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2.
Pediatr Radiol ; 53(3): 415-425, 2023 03.
Article in English | MEDLINE | ID: mdl-36622404

ABSTRACT

BACKGROUND: The outcome measure of neonatal hip screening is usually the radiographic acetabular index. OBJECTIVE: To assess the feasibility of magnetic resonance imaging (MRI) without sedation and compare the utility of outcome parameters measured from MRI images. MATERIALS AND METHODS: The invitation for MRI scanning at 5 years of age was incorporated into follow-up for babies who had more than one ultrasound examination during treatment or surveillance. RESULTS: Diagnostic images were obtained in 132 of 134 children. The mean osseous acetabular index (standard deviation [SD]) was 16.6 (3.3) degrees for the right hip and 17.8 (3.2) for the left; the values for the cartilaginous acetabular index were 3.1 (3) and 3.4 (3.2). The mean downslope of a tangent to the lateral bony acetabular roof was 10.4 (4.5) and 9.0 (4.3) with respect to Hilgenreiner's line and that of a line drawn through the apex to the margin of the acetabulum was 3.7 (4.6) and 3.9 (4.7). Intra- and interobserver variation was greater for measures specific to the lateral acetabular roof than for ossific and cartilaginous indices. There was significant negative correlation between the downslope of the tangent to the lateral roof index and the age at onset of treatment on both sides, but no significant correlation for ossific or cartilaginous acetabular indices or apex-marginal index. CONCLUSION: MRI without sedation at 5 years of age is feasible as an outcome measure for hip screening programmes. Parameters specific to the lateral acetabulum may better reflect acetabular sufficiency, despite having greater observer variation than cartilaginous and ossific acetabular indices.


Subject(s)
Acetabulum , Magnetic Resonance Imaging , Child , Infant , Infant, Newborn , Humans , Child, Preschool , Observer Variation , Acetabulum/pathology , Magnetic Resonance Imaging/methods , Treatment Outcome , Retrospective Studies , Hip Joint
3.
Harm Reduct J ; 20(1): 9, 2023 Jan 23.
Article in English | MEDLINE | ID: mdl-36691010

ABSTRACT

BACKGROUND: Gay, bisexual and other men who have sex with men (GBMSM) are overrepresented in cohorts of people who inject drugs. GBMSM's substance use is usually explored in the context of its contribution to sexual risk. We examined drug use practices, connectedness to other people who inject drugs, peer-to-peer injecting, and access to care among men who inject drugs in Melbourne, Australia. We aim to describe similarities and differences in these parameters for GBMSM and other men. METHODS: Data were drawn from a prospective cohort study of people who inject drugs conducted in Melbourne, Australia, since 2009. This cross-sectional study used data collected between 2016 and 2021. Descriptive statistics were used to assess differences between GBMSM and other men. RESULTS: Of 525 men who injected drugs over the study period, 48 (9%) identified as gay or bisexual, or reported sex with other men in the past 12 months. GBMSM and other men reported similar socio-demographics, drug practices (age of injecting initiation, most injected drug, peer-to-peer injecting, receptive syringe sharing) and access to injecting-specific care (drug treatment, source of needle-syringes). A significantly greater percentage of GBMSM reported past 12-month hepatitis C testing (69% vs. 52%, p = 0.028) and preferring methamphetamine (31% vs. 16%, p = 0.022). A higher percentage of GBMSM reported knowing > 50 other people who inject drugs (46% vs. 37%), but this difference was not statistically significant. Both groups primarily obtained injecting equipment from needle-syringe programs; a minority had accessed injecting-specific primary care. CONCLUSION: Men who injected drugs in this cohort and those who identified as GBMSM reported similar drug and health-seeking practices. The higher prevalence of methamphetamine injecting among GBMSM may warrant different harm reduction support for this group. Health promotion should utilise opportunities to connect men who inject drugs in Melbourne to injecting-specific primary health care.


Subject(s)
Methamphetamine , Sexual and Gender Minorities , Substance Abuse, Intravenous , Substance-Related Disorders , Male , Humans , Substance Abuse, Intravenous/epidemiology , Cross-Sectional Studies , Homosexuality, Male , Prospective Studies , Substance-Related Disorders/epidemiology , Australia/epidemiology
4.
J Affect Disord ; 311: 631-636, 2022 08 15.
Article in English | MEDLINE | ID: mdl-35623482

ABSTRACT

BACKGROUND: While the serotonin transporter (SLC6A4) gene, 5-HTTLPR, interacts with the social environment to influence both emotional self-regulation and smoking behavior, less is known about interactions between emotional self-regulation and 5-HTTLPR or their joint influence on tobacco use. Here, we examined such interactions among psychiatric inpatients, the population with the highest rates of smoking. METHODS: Participants (506 adults) were psychiatric inpatients at The Menninger Clinic in Houston TX between 2012 and 16. Most were white (89%), male (55%), with a mean age of 32.3 years. Participants completed the Difficulties in Emotional Regulation Scale (DERS) at admission. We examined interactions with smoking among three DERS subscales and 5-HTTLPR, controlling for sex, race and age. RESULTS: Smoking rates were higher among those with the 5-HTTPLR L'L' genotype compared to peers carrying an S' allele (47.9% vs. 37.4%, respectively). Among S' allele carrying participants, impulse control difficulties (OR = 1.09; 95%CI: 1.03-1.14) and lack of emotion clarity (OR = 1.06; 95%CI: 1.00-1.11) increased risk for ever using tobacco, while accessing more ways to regulate emotion (OR = 0.95; 95%CI: 0.92-0.99) offered a protective effect against ever using tobacco. Neither demographic nor DERS covariates were associated with using tobacco among the L'L' group. LIMITATIONS: This ethnically homogenous sample limits generalizability and using a binary outcome can over-estimate a gene environment interaction effect. CONCLUSIONS: Emotional self-regulation exerts a stronger influence on using tobacco among carriers of an S' allele of 5-HTTLPR than peers with the L'L' genotype. Promoting emotional self-regulatory skills may have benefits for preventing tobacco use.


Subject(s)
Emotional Regulation , Adult , Genotype , Humans , Impulsive Behavior , Inpatients , Male , Polymorphism, Genetic , Serotonin Plasma Membrane Transport Proteins/genetics , Tobacco Use
5.
J Small Anim Pract ; 63(2): 120-127, 2022 02.
Article in English | MEDLINE | ID: mdl-33900656

ABSTRACT

OBJECTIVES: To assess platelet function, buccal mucosal bleeding time and plasma von Willebrand factor concentration in dogs with chronic inflammatory and/or fibrotic liver disease and to compare results with those obtained in healthy dogs. MATERIALS AND METHODS: Preliminary study including 18 dogs with chronic inflammatory and/or fibrotic liver disease undergoing liver biopsy and 18 healthy age-matched control dogs. Platelet function was assessed by measuring closure time with the PFA-100® analyser using adenosine diphosphate (ADP) as an agonist. Buccal mucosal bleeding time, closure time and plasma von Willebrand factor antigen were measured in dogs in both groups. After undergoing ultrasound-guided needle biopsy, dogs were monitored for haemorrhage to determine if there was an association of any measurement with post-biopsy bleeding. RESULTS: The closure time was not different between the liver disease group (median 76.3; range 53 to 118.5 seconds) and control group (72.8; 57 to 89.5 seconds). The buccal mucosal bleeding time was longer in the liver disease group (median 138; range 95 to 229 seconds) than the control group (103; 63 to 200 seconds). The plasma von Willebrand factor antigen concentration was not different between the liver disease group (median 203; range 109 to 351%) and control group (165.5; 63 to 246%). CLINICAL SIGNIFICANCE: In this study, dogs with chronic necroinflammatory and/or fibrotic liver disease did not have overt, clinically relevant derangements in platelet function as assessed by buccal mucosal bleeding time, closure time and von Willebrand factor analysis. In addition, none of the dogs undergoing percutaneous ultrasound-guided biopsy in the study exhibited bleeding complications post-biopsy procedure.


Subject(s)
Dog Diseases , Liver Diseases , Animals , Dogs , Liver Diseases/veterinary , Platelet Function Tests/veterinary , von Willebrand Factor/analysis
6.
Int Nurs Rev ; 68(2): 166-171, 2021 Jun.
Article in English | MEDLINE | ID: mdl-34036594

ABSTRACT

BACKGROUND: In the 121st anniversary year of the birth of Florence Nightingale, and during the COVID-19 pandemic, it is both interesting and salient to be reminded of the foundational work of this famous woman who began modern nursing. Her work in nursing care and nursing, health and public policy has been a continuing strong foundation to practices in societies around the world. METHODS: In this short communication about historical research, various aspects of Florence's life and work are described, as well as the locations, memorials and museum significant to our remembrance of her. RESULTS: A particular focus of this paper is the description of a larger but little-known medicine chest located at the College of Nursing, University of Saskatchewan, in Saskatoon, SK, Canada, and attributed as belonging to Florence. CONCLUSION: Best known to this point in time is a smaller medicine chest at the Florence Nightingale Museum in London.


Subject(s)
History of Nursing , Medicine Chests/history , History, 19th Century , Humans , Italy , London , Saskatchewan , Turkey
7.
Res Social Adm Pharm ; 17(11): 2006-2014, 2021 11.
Article in English | MEDLINE | ID: mdl-33775557

ABSTRACT

AIMS: To explore the impact of a prescribing feedback intervention on insulin prescribing. METHODS: This was a mixed-methods study in a hospital setting. An insulin prescribing feedback intervention was delivered verbally and in writing to twelve doctors. Insulin prescribing error frequency was compared to ten doctors who had not received the feedback intervention. Insulin prescribing was audited over four weeks at the start and end of the intervention period. Semi-structured interviews were conducted with participating doctors who had received feedback, and qualitative data analysed thematically to explore the impact of the intervention on their prescribing practice. RESULTS: Prescribing data were collected on 370 insulin prescriptions with 241 errors identified. A significant reduction (χ2 = 22.6, p=<0.05) in insulin prescribing error frequency was observed in the intervention group, with a non-significant increase reported in the control group. Feedback was received positively and considered valuable by doctors, supporting development of their knowledge and skills and encouraging reflection on their prescribing performance. Doctors described enhanced confidence in insulin prescribing and a desire to improve as a prescriber and avoid harm, with feedback raising awareness of their development needs. Prescribers also described enhanced team work, with greater information and feedback seeking behavior to inform future prescribing decisions. CONCLUSIONS: Feedback has potential to improve insulin prescribing and is a valued and acceptable process intervention for doctors. The impact on insulin prescribing practice is varied and complex influencing the capability, opportunity and motivation of prescribers to adapt and evolve their behavior in response to ongoing feedback.


Subject(s)
Insulin , Pharmacists , Drug Prescriptions , Feedback , Hospitals , Humans , Medication Errors/prevention & control , Pilot Projects
8.
J Pediatr Orthop B ; 29(3): 219-227, 2020 May.
Article in English | MEDLINE | ID: mdl-32218018

ABSTRACT

The aim of this study was to determine the relationship of tangent to the lateral roof angle (TLRA), Graf's alpha angle and percentage femoral head cover (PHC) and to observed stability, and to establish intraobserver and interobserver errors for measurement of alpha angle and TLRA. In total, 2235 babies referred to the hip review clinic over a period of 8 years. Intraobserver and interobserver errors were calculated from readings of 383 hip images by an experienced paediatric radiologist and a trainee. Taking TLRA <70° as abnormal resulted in sensitivity for unstable right hips of 88% compared with 77% for alpha angle <60° (P = 0.002) and 81% for PHC <60% (P = 0.028) and specificity of TLRA 89%, alpha angle 90% (P = 0.07) and PHC 83% (P < 0.001). Corresponding figures for left hips are sensitivity of TLRA 99%, alpha angle 91% (P < 0.001) and PHC 96% (P = 0.013), and specificity TLRA 86%, alpha angle 83% (P = 0.001) and PHC 67% (P < 0.001). Mean intraobserver errors for alpha angle were 1.85° and 1.81° for consultant and trainee compared to 2.54 and 2.55 for TLRA. Mean interobserver errors were 2.22 for alpha angle and 3.42 for TLRA. TLRA, a new parameter, correlated better with observed stability with significant improvement in sensitivity in both hips and specificity in left hips compared with Graf's alpha angle, and significantly improved sensitivity and specificity in both hips compared with percentage femoral head cover.


Subject(s)
Femur Head/diagnostic imaging , Hip Dislocation, Congenital/diagnostic imaging , Joint Instability/diagnostic imaging , Neonatal Screening/standards , Ultrasonography/standards , Female , Hip Dislocation, Congenital/classification , Humans , Infant, Newborn , Joint Instability/classification , Male , Neonatal Screening/classification , Retrospective Studies , Ultrasonography/classification
10.
Ultramicroscopy ; 207: 112845, 2019 Dec.
Article in English | MEDLINE | ID: mdl-31586829

ABSTRACT

Electron backscatter diffraction (EBSD) is a well-established method of characterisation for crystalline materials. Using this technique, we can rapidly acquire and index diffraction patterns to provide phase and orientation information about the crystals on the material surface. The conventional analysis method uses signal processing based on a Hough/Radon transform to index each diffraction pattern. This method is limited to the analysis of simple geometric features and ignores subtle characteristics of diffraction patterns, such as variations in relative band intensities. A second method, developed to address the shortcomings of the Hough/Radon transform, is based on template matching of a test experimental pattern with a large library of potential patterns. In the present work, the template matching approach has been refined with a new cross correlation function that allows for a smaller library and enables a dramatic speed up in pattern indexing. Refinement of the indexed orientation is performed with a follow-up step to allow for small alterations to the best match from the library search. The refined template matching approach is shown to be comparable in accuracy, precision and sensitivity to the Hough based method, even exceeding it in some cases, via the use of simulations and experimental data collected from a silicon single crystal and a deformed α-iron sample. The speed up and pattern refinement approaches should increase the widespread utility of pattern matching approaches.

11.
J Laryngol Otol ; 133(9): 822-824, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31439076

ABSTRACT

BACKGROUND: Evidence from the literature shows that clinicians' knowledge of rules and legislation surrounding driving can often be poor. A closed-loop audit was conducted to gauge the level of driving advice given to patients with dizziness. METHODS: The clinical notes of 100 patients referred to the vertigo clinic at a tertiary referral centre were retrospectively searched for evidence of driving advice. Education sessions were undertaken and a patient information leaflet was developed before a second cycle of the audit. RESULTS AND CONCLUSION: The proportion of patients having documented evidence of receiving driving advice increased from 6.3 per cent to 10.4 per cent. It is therefore clear that, despite this improvement, a significant proportion of patients' notes did not contain documentation about driving. This is likely because of many reasons, including individual interpretation by clinicians. This paper provides a reminder of the rules, and discusses their interpretation and implementation in an increasingly medicolegal environment.

12.
Health Policy ; 123(7): 661-665, 2019 07.
Article in English | MEDLINE | ID: mdl-31076201

ABSTRACT

OBJECTIVE: This study aimed to establish whether longitudinal participation in an accreditation program is translated into improvement in continuity of quality patient care and human resource management (HRM) processes outcomes. MATERIALS AND METHODS: This was a secondary data analysis of accreditation panel data from acute hospitals participating in the Australian Council on Healthcare Standards' Evaluation and Quality Improvement Program (EQuIP). EQuIP criteria data from 311 hospitals were collected by external surveyors across 2003-2006 (Time 1) and 2007-2010 (Time 2). Mandatory accreditation criteria ratings at Time 1 were used to determine hospital performance group membership (1 = below moderate, 2 = moderate, 3 = above moderate). Analysis was undertaken of ratings across continuity of quality patient care and HRM process criteria, at Time 1 and 2. RESULTS: Continuity of quality patient care and HRM processes improved across time in the three performance groups. Lower performing hospitals improved at a greater rate than moderate and higher performing hospitals. The groupings and performance order did not change over time. CONCLUSIONS: An accreditation program is an external driver that facilitates continual and systemic quality improvement changes to sub-systems with an organisation.


Subject(s)
Accreditation , Hospitals/standards , Quality of Health Care/standards , Workforce/organization & administration , Australia , Continuity of Patient Care , Humans , Quality Assurance, Health Care/organization & administration , Quality Improvement
13.
Sci Rep ; 8(1): 11946, 2018 08 09.
Article in English | MEDLINE | ID: mdl-30093703

ABSTRACT

Major cardiac organisations recommend U wave abnormalities should be reported during ECG interpretation. However, U waves cannot be measured in patients with atrial fibrillation (AF) due to the obscuring fibrillatory wave. The aim was to validate a U wave measurement algorithm for AF patients. Multi-beat averaging was applied to ECGs of 25 patients during paroxysms of AF and the presence of U waves compared to those from the same patients during sinus rhythm (SR). In a further database of 10 long-term AF recordings, the number of beats for effective U wave extraction by the algorithm was calculated. U waves were revealed in all AF recordings and there was no significant difference between the presence of U waves in AF and SR (p = 0.88). U wave amplitude was significantly increased in AF (mean (s.d.) amplitude 55 (39) AF vs 37 (28) µV SR, p = 0.005). The presence of U waves could easily be discerned when as few as 10 beats were used in the algorithm. The study demonstrates the validity of the algorithm to reveal U waves in AF recordings. The algorithm offers the potential to detect U wave abnormalities in patients with AF.


Subject(s)
Algorithms , Atrial Fibrillation/physiopathology , Electrocardiography/methods , Heart Conduction System/physiopathology , Atrial Fibrillation/diagnosis , Heart Rate , Humans , Reproducibility of Results , Sinoatrial Node/physiopathology
14.
Article in English | MEDLINE | ID: mdl-30104426

ABSTRACT

Behavioural and cognitive processes play important roles in mediating an individual's interactions with its environment. Yet, while there is a vast literature on repeatable individual differences in behaviour, relatively little is known about the repeatability of cognitive performance. To further our understanding of the evolution of cognition, we gathered 44 studies on individual performance of 25 species across six animal classes and used meta-analysis to assess whether cognitive performance is repeatable. We compared repeatability (R) in performance (1) on the same task presented at different times (temporal repeatability), and (2) on different tasks that measured the same putative cognitive ability (contextual repeatability). We also addressed whether R estimates were influenced by seven extrinsic factors (moderators): type of cognitive performance measurement, type of cognitive task, delay between tests, origin of the subjects, experimental context, taxonomic class and publication status. We found support for both temporal and contextual repeatability of cognitive performance, with mean R estimates ranging between 0.15 and 0.28. Repeatability estimates were mostly influenced by the type of cognitive performance measures and publication status. Our findings highlight the widespread occurrence of consistent inter-individual variation in cognition across a range of taxa which, like behaviour, may be associated with fitness outcomes.This article is part of the theme issue 'Causes and consequences of individual differences in cognitive abilities'.


Subject(s)
Behavior, Animal , Biological Variation, Individual , Cognition , Animals
15.
J Stat Comput Simul ; 88(3): 575-596, 2018.
Article in English | MEDLINE | ID: mdl-29731525

ABSTRACT

We develop a Bayesian variable selection method for logistic regression models that can simultaneously accommodate qualitative covariates and interaction terms under various heredity constraints. We use expectation-maximization variable selection (EMVS) with a deterministic annealing variant as the platform for our method, due to its proven flexibility and efficiency. We propose a variance adjustment of the priors for the coefficients of qualitative covariates, which controls false-positive rates, and a flexible parameterization for interaction terms, which accommodates user-specified heredity constraints. This method can handle all pairwise interaction terms as well as a subset of specific interactions. Using simulation, we show that this method selects associated covariates better than the grouped LASSO and the LASSO with heredity constraints in various exploratory research scenarios encountered in epidemiological studies. We apply our method to identify genetic and non-genetic risk factors associated with smoking experimentation in a cohort of Mexican-heritage adolescents.

16.
J Pediatr Orthop B ; 27(3): 236-243, 2018 May.
Article in English | MEDLINE | ID: mdl-28230611

ABSTRACT

Published maturation curves for bony acetabular roof or α angle (AA) and percentage femoral head cover (FHC) with age are sparse. We aimed to determine typical values for AA and FHC in 2236 infants referred to a selective ultrasound screening programme. There was increase in the values of first measurement of AA and FHC related to the logarithm of age. Males had greater values than females (P<0.001) and right hips had greater values than left (P<0.001) for both measurements. Significant side differences have not been reported previously. Treatment decisions should be made on the basis of sex, side and age-specific data.


Subject(s)
Acetabulum/diagnostic imaging , Femur Head/diagnostic imaging , Hip Dislocation, Congenital/diagnostic imaging , Neonatal Screening/methods , Ultrasonography, Interventional/methods , Age Factors , Female , Hip Dislocation, Congenital/epidemiology , Humans , Infant , Infant, Newborn , Male , Neonatal Screening/standards , Prospective Studies , Sex Factors , Ultrasonography, Interventional/standards
17.
J Microbiol Methods ; 142: 46-51, 2017 11.
Article in English | MEDLINE | ID: mdl-28870772

ABSTRACT

In vitro biofilm assays are a vital first step in the assessment of therapeutic effectiveness. Current biofilm models have been found to be limited by throughput, reproducibility, and cost. We present a novel in vitro biofilm model, utilising a sodium alginate substratum for surface biofilm colony formation, which can be readily dissolved for accurate evaluation of viable organisms. The dissolving bead biofilm assay was evaluated using a range of clinically relevant strains. The reproducibility and responsiveness of the assay to an antimicrobial challenge was assessed using standardised methods. Cryo-scanning electron microscopy was used to image biofilm colonies. Biofilms were grown for 20h prior to testing. The model provides a reproducible and responsive assay to clinically-relevant antimicrobial challenges, as defined by established guidelines. Moreover cryo-scanning electron microscopy demonstrates that biofilm formation is localised exclusively to the alginate bead surface. Our results suggest that this simple model provides a robust and adaptable assay for the investigation of bacterial biofilms.


Subject(s)
Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Biofilms/growth & development , Drug Resistance, Bacterial/physiology , Gentamicins/pharmacology , Alginates/chemistry , Cryoelectron Microscopy , Enterococcus faecalis/growth & development , Enterococcus faecalis/isolation & purification , Escherichia coli/growth & development , Escherichia coli/isolation & purification , Glucuronic Acid/chemistry , Hexuronic Acids/chemistry , Humans , Klebsiella pneumoniae/growth & development , Klebsiella pneumoniae/isolation & purification , Microbial Sensitivity Tests , Microscopy, Electron, Scanning , Pseudomonas aeruginosa/growth & development , Pseudomonas aeruginosa/isolation & purification , Staphylococcus aureus/growth & development , Staphylococcus aureus/isolation & purification , Streptococcus mutans/growth & development , Streptococcus mutans/isolation & purification
18.
Sci Rep ; 7(1): 10916, 2017 09 07.
Article in English | MEDLINE | ID: mdl-28883500

ABSTRACT

Advanced structural characterisation techniques which are rapid to use, non-destructive and structurally definitive on the nanoscale are in demand, especially for a detailed understanding of extended-defects and their influence on the properties of materials. We have applied the electron backscatter diffraction (EBSD) technique in a scanning electron microscope to non-destructively characterise and quantify antiphase domains (APDs) in GaP thin films grown on different (001) Si substrates with different offcuts. We were able to image and quantify APDs by relating the asymmetrical intensity distributions observed in the EBSD patterns acquired experimentally and comparing the same with the dynamical electron diffraction simulations. Additionally mean angular error maps were also plotted using automated cross-correlation based approaches to image APDs. Samples grown on substrates with a 4° offcut from the [110] do not show any APDs, whereas samples grown on the exactly oriented substrates contain APDs. The procedures described in our work can be adopted for characterising a wide range of other material systems possessing non-centrosymmetric point groups.

19.
Philos Trans R Soc Lond B Biol Sci ; 372(1725)2017 Jul 19.
Article in English | MEDLINE | ID: mdl-28584172

ABSTRACT

This paper argues for an integrative modelling approach for understanding zoonoses disease dynamics, combining process, pattern and participatory models. Each type of modelling provides important insights, but all are limited. Combining these in a '3P' approach offers the opportunity for a productive conversation between modelling efforts, contributing to a 'One Health' agenda. The aim is not to come up with a composite model, but seek synergies between perspectives, encouraging cross-disciplinary interactions. We illustrate our argument with cases from Africa, and in particular from our work on Ebola virus and Lassa fever virus. Combining process-based compartmental models with macroecological data offers a spatial perspective on potential disease impacts. However, without insights from the ground, the 'black box' of transmission dynamics, so crucial to model assumptions, may not be fully understood. We show how participatory modelling and ethnographic research of Ebola and Lassa fever can reveal social roles, unsafe practices, mobility and movement and temporal changes in livelihoods. Together with longer-term dynamics of change in societies and ecologies, all can be important in explaining disease transmission, and provide important complementary insights to other modelling efforts. An integrative modelling approach therefore can offer help to improve disease control efforts and public health responses.This article is part of the themed issue 'One Health for a changing world: zoonoses, ecosystems and human well-being'.


Subject(s)
Hemorrhagic Fever, Ebola/transmission , Lassa Fever/transmission , Models, Theoretical , One Health , Zoonoses/transmission , Africa , Animals , Hemorrhagic Fever, Ebola/virology , Humans , Lassa Fever/virology , Zoonoses/etiology
20.
J Microsc ; 267(3): 330-346, 2017 09.
Article in English | MEDLINE | ID: mdl-28474742

ABSTRACT

We analyse the signal formation process for scanning electron microscopic imaging applications on crystalline specimens. In accordance with previous investigations, we find nontrivial effects of incident beam diffraction on the backscattered electron distribution in energy and momentum. Specifically, incident beam diffraction causes angular changes of the backscattered electron distribution which we identify as the dominant mechanism underlying pseudocolour orientation imaging using multiple, angle-resolving detectors. Consequently, diffraction effects of the incident beam and their impact on the subsequent coherent and incoherent electron transport need to be taken into account for an in-depth theoretical modelling of the energy- and momentum distribution of electrons backscattered from crystalline sample regions. Our findings have implications for the level of theoretical detail that can be necessary for the interpretation of complex imaging modalities such as electron channelling contrast imaging (ECCI) of defects in crystals. If the solid angle of detection is limited to specific regions of the backscattered electron momentum distribution, the image contrast that is observed in ECCI and similar applications can be strongly affected by incident beam diffraction and topographic effects from the sample surface. As an application, we demonstrate characteristic changes in the resulting images if different properties of the backscattered electron distribution are used for the analysis of a GaN thin film sample containing dislocations.


Subject(s)
Electrons , Microscopy, Electron, Scanning/methods , Models, Theoretical
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