The Interpretation of X-Ray and Electron Signals Generated in Thin or Layered Targets

This work outlines the development of a comprehensive theory for the electron probe microanalyser and scanning electron microscope or SEM, that is intended to serve as a framework of understanding for those employing electron beam methods and as a basis for improved correction procedures. There is particular emphasis on applications to layered and non-uniform specimens. Starting from a simple Gaussian depth distribution of electrons and making assumptions about the X-ray production, a series of predictions of X-ray and electron signals are made for various target configurations. When compared with experimental measurements a series of interesting discoveries follow, which, taken altogether, lead to a more refined model with the promise of more accurate analyses and a better understanding of the physics involved

Optical Microreflectometry and Microscopy of Chalcopyrite Specimens: Reflectance Calculation and Comparison to Backscattered Electron Microscopy

A model was developed to calculate the optical reflectance of an absorbing substrate covered by multiple thin layers of absorbing materials. Both multiple homogeneous thin layers and thin surface layers of mixed phases were modeled. Reflectance versus wavelength was measured for polished chalcopyrite (CuFeS2) and compared to calculated data. The identity and thickness of surface compounds used to calculate reflectance curves were partially determined using X-ray photoelectron and Auger electron spectroscopies. Very good agreement between theoretical and experimental reflectance curves were observed as a function of surface composition. The hue (color) and luminosity (brightness) of the polished surface were also calculated from both experimental and theoretical curves and were found to also be valuable for evaluating surface composition. Contrast in optical photomicrographs resulting from both luminosity and hue was illustrated. Secondary and backscattered electron microscopy were also used to image chalcopyrite polished surfaces which were naturally oxidized by an exposure before and after ion etching. For a substrate covered with thin layers, the resulting backscattered coefficient was calculated as a function of the backscattered coefficient for the surface and the substrate, respectively. The variations of the relative difference between the effective backscattered coefficients vs the primary beam energy exhibited a maximum for a critical thickness difference of the surface layer. The dependence of the variations in thickness of the oxidized layer with the crystallographic orientation changes of the substrate as well as the resulting contrasts of the optical and electron images were discussed

Spectral Decomposition of Wavelength Dispersive X-Ray Spectra: Implications for Quantitative Analysis in the Electron Probe Microanalyzer

The line shapes of Kα, Lα,β and Mα X-ray peaks of pure elements were analyzed by means of commercial wavelength dispersive spectrometers (WDS) attached to an electron probe micro-analyzer (EPMA). A pseudo-Voigt function, i.e., a linear combination of Gaussian and Lorentzian distributions, was used as a fitting profile for the X-ray peaks, with Gaussian offsets incorporated in the short wavelength (high energy) side to describe the observed asymmetry. The asymmetry of X-ray peaks resulting from both instrumental distortions and satellite bands may lead to discrepancies in quantitative analysis with the EPMA as a function of the procedure used for deriving X-ray intensities from WDS spectra, e.g., peak height, peak area, or peak decomposition. These effects have been illustrated by analyzing gold-copper metallic alloys and minerals containing gold at trace levels

Predictors and Moderators Two Treatments of Oppositional Defiant Disorder in Children

OBJECTIVE: The aim of this study was to examine predictors and moderators of behavioral improvement in children with Oppositional Defiant Disorder (ODD) following treatment with Parent Management Training (PMT) and Collaborative and Proactive Solutions (CPS). Initial problem severity, inconsistent discipline, parental attributions of child misbehavior, and child lagging cognitive skills were examined. METHOD: One hundred and forty-five children aged between 7 and 14 (103 males, M = 8.88 years, ethnicity representative of the wider Australian population) were randomly assigned to PMT and CPS. Assessment was conducted at baseline, post-intervention, and at 6-month follow-up, using independently rated semi-structured diagnostic interviews and parent-ratings of ODD symptoms. Using an intent-to-treat sample in this secondary analysis (Murrihy et al., 2022), linear regressions and PROCESS (Hayes, 2017) were used to examine these predictors and possible moderators of treatment. RESULTS: Higher pre-treatment levels of conduct problems, lagging skills, and inconsistent discipline predicted poorer behavioral outcomes following both treatments. The only characteristic that moderated treatment outcome was child-responsible attributions - mothers who were more likely to attribute their child's problematic behaviors to factors in the child had significantly poorer outcomes in PMT than CPS at 6-month follow-up. CONCLUSIONS: CPS may be a more beneficial treatment than PMT for families who have been identified as having higher levels of child-responsible attributions before commencing treatment for ODD. While tentative, this provides promising insights as to how treatment outcomes for children with ODD may be improved

Cathodoluminescence Applied to the Microcharacterization of Mineral Materials: A Present Status in Experimentation and Interpretation

Experimentation and interpretation of cathodoluminescence (CL) microscopy and spectroscopy applied to the microcharacterization of material minerals are reviewed. The origins of the intrinsic (host lattice) and extrinsic (impurities) luminescence emissions in crystals are briefly discussed. Merits and limitations of the available techniques are illustrated. CL emission changes as a function of the incident electron dose are illustrated for the case of natural quartz and sphalerite (ZnS) crystals. These effects are discussed in terms of the development of bulk charging, production of heat, diffusion of impurities, and creation of lattice defects induced by the incident ionizing particles. Although CL emission is mostly extrinsic in origin there is no general rule for identifying the nature of impurities from the CL emission spectra of minerals. However there is potential for using CL spectroscopy for trace element analysis as presented for the case of minerals containing rare-earth luminescent ions. The CL emission is a signature of the crystal-chemistry properties of minerals and hence contains potential genetic information. Some of the applications of CL emissions in the geosciences are summarized

Effects of the Connections program on return-to-custody, mortality and treatment uptake among people with a history of opioid use: Retrospective cohort study in an Australian prison system.

BACKGROUND AND AIMS: Connections is a voluntary health program that facilitates access to opioid agonist treatment (OAT) and social services for people with opioid use exiting prison. This study aimed to measure the effectiveness of Connections in reducing recidivism and improving health outcomes for people with a history of opioid use on leaving prison. DESIGN: Retrospective cohort study with quasi-random allocation to the program. SETTING: Public adult prisons in New South Wales, Australia, 2008-2015. PARTICIPANTS: Adults released from custody with a history of opioid use. Of 5549 eligible releasees, 3973 were allocated to Connections and 1576 to treatment-as-usual. MEASUREMENTS: Outcomes were return-to-custody, all-cause mortality, and OAT participation. FINDINGS: Regression analyses on an intention-to-treat basis, and adjusting for baseline propensity scores, comparing patients allocated to Connections versus treatment-as-usual showed no difference in rates of return-to-custody within 2 years (hazard ratio [HR]: 1.01; 95% confidence interval [CI]: 0.92 -1.12). Patients allocated to the Connections program were more likely to access OAT (odds ratio [OR]: 1.21; 95% CI: 1.06-1.39) and had lower mortality within 28 days of release (0.25% vs. 0.66%; HR: 0.38; 95% CI: 0.14-1.03). Differences in mortality did not persist beyond 28 days. Subgroup analyses showed that allocation to Connections was associated with higher risk of return-to-custody within 28 days for Aboriginal and/or Torres Strait Islander (Indigenous) and female releasees. CONCLUSIONS: The Connections program for people with opioid use exiting prison did not reduce the likelihood of return-to-custody but did facilitate opioid agonist treatment participation on release from prison

Diseño y puesta en funcionamiento de un SIG como herramienta para el estudio del turismo y su planificación en las regiones del archipiélago de Las Canarreos y Cienfuegos-Trinidad-Topes de Collantes, Cuba

Today, geographic information systems are being used as a platform for managing hugh volumes of information related to the decision making process withing different fields. Given the great variety of touristic resources that Cuba has, different systems have been generated at the Faculty of Geography of the University of Havana, oriented to tourism plainning and study. In this article, two of those results are presented involving different territories: Los Canarreos Archipielago and Cienfuegos -Trinidad - Topes de Collantes region.En la época actual, los Sistemas de Información Geográfica están siendo cada vez más utilizados como plataforma para el manejo de grandes volúmenes de información relacionados con la toma de decisiones en diferentes ramas. Dada la gran variedad de recursos turísticos con que Cuba cuenta y dado el incremento de la actividad en el país, se han generado por la Facultad de Geografía de la Universidad de La Habana diferentes sistemas orientados al estudio y la planificación del turismo. En el presente trabajo se presentan dos de estos resultados vinculados con territorios específicos: El Archipiélago de los Canarreos y la región Cienfuegos-Trinidad-Topes de Collaiites

Early evaluation of the effectiveness and cost-effectiveness of ctDNA-guided selection for adjuvant chemotherapy in stage II colon cancer

Background: Current patient selection for adjuvant chemotherapy (ACT) after curative surgery for stage II colon cancer (CC) is suboptimal, causing overtreatment of high-risk patients and undertreatment of low-risk patients. Postoperative circulating tumor DNA (ctDNA) could improve patient selection for ACT. Objectives: We conducted an early model-based evaluation of the (cost-)effectiveness of ctDNA-guided selection for ACT in stage II CC in the Netherlands to assess the conditions for cost-effective implementation. Methods: A validated Markov model, simulating 1000 stage II CC patients from diagnosis to death, was supplemented with ctDNA data. Five ACT selection strategies were evaluated: the current guideline (pT4, pMMR), ctDNA-only, and three strategies that combined ctDNA status with pT4 and pMMR status in different ways. For each strategy, the costs, life years, quality-adjusted life years (QALYs), recurrences, and CC deaths were estimated. Sensitivity analyses were performed to assess the impact of the costs of ctDNA testing, strategy adherence, ctDNA as a predictive biomarker, and ctDNA test performance. Results: Model predictions showed that compared to current guidelines, the ctDNA-only strategy was less effective (+2.2% recurrences, −0.016 QALYs), while the combination strategies were more effective (−3.6% recurrences, +0.038 QALYs). The combination strategies were not cost-effective, since the incremental cost-effectiveness ratio was €67,413 per QALY, exceeding the willingness-to-pay threshold of €50,000 per QALY. Sensitivity analyses showed that the combination strategies would be cost-effective if the ctDNA test costs were lower than €1500, or if ctDNA status was predictive of treatment response, or if the ctDNA test performance improved substantially. Conclusion: Adding ctDNA to current high-risk clinicopathological features (pT4 and pMMR) can improve patient selection for ACT and can also potentially be cost-effective. Future studies should investigate the predictive value of post-surgery ctDNA status to accurately evaluate the cost-effectiveness of ctDNA testing for ACT decisions in stage II CC.</p

Modeling Personalized Adjuvant TreaTment in EaRly stage coloN cancer (PATTERN)

Aim: To develop a decision model for the population-level evaluation of strategies to improve the selection of stage II colon cancer (CC) patients who benefit from adjuvant chemotherapy. Methods: A Markov cohort model with a one-month cycle length and a lifelong time horizon was developed. Five health states were included; diagnosis, 90-day mortality, death other causes, recurrence and CC death. Data from the Netherlands Cancer Registry were used to parameterize the model. Transition probabilities were estimated using parametric survival models including relevant clinical and pathological covariates. Subsequently, biomarker status was implemented using external data. Treatment effect was incorporated using pooled trial data. Model development, data sources used, parameter estimation, and internal and external validation are described in detail. To illustrate the use of the model, three example strategies were evaluated in which allocation of treatment was based on (A) 100% adherence to the Dutch guidelines, (B) observed adherence to guideline recommendations and (C) a biomarker-driven strategy. Results: Overall, the model showed good internal and external validity. Age, tumor growth, tumor sidedness, evaluated lymph nodes, and biomarker status were included as covariates. For the example strategies, the model predicted 83, 87 and 77 CC deaths after 5 years in a cohort of 1000 patients for strategies A, B and C, respectively. Conclusion: This model can be used to evaluate strategies for the allocation of adjuvant chemotherapy in stage II CC patients. In future studies, the model will be used to estimate population-level long-term health gain and cost-effectiveness of biomarker-based selection strategies

Modeling Personalized Adjuvant TreaTment in EaRly stage coloN cancer (PATTERN)

Aim To develop a decision model for the population-level evaluation of strategies to improve the selection of stage II colon cancer (CC) patients who benefit from adjuvant chemotherapy. Methods A Markov cohort model with a one-month cycle length and a lifelong time horizon was developed. Five health states were included; diagnosis, 90-day mortality, death other causes, recurrence and CC death. Data from the Netherlands Cancer Registry were used to parameterize the model. Transition probabilities were estimated using parametric survival models including relevant clinical and pathological covariates. Subsequently, biomarker status was implemented using external data. Treatment effect was incorporated using pooled trial data. Model development, data sources used, parameter estimation, and internal and external validation are described in detail. To illustrate the use of the model, three example strategies were evaluated in which allocation of treatment was based on (A) 100% adherence to the Dutch guidelines, (B) observed adherence to guideline recommendations and (C) a biomarker-driven strategy. Results Overall, the model showed good internal and external validity. Age, tumor growth, tumor sidedness, evaluated lymph nodes, and biomarker status were included as covariates. For the example strategies, the model predicted 83, 87 and 77 CC deaths after 5 years in a cohort of 1000 patients for strategies A, B and C, respectively. Conclusion This model can be used to evaluate strategies for the allocation of adjuvant chemotherapy in stage II CC patients. In future studies, the model will be used to estimate population-level long-term health gain and cost-effectiveness of biomarker-based selection strategies.Financial support for this study was provided by a grant from ZonMw (Grant number: 848015007). ZonMw had no role in designing the study, interpreting the data, writing the manuscript, and publishing the report