Functional lasing microcapillaries for surface-specific sensing.

Lasing-based sensors have several advantages over fluorescent devices, specifically related to the high light intensity and narrow mode linewidth that can improve the speed and accuracy of the sensor performance. In this work, a microcapillary-based lasing sensor is demonstrated, in which the lasing wavelengths are sensitive to the surface binding of specific materials. In order to achieve this, we utilized lasing into the "star" and "triangle" modes of a conventional microcapillary and tracked the mode positions after the deposition of a polyelectrolyte tri-layer and the subsequent amide binding of carboxy-functionalized polystyrene microspheres. While the lasing mode spectrum becomes increasingly complicated by the addition of the surface layers, careful mode selection can be used to monitor the layer-by-layer surface binding in a mechanically and optically robust device. For polystyrene microspheres, the detection limits were 9.75 nM based upon the lasing mode shift, which compares favorably with fluorescence-based devices. The methods presented in this work could readily be extended to other surface binding schemes and lasing wavelengths, showing that capillary microlasers could be used for many potential applications that capitalize on stable lasing-based detection methods.

Wide-gamut lasing from a single organic chromophore.

The development of wideband lasing media has deep implications for imaging, sensing, and display technologies. We show that a single chromophore can be engineered to feature wide-gamut fluorescence and lasing throughout the entire visible spectrum and beyond. This exceptional color tuning demonstrates a chemically controlled paradigm for light emission applications with precise color management. Achieving such extensive color control requires a molecular blueprint that yields a high quantum efficiency and a high solubility in a wide variety of liquids and solids while featuring a heterocyclic structure with good steric access to the lone pair electrons. With these requirements in mind, we designed a lasing chromophore that encloses a lasing color space twice as large as the sRGB benchmark. This record degree of color tuning can in principle be adapted to the solid state by incorporating the chromophore into polymer films. By appropriately engineering the base molecular structure, the widest range of lasing wavelengths observed for a conventional gain medium can be achieved, in turn establishing a possible route toward high-efficiency light emitters and lasers with near-perfect chromaticity.

Dental students' and staff perceptions of the impact of learning environment disruption on their learning and teaching experiences.

INTRODUCTION: This project is a qualitative investigation into student and staff experiences of the effect of a major building redevelopment on their Dental School learning and teaching environments. Currently, there is little research exploring the impact of disruptions to the learning environment on students' learning and staff teaching experiences. METHOD: Data were collected in 2016 using an online survey, semi-structured interviews and focus groups with students and staff. Data were analysed using a general inductive approach. RESULTS: Four broad themes emerged as follows: (i) students valued having a space for personal and collaborative work within the Dental School; (ii) both staff and students positioned staff contributions to learning experiences above the role of the physical learning environment; (iii) the majority of staff and students not feel that the physical environment limited their clinical training; and (iv) staff and students were able to adapt to the impact of building redevelopment through resilience and organisation. DISCUSSION: Results of this research have informed the provision of collegial spaces at the School, both as the building redevelopment continues, and in planning for the completed building.

How do educators in one New Zealand undergraduate Bachelor of Oral Health course teach and nurture professionalism?

INTRODUCTION: Research on integrated dental hygiene and dental therapy courses is scarce; studies reporting on how staff in these combined scope courses teach professionalism are even more scarce. This study aimed to partially fill these research gaps. METHOD AND MATERIALS: In 2016, online surveys were sent to 34 staff members who taught into the integrated Bachelor of Oral Health (BOH) course at the University of Otago's Faculty of Dentistry; 13 were returned. Two focus groups were conducted with six BOH educators. RESULTS: Aspects of professionalism were taught and nurtured in the formal curriculum, the clinic and the informal curriculum. In the formal curriculum, policies outlining the professional standards of behaviour expected of oral health practitioners and students in New Zealand and the Faculty were discussed. In the clinic, educators taught professionalism through modelling clinical skills, assessing students' performance and commenting on their reflective logbooks. In the informal curriculum, BOH teachers nurtured professionalism through discussions about standards of behaviour outside of the university. Role modelling was the most common method that participants reported they taught or nurtured professionalism in their students. DISCUSSION: Professionalism is a complex concept that is taught and nurtured in a number of ways over all aspects of the course. CONCLUSION: Oral Health educators need to maintain a high standard of professionalism when interacting with students and patients, as well as in public spaces, in order to model professionalism to their students.

Effects of environmental tobacco smoke on the oral health of preschool children.

AIMS: This study investigated the association between the prevalence of oral health problems (caries, gingivitis, mucosal pigmentation and enamel defects in one to 5 year-old children exposed and not exposed to environmental tobacco smoke before and/or after birth. Exposure to environmental tobacco smoke (ETS) in childhood may have significant health effects. METHODS: A structured questionnaire was used to collect data on a child's current and previous illnesses, oral health behaviours, dietary habits, parental smoking behaviours and parents' dental history. The intraoral examination recorded dental caries (dmfs), enamel defects, gingival health, melanin pigmentation and soft tissue health. Stimulated saliva was collected. Total sIgA levels were quantified using indirect competitive ELISA with a SalimetricsTM kit. RESULTS: The 44 children (aged 15-69 months) recruited were divided into two groups: ETS and non-ETS (control). There were 22 children in each: 16 who were exposed to ETS during and after gestation were identified as the ETSB subgroup. Participants exposed to ETS were more likely to have had upper respiratory tract and middle ear infections during the neonatal period and had higher mean dmft, mean dmfs, mean percent of surfaces with demarcated opacities and mean GI than the non-ETS participants. The children exposed to ETS before and after birth had the highest occurrence of enamel opacities showed a higher risk for dental caries even though more children in this group used the recommended fluoride toothpaste (1000 ppm fluoride). Mothers who smoked either never breastfed their children or breastfed their children for less than the recommended period of 6 months. Children exposed to ETS were shown to have higher mean total sIgA (µg/ml) than the children in the control group. CONCLUSIONS: Associations between ETS exposure before and after gestation and oral health, including salivary changes in young children were shown in the present study. Dental health professionals should include a question about household smoking in children's dental histories, which would allow opportunities to discuss the impact of smoking on child oral health. Longitudinal oral health studies should include a history of maternal smoking during pregnancy and afterwards.

Resin Infiltration of Caries in Primary Molars in a Community Setting: 24-Month Randomized Controlled Trial Findings.

This study aimed to assess whether resin infiltration of primary molar proximal lesions is more effective than noninvasive measures in radiographically controlling carious lesion progression into the dentin. A split-mouth randomized controlled trial included 90 children, each with 2 proximal lesions confined to the inner half of the enamel or ≤0.5 mm into the dentin. For each child, lesions were randomly allocated to test (infiltration: DMG Icon preproduct and fluoride varnish) or control (fluoride varnish) status. The primary outcome measure was 24-mo radiographic lesion progression. Placement of a restoration during the study period was counted as lesion progression. Proportions of teeth with progressed lesions were compared using the McNemar test. Children also reported on the treatment's acceptability to them. Children (46% female) ranged in age from 6 to 9 y. Their mean number of decayed, missing, and filled teeth (d3mft) was 2.8 (SD 2.6). At baseline, 58% and 42% of children were at moderate and low risk, respectively. Test and control lesions presented with similar radiographic lesions at baseline. At the 24-mo follow-up, 6 children had moved and 30 teeth had exfoliated. In the test and control groups, 15 of 66 lesions (22.7%) and 30 of 69 lesions (43.5%) had progressed, respectively (P < 0.05). The 2-y therapeutic effect (based on pairwise radiographic readings) of infiltration over fluoride varnish was 20.8% (95% confidence interval, 10.6%-30.2%). Nearly all children (96.7%) had enjoyed their visit to the clinic, and more than two-thirds (72.2%) were not worried about returning for treatment. Infiltration is more efficacious than fluoride varnish for controlling carious lesion progression in proximal lesions in primary molars, and most children find the treatment acceptable (Australian New Zealand Clinical Trials Registry ANZCTR.org.au ACTRN12611000827932). Knowledge Transfer Statement: These study findings can help clinicians decide which caries management approach they wish to use to prevent progression of proximal lesions in primary molars. With consideration of cost and patient preference, this information could lead to more appropriate therapeutic decisions.

Refractometric sensitivity and thermal stabilization of fluorescent core microcapillary sensors: theory and experiment.

Fluorescent-core microcapillaries (FCMs) present a robust basis for the application of optical whispering gallery modes toward refractometric sensing. An important question concerns whether these devices can be rendered insensitive to local temperature fluctuations, which may otherwise limit their refractometric detection limits, mainly as a result of thermorefractive effects. Here, we first use a standard cylindrical cavity formalism to develop the refractometric and thermally limited detection limits for the FCM structure. We then measure the thermal response of a real device with different analytes in the channel and compare the result to the theory. Good stability against temperature fluctuations was obtained for an ethanol solvent, with a near-zero observed thermal shift for the transverse magnetic modes. Similarly good results could in principle be obtained for any other solvent (e.g., water), if the thickness of the fluorescent layer can be sufficiently well controlled.

Protein biosensing with fluorescent microcapillaries.

Capillaries with a high-index fluorescent coating represent a new type of whispering-gallery-mode (WGM) microcavity sensor. By coating silicon quantum dots (Si-QDs) onto the channel wall of a microcapillary, a cylindrical microcavity forms in which the optical confinement arises from the index contrast at the interface between the QD layer and the glass capillary wall. However, the ability to functionalize the QD layer for biosensing applications is an open question, since the layer consists of a mixture of Si-QDs embedded in a glassy SiOx matrix. Here, we employ a polyelectrolyte (PE) multilayer approach to functionalize the microcapillary inner surface and demonstrate the potential of this refractive index sensing platform for label-free biosensing applications, using biotin-neutravidin as a specific interaction model.

Transparency and stability of Ag-based metal-dielectric multilayers.

We fabricated and tested periodic metal (Ag)-dielectric (SiO2 or TiO2) multilayers with transparency bands in the visible range. For samples with Ag-TiO2 interfaces, the optical properties exhibited relatively poor predictability, likely due to oxidation of the Ag layers. Ag/SiO2-based multilayers were found to be more predictable and stable, but the relatively low refractive index of SiO2 limits their inherent transparency and pass-band bandwidth. We show that termination of the multilayer with a single high-index layer reduces the admittance mismatch with the ambient media, and thus improves the properties of the transparency band.

Influence of dental care on children's oral health and wellbeing.

BACKGROUND: Dental problems in early childhood can have a very significant effect not only on the oral health of young children but on their quality of life and that of their families. Added to this are the long term risks they carry into the permanent dentition. AIM: To review current literature on the management of early childhood caries and its influence on wider oral and general health. RESULTS: Recent studies suggest that the risks for dental caries, periodontal disease, malocclusion and other general health problems including overweight and obesity may be increased in children who have had early childhood caries. Traditional restoration of damaged primary teeth has been shown to have only moderate outcomes depending on the techniques and materials used and the ability of children to cooperate because of age or other factors. CONCLUSIONS: More recent interesting approaches that seal enamel caries, only partially remove carious dentine or attempt to entirely seal carious dentine lesions merit not only discussion but also longer term investigation. With increasing demands on health funding, dentistry must look at how the most appropriate care can be provided to allow children to reach adulthood with healthy permanent dentitions - something that less than half the population currently achieve.

Changes in Bachelor of Oral Health students' perceptions of their dental education environment.

This study used the Dundee Ready Educational Environment Measure (DREEM) to examine how a cohort of Bachelor of Oral Health (BOH) students at the University of Otago's Faculty of Dentistry perceived their educational environment. Four DREEM questionnaires were administered over the three-year programme; a modified version at the beginning of the first year asked students what they expected their year would be like, while questionnaires at the end of each subsequent year surveyed students on their actual experiences within the BOH programme. All four questionnaires were completed by 78% of students (N=31). Overall, the students' perceptions of their educational environment were more positive than negative, and they identified both strengths and weaknesses in the BOH programme. Both positive and negative shifts occurred between the 'Expected' and 'Actual' individual DREEM outcomes. The difference between students' 'Expected' and 'Actual' DREEM responses indicates, in some areas, that BOH students expected more from their educational environment than what they actually experienced. The changes in BOH students' perception of their educational environment over the three years can be explained, in part, by changes in the curriculum from year to year.

Ultimate resolution for refractometric sensing with whispering gallery mode microcavities.

Many proposed microfluidic biosensor designs are based on the measurement of the resonances of an optical microcavity. Fluorescence-based resonators tend to be simpler and more robust than setups that use evanescent coupling from tuneable laser to probe the cavity. In all sensor designs the detection limits depend on the wavelength resolution of the detection system, which is a limitation of fluorescence-based devices. In this work, we explore the ultimate resolution and detection limits of refractometric microcavity sensor structures. Because many periodic modes are collected simultaneously from fluorescent resonators, standard Fourier methods can be best suited for rapid and precise analysis of the resonance shifts. Simple numerical expressions to calculate the ultimate sensor resolution and detection limits were found, and the results compared to experiments in which the resonances of fluorescent-core microcapillaries responded to various sucrose concentrations in water.

Refractometric sensing with fluorescent-core microcapillaries.

Capillaries present a promising structure for microfluidic refractive index sensors. We demonstrate a capillary-type fluorescent core microcavity sensor based on whispering gallery mode (WGM) resonances. The device consists of a microcapillary having a layer of fluorescent silicon quantum dots (QDs) coated on the channel surface. The high effective index of the QD layer confines the electric field near the capillary channel and causes the development of WGM resonances in the fluorescence spectrum. Solutions consisting of sucrose dissolved in water were pumped through the capillary while the fluorescence WGMs were measured with a spectrometer. The device showed a refractometric sensitivity of 9.8 nm/RIU (up to 13.8 nm/RIU for higher solution refractive index) and a maximum detection limit of ~7.2 x 10(-3) RIU. Modeling the field inside the capillary structure, which is analogous to a layered hollow ring resonator, shows that sensitivities as high as 100 nm/RIU and detection limits as low as ~10(-5) RIU may be achievable by optimizing the QD film thickness.

High-finesse cavities fabricated by buckling self-assembly of a-Si/SiO2 multilayers.

Arrays of half-symmetric Fabry-Perot micro-cavities were fabricated by controlled formation of circular delamination buckles within a-Si/SiO(2) multilayers. Cavity height scales approximately linearly with diameter, in reasonable agreement with predictions based on elastic buckling theory. The measured finesse (F > 10(3)) and quality factors (Q > 10(4) in the 1550 nm range) are close to reflectance limited predictions, indicating that the cavities have low roughness and few defects. Degenerate Hermite-Gaussian and Laguerre-Gaussian modes were observed, suggesting a high degree of cylindrical symmetry. Given their silicon-based fabrication, these cavities hold promise as building blocks for integrated optical sensing systems.

Hollow Bragg waveguides fabricated by controlled buckling of Si/SiO2 multilayers.

We describe integrated air-core waveguides with Bragg reflector claddings, fabricated by controlled delamination and buckling of sputtered Si/SiO2 multilayers. Thin film deposition parameters were tailored to produce a desired amount of compressive stress, and a patterned, embedded fluorocarbon layer was used to define regions of reduced adhesion. Self-assembled air channels formed either spontaneously or upon heating-induced decomposition of the patterned film. Preliminary optical experiments confirmed that light is confined to the air channels by a photonic band-gap guidance mechanism, with loss ~5 dB/cm in the 1550 nm wavelength region. The waveguides employ standard silicon processes and have potential applications in MEMS and lab-on-chip systems.

Silicon nanocrystals on bottle resonators: mode structure, loss mechanisms and emission dynamics.

Bottle resonators can support high Q-factor whispering gallery modes (WGMs) and demonstrate a rich mode spectrum. Resonators were fabricated using a fiber tapering apparatus and were coated with a thin, smooth layer of luminescent silicon nanocrystals. The photoluminescence spectrum showed WGM peaks with Q-factors near 2,500; however, evanescent measurements showed that these modes are a composite of many modes with Q-factors exceeding 106, the highest yet seen for a silicon-nanocrystalcoated microresonators. The mode structure showed strong polarization and sensitivity to position within the bottle resonator. An analysis of loss mechanisms establishes surface roughness scattering as the limiting factor in these nanocrystal-coated bottle resonators in the absence of excited carriers.

Modification of ensemble emission rates and luminescence spectra for inhomogeneously broadened distributions of quantum dots coupled to optical microcavities.

We investigate the spontaneous emission modifications when ensembles of quantum dots (QDs) with differing emission frequencies and finite Lorentzian linewidths are coupled to a microcavity. Using contour integrals we develop a general expression for the rate enhancement when neither the emitter nor the cavity resonance can be treated as a delta function. We show that the ensemble cavity-coupled luminescence lifetimes are generally suppressed in the case of spherical cavities and that the spontaneous emission dynamics of the cavity coupled component becomes increasingly stretched as the coupling factor increases. The Q-factor measured from the luminescence spectrum can be much lower than the intrinsic cavity Q-factor, and is in many practical situations limited by the QD spectral width. The mode spectrum observed in the photoluminescence (PL) spectrum can be largely determined by the QD emission linewidth, permitting this parameter to be extracted without requiring single-particle spectroscopy. In the case of Si-QDs, the linewidth cannot be significantly greater than 10 meV in order to observe spherical cavity resonances in the PL spectrum.

The working practices and career satisfaction of dental therapists in New Zealand.

OBJECTIVE: To describe the working practices and level of career satisfaction of dental therapists in New Zealand. DESIGN: Postal survey of dental therapists identified from the New Zealand Dental Council's dental therapy database. One mailing with one follow-up. PARTICIPANTS: Questionnaires were sent to 683 registered dental therapists. Replies were received from 566 (82.9%). OUTCOME MEASURES: Current working practice, career breaks, continuing education, career satisfaction. RESULTS: Respondents had a high career satisfaction, but were much less satisfied with their remuneration. After controlling for age and income satisfaction, therapists who felt that they were valued members of the dental community had over four times the odds of having higher overall job satisfaction. There were no differences in the mean career satisfaction scale score by age, but respondents aged 45 and over had a lower mean income satisfaction scale score than their younger counterparts (p<0.05). Older respondents were more likely to report regularly placing fissure sealants (p<0.05), participating in peer review (p<0.05), and playing a role in team management/coordination (p<0.05) than younger respondents. Most therapists (412; 82.2%) had taken at least one career break, usually for child rearing. A mean of 6.5 years (SD 5.9; range six weeks to 25 years) had been taken in career breaks. Younger therapists were more interested in moving into private practice than their older colleagues (p<0.05). More than half of respondents planned to retire from dental therapy within 10 years. CONCLUSION: Urgent action is required to improve the recruitment and retention of dental therapists in the New Zealand School Dental Service. Measures to reduce the time taken in career breaks could increase the productivity of this workforce. Remuneration and career progression are key issues; therapists need to feel that they are valued members of the dental profession.

Nanocluster sensitized erbium-doped silicon monoxide waveguides.

We describe the fabrication and characterization of micron-scale buried strip waveguides with erbium-doped (~ 1 at. %) silicon monoxide (SiO) cores and SiO(2) and polymer claddings. In spite of large core-cladding index offset (Deltan~0.4), propagation loss is as low as ~ 1 dB/cm. The cross-section for the (4)I(13/2) to (4)I(15/2) erbium transition was estimated as ~10(-20) cm(2), a factor of 2 to 3 higher than in silica glass. The annealed core material contains a high density of amorphous silicon nanoclusters, which act as efficient broadband sensitizers for erbium. Both a traditional co-propagating pump (980 nm wavelength) configuration and a transverse pump (532 nm wavelength, < 10 W/cm(2)) configuration were tested. In either case, free carrier absorption loss is the dominant pump-induced mechanism and approximately 15-20 % of the erbium population is invertible.

Frontal-striatal disconnection disrupts cognitive performance of the frontal-type in the rat.

The prefrontal cortex is considered to provide executive control of response selection and planning in diverse cognitive tasks, translated into action via descending subcortical projections (or 'loops') through the basal ganglia. We have used a disconnection strategy to demonstrate first that bilateral fronto-striatal disconnection disrupts rats' abilities to perform delayed alternation, the classic test of prefrontal function in rats and monkeys, and second that crossed unilateral cortical and striatal lesions on opposite sides similarly disrupt rats' abilities to perform the same cognitive task. We found that effective disconnection requires interruption of interhemispheric transfer, achieved by transection of the anterior corpus callosum. This produces a moderate deficit in its own right, which is not exacerbated by additional prefrontal and striatal lesions in one hemisphere. Conversely, the animals are significantly more impaired after crossed prefrontal and striatal lesions of similar total magnitude. The results demonstrate than an intact cortico-striatal pathway is necessary to sustain performance on a classical prefrontal task, and provide a model within which to assess circuit reconstruction with novel cell therapies for brain repair.