levels in three trimesters of pregnancy.
Material and methods: This longitudinal study was conducted in collaboration with the Gynecology & Obstetric and Pathology department of Fauji foundation hospital, Rawalpindi. Eighty pregnant females were included in the study and tested for vitamin D at three points of time i.e. first trimester gestational age: (7-13 weeks), second trimester (20-26weeks), and third trimester (33 weeks till term). Pregnant females at their first visit and healthy nonpregnant females (controls) were analyzed for vitamin D, vitamin B12, folate, ferritin, and Hemoglobin (Hb) levels and compared using the Mann- Whitney U test for vitamin D and independent sample t-test for other parameters. Vitamin D and Hemoglobin (Hb) testing was done during the first, second, and third trimesters among pregnant females and compared between three groups using the Kruskal Wallis test and paired t-test respectively.
Results: Mean age of the pregnant females was 35 years. Mean vitamin D levels showed a significant decline from 30.7 ng/ml vs 19.5 ng/ml vs 18.6 ng/ml for the first, second, and third trimesters respectively (p-value<0.05). The frequency of vitamin D deficiency was 15.1% for pregnant females at their first visit which progressed to 20% and 25% in the second and third trimesters respectively.
Conclusion: Increased vitamin D deficiency and insufficiency rates exist in pregnant females, which progresses to further decline in the ensuing trimesters.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.