595 research outputs found

    Caries associated with orthodontic care part 1: aetiology, prevalence and prevention

    Get PDF
    The prevalence of demineralization, or enamel caries which is the first clinically recognizable stage of caries, has been reported to be as high as 73% during fixed appliance treatment. It is recognized that wearing an orthodontic appliance increases the caries risk of the individual. The orthodontist can effectively reduce demineralization by applying fluoride varnish at each visit. Selecting patients on their oral hygiene clearly is one factor which can prevent patients suffering from demineralization. Excellent home care with optimal use of fluoride will also help prevent the condition. There is little evidence that fluoride-releasing materials used for bonding orthodontic appliances offer protection from demineralization. The first of these two papers describes the aetiology, prevalence and prevention of demineralization associated with orthodontic care. The second paper will describe the treatments available to manage caries focusing on demineralization post orthodontic treatment. CPD/Clinical Relevance: Demineralization is the most common complication of orthodontic care. The clinician should understand how to prevent this

    A química na junk food: uma proposta para o ensino de ligações químicas por meio do enfoque CTS

    Get PDF
    Acompanha : Guia didático: a química na junk food: uma proposta para o ensino de ligações químicas por meio do enfoque CTSThe aim of this study is to propose teaching strategies in CTS approach to teaching with emphasis on Chemical Bonds Ionic and Covalent Links . In this sense the present study was developed and applied in a public school teaching of Paraná, in the town of Telêmaco Borba , in two classes of the second ( 2nd ) series of technical education integrated into the school , totaling 42 students . The methodological approach was qualitative approach, interpretative participant observation . For data collection were used : photos , recordings and videos Pleas oral activities fully transcribed , field notes on observation protocols of interactions of day- to-day classroom , quizzes and activities for students . The activities we developed in eighteen (18) classes, which interlinked the chemical concepts of Chemical Bonds to controversial social issue (Junk Food), in order to promote inter - relations aspects of science, technology and society. The main results showed that the proposed activities, the teaching of Chemical Bonds, through social theme Junk Food, promoted the appreciation of scientific knowledge surpassing the barriers of the classroom to the social context of the learners. For the activities in the modules, provided the relationships between school subjects and everyday aspects of students. Achieving the goals of the proposed CTS for citizenship. Another result obtained includes the preparation of a didactic guide which aims to share activities developed in this study as methodological suggestion for professionals who teach chemistry, and act in the final year of elementary school, high school and technical.O objetivo deste estudo é propor estratégias de ensino no enfoque CTS para o ensino de Ligações Químicas com ênfase nas Ligações Iônica e Covalente. Nesse sentido o presente estudo foi desenvolvido e aplicado em uma escola da rede pública de ensino do Paraná, na cidade de Telêmaco Borba, em duas turmas da segunda (2ª) série do ensino técnico integrado ao ensino médio, totalizando 42 alunos. A abordagem metodológica foi abordagem qualitativa, de natureza interpretativa com observação participante. Para a coleta de dados foram utilizados: fotos, gravações de arguições orais e vídeos de atividades transcritos na íntegra, anotações de campo em protocolos de observação das interações do dia-a-dia na sala de aula, questionários e atividades desenvolvidas pelos alunos. As atividades foram desenvolvidas em dezoito (18) aulas, as quais interligaram os conceitos químicos de Ligações Químicas ao tema social controverso (Junk Food), de forma a promover as inter-relações dos aspectos da ciência, tecnologia e sociedade. Os principais resultados obtidos evidenciaram que pelas atividades propostas, o ensino de Ligações Químicas, por meio do tema social Junk Food, promoveu a valorização do conhecimento científico extrapolando as barreiras da sala de aula para o contexto social dos educandos. Pois as atividades desenvolvidas nos módulos, proporcionou as relações entre os conteúdos escolares e os aspectos cotidianos dos alunos. Alcançando os objetivos da proposta CTS para a cidadania. Outro resultado alcançado compreende a elaboração de um guia didático que tem por objetivo compartilhar atividades desenvolvidas neste estudo, como sugestão metodológica para os profissionais que lecionam Química, e atuam no ano final do Ensino Fundamental, Ensino Médio e Técnico

    Monolithic MHz-frame rate digital SiPM-IC with sub-100 ps precision and 70 μ~\mum pixel pitch

    Full text link
    This paper presents the design and characterization of a monolithic integrated circuit (IC) including digital silicon photomultipliers (dSiPMs) arranged in a 32 × ~\times~32 pixel matrix at 70 μ~\mum pitch. The IC provides per-quadrant time stamping and hit-map readout, and is fabricated in a standard 150-nm CMOS technology. Each dSiPM pixel consists of four single-photon avalanche diodes (SPADs) sharing a quenching and subsequent processing circuitry and has a fill factor of 30 %~\%. A sub-100 ~ps precision, 12-bit time-to-digital converter (TDC) provides timestamps per quadrant with an acquisition rate of 3 ~MHz. Together with the hit map, the total sustained data throughput of the IC amounts to 4 ~Gbps. Measurements obtained in a dark, temperature-stable environment as well as by using a pulsed laser environment show the full dSiPM-IC functionality. The dark-count rate (DCR) as function of the overvoltage and temperature, the TDC resolution, differential and integral nonlinearity (DNL/INL) as well as the propagation-delay variations across the matrix are presented. With aid of additional peripheral test structures, the main building blocks are characterized and key parameters are presented.Comment: 16 pages, 13 figures, 1 tabl

    King cobra bite - Can early decompression prevent digital amputation?

    Get PDF
    King cobra bites are extremely rare in the western world. These bites can be fatal due to the large volume of the venom injected. We report a case of digital ischaemia from a King cobra bite in a young man who was working in a zoo in Netherlands. He was protected from systemic envenomation as he was wearing a protective glove. However, his right index finger developed subsequent gangrene and he underwent a ray amputation. The current literature on the management of snake bites to hands is reviewed and the role of early decompression discussed

    DTS-100G — a versatile heterogeneous MPSoC board for cryogenic sensor readout

    Get PDF
    Heterogeneous devices such as the Multi-Processor System-on-Chip (MPSoC) from Xilinx are extremely valuable in custom instrumentation systems. This contribution presents the joint development of a heterogeneous MPSoC board called DTS-100G by DESY and KIT. The board is built around a Xilinx Zynq Ultrascale+ chip offering all available high-speed transceivers using QSFP28, 28 Gbps FireFly, FMC, and FMC+ interfaces. The board is not designed for a particular application, but can be used as a generic DAQ platform for a variety of physics experiments. The DTS-100G board was successfully developed, built and commissioned. ECHo-100k is the first experiment which will employ the board. This contribution shows the system architecture and explains how the DTS-100G board is a crucial component in the DAQ chain

    Enhanced production of multi-strange hadrons in high-multiplicity proton-proton collisions

    Get PDF
    At sufficiently high temperature and energy density, nuclear matter undergoes a transition to a phase in which quarks and gluons are not confined: the quark-gluon plasma (QGP)(1). Such an exotic state of strongly interacting quantum chromodynamics matter is produced in the laboratory in heavy nuclei high-energy collisions, where an enhanced production of strange hadrons is observed(2-6). Strangeness enhancement, originally proposed as a signature of QGP formation in nuclear collisions(7), is more pronounced for multi-strange baryons. Several effects typical of heavy-ion phenomenology have been observed in high-multiplicity proton-proton (pp) collisions(8,9), but the enhanced production of multi-strange particles has not been reported so far. Here we present the first observation of strangeness enhancement in high-multiplicity proton-proton collisions. We find that the integrated yields of strange and multi-strange particles, relative to pions, increases significantly with the event charged-particle multiplicity. The measurements are in remarkable agreement with the p-Pb collision results(10,11), indicating that the phenomenon is related to the final system created in the collision. In high-multiplicity events strangeness production reaches values similar to those observed in Pb-Pb collisions, where a QGP is formed.Peer reviewe

    Transient Monte Carlo Simulations for the Optimisation and Characterisation of Monolithic Silicon Sensors

    Full text link
    An ever-increasing demand for high-performance silicon sensors requires complex sensor designs that are challenging to simulate and model. The combination of electrostatic finite element simulations with a transient Monte Carlo approach provides simultaneous access to precise sensor modelling and high statistics. The high simulation statistics enable the inclusion of Landau fluctuations and production of secondary particles, which offers a realistic simulation scenario. The transient simulation approach is an important tool to achieve an accurate time-resolved description of the sensor, which is crucial in the face of novel detector prototypes with increasingly precise timing capabilities. The simulated time resolution as a function of operating parameters as well as the full transient pulse can be monitored and assessed, which offers a new perspective on the optimisation and characterisation of silicon sensors. In this paper, a combination of electrostatic finite-element simulations using 3D TCAD and transient Monte Carlo simulations with the Allpix Squared framework are presented for a monolithic CMOS pixel sensor with a small collection diode, that is characterised by a highly inhomogeneous, complex electric field. The results are compared to transient 3D TCAD simulations that offer a precise simulation of the transient behaviour but long computation times. Additionally, the simulations are benchmarked against test-beam data and good agreement is found for the performance parameters over a wide range of different operation conditions

    Assessment of Renal Functions and Lesions in Dogs with Serological Diagnosis of Canine Visceral Leishmaniasis

    Get PDF
    Background: Visceral leishmaniasis is a complex vector-borne disease caused by the protozoan Leishmania infantum. In urban centers of South America, where this zoonotic cycle occurs, dogs seem to be the main reservoirs and infection sources. Animals with canine visceral leishmaniasis (CVL) may have a wide clinical spectrum, and dogs are usually classified as asymptomatic, oligosymptomatic, and symptomatic. Several organs are affected in canine CVL, and renal involvement is often a determining factor in dog prognosis. Nevertheless, serum markers are slow to indicate loss of renal function. The aim of this studywas to evaluate kidney impairment in dogs diagnosed with CVL.Material, Methods & Results: Blood and urine samples were collected from 45 dogs from Barra Mansa-RJ, and used for urinalysis, urine protein/creatinine (UPC) ratio, and serum concentrations of urea and creatinine. The animals were classified as symptomatic (42.2%), oligosymptomatic (37.8%), and asymptomatic (20.0%). Some alterations were found in the urine samples; pale-yellow color in 17.8%, low specific gravity in 6.7%, turbidity in 51.1%, proteinuria in 80%, occult blood in 46.7%, bilirubin in 8.89%, and glucose in 6.7% of the samples. According to the UPC ratio, 60% of dogs were proteinuric, and UPC > 2.0 was high in symptomatic dogs. Azotemia was observed only in three dogs with CVL.Discussion: The majority of dogs presented one or more symptoms of CVL, as expected in an endemic area from Brazil. Pale-yellow urine was observed in some samples, and this change, when accompanied by the decreased urine specific gravity in dogs with CVL, suggests some degree of kidney disease. The presence of epithelial and red blood cells, leukocytes, bacteria, suspended mucus, and phosphate crystals that precipitate in alkaline urines could be associated, to some degree, with the urine turbidity found in the present study. The alkaline urine identified in some dogs could be related to the animals’ diet, but renal tubular acidosis (RTA) is another possible cause when referring to animals with CVL. The abnormal presence of bilirubin and glycosuria can be justified by liver damage and glomerular and tubular damage, respectively. Occult blood was found in the urine of almost half of the tested dogs, which occurred because of the presence of red blood cells in the urine sediment and hematuria in some animals, could be caused by tubular and glomerular lesions. The presence of granular and hyaline casts found in the samples reinforce the possibility of tubular injury. We found different levels of proteinuria; it was an important result, possibly caused by immune complex deposition in addition to tubular disease. Most tested dogs, including animals without clinical manifestation, were classified as proteinuric or borderline proteinuric, showing that the renal disease could be the only clinical manifestation of CVL and that it could progress from slight proteinuria to end-stage renal disease, resulting in chronic renal failure, which is the main cause of death. The UPC ratio > 2.0 was significantly the more frequent finding in this study, mainly in symptomatic dogs. This result indicates a glomerular disease in these animals, reinforcing that the progression of renal disease follows the clinical progression of CVL. A few serum samples showed increased urea and creatinine levels, proving that azotemia is an uncommon finding in CVL-infected dogs. In conclusion, urinalysis helped in the early identification of renal injury in CVL-infected dogs, highlighting elements that reinforce the presence of tubular or glomerular lesions, or both, even in non-azotemic dogs. The high frequency of symptomatic dogs with UPC ratio > 2.0 suggests a relationship between the progression of renal disease and the clinical progression of CVL
    corecore