Nivelación propedéutica y rendimiento académico en la Universidad Bernardo O'Higgins de Chile / Preparatory leveling and academic performance in Bernardo O'Higgins University of Chile

Introducción: Esta investigación presenta los resultados preliminares del plan de Nivelación académica de la Universidad Bernardo O´Higgins, realizado en 2018 y denominado Nivelación Cero. Este proyecto es parte de la estrategia institucional, diseñada como una extensión del programa de nivelación de la universidad, para apoyar a los estudiantes nuevos en el repaso de contenidos escolares y estrategias de autogestión, para afrontar las exigencias del primer año de estudios. Objetivo: Exponer en qué medida un plan de acompañamiento propedéutico contribuye con la mejora del rendimiento en los estudiantes de nuevo ingreso. Métodos: En marzo de 2018 se llevó a cabo un estudio comparativo basado en un análisis estadístico multivariado (hj-Biplot), sobre los resultados obtenidos en la aprobación semestral general y en las asignaturas críticas de la formación, situados en el primer semestre de carrera. Resultado: La aplicación del programa de Nivelación Cero en el primer semestre de 2018 determinó de forma positiva la cantidad de aprobación en materias críticas de la carrera elegida. Conclusiones: Esta experiencia da cuenta de la importancia que tiene la realización de procesos de nivelación, tendientes a hacer del sistema universitario un espacio que promueva la equidad(AU)

ABSTRACT Introduction: This research presents the preliminary results of Bernardo O'Higgins University's academic leveling plan, carried out in 2018 and called "Nivelación Cero" [Zero Leveling]. This project is part of the institutional strategy designed as an extension of the university's leveling program, in order to support new students in reviewing school content and regarding self-management strategies, to face the demands of the first academic year. Objective: To expose to what extent a preparatory support plan contributes to improving the performance of new students. Methods: In March 2018, a comparative study was carried out based on a multivariate statistical analysis (hj-Biplot), on the results obtained in the general semester completion qualification as well as in the critical subjects of the training, located in the first semester of the major. Results: The application of the "Nivelación Cero" program in the first semester of 2018 positively determined the amount of completion qualification in critical subjects of the chosen major. Conclusions: This experience shows the importance of carrying out leveling processes, aimed at making the university system a space that promotes equity.

Separation of aligning and leveling stages to control mandibular incisor inclination: A randomized clinical trial

ABSTRACT Objective: To determine whether separating the alignment and leveling phases can reduce proclination of the mandibular incisors. Methods: Eligibility criteria included Class I subjects with an irregularity index of 3-5 mm, 3-4 mm curve-of-Spee (COS), and non-extraction treatment. Thirty adults were randomly allocated into two groups: (1) Control group was leveled and aligned simultaneously with flat archwires progressively to 0.016x0.022-in stainless-steel; (2) Experimental group was aligned first with 0.014-in-superelastic NiTi with mild accentuated COS, then leveled using 0.016x0.022-in beta-titanium accentuated COS archwires and gradually reduced the curve until flat. Mandibular incisor position and inclination were evaluated by cephalometric analysis. COS and irregularity index were evaluated in study models. Assessment was conducted twice after 0.016-in NiTi and after 0.016x0.022-in stainless-steel archwire placements. Dental changes from cephalograms and models were compared within group using paired t-test and between groups using independent t-test. Results: Control group: Round-wire-phase, mandibular incisors tipped labially (4.38° and 1 mm) with intrusion (-1.13 mm); Rectangular-wire-phase, mandibular incisors further intruded and proclined (-0.63 mm and 1.38°). Experimental group: During aligning with round accentuated COS archwires, mandibular incisors tipped very slightly labially (0.75° and 0.50 mm) with no significant intrusion; during leveling with rectangular archwires, incisors majorly intruded (1.75 mm) with slight proclination (1.81°). The experimental group had significant less incisor proclination (control: 5.76°, experimental: 2.56°) with more incisor intrusion (control: -1.75 mm, experimental: -2.13 mm). The COS in experimental group showed significant greater reduction (-2.88 mm) than that of the control group (-1.69 mm). Conclusion: In control group, mandibular incisor proclination was markedly observed in round archwires, with further proclination caused by rectangular archwires. In experimental group, minimal proclination was exhibited when accentuated COS round archwires were used for aligning. Leveling with rectangular archwires caused less proclination with more COS reduction.

RESUMO Objetivo: Avaliar se separar os estágios de alinhamento e nivelamento reduz a projeção dos incisivos inferiores. Métodos: Os critérios de inclusão foram indivíduos Classe I com índice de irregularidade de 3-5mm, Curva de Spee (CS) de 3-4mm e tratamento sem extrações. Trinta adultos foram alocados aleatoriamente em dois grupos: o Grupo Controle (1) foi simultaneamente alinhado e nivelado com arcos planos progressivamente até atingir o 0,016" x 0,022" de aço inoxidável; o Grupo Experimental (2) foi inicialmente alinhado com arcos superelásticos NiTi 0,014" com CS levemente aumentada, em seguida nivelado com arcos de beta-titânio 0,016" x 0,022" com CS acentuada, que foi gradualmente reduzida até ficar plana. A posição e inclinação dos incisivos inferiores foram avaliadas por meio de análise cefalométrica. A CS e o índice de irregularidade foram avaliados por meio de modelos de estudo. A avaliação foi realizada duas vezes, sendo após a inserção dos arcos NiTi 0,016" e dos arcos 0,016" x 0,022" de aço. As mudanças dentárias visualizadas nos cefalogramas e nos modelos foram comparadas dentro dos grupos utilizando teste t pareado e entre os grupos utilizando o teste t independente. Resultados: Grupo Controle: estágio de arco redondo: os incisivos inferiores se inclinaram vestibularmente (4.38° e 1 mm) e intruíram (-1,13mm); estágio de arco retangular: os incisivos inferiores intruíram e se projetaram adicionalmente (-0.63mm e 1,38°). Grupo Experimental: Durante o alinhamento com arcos redondos e CS acentuada, os incisivos inferiores se inclinaram levemente para vestibular (0,75° e 0,50mm), sem intrusão significativa; durante o nivelamento com arcos retangulares, os incisivos, em sua maioria, intruíram (1,75mm), com uma leve projeção (1,81°). O grupo experimental apresentou projeção dos incisivos significativamente menor (controle: 5,76°; experimental: 2,56°), com maior intrusão dos incisivos (controle: -1,75mm; experimental: -2,13mm). A CS no Grupo Experimental apresentou redução significativamente maior (-2,88 mm) do que no grupo controle (-1,69 mm). Conclusão: No Grupo Controle, foi observada de forma notória a projeção dos incisivos inferiores nos arcos redondos, com projeção adicional causada pelos arcos retangulares. No Grupo Experimental, foi observada uma projeção mínima quando foram utilizados arcos redondos com CS acentuada para alinhamento. O nivelamento com arcos retangulares causou menos projeção com maior redução da CS.

Effects of single-dose, low-level laser therapy on pain associated with the initial stage of fixed orthodontic treatment: A randomized clinical trial / 대한치과교정학회지

OBJECTIVE: The aim of this study was to assess the analgesic effect of a single application of low-level laser therapy (LLLT) on spontaneous pain and pain on chewing after placement of initial archwires. METHODS: Forty-two patients (26 women, 16 men) were randomly recruited for this split-mouth randomized clinical trial. Each patient received super-elastic nickel-titanium (NiTi) initial archwires (0.012, 0.014, 0.016, and 0.018-inch [in]) in the maxilla for leveling and alignment for an interval of 4 weeks between archwires. One side of the mouth was randomly designated as experimental, while the other side served as placebo. After insertion of each archwire, the experimental side was irradiated with a diode laser for 3 seconds each on 5 points facially and palatally per tooth, from the central incisor to first molar. On the placebo side, the laser device was held the same way but without laser application. A numerical rating scale was used to assess the intensity of spontaneous and masticatory pain for the following 7 days. The Mann-Whitney U test was used to compare pain scores between sides. RESULTS: Patients in the LLLT group exhibited significantly lower mean scores for spontaneous pain after insertion of the initial two archwires (0.012-in and 0.014-in NiTi; p < 0.05), while there was no significant difference for 0.016-in and 0.018-in wires between the LLLT and placebo groups. LLLT significantly reduced chewing pain scores (p < 0.05) for all archwires. CONCLUSIONS: A single dose of LLLT considerably lessened postoperative pain accompanying the placement of super-elastic NiTi wires for initial alignment and leveling.

Hybrid Geoid Model: Theory and Application in Brazil

Determination of the ellipsoidal height by Global Navigation Satellite Systems (GNSS) is becoming better known and used for purposes of leveling with the aid of geoid models. However, the disadvantage of this method is the quality of the geoid models, which degrade heights and limit the application of the method. In order to provide better quality in transforming height using GNSS leveling, this research aims to develop a hybridization methodology of gravimetric geoid models EGM08, MAPGEO2015 and GEOIDSP2014 for the State of São Paulo, providing more consistent models with GNSS technology. Radial Basis Function (RBF) neural networks were used to obtain the corrector surface, based on differences between geoid model undulations and the undulations obtained by GNSS tracking in benchmarks. The experiments showed that the most suitable interpolation for correction modeling is the linear RBF. Checkpoints indicate that the geoid hybrid models feature root mean square deviation ± 0.107, ± 0.104 and ± 0.098 m, respectively. The results shows an improvement of 30 to 40% in consistencies compared with the gravimetric geoids, providing users with better quality in transformation of geometric to orthometric heights.

Contenidos en el área de salud y competencias específicas en el ciclo de nivelación de la Facultad de Ciencias Médicas / Contents in the health section and specific competences in the leveling course in the School of Medicine / Conteúdos na área de saúde e habilidades específicas no ciclo de nivelamento da Faculdade de Ciências Médicas

Las instituciones universitarias para lograr excelencia académica en los futuros profesionales exigen considerar a la educación con un signifi cado primordial. El presente trabajo identifi ca los contenidos en el área de salud en los materiales de ejercitación del Ciclo de Nivelación y las competencias específi cas en los diferentes Ejes Temáticos, desde la perspectiva de los profesores. Para identifi car los contenidos del área de salud se aplicó un instrumento con los ítems: objetivos, contenidos, actividades y bibliografía. Para indagar la perspectiva de los profesores se implementó un cuestionario a ocho informantes claves, que incluyó la valoración de las competencias específi cas en el área a su cargo. De acuerdo a lo trabajado, se reconoce la importancia de articulación entre educación y salud, en términos de vincular experiencia-formación de los docentes, conocimientos de los estudiantes y contenidos específi cos en relación al proceso salud-enfermedad, porque se transforma en retroalimentación para los Ciclos de Nivelación.

In order to achieve academic excellence in their future professionals, university institutions require the consideration of education with a fundamental meaning. This work identifi es the contents in the health section of the exercise material included in the Leveling Course and the specifi c competences in the different Main Topics, from the teachers´perspective. An instrument including the following items: objectives, contents, activities and biography was applied to identify the contents in the health section. To inquire about the teachers’ perspective a questionnaire was used with eight key informants; it included the assessment of specifi c competences in the area they are in charge of. As a conclusion, it is observed that it is important to articulate education and health, in terms of linking teachers’ experience-training, students’ knowledge and specifi c contents regarding the process health-illness, since it becomes feedback for the Leveling Courses.

As instituições universitárias, visando a excelência acadêmica nos futuros profi ssionais, exigem considerar a educação como tendo um signifi cado fundamental. Este documento identifi ca os conteúdos na área da saúde dos materiais de treinamento do Ciclo de Nivelamento e as competências específi cas nos diferentes Eixos Temáticos a partir da perspectiva dos professores. Para identifi car os conteúdos da área de saúde aplicou-se um instrumento composto dos itens: objetivos, conteúdos, atividades e bibliografi a. Para pesquisar a perspectiva dos professores aplicou-se um questionário a oito docentes-chave, que incluiu a avaliação de competências específi cas na área da sua responsabilidade.. De acordo com o trabalho, pode-se reconhecer a importância da articulação entre educação e saúde, em termos de articular a experiência-formação dos professores, os conhecimentos dos estudantes e os conteúdos específi cos em relação ao processo saúde-doença, pois ele torna-se em retroalimentacão para os Ciclos de Nivelamento.

Frictional property comparisons of conventional and self-ligating lingual brackets according to tooth displacement during initial leveling and alignment: an in vitro mechanical study / 대한치과교정학회지

OBJECTIVE: We evaluated the effects of tooth displacement on frictional force when conventional ligating lingual brackets (CL-LBs), CL-LBs with a narrow bracket width, and self-ligating lingual brackets (SL-LBs) were used with initial leveling and alignment wires. METHODS: CL-LBs (7th Generation), CL-LBs with a narrow bracket width (STb), and SL-LBs (In-Ovation L) were tested under three tooth displacement conditions: no displacement (control); a 2-mm palatal displacement (PD) of the maxillary right lateral incisor (MXLI); and a 2-mm gingival displacement (GD) of the maxillary right canine (MXC) (nine groups, n = 7 per group). A stereolithographic typodont system and artificial saliva were used. Static and kinetic frictional forces (SFF and KFF, respectively) were measured while drawing a 0.013-inch copper-nickel-titanium archwire through brackets at 0.5 mm/min for 5 minutes at 36.5℃. RESULTS: The In-Ovation L exhibited lower SFF under control conditions and lower KFF under all displacement conditions than the 7th Generation and STb (all p < 0.001). No significant difference in SFF existed between the In-Ovation L and STb for a 2-mm GD of the MXC and 2-mm PD of the MXLI. A 2-mm GD of the MXC produced higher SFF and KFF than a 2-mm PD of the MXLI in all brackets (all p < 0.001). CONCLUSIONS: CL-LBs with narrow bracket widths exhibited higher KFF than SL-LBs under tooth displacement conditions. CL-LBs and ligation methods should be developed to produce SFF and KFF as low as those in SL-LBs during the initial and leveling stage.

Pretest about the nurse post ability of the leveling exam plan / 中国医师进修杂志

Objective To explore and set up the nurse post ability of the leveling exam plan in a third-grade class-A hospital.Methods The entry of more than one year of nurses will participate in the examination of N1-N4 is divided into four levels.According to different levels to set up the post ability of the leveling exam plan,through the review and interview,evaluate its effects and satisfaction in a third-grade class-A hospital.Results After the post ability of the leveling exam plan,nurses of different levels get more satisfied with the score on the assessment form,specialized knowledge,the core system,emergency plan,communication skills,ability of operation and emergency disposal,which significantly higher than the traditional methods,there were statistical differences between two groups.(t value was as follows:1.46,2.13,1.98,2.57,2.69,1.87,P ＜ 0.05),but the difference of foundation knowledge was not obvious (P ＞ 0.05).The new program get higher scores of nurses in critical thinking,clinical care,ethical,legal practice and professional ability,results were significant differences (t value was as follows:2.18,2.01,1.46,2.78,P＜ 0.05),but the scores in scientific research ability,leadership,interpersonal relationship,education and consulting capacity was not significantly different (P ＞ 0.05).Conclusion It is concluded that nurses of different levels on the leveling exam plan get a higher satisfaction.Through the new program,to assess the level of nurses,effectively improve the capacity on critical thinking,clinical nursing,ethical standards,law practice and professional development.

Sea-land limits: a case study

The limits between sea and land were estimated at "Pulso" beach located in the Southeastern Brazilian shelf (φ = 23°33/17.4886"S; Λ = 045° 13'13.0504"W - WGS84), between the island of São Sebastião and the city of Ubatuba, SP, Brazil. The relative sea level of the year 1831 at "Pulso" beach, as per Brazilian law Number 9760 dated from 1946, was estimated and materialized. The retro-estimation allowed the demarcation of the Legal Sea-Land Limits at "Pulso" beach as per the terms of the law. The accuracy of the procedure for the transference of the long-term sea level from the research station of Ubatuba to "Pulso" beach was assessed by parallel work of geometrical leveling referred to the IBGE (Brazilian Institute of Geography and Statistics) geodetic network. The motivation, the hypotheses (Brest, Cananeia and IPCC) and the methods here used are described, together with a short history of the Legal Sea-Land Limits. The results indicated that the legal Sea-Land Limits at "Pulso" beach are well within the beach area. They were determined as per law 9760, and there is the need to reactivate the national network of sea level gauge.

Os limites entre mar e terra foram estimados na praia chamada Pulso, localizada na costa sudeste do Brasil (φ = 23°33'17, 4886"S; Λ = 045°13'13, 0504"W) entre a Ilha de São Sebastião e a cidade de Ubatuba, no Estado de São Paulo, SP, Brasil. O nível relativo do mar do ano de 1831 na praia do Pulso, ou "Praia do Pulso" (PP), foi estimado e materializado, de acordo com a Lei brasileira Número 9760 de 1946. A acurácia do procedimento foi acompanhada por trabalho paralelo de nivelamento geométrico referido ao sistema nacional de geodésia do IBGE (Instituto Brasileiro de Geografia e Estatística). A motivação, as hipóteses (Brest, Cananeia e IPCC) e os métodos utilizados são descritos, acompanhados por um breve histórico dos "Terrenos de Marinha". Os resultados indicaram que os limites em (PP) estão bem dentro da área da praia. Eles fora deterinados de acordo co a Lei No. 9760 e há a necessidade de reativar a rede nacional de medidores do nível do mar.

Efeitos dos fios de nivelamento de níquel-titânio e de aço inoxidável na posição dos incisivos inferiores / Effects of nickel-titanium and stainless steel leveling wires on the position of mandibular incisors

OBJETIVO: estudar os efeitos do nivelamento realizado com fios de NiTi termoativado e de aço inoxidável, avaliando-se as possíveis alterações na posição dos incisivos inferiores, em casos com extrações, correlacionando com o tempo de tratamento. MÉTODOS: a amostra foi composta de 36 indivíduos, de ambos os sexos, leucodermas brasileiros, com idade média inicial de 15 anos e 5 meses, portadores de más oclusões de Classes I e II, distribuídos em dois grupos. No Grupo 1 (n=17), o nivelamento foi realizado com a sequência 1, utilizando-se três fios - 0,016" e 0,019"x0,025" de NiTi termoativado, e 0,019"x0,025" de aço inoxidável. No Grupo 2 (n=19), foi testada a sequência 2, na qual foram utilizados apenas fios de aço inoxidável (0,014"; 0,016"; 0,018"; 0,020" e 0,019"x0,025" com torque passivo nos incisivos inferiores). Os dados foram coletados utilizando-se o método cefalométrico computadorizado e comparados pelo teste t de Student com o nível de significância de 5 por cento. RESULTADOS: no Grupo 1, os incisivos inferiores inclinaram-se para lingual, com movimento significativo apenas da coroa (1,6mm). No Grupo 2, os incisivos inferiores permaneceram estáveis. Não houve alteração vertical em nenhum dos grupos. CONCLUSÕES: a sequência 2 proporcionou um melhor controle dos incisivos inferiores, não alterando suas posições iniciais, enquanto a sequência 1 permitiu a expressão do torque da prescrição utilizada, levando a uma inclinação lingual desses dentes. O tempo de tratamento foi menor utilizando-se a sequência 1. As variações biomecânicas estudadas apresentaram vantagens e desvantagens que devem ser conhecidas e ponderadas pelo ortodontista no planejamento do caso.

OBJECTIVE: Investigate the effects of heat-activated NiTi and stainless steel wires to evaluate potential changes in the position of mandibular incisors in extraction cases as correlated with treatment length.METHOD: The sample consisted of 36 individuals of both genders, Brazilian Caucasians with mean initial age of 15 years and 5 months with Class I and Class II malocclusions, divided into two groups. In Group 1 (n=17) leveling was performed with Sequence 1, comprised of three different wire cross-sections: 0.016-in and 0.019 x 0.025-in heat-activated NiTi wires and 0.019 x 0.025-in stainless steel wires. In Group 2 (n=19) Sequence 2 was tested using only stainless steel wires (0.014-in, 0.016-in, 0.018-in, 0.020-in and 0.019 x 0,025-in) with passive torque in the mandibular incisors. Data were collected using computerized cephalometry and compared using Student's t-test with 5% significance level.RESULTS: In Group 1, mandibular incisors were inclined lingually although only the crowns showed significant movement (1.6 mm). In Group 2, mandibular incisors remained stable. No vertical changes were noted in either group.CONCLUSIONS: Sequence 2 yielded better mandibular incisor control with no changes in their initial positions, while Sequence 1 allowed torques in the bracket prescription to be expressed, leading to the lingual inclination of these teeth. Treatment length was shorter when Sequence 1 was used. The evaluated biomechanic variations presented advantages and disadvantages that should be known and considered by the orthodontist during treatment planning.

Variabilidade espacial de Planossolo e produtividade de soja em várzea sistematizada: análise geoestatística e análise de regressão / Spatial variability of a Planosol and soybean yield on a land-leveled paddy soil: geoestatistical and regression analysis

Atributos do solo e da planta, espacialmente definidos, contribuem para o planejamento de lavouras comerciais e a locação de experimentos. O presente trabalho teve por objetivo estudar a variabilidade espacial de alguns atributos físicos e químicos do solo e sua relação com a produtividade de soja em várzea sistematizada. O experimento foi realizado no ano agrícola de 2000, na área experimental do Departamento de Solos da Universidade Federal de Santa Maria, Santa Maria, RS, em um Planossolo Hidromórfico distrófico típico. Uma área de 160 x 88m foi amostrada em grade de 8 x 8m, totalizando 240 pontos. A produtividade e a altura de plantas de soja e atributos químicos e físicos do solo superficial (0 a 0,15m) e subsuperficial (0,15 a 0,30m) foram avaliadas. Para os atributos edáficos da camada de solo de 0-0,15m de profundidade, que apresentaram correlação com os atributos de planta, usaram-se técnicas de geoestatística, sendo a dependência espacial dos atributos avaliada por semivariogramas escalonados. Com exceção da densidade de partículas e do grau de floculação, todas as demais variáveis apresentaram dependência espacial de moderada (0,64 a 0,75) a forte (>0,75). A variabilidade espacial dos atributos físicos e químicos do solo afetou a produtividade de soja. Os atributos do solo analisados foram divididos, quanto ao alcance e ao modelo de semivariograma, em dois grupos: um grupo com modelo exponencial e alcance menor que 40m e outro com modelo gaussiano e alcance menor que 67m. A variabilidade espacial da produtividade de soja foi descrita pelo modelo gaussiano com alcance menor que 45m.

Spatially-defined soil and plant properties contribute to better planning of experiments and commercial fields. This research had as objective the study of spatial variability of some physical and chemical properties of the soil and their relationship with soybean productivity. The experiment was conducted in the agricultural year of 2000, at the Federal University of Santa Maria, RS, Brazil, on land-leveled paddy soil. An area of 160 x 88m was sampled at an interval of 8 x 8m, resulting in 240 sampling points. The plant properties studied were soybean yield and plant height. Several chemical and physical properties of the topsoil (0 to 0.15m) and subsoil (0.15 to 0.30m) were determined. Geostatistical analysis was done only for the soil layer that presented correlation with the plant properties (0-0.15m), and the space dependence of the attributes was evaluated by scaled semivariograms. Except for soybean production, particle density and flocculation degree, all soil properties presented moderate (0.64 to 0.75) to strong (>0.75) space dependence. The production of soybean was influenced by space variability of the analyzed soil properties. The spatial variability of the soil physical and chemical properties in land-leveled paddy soil affected the production of soybean. The properties were classified in two different categories, based on semivariogram model and range: (i) exponential model and range smaller than 40m and (ii) gaussian model and range smaller than 67m. A gaussian model with range smaller than 45m described the spatial variation of soybean yeild.

Root surface changes during the initial leveling and alignment phase in orthodontics: a scanning electron microscopic study / 대한치과교정학회지

The purpose of this study was to investigate the root resorption and repair pattern of human teeth according to the force magnitude, direction and duration during the initial leveling and alignment phase. 40gms to 500gms of force applied to the 37 experimental teeth with duration of 3 weeks to 7 months. Then, the experimental teeth were extracted. 13 control teeth were extracted without treatment. The results are as follows: 1. 59.5% of 37 teeth exhibited root resorption. The initial resorption site was visible at the apex within 3 weeks with 100 gins samples, and the initial repair site was visible at the apex within 3 months with 400 gms samples. 2. Number of resorbed teeth increased with the duration of the force. 3. The depth of the resorption increased with the magnitude of the,force. 4. The areas of resorbed root corresponded with the loading pattern. 5. The areas of resorbed root were highly correlated with the magnitude of the force. The result of this study suggest that root resorption could occur during the initial leveling and alignment phase. These initial injuries are all small and insignificant. It is the extensive type of apical root resorption that must be regarded as deleterious to the function and stability of the tooth moved. During the initial leveling and alignment phase lighter force of the interrupted type and short treatment period would be favorable with regard to avoidance of root resorption and repair of resorbed root surface.

Clinical consideration on using the elastic "tie backs" during space closure / 대한치과교정학회지

Preadjusted appliance, following the original concept of the Andrews Straight-Wire appliance, became increasingly common in the 1980s. In six phases of treatment, anchorage control, leveling and aligning, overbite control, overjet reduction, space closure, and finishing are very effective with using the preadjusted appliances. Space closure is the phase of treatment in which the difference between standard edgewise and preadjusted mechanics is most noticeable. Orthodontists have been able to reduce the use of closing loops and, because of the level slot lineup, enjoy the advantages of sliding mechanics. In 1990, Dr. John C. Bennett and Richard P. McLaughlin introduced the new space closure system, namely, elastic "tiebacks". They found an .019"X.025" working archwire most effective in an .022"-slot system. Hooks of .024" stainless steel or .028" brass wire are soldered to the upper and lower archwires. The force required for space closure is delivered by elastic "tiebacks". An elastic module stretched by 2-3mm(to twice its normal length) usually delivers 0.5-1.5mm of space closure per month. Group movement and sliding mechanics are combined for gentle, controlled space closure, so that about 0.5mm of incisor retraction and 0.5mm of mesial molar movement can be seen each month. The tiebacks are replaced every four to six weeks. By using the elastic "tiebacks", the next two cases were treated during space closure. Even though we found some clinical problems of this mechanics, long treatment time, hard to control of vertical dimension and anchorage, the application method of this system is so simple that orthodontists can manage many patients during short chair time. But we must apply this mechanics after perfect understanding of the biomechanics in tooth movement.

DYNAMIC OBSERVATIONS ON SNAIL SITUATION AND WILD FAECES POLLUTION IN MARSHLANDS IN PILOT AREAS OF HUBEI PROVINCE / 中国血吸虫病防治杂志

Objective To understand the dynamic changes of snail situation and wild faeces pollution in marshlands in the pilot areas after leveling embankment for flood running and moving people from outside embankment to town for providing the scientific basis of schistosomiasis control in the same type areas. Methods Shishou City,Jiangxia District,Tuanfeng County and Huangzhou District were selected as the pilot areas. Snails were surveyed by the systematic and environmental sampling. Wild faeces were also investigated. The data were processed by Excel. Results Snail areas in Huangzhou Yeluzhou increased by 12.71%,in the others it did not change. For the snail density,there was a decline trend in Jiangxia Sanjiaozhou from 1999 to 2001,but it increased in 2002 obviously;in Huangzhou Yeluzhou it decreased in 2000,but increased again from 2001 to 2002;in Tuanfeng Luohuozhou it was fluctuation;it did not change in Shishou Fuxingzhou. Except Shishou City,the other three sites had infected snails distribution. The densities of wild faeces in the pilot areas were 1.14～15.60/hm~2. The positive rates of wild faeces were 1.35%～37.21%. Conclusion The marshlands in pilot areas were seriously polluted by wild faeces. There seemed to be an increase trend in the snail density. Snail areas did not change significantly in the last few years. However,the high transmission areas will expand. So the snail survey and snail control should be strengthened.