At the interface of asymptotics, conformal methods and analysis in general relativity.

This is an introductory article for the proceedings associated with the Royal Society Hooke discussion meeting of the same title which took place in London in May 2023. We review the history of Penrose's conformal compactification, null infinity and a number of related fundamental developments in mathematical general relativity from the last 60 years. This article is part of a discussion meeting issue 'At the interface of asymptotics, conformal methods and analysis in general relativity'.

Lipoprotein(a) levels and carotid intima-media thickness in children: A 20-year follow-up study.

Elevated lipoprotein(a) [Lp(a)] is independently associated with cardiovascular disease (CVD). In a recent long-term follow-up study involving children with familial hypercholesterolemia, Lp(a) levels contributed significantly to early atherosclerosis, as measured by carotid intima-media thickness (cIMT). To determine if this holds true for children without FH, we conducted a 20-year follow-up study, examining 88 unaffected siblings (mean age: 12.9 years) of children with FH. No significant association was found between Lp(a) and cIMT during follow-up (ß-adjusted [95% CI] = 0.0001 [-0.008 to 0.008] mm per 50 nmol/L increase Lp(a), p = 0.97). In conclusion, our findings suggest that elevated levels of Lp(a) do not play a significant role in arterial wall thickening among children without FH during the 20-year follow-up period. This leads us to consider the possibility that cIMT may not be a suitable marker for detecting potential subtle changes in the arterial wall mediated by Lp(a) in the young, general population. However, it could also be that elevated Lp(a) is only a significant risk factor for atherosclerosis in the presence of other risk factors such as FH.

Systematic review of hearing loss in dental professionals.

BACKGROUND: Hearing loss leads to increased irritability and disengagement in social activities and conversations, which may impact quality of life. Dental professionals are at risk of developing hearing loss through daily exposure to noise from a wide range of equipment that produces significantly high decibels and noise frequencies. AIMS: The aim of this systematic review was to investigate the risk of hearing loss in dental professionals, including dentists, dental specialists, dental hygienists and dental assistants. METHODS: This review was conducted following the Cochrane Handbook for Systematic Reviews. PubMed, Scopus, Embase, Cochrane, Science Direct, Google Scholar and ProQuest were searched up to March 2023. Seventeen of 416 studies met the inclusion criteria. Quality assessment was performed according to the Newcastle-Ottawa Scale for cohort and case-control studies, and a modified version of this tool for cross-sectional studies. RESULTS: The majority of included studies (82%) found a positive association with hearing loss for dentists and dental specialists, with years of clinical experience identified as a prominent risk factor. Dental hygienists and dental assistants were less commonly reported in the literature. Difference between the left and right ears was found in 71% of studies, with the left ear more affected in both dentists and dental assistants due to proximity to the noise-inducing equipment. CONCLUSIONS: Dental professionals are at risk of hearing loss in their workplace, especially linked to years of clinical experience, which highlights the need for prevention and appropriate ear-protective devices.

[Reaction on 'The psychodynamic psychiatry has the future']. / Reactie op 'De toekomst is aan de psychodynamische psychiatrie'.

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De toekomst is aan de psychodynamische psychiatrie.

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Salivary characteristics and dental caries experience in remote Indigenous children in Australia: a cross-sectional study.

BACKGROUND: While associations between salivary characteristics and dental caries have been well studied, we are not aware of this being assessed in a remote Indigenous child population, where lifestyles may be different from urban children. Our aim was to assess associations between caries experience and putative biomarkers in saliva, accounting for oral hygiene and dietary habits. METHODS: Children attending schools in an Indigenous community in remote north Queensland, Australia were invited to an oral examination by qualified and calibrated examiners. Salivary flow rate, pH, buffering capacity and loads of mutans streptococci (MS), lactobacilli (LB) and yeasts were determined. Also, data on tooth brushing frequency and soft drinks consumption were obtained via a questionnaire. Caries experience was recorded by the International Caries Detection and Assessment System (ICDAS-II), and quantified as decayed, missing and filled surfaces. Relationships between the salivary variables and the cumulative caries experience (dmfs+DMFS) in the deciduous and permanent dentitions were examined by multivariate analyses to control the effect of confounders. RESULTS: The mean cumulative decayed (DS + ds), missing (MS + ms) and filled (FS + fs) surfaces were 3.64 (SD: 4.97), 1.08 (4.38) and 0.79 (1.84) respectively. Higher salivary MS and LB counts, low tooth brushing frequency and daily soft drink consumption were significantly related to greater caries experience. Caries experience was about twice in those with ≥10^5 CFU/ml saliva counts of MS (mean = 6.33, SD: 8.40 vs 3.11, 5.77) and LB (7.03, 7.49 vs 4.41, 8.00). In the fully-adjusted multivariate model, caries experience in those with higher counts of MS and LB were 51 and 52% more than those with lower counts. CONCLUSIONS: As with studies in other populations, childhood salivary counts of MS and LB were significantly associated with greater caries experience in this remote Indigenous community. To address the serious burden of oral disease, we are researching ways to promote a healthy oral environment by encouraging good dietary habits, and emphasising the importance of daily tooth brushing with a fluoridated toothpaste. Our ongoing longitudinal studies will indicate the success of measures employed to reduce the counts of bacteria closely associated with cariogenesis and their impact on caries increment. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry ( ANZCTR ), No: ACTRN12615000693527; date of registration: 3rd July 2015.

Parenting practices and children's dental caries experience: A structural equation modelling approach.

AIM: To evaluate the direct and mediated associations between parenting practices and dental caries experience in Indian school children. METHODS: The target population consisted of school children and their parents (N=1539) of Medak district in the state of Telangana, India. Parents completed a questionnaire that consisted of questions related to socioeconomic status (SES), family structure, the number of children, their own oral hygiene behaviour and parenting practices. Parenting practices were assessed using a translated version of the short form of Parent-Child Relationship Questionnaire (PCRQ) which was found to have two factors, power assertion (ie over control and coercion) and positive parenting (warmth and positive parent-child interaction). Children completed a questionnaire on tooth brushing frequency, dental visiting and sugar consumption practices to evaluate their oral hygiene behaviour, and underwent a clinical examination for dental caries by a single examiner. Path analysis was used to explore the influence of parent-child relationship, SES and other family-level variables on dental caries experience of children. RESULTS: Parents' oral hygiene behaviour was positively (ß=0.18, P=0.009), and power assertion negatively (ß=-0.06, P=0.041) associated with children's oral hygiene behaviours. Families reporting higher SES had children with less dental caries experience (ß=-0.10, P=0.028) and better oral hygiene behaviour (ß=0.13, P=0.009). Power assertion parenting had an indirect association with dental caries experience (ß=0.003, P=0.038). CONCLUSIONS: Children had higher dental caries experience when they lived in families with lower SES and used more power assertion parenting practices.

The role of parental rearing practices and family demographics on oral health-related quality of life in children.

OBJECTIVES: To evaluate the direct and indirect (via oral health-related behaviour) effects of parental rearing practices on children's Oral Health-Related Quality of Life (OHRQoL) within a family-focused, comprehensive predictive model. METHODS: Participants were 11- to 14-year-old children and their parents living in Telangana State, India (N = 1130). Children were clinically assessed for dental caries, gingivitis, oral hygiene status, fluorosis, and malocclusion, and completed a self-administered questionnaire on oral health-related behaviour and OHRQoL. Parents answered questions related to their socioeconomic status (SES), family circumstances, parent's perceptions of child's OHRQoL, and child rearing practices. Structural equation modelling was used to evaluate the pathways through which parenting practices were associated with children's OHRQoL. RESULTS: Parents with higher positive (ß = -0.106) and lower power assertion rearing practices (ß = 0.103) had children with better OHRQoL. Parental rearing practices did not have any effect on children's oral hygiene behaviour. Children who had malocclusion (ß = 0.076) and fluorosis (ß = 0.38) had lower OHRQoL. Family SES had a significant effect on children's oral hygiene behaviour and oral hygiene status with children of higher SES demonstrating better oral hygiene behaviour and status. Children living in single-parent families reported poorer oral hygiene behaviour (ß = -0.048) than those living in other types of families. CONCLUSIONS: Parental rearing practices had direct effects on OHRQoL. However, the hypothesised indirect effects of these practices on OHRQoL via poor oral health behaviour were not supported.

Illusions and cloaks for surface waves.

Ever since the inception of Transformation Optics (TO), new and exciting ideas have been proposed in the field of electromagnetics and the theory has been modified to work in such fields as acoustics and thermodynamics. The most well-known application of this theory is to cloaking, but another equally intriguing application of TO is the idea of an illusion device. Here, we propose a general method to transform electromagnetic waves between two arbitrary surfaces. This allows a flat surface to reproduce the scattering behaviour of a curved surface and vice versa, thereby giving rise to perfect optical illusion and cloaking devices, respectively. The performance of the proposed devices is simulated using thin effective media with engineered material properties. The scattering of the curved surface is shown to be reproduced by its flat analogue (for illusions) and vice versa for cloaks.

Effectiveness of water fluoridation in caries reduction in a remote Indigenous community in Far North Queensland.

BACKGROUND: Children in remote Indigenous communities in Australia have levels of dental caries much greater than the national average. One such, the Northern Peninsula Area of Far North Queensland (NPA), had an oral health survey conducted in 2004, shortly before the introduction of fluoridated, reticular water. Children were again surveyed in 2012, following five years exposure. METHODS: An oral examination was conducted on all consenting children enrolled in schools across the community, using WHO Basic Oral Health Survey methodology. RESULTS: Few teeth had restorations in both surveys. Age-weighted overall caries prevalence and severity declined from 2005 to 2012 by 37.3%. The effect was most marked in younger children, dmft decreasing by approximately 50% for ages 4-9 years; at age 6, mean decayed score decreased from 5.20 to 3.43. DMFT levels also decreased by almost half in 6-9 year olds. However, significant unmet treatment needs exist at all ages. CONCLUSIONS: There has been considerable improvement in child dental health in the NPA over the past 6-7 years. In light of continued poor diet and oral hygiene, water fluoridation is the most likely explanation. The cost-effectiveness for this small community remains an issue which, in the current climate of political antagonism to water fluoridation in many quarters, requires continued study.

Describing the light intensity dependence of polymer:fullerene solar cells using an adapted Shockley diode model.

Solar cells are generally optimised for operation under AM1.5 100 mW cm(-2) conditions. This is also typically done for polymer solar cells. However, one of the entry markets for this emerging technology is portable electronics. For this market, the spectral shape and intensity of typical illumination conditions deviate considerably from the standard test conditions (AM1.5, 100 mW cm(-2), at 25 °C). The performance of polymer solar cells is strongly dependent on the intensity and spectral shape of the light source. For this reason the cells should be optimised for the specific application. Here a theoretical model is presented that describes the light intensity dependence of P3HT:[C60]PCBM solar cells. It is based on the Shockley diode equation, combined with a metal-insulator-metal model. In this way the observed light intensity dependence of P3HT:[C60]PCBM solar cells can be described using a 1-diode model, allowing fast optimization of polymer solar cells and module design.

Bortezomib and TRAIL: a perfect match for apoptotic elimination of tumour cells?

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) is a cytokine that selectively eradicates tumour cells via specific cell surface receptors and is intensively explored for use as a novel anticancer approach. To enhance the efficacy of TRAIL receptor agonists the proteasome inhibitor bortezomib is one of the most potent sensitizers. Here we review the main mechanisms underlying bortezomib-dependent TRAIL sensitization, including stimulation of apoptosis by increasing expression of TRAIL receptors, reduction of cFLIP and enhancement of caspase 8 activation, and modulation of Bcl-2 family proteins and inhibitor of apoptosis proteins (IAPs). Concomitantly, pro-survival signals are suppressed such as elicited by NF-κB and Akt. The different preclinical tumour models explored with this combination, including primary tumour (stem) cells, stroma co-culture and mice models, are discussed, as well as possible hurdles for clinical activity. Collectively, anticipating a solid rationale for bortezomib-TRAIL combination and very promising preclinical results, its clinical activity remains to be demonstrated.

The BMP2/7 heterodimer inhibits the human breast cancer stem cell subpopulation and bone metastases formation.

Accumulating evidence suggests that a subpopulation of breast cancer cells, referred to as cancer stem cells (CSCs), have the ability to propagate a tumor and potentially seed new metastases. Furthermore, stimulation of an epithelial-to-mesenchymal transition by factors like transforming growth factor-ß (TGFß) is accompanied with the generation of breast CSCs. Previous observations indicated that bone morphogenetic protein-7 (BMP7) antagonizes the protumorigenic and prometastatic actions of TGFß, but whether BMP7 action is mechanistically linked to breast CSCs has remained elusive. Here, we have studied the effects of BMP7, BMP2 and a BMP2/7 heterodimer on the formation of human breast CSCs (ALDH(hi)/CD44(hi)/CD24(-/low)) and bone metastases formation in a preclinical model of intra-cardiac injection of MDA-MB-231 cells in athymic nude (Balb/c nu/nu) mice. The BMP2/7 heterodimer was the most efficient stimulator of BMP signaling and very effectively reduced TGFß-driven Smad signaling and cancer cell invasiveness. The tested BMPs-particularly the heterodimeric BMP2/7-strongly reduced the size of the ALDH(hi)/CD44(hi)/CD24(-/low) CSC subpopulation. In keeping with these in vitro observations, pretreatment of cancer cells with BMPs for 72 h prior to systemic inoculation of the cancer cells inhibited the formation of bone metastases. Collectively, our data support the notion that breast CSCs are involved in bone metastasis formation and describe heterodimeric BMP2/7 as a powerful TGFß antagonist with anti-metastatic potency.

Determination of brachial artery stiffness prior to vascular access creation: reproducibility of pulse wave velocity assessment.

BACKGROUND: Despite routine ultrasound mapping of upper extremity arteries and veins, early thrombosis and nonmaturation remain frequent complications following vascular access (VA) surgery. Besides vascular diameters, brachial artery stiffness is assumed to play an important role; however, reproducibility of measurements has never been established. The purpose of this study was to determine within-session and between-session variabilities of pulse wave velocity (PWV) assessment by using ultrasonography and blood pressure registration. METHODS: Beat-to-beat changes in brachial artery diameter and pressure were obtained in 21 subjects in measurement sessions on Day 1 and Day 3. Each session consisted of three acquisitions. For each acquisition, systolic and diastolic diameter and pressure were determined and used for calculation of brachial artery PWV. Within-session variability of diameter and pressure, as well as the estimated PWV, was expressed using the intraclass correlation coefficient with corresponding coefficient of variation (CoV). Between-session variability was reported using Bland-Altman analysis in combination with CoV analysis. RESULTS: Significant agreement (P < 0.001) was obtained for all diameter and pressure measurements obtained on Day 1 and Day 3. Within-session CoV of pulse pressure, diastolic diameter and distension were 7.0, 1.6 and 18.3%, respectively. Subsequent estimation of local PWV resulted in a CoV of 10.6%. Between-session CoV was 15.1, 3.8 and 18.9% for pulse pressure, diastolic diameter and distension, respectively. For PWV estimation, this resulted in a CoV of 13.5%. CONCLUSIONS: Diameter and pressure can be recorded accurately over the cardiac cycle, and calculations of distensibility, pulse pressure and PWV show a slight to moderate degree of variation. Larger studies elaborating on interindividual differences need to determine the clinical efficacy of PWV measurements prior to VA creation.

Influence of a TiCl4 post-treatment on nanocrystalline TiO2 films in dye-sensitized solar cells.

In this study, the influence of the TiCl(4) post-treatment on nanocrystalline TiO(2) films as electrodes in dye-sensitized solar cells is investigated and compared to nontreated films. As a result of this post-treatment cell efficiencies are improved, due to higher photocurrents. On a microscopic scale TiO(2) particle growth on the order of 1 nm is observed. Despite a corresponding decrease of BET surface area, more dye is adsorbed onto the oxide surface. Although it seems trivial to match this finding with the improved photocurrent, this performance improvement cannot be attributed to higher dye adsorption only. This follows from comparison between incident photon to current conversion efficiency (IPCE) and light absorption characteristics. Since the charge transport properties of the TiO(2) films are already more than sufficient without treatment, the increase in short circuit current density J(SC) cannot be related to improvements in charge transport either. Transient photocurrent measurements indicate a shift in the conduction band edge of the TiO(2) upon TiCl(4) treatment. It is concluded that the main contribution to enhanced current originates from this shift in conduction band edge, resulting in improved charge injection into the TiO(2).

3-Dimensional rotational X-ray imaging, 3D-RX: image quality and patient dose simulation for optimisation studies.

We have developed a full-scale simulation model as a tool for X-ray system design, image quality optimisation and patient dose reduction. The model supports the (de-)composition of system level requirements and takes inherent care of the prerequisite mutual coherence between component requirements. Furthermore, the model is equipped with several types of automatic X-ray control loop simulations. All relevant patient dose and image quality items are calculated, such as contrast, sharpness, lag and noise and finally combined in 'IQ figures of merit'. The short calculation times realised enable comprehensive multi-parameter optimisation studies. Initially, the IQ model dealt with the performance of 'flat' projection X-ray systems referred to as two-dimensional (2D). Nowadays, 2D X-ray systems are increasingly used for three-dimensional rotational X-ray imaging (3D-RX). An additional 3D-RX module, dealing with patient dose as well as image quality, will simplify and accelerate specific 3D-RX optimisations concerning, e.g. exposure factors, dose control concepts and image processing algorithms.

Vertical and horizontal integration of knowledge and skills - a working model.

The new integrated outcomes-based curriculum for dentistry was introduced at the University of Pretoria in 1997. The first participants graduated at the end of 2001. Educational principles that underpin the new innovative dental curriculum include vertical and horizontal integration, problem-oriented learning, student-centred learning, a holistic attitude to patient care and the promotion of oral health. The aim of this research project was to develop and assay a model to facilitate vertical integration of knowledge and skills thereby justifying the above mentioned action. The learning methodology proposed for the specific outcome of the Odontology module, namely the diagnosis of dental caries and the design of a primary preventive programme, included problem-solving as the driving force for the facilitation of vertical and horizontal integration, and an instructional design for the integration of the basic knowledge and clinical skills into a single learning programme. The paper describes the methodology of problem-oriented learning as applied in this study together with the detail of the programme. The consensus of those teachers who represent the basic and clinical sciences and who participate in this learning programme is that this model is practical and can assist vertical as well as horizontal integration of knowledge.