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1.
J Dent Res ; 101(13): 1590-1596, 2022 12.
Artigo em Inglês | MEDLINE | ID: mdl-36271667

RESUMO

Choosing hypodontia treatment requires young people and parents to consider a large amount of information, identify what is important to them, and make trade-offs between options. This study aimed to examine young people and parents' preferences for hypodontia treatment using discrete choice experiment (DCE). This was a cross-sectional survey of young people (12-16 y) with hypodontia of any severity, at any stage of treatment, and their parents. Participants were recruited from NHS Hospitals in England and Wales. A bespoke DCE questionnaire was developed to measure preferences for 6 attributes of hypodontia treatment (waiting time, treatment time, problems during treatment, discomfort during treatment, bite, appearance). The questionnaire was completed 1) online by young people and parents, individually or together, and 2) by child-parent dyads under observation. Preferences were analyzed using regression models. In total, 204 participants (122 young people, 56 parents, 26 dyads) completed the online questionnaire and 15 child-parent dyads completed the questionnaire under observation. The most important attribute in hypodontia treatment was improvement in appearance, but significant heterogeneity was found in preferences. Four distinct groups of participants were found: group 1 (39%): severe discomfort and problems were most important; group 2 (31%): most concerned about improvement in appearance of teeth and improvement in bite; group 3 (22%): appearance 3 times more important than any other attribute; and group 4 (9%): preferences difficult to interpret. There was variation in how child-parent dyads approached decision-making, with some negotiating joint preferences, while for others, one individual dominated. Making trade-offs in DCE tasks helped some people think about treatment and identify their preferences. Appearance is an important outcome from hypodontia treatment, but preferences vary and potential risks and functional outcome are also important to some people. There is a notable level of uncertainty in decision-making, which suggests further shared decision support would be valuable.


Assuntos
Anodontia , Humanos , Adolescente , Anodontia/terapia , Estudos Transversais , Pais , Inquéritos e Questionários , Inglaterra , Preferência do Paciente
2.
Epidemiol Psychiatr Sci ; 29: e82, 2019 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-31839013

RESUMO

AIMS: This review aims to understand the scope of the literature regarding mental health-related microaggressions towards people affected by mental health problems. METHODS: A scoping review was conducted to explore this question. Four electronic health-oriented databases were searched alongside Google Scholar. As per scoping review principles, the inclusion criteria were developed iteratively. The results of included studies were synthesised using a basic narrative synthesis approach, utilising principles of thematic analysis and thematic synthesis where appropriate. RESULTS: A total of 1196 records were identified, of which 17 met inclusion criteria. Of these, 12 were peer-reviewed journal articles, three were research degree theses and two were book chapters. Six included empirical studies were qualitative, four were quantitative and two employed a mixed-methods design. Within these, five qualitative studies aimed to describe the nature of mental health microaggressions experienced by people with mental health problems. Themes identified in a thematic synthesis of these five studies included stereotypes about mental illness, invalidating peoples' experience and blaming people with mental illness for their condition. The included publications informed on the perpetration of mental health microaggressions by family, friends, health professionals and social workers. In addition, two studies created scales, which were then used in cross-sectional surveys of the general public and community members to assess characteristics, such as right-wing political views, associated with endorsement of mental health microaggressions. A consensus definition of microaggressions emerged from the included studies: microaggressions are brief, everyday slights, snubs or insults, that may be subtle or ambiguous, but communicate a negative message to a target person based on their membership of a marginalised group, in this case, people affected by mental illness. CONCLUSIONS: The study of mental health microaggressions is an emerging, heterogeneous field, embedded in the wider stigma and discrimination literature. It has been influenced by earlier work on racial microaggressions. Both can be ambiguous and contradictory, which creates difficulty defining the boundaries of the concept, but also underpins the key theoretical basis for the negative impact of microaggressions. Mental illness is a more concealable potential type of identity, so it follows that the reported perpetrators of microaggressions are largely friends, family and professionals. This has implications for intervening to reduce the impact of microaggressions. There are several challenges facing research in this area, and further work is needed to understand the impact of mental health microaggressions on people affected by mental health problems.


Assuntos
Agressão/psicologia , Discriminação Psicológica , Transtornos Mentais/psicologia , Pessoas Mentalmente Doentes/psicologia , Preconceito/psicologia , Discriminação Social , Estigma Social , Humanos , Saúde Mental , Grupos Raciais/psicologia , Estereotipagem
3.
Phys Rev Lett ; 123(13): 134801, 2019 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-31697514

RESUMO

An intense, subpicosecond, relativistic electron beam traversing a dielectric-lined waveguide generates very large amplitude electric fields at terahertz (THz) frequencies through the wakefield mechanism. In recent work employing this technique to accelerate charged particles, the generation of high-power, narrow-band THz radiation was demonstrated. The radiated waves contain fields with measured amplitude exceeding 2 GV/m, orders of magnitude greater than those available by other THz generation techniques at a narrow bandwidth. For fields approaching the GV/m level, a strong damping has been observed in SiO_{2}. This wave attenuation with an onset near 850 MV/m is consistent with changes to the conductivity of the dielectric lining and is characterized by a distinctive latching mechanism that is reversible on longer timescales. We describe the detailed measurements that serve to clarify the underlying physical mechanisms leading to strong field-induced damping of THz radiation (hω=1.59 meV, f=0.38 THz) in SiO_{2}, a bulk, wide band-gap (8.9 eV) dielectric.

4.
BMC Vet Res ; 15(1): 27, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30646904

RESUMO

BACKGROUND: Producing graduates for a breadth of sectors is a priority for veterinary science programs. Undergraduate career intentions represent de-facto 'outcome' measures of admissions policy and curricula design, as intentions are strong predictors of eventual behaviour. Informed by Ajzen's Theory of Planned Behaviour, this study aimed to identify if contextually relevant attitudes and self-ratings affect student intentions for veterinary career sectors. RESULTS: Survey responses from 844 students enrolled in five Australian veterinary programs in 2014 were analysed. Intention was measured for biomedical research/academia, industry, laboratory animal medicine, public health/government/diagnostic laboratory services, mixed practice, intensive animal production, companion animal practice, not work in the veterinary profession, and business/entrepreneurship. Hierarchical multiple linear regression analysis enabled comparison of explanation of variance in intent by demographics, animal handling experience, species preference, and attitudes to aspects of veterinary work. Career sector intentions were highest for mixed or companion animal clinical practice, then business/entrepreneurship, then non-clinical sectors. Overall, intent was explained to a greater extent by species preferences than by animal experience, attitudes to aspects of veterinary work and demographics (with the exception of mixed practice intent) with gender having no significant effect. Several variables exerted negative effects on career intent for less popular career sectors. CONCLUSION: Ajzen's Theory of Planned Behaviour (TPB) provides a framework to increase understanding of and predict career sector intentions. Incorporation of attitude and self-efficacy measures in our study revealed preference for species types contributes greatly to career sector intentions for veterinary students, particularly for the more popular practice based sectors. Importantly, specific species preferences and other attitudes can have a negative effect on intent for non-aligned veterinary sectors. Further research is required to identify additional attitudes and/or beliefs to better explain variance in intent for less popular career sectors. Veterinary admissions processes may benefit from utilising the TPB framework. Identified effects revealed by this study may stimulate innovation in marketing, recruitment, admissions and curricular design, such as timing and role modelling, to utilise positive effects and mitigate against negative effects identified for sectors requiring greater representation of career intent in the student body.


Assuntos
Escolha da Profissão , Medicina Veterinária , Atitude , Austrália , Estudos Transversais , Demografia , Feminino , Humanos , Masculino , Medicina Veterinária/tendências , Recursos Humanos
5.
JDR Clin Trans Res ; 3(4): 326-335, 2018 10.
Artigo em Inglês | MEDLINE | ID: mdl-30931788

RESUMO

BACKGROUND: Preference experiments are used to understand how patients and stakeholders value aspects of health care. These methods are gaining popularity in dentistry, but quality and breadth of use have not been evaluated. OBJECTIVES: To describe multiattribute stated preference experiment use in dentistry through illustration and critique of existing studies. DATA SOURCES: Systematic literature search of PubMed, Econlit and Ovid for Medline, Embase, PsychINFO, PsychARTICLES, and All EBM Reviews, as well as gray literature. STUDY ELIGIBILITY: Multiattribute stated preference experiments eliciting preferences for dental service delivery, treatments, and oral health states from the perspective of patients, the public, and dental professionals. Outcomes of interest were preference weights and marginal rates of substitution. Study selection was independently performed by 2 reviewers. APPRAISAL: Ten-point checklist published by the International Society of Pharmacoeconomics and Outcomes Research was used for quality assessment. SYNTHESIS: Descriptive analysis. RESULTS: Searches identified 12 records published between 1999 and 2015, mostly in nondental academic journals. Studies were undertaken in high-income countries in Europe and the United States. The studies aimed to elicit preference for service delivery, treatment, or oral health states from the perspective of the patients, dentists, or the public via discrete choice experiment methods. The quality scores for the studies ranged from 53% to 100%. LIMITATIONS: A detailed description and critique of stated preference methods are provided, but it was not possible to provide synthesized preference data. CONCLUSIONS: Multiattribute stated preference experiments are increasingly popular, but understanding the methods and outputs is essential for designing and interpreting preference studies to improve patient care. Patient preferences highlight important considerations for decision making during treatment planning. Valuation of health states and estimation of willingness-to-pay are important for resource planning and allocation and economic evaluation. Preference estimates and relative value of attributes for interventions and service delivery inform development and selection of treatments and services (PROSPERO 21.3.17: CRD42017059859). KNOWLEDGE TRANSFER STATEMENT: Understanding patient, professional, and public preferences is fundamental for evidence-based decision making and treatment delivery. Preference elicitation methods can be used to estimate the value given to health states, service delivery, individual treatments, and health outcomes. By describing and appraising the methodology and application of multiattribute stated preference experiments in dentistry, this review provides an essential first step to wider use of well-designed, high-quality preference elicitation methods.


Assuntos
Tomada de Decisões , Preferência do Paciente , Atenção à Saúde , Odontologia , Europa (Continente) , Humanos , Estados Unidos
6.
Aust Vet J ; 95(10): 392-400, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28948623

RESUMO

OBJECTIVE: Regarded as one of the most expensive production diseases of dairy sheep and goats, contagious agalactia (CA) is caused by any of four agents: Mycoplasma agalactiae, M. mycoides subspecies capri (Mmc), M. capricolum subspecies capricolum (Mcc) and M. putrefaciens. Although CA is worldwide in distribution, it has not been reported in Australia, even though studies between the 1950s and 1980s isolated each agent from sheep or goats without any clinical signs associated with it. The aim of this study was to examine sheep and goats in Victoria, Australia, for the presence of CA-associated mycoplasmas and to investigate the evolutionary relationships of these isolates by comparing their genetic differences with their counterparts from other parts of the world. METHODS: A 3-year epidemiological survey of small ruminant populations in Victoria, Australia, was conducted for the presence of CA-associated mycoplasmas and the isolates obtained were genotyped by multilocus sequence typing (MLST). RESULTS: Mmc was the only CA-associated agent isolated from the 1358 samples analysed in the study, but was not associated with CA on the property where it was found. MLST analyses of Mmc strains revealed a distinct clustering of Australian isolates into a novel clade, with the closest relatives being strains from Europe. The distinct clustering is consistent with the absence of clinical disease in Australia. CONCLUSION: The isolation of Mmc indicates that this subspecies persists in Australian small ruminant populations. However, full genome sequencing and in vitro animal experimentation are needed to unequivocally demonstrate the avirulence of Australian strains.


Assuntos
Doenças das Cabras/epidemiologia , Infecções por Mycoplasma/veterinária , Mycoplasma mycoides/isolamento & purificação , Doenças dos Ovinos/epidemiologia , Animais , Doenças das Cabras/microbiologia , Cabras , Epidemiologia Molecular , Tipagem de Sequências Multilocus , Infecções por Mycoplasma/microbiologia , Mycoplasma mycoides/classificação , Mycoplasma mycoides/genética , Ovinos , Doenças dos Ovinos/microbiologia , Inquéritos e Questionários , Vitória/epidemiologia
7.
Phys Rev Lett ; 119(10): 104801, 2017 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-28949165

RESUMO

Single-shot, charge-dependent emittance measurements of electron beams generated by a laser plasma accelerator (LPA) reveal that shock-induced density down-ramp injection produces beams with normalized emittances a factor of 2 smaller than beams produced via ionization injection. Such a comparison is made possible by the tunable LPA setup, which allows electron beams with nearly identical central energy and peak spectral charge density to be produced using the two distinct injection mechanisms. Parametric measurements of this type are essential for the development of LPA-based applications which ultimately require high charge density and low emittance.

8.
Diabet Med ; 34(11): 1575-1583, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28744894

RESUMO

AIMS: To validate the Leicester Self-Assessment score using a representative English dataset for detecting prevalent non-diabetic hyperglycaemia or undiagnosed Type 2 diabetes (defined as HbA1c ≥6.0%) and for identifying those who may go on to develop Type 2 diabetes within 10 years. METHODS: Data were taken from the English Longitudinal Study of Ageing, a nationally representative dataset of people aged ≥50 years. The area under the receiver-operator curve and performance metrics for the score at the recommended score threshold (≥16), were calculated for the outcomes of HbA1c ≥42 mmol/mol (6.0%) at baseline and self-reported Type 2 diabetes within 10 years in those aged 50-75 years at baseline. RESULTS: A total of 3203 individuals had a baseline HbA1c measurement, of whom 247 (7.7%) had an HbA1c concentration ≥42 mmol/mol (6.0%). The area under the receiver-operator curve was 69.4% (95% CI 66.0-72.9) for baseline HbA1c ≥42 mmol/mol. A total of 3550 individuals had diabetes status recorded at 10 years, of whom 324 (9.1%) were diagnosed with Type 2 diabetes within this time; the area under the receiver-operator curve for this outcome was 74.9% (95% CI 72.4-77.5). The score threshold of ≥16 had a sensitivity of 89.2% (95% CI 85.3-92.4) and a specificity of 42.3% (95% CI 40.5-44.0) for Type 2 diabetes within 10 years. CONCLUSIONS: The Leicester Self-Assessment score is validated for use across England to identify people with non-diabetic hyperglycaemia or undiagnosed Type 2 diabetes. Those with a high score are at high risk of developing diabetes in the future.


Assuntos
Envelhecimento/sangue , Diabetes Mellitus Tipo 2/diagnóstico , Autoavaliação Diagnóstica , Adulto , Idoso , Envelhecimento/fisiologia , Doenças Assintomáticas , Glicemia/análise , Diabetes Mellitus Tipo 2/sangue , Inglaterra , Feminino , Hemoglobinas Glicadas/análise , Humanos , Hiperglicemia/sangue , Hiperglicemia/diagnóstico , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Estado Pré-Diabético/sangue , Estado Pré-Diabético/diagnóstico , Projetos de Pesquisa , Sensibilidade e Especificidade
9.
Philos Trans A Math Phys Eng Sci ; 375(2094)2017 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-28416724

RESUMO

The Ptolemy instrument on the Philae lander (of the Rosetta space mission) was able to make measurements of the major volatiles, water, carbon monoxide and carbon dioxide, directly at the surface of comet 67P/Churyumov-Gerasimenko. We give some background to the mission and highlight those instruments that have already given insights into the notion of water in comets, and which will continue to do so as more results are either acquired or more fully interpreted. On the basis of our results, we show how comets may in fact be heterogeneous over their surface, and how surface measurements can be used in a quest to comprehend the daily cycles of processes that affect the evolution of comets.This article is part of the themed issue 'The origin, history and role of water in the evolution of the inner Solar System'.

10.
Br Dent J ; 222(5): 368-372, 2017 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-28281597

RESUMO

Introduction The Index of Orthognathic Functional Treatment Need (IOFTN) was developed to measure functional difficulties arising from malocclusions related to facial deformity. The IOFTN is not currently being used to determine suitability for orthognathic treatment, however, it is a useful aid for assessing and referring patients and takes into account functional and facial appearance. This paper aims to evaluate the potential impact of introduction of the IOFTN on the future provision of orthognathic services.Methods Two methods were used to consider the impact of the IOFTN on orthognathic provision. Firstly, a local retrospective audit was undertaken in Leeds Teaching Hospital NHS Trust involving thirty consecutively treated patients, for whom full records were retrieved. Data was collected using a standardised data caption form. Local standards were agreed concerning the need for treatment. Secondly, a systematic search of published studies was completed to assess evidence from across the UK.Results The audit standard, that is, 90% of patients treated with orthognathic surgery should be categorised as grade 4 (great need) or 5 (very great need) using the IOFTN, was fulfilled. The most common reason for seeking treatment related to dental and facial aesthetics and no patients were treated for speech or TMJ problems alone. The systematic review searches identified four suitable records for inclusion in the review, including two audits and two retrospective studies undertaken in secondary care settings across England and Scotland. These studies showed that at least 86% of all participants scored 4 or 5 using the IOFTN.Conclusions The findings from the audit and literature review indicate that referrals from general dentists and acceptance for orthognathic treatment in secondary care is unlikely to be significantly affected by introduction of the IOFTN. Referring dentists may find the IOFTN a useful prompt for determining whether people are suitable for orthognathic treatment.


Assuntos
Índice de Necessidade de Tratamento Ortodôntico , Procedimentos Cirúrgicos Ortognáticos , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Encaminhamento e Consulta , Estudos Retrospectivos , Adulto Jovem
11.
Phys Rev Lett ; 118(5): 054802, 2017 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-28211719

RESUMO

Temporal pulse tailoring of charged-particle beams is essential to optimize efficiency in collinear wakefield acceleration schemes. In this Letter, we demonstrate a novel phase space manipulation method that employs a beam wakefield interaction in a dielectric structure, followed by bunch compression in a permanent magnet chicane, to longitudinally tailor the pulse shape of an electron beam. This compact, passive, approach was used to generate a nearly linearly ramped current profile in a relativistic electron beam experiment carried out at the Brookhaven National Laboratory Accelerator Test Facility. Here, we report on these experimental results including beam and wakefield diagnostics and pulse profile reconstruction techniques.

12.
Nat Commun ; 7: 12763, 2016 09 14.
Artigo em Inglês | MEDLINE | ID: mdl-27624348

RESUMO

There is urgent need to develop new acceleration techniques capable of exceeding gigaelectron-volt-per-metre (GeV m(-1)) gradients in order to enable future generations of both light sources and high-energy physics experiments. To address this need, short wavelength accelerators based on wakefields, where an intense relativistic electron beam radiates the demanded fields directly into the accelerator structure or medium, are currently under intense investigation. One such wakefield based accelerator, the dielectric wakefield accelerator, uses a dielectric lined-waveguide to support a wakefield used for acceleration. Here we show gradients of 1.347±0.020 GeV m(-1) using a dielectric wakefield accelerator of 15 cm length, with sub-millimetre transverse aperture, by measuring changes of the kinetic state of relativistic electron beams. We follow this measurement by demonstrating accelerating gradients of 320±17 MeV m(-1). Both measurements improve on previous measurements by and order of magnitude and show promise for dielectric wakefield accelerators as sources of high-energy electrons.

13.
Rev Sci Instrum ; 87(5): 051906, 2016 05.
Artigo em Inglês | MEDLINE | ID: mdl-27250378

RESUMO

During the last ten years, deflectometric profilometers have become indispensable tools for the precision form measurement of optical surfaces. They have proven to be especially suitable for characterizing beam-shaping optical surfaces for x-ray beamline applications at synchrotrons and free electron lasers. Deflectometric profilometers use surface slope (angle) to assess topography and utilize commercial autocollimators for the contactless slope measurement. To this purpose, the autocollimator beam is deflected by a movable optical square (or pentaprism) towards the surface where a co-moving aperture limits and defines the beam footprint. In this paper, we focus on the precise and reproducible alignment of the aperture relative to the autocollimator's optical axis. Its alignment needs to be maintained while it is scanned across the surface under test. The reproducibility of the autocollimator's measuring conditions during calibration and during its use in the profilometer is of crucial importance to providing precise and traceable angle metrology. In the first part of the paper, we present the aperture alignment procedure developed at the Advanced Light Source, Lawrence Berkeley National Laboratory, USA, for the use of their deflectometric profilometers. In the second part, we investigate the topic further by providing extensive ray tracing simulations and calibrations of a commercial autocollimator performed at the Physikalisch-Technische Bundesanstalt, Germany, for evaluating the effects of the positioning of the aperture on the autocollimator's angle response. The investigations which we performed are crucial for reaching fundamental metrological limits in deflectometric profilometry.

14.
Science ; 349(6247): aab0673, 2015 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-26228155

RESUMO

The surface and subsurface of comets preserve material from the formation of the solar system. The properties of cometary material thus provide insight into the physical and chemical conditions during their formation. We present mass spectra taken by the Ptolemy instrument 20 minutes after the initial touchdown of the Philae lander on the surface of comet 67P/Churyumov-Gerasimenko. Regular mass distributions indicate the presence of a sequence of compounds with additional -CH2- and -O- groups (mass/charge ratios 14 and 16, respectively). Similarities with the detected coma species of comet Halley suggest the presence of a radiation-induced polymer at the surface. Ptolemy measurements also indicate an apparent absence of aromatic compounds such as benzene, a lack of sulfur-bearing species, and very low concentrations of nitrogenous material.

15.
J Aging Phys Act ; 23(1): 133-43, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24515976

RESUMO

BACKGROUND: Physical activity is important for maintaining independence and quality of life in older people living in care homes. Little is known about patterns of physical activity or sedentary behavior in this population. METHODS: Thirty-three care home residents (82.6 ± 9.2 years) wore an ActiGraph GTX3 accelerometer for seven days, which provided minutes of sedentary behavior and low, light, and moderate-to-vigorous physical activity. Participants undertook the Mini-Mental State Examination and care staff reported activities of daily living (Barthel index) and functional ambulation classification (FAC) for each participant. RESULTS: Participants spent on average 79% of their day sedentary, 14% in low, 6% in light, and 1% in moderate-to-vigorous physical activity. Activity levels did not significantly differ between days or hours of the day (P > .05). CONCLUSION: Levels of physical activity were very low and time being sedentary was high. This study can inform physical activity and sedentary behavior interventions for care homes' residents.


Assuntos
Atividades Cotidianas , Comportamentos Relacionados com a Saúde , Atividade Motora/fisiologia , Qualidade de Vida/psicologia , Comportamento Sedentário , Acelerometria , Actigrafia , Idoso , Idoso de 80 Anos ou mais , Feminino , Serviços de Assistência Domiciliar , Humanos , Masculino , Reino Unido
16.
Nat Commun ; 5: 4962, 2014 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-25230052

RESUMO

Knowledge of and control over the curvature of ripples in freestanding graphene are desirable for fabricating and designing flexible electronic devices, and recent progress in these pursuits has been achieved using several advanced techniques such as scanning tunnelling microscopy. The electrostatic forces induced through a bias voltage (or gate voltage) were used to manipulate the interaction of freestanding graphene with a tip (substrate). Such forces can cause large movements and sudden changes in curvature through mirror buckling. Here we explore an alternative mechanism, thermal load, to control the curvature of graphene. We demonstrate thermal mirror buckling of graphene by scanning tunnelling microscopy and large-scale molecular dynamic simulations. The negative thermal expansion coefficient of graphene is an essential ingredient in explaining the observed effects. This new control mechanism represents a fundamental advance in understanding the influence of temperature gradients on the dynamics of freestanding graphene and future applications with electro-thermal-mechanical nanodevices.

17.
Nat Commun ; 5: 3720, 2014 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-24770734

RESUMO

Intrinsic ripples in freestanding graphene have been exceedingly difficult to study. Individual ripple geometry was recently imaged using scanning tunnelling microscopy, but these measurements are limited to static configurations. Thermally-activated flexural phonon modes should generate dynamic changes in curvature. Here we show how to track the vertical movement of a one-square-angstrom region of freestanding graphene using scanning tunnelling microscopy, thereby allowing measurement of the out-of-plane time trajectory and fluctuations over long time periods. We also present a model from elasticity theory to explain the very-low-frequency oscillations. Unexpectedly, we sometimes detect a sudden colossal jump, which we interpret as due to mirror buckling. This innovative technique provides a much needed atomic-scale probe for the time-dependent behaviours of intrinsic ripples. The discovery of this novel progenitor represents a fundamental advance in the use of scanning tunnelling microscopy, which together with the application of a thermal load provides a low-frequency nano-resonator.


Assuntos
Grafite/química , Microscopia de Tunelamento/métodos , Modelos Químicos , Nanotecnologia/métodos , Elasticidade , Fônons , Temperatura
18.
Phys Rev Lett ; 113(26): 264801, 2014 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-25615344

RESUMO

We report experimental measurements of narrow-band, single-mode excitation, and drive beam energy modulation, in a dielectric wakefield accelerating structure with planar geometry and Bragg-reflector boundaries. A short, relativistic electron beam (∼1 ps) with moderate charge (∼100 pC) is used to drive the wakefields in the structure. The fundamental mode of the structure is reinforced by constructive interference in the alternating dielectric layers at the boundary, and is characterized by the spectral analysis of the emitted coherent Cherenkov radiation signal. Data analysis shows a narrow-band peak at 210 GHz corresponding to the fundamental mode of the structure. Simulations in both 2D and 3D provide insight into the propagating fields and reproduction of the electron beams dynamics observables and emitted radiation characteristics.

19.
Ann Clin Biochem ; 50(Pt 3): 267-70, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23605131

RESUMO

BACKGROUND: Cystic fibrosis (CF) is an autosomal recessive condition that has an incidence of 1:2500 live births in Northern Europe. Due to the large number of mutations that can result in classical or atypical CF phenotype, the sweat test, which quantifies the amount of chloride and sodium in sweat, is vital in supporting the diagnosis of CF. Patients with CF have raised concentrations of chloride and sodium in their sweat; however, it is the concentration of chloride in sweat which provides the greatest diagnostic sensitivity for CF. METHOD: An inductively coupled plasma mass spectrometry (ICP-MS) method for the analysis of sweat chloride and sodium was evaluated for the routine measurement of sweat collected using the Wescor Macroduct(®) Sweat Collection System. The precision, linearity and agreement with the all laboratories trimmed means (ALTMs) and 'weighed-in' concentrations of sodium and chloride in samples supplied by the UK NEQAS external quality assessment (EQA) Sweat Testing Scheme were assessed. RESULTS: This ICP-MS method for the quantification of chloride and sodium in sweat samples was shown to be accurate, precise and suitable for the routine analysis of sweat chloride and sodium. CONCLUSION: The method performs well and is now used in the routine analysis of sweat in this laboratory.


Assuntos
Cloretos/análise , Fibrose Cística/diagnóstico , Espectrometria de Massas/métodos , Sódio/análise , Suor/química , Fibrose Cística/genética , Humanos
20.
Int Endod J ; 45(11): 1042-52, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23039120

RESUMO

The aim of designing and fabricating the surgical templates was to assist the surgical component of premolar transplantation, by establishing and replicating the root dimensions of the donor premolar tooth. The correct template could be used to assess the socket preparation (width and depth) prior to placement of the transplant in the recipient site, obviating the need to repeatedly try the donor tooth for fit at the recipient site, thereby minimising trauma to the periodontal ligament of the donor tooth. Seventy-five mandibular premolars and 50 maxillary second premolars were selected with varying stages of root development. All teeth had been extracted for orthodontic reasons. The root was measured for its length (maxL) and maximum (maxW) and minimum width (minW) with digital callipers from standardised reference points. These measurements were then used in the design of premolar transplant templates. The mean measurements for second maxillary premolars were maxL 14.6 mm (± 1.7), maxW 8.3 mm (± 0.5) and minW 4.9 (± 0.3). The mean measurements for mandibular premolars were maxL 14.8 (± 1.6), maxW 7.4 (± 0.6) and minW 5.3 (± 0.5). From these measurements, a range of maxillary second premolar and mandibular premolar templates have been fabricated. These figures also inform the multidisciplinary planning process for the space requirements at the donor site prior to transplantation.


Assuntos
Anatomia Transversal , Dente Pré-Molar/transplante , Modelos Anatômicos , Alvéolo Dental/anatomia & histologia , Adolescente , Dente Pré-Molar/anatomia & histologia , Precisão da Medição Dimensional , Humanos , Planejamento de Assistência ao Paciente , Estudos Prospectivos , Raiz Dentária/anatomia & histologia , Transplante Autólogo
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