Finite Element Analysis of 2 Immediate Loading Systems in Edentulous Mandible: Rigid and Semirigid Splinting of Implants

Purpose: The objective of this study was to evaluate the stress on the cortical bone around single body dental implants supporting mandibular complete fixed denture with rigid (Neopronto System-Neodent) or semirigid splinting system (Barra Distal System-Neodent). Methods and Materials: Stress levels on several system components were analyzed through finite element analysis. Focusing on stress concentration at cortical bone around single body dental implants supporting mandibular complete fixed dentures with rigid ( Neopronto System-Neodent) or semirigid splinting system ( Barra Distal System-Neodent), after axial and oblique occlusal loading simulation, applied in the last cantilever element. Results: The results showed that semirigid implant splinting generated lower von Mises stress in the cortical bone under axial loading. Rigid implant splinting generated higher von Mises stress in the cortical bone under oblique loading. Conclusion: It was concluded that the use of a semirigid system for rehabilitation of edentulous mandibles by means of immediate implant-supported fixed complete denture is recommended, because it reduces stress concentration in the cortical bone. As a consequence, bone level is better preserved, and implant survival is improved. Nevertheless, for both situations the cortical bone integrity was protected, because the maximum stress level findings were lower than those pointed in the literature as being harmful. The maximum stress limit for cortical bone (167 MPa) represents the threshold between plastic and elastic state for a given material. Because any force is applied to an object, and there is no deformation, we can conclude that the elastic threshold was not surpassed, keeping its structural integrity. If the force is higher than the plastic threshold, the object will suffer permanent deformation. In cortical bone, this represents the beginning of bone resorption and/or remodeling processes, which, according to our simulated loading, would not occur. ( Implant Dent 2010; 19:39-49)

Effect of simulated masticatory loading on the retention of stud attachments for implant overdentures

P>This study assessed the effect of simulated mastication on the retention of two stud attachment systems for 2-implants overdentures. Sixteen specimens, each simulating an edentulous ridge with implants and an overdenture were divided into two groups, according to the attachment system: Group I (Nobel Biocare ball-socket attachments) and Group II (Locator attachments). Retention forces were measured before and after 400 000 simulated masticatory loads in a customised device. Data were compared by two-way anova followed by Bonferroni test (alpha = 0 center dot 05). Group I presented significantly lower retention forces (Newtons) than Group II at baseline (10 center dot 6 +/- 3 center dot 6 and 66 center dot 4 +/- 16 center dot 0, respectively). However, differences were not significant after 400 000 loads (7 center dot 9 +/- 4 center dot 3 and 21 center dot 6 +/- 17 center dot 0). The number of cycles did not influence the measurements in Group I, whereas a non-linear descending curve was found for Group II. It was concluded that simulated mastication resulted in minor changes for the ball attachment tested. Nevertheless, it reduced the retention of Locator attachments to 40% of the baseline values, what suggests that mastication is a major factor associated with maintenance needs for this system.

Developments in the understanding of South African style SAG mills

The South African style SAG (RoM) mills operate in a window that is almost exclusive from the operation of the Australian and North American mills that have been used for the development of SAG mill models. Combining good quality, test data from the RoM mills is extending and improving these models, and assisting in a practical manner in improving our understanding of SAG/AG milling. Data from high mill loads, both in absolute filling and ball loading, have been used to extend and improve the JK SAG mill model. This improved understanding has been successfully applied to increasing the throughput of a mill by 8%. Data is presented on relationships between power and load for high mill loading. Slurry pooling is common in closed-circuit RoM mills, and the detrimental effect of this has been dramatically demonstrated at ALCOA with a mill throughput increase of over 20%. Techniques for calculating the effects of slurry pooling have been developed and a new pulp lifter system designed to give optimal slurry discharge. The influence of mill speed in shifting the product size distribution has also been measured. (C) 2001 Elsevier Science Ltd. All rights reserved.

Human GC-AG alternative intron isoforms with weak donor sites show enhanced consensus at acceptor exon positions

It has been previously observed that the intrinsically weak variant GC donor sites, in order to be recognized by the U2-type spliceosome, possess strong consensus sequences maximized for base pair formation with U1 and U5/U6 snRNAs. However, variability in signal strength is a fundamental mechanism for splice site selection in alternative splicing. Here we report human alternative GC-AG introns (for the first time from any species), and show that while constitutive GC-AG introns do possess strong signals at their donor sites, a large subset of alternative GC-AG introns possess weak consensus sequences at their donor sites. Surprisingly, this subset of alternative isoforms shows strong consensus at acceptor exon positions 1 and 2. The improved consensus at the acceptor exon can facilitate a strong interaction with U5 snRNA, which tethers the two exons for ligation during the second step of splicing. Further, these isoforms nearly always possess alternative acceptor sites and always possess alternative acceptor sites and exhibit particularly weak polypyrimidine tracts characteristic of AG-dependent introns. The acceptor exon nucleotides are part of the consensus required for the U2AF(35)-mediated recognition of AG in such introns. Such improved consensus at acceptor exons is not found in either normal or alternative GT-AG introns having weak donor sites or weak polypyrimidine,tracts. The changes probably reflect mechanisms that allow GC-AG alternative intron isoforms to cope with two conflicting requirements, namely an apparent need for differential splice strength to direct the choice of alternative sites and a need for improved donor signals to compensate for the central mismatch base pair (C-A) in the RNA duplex of U1 snRNA and the pre-mRNA. The other important findings include (i) one in every twenty alternative introns is a GC-AG intron, and (ii) three of every five observed GC-AG introns are alternative isoforms.

Growth hormone is permissive for skeletal adaptation to mechanical loading

The Lewis dwarf (DW) rat was used as a model to test the hypothesis that growth hormone (GH) is permissive for new bone formation induced by mechanical loading in vivo. Adult female Lewis DW rats aged 6.2 +/- 0.1 months (187 +/- 18 g) were allocated to four vehicle groups (DW), four GH treatment groups at 32.5 mug/100 g body mass (DWGH1), and four GH treatment groups at 65 mug/100 g (DWGH2). Saline vehicle or GH was injected intraperitoneally (ip) at 6:30 p.m. and 6:30 a.m. before mechanical loading of tibias at 7:30 a.m. A single period of 300 cycles of four-point bending was applied to right tibias at 2.0 Hz, and magnitudes of 24, 29, 38, or 48N were applied. Separate strain gauge analyses in 5 DW rats validated the selection of loading magnitudes. After loading, double-label histomorphometry was used to assess bone formation at the periosteal surface (Ps.S) and endocortical surface (Ec.S) of tibias. Comparing left (unloaded) tibias among groups, GH treatment had no effect on bone formation. Bone formation in tibias in DW rats was insensitive to mechanical loading. At the Ec.S, mechanically induced lamellar bone formation increased in the DWGH2 group loaded at 48N (p < 0.05), and no significant increases in bone formation were observed among other groups. The percentage of tibias expressing woven bone formation (Wo.B) at the Ps.S was significantly greater in the DWGH groups compared with controls (p < 0.05). We concluded that GH influences loading-related bone formation in a permissive manner and modulates the responsiveness of bone tissue to mechanical stimuli by changing thresholds for bone formation.

Postural control of the trunk in response to lateral support surface translations during trunk movement and loading

The postural response to translation of the support surface may be influenced by the performance of an ongoing voluntary task. This study was designed to test this proposal by applying lateral perturbations while subjects handled a load in the frontal plane. Measurements were made of medio-lateral displacement of the centre of pressure, angular displacement of the trunk and thigh in the frontal plane and intra-abdominal pressure. Subjects were translated randomly to the left and right in a variety of conditions that involved standing either quietly or with a 5 kg load in their left hand, which they were required either to hold statically or to lift or lower. The results indicate that when the perturbation occurred towards the loaded left side the subjects were able to return their centre of pressure, trunk and thigh rapidly and accurately to the initial position. However, when the perturbation occurred towards the right (away from the load) this correction was delayed and associated with multiple changes in direction of movement, suggesting decreased efficiency of the postural response. This reduced efficiency can be explained by a conflict between the motor commands for the ongoing voluntary task and the postural response, and/or by the mechanical effect of the asymmetrical addition of load to the trunk.

Placental growth hormone is not suppressed by oral glucose loading in normal human pregnancy

Placental growth hormone (PGH) progressively replaces pituitary growth hormone in the maternal circulation from mid-gestation onwards in human pregnancy. Our previous investigations have shown that placental growth hormone concentrations correlate well with foetal growth. Despite the apparent correlation between PGH and birthweight, the physiology of its secretion during pregnancy has not been well defined. We investigated the response of maternal serum PCH to oral glucose loading in pregnant women (n = 24) who demonstrated normal glucose tolerance at a mean gestation of 29 weeks. Mean (SEM) fasting PGH concentrations were high (36.9 [6.4] ng/ml). No suppression of PGH was noted at one, two or three hours after a 75 g oral glucose load. Similarly, no changes were noted in growth hormone binding protein or in calculated free PGH over the course of the glucose tolerance test. As expected, insulin concentrations rose sixfold and insulin like growth factor binding protein 1 concentrations fell by 20% with glucose loading. Cot-relation analysis showed maternal weight, BMI, fasting serum glucose serum insulin to be significantly correlated with the babies' birthweight. Our results support the proposition that PGH concentrations in maternal serum are not Suppressed by oral glucose loading in non-diabetic mothers.

Postbuckling of piezoelectric FGM plates subject to thermo-electro-mechanical loading

In this paper, we examine the postbuckling behavior of functionally graded material FGM rectangular plates that are integrated with surface-bonded piezoelectric actuators and are subjected to the combined action of uniform temperature change, in-plane forces, and constant applied actuator voltage. A Galerkin-differential quadrature iteration algorithm is proposed for solution of the non-linear partial differential governing equations. To account for the transverse shear strains, the Reddy higher-order shear deformation plate theory is employed. The bifurcation-type thermo-mechanical buckling of fully clamped plates, and the postbuckling behavior of plates with more general boundary conditions subject to various thermo-electro-mechanical loads, are discussed in detail. Parametric studies are also undertaken, and show the effects of applied actuator voltage, in-plane forces, volume fraction exponents, temperature change, and the character of boundary conditions on the buckling and postbuckling characteristics of the plates. (C) 2003 Elsevier Science Ltd. All rights reserved.

Implanta????o do pr??-atendimento na ag??ncia dos correios Adolfina de Pinheiros em S??o Paulo

A experi??ncia da Diretoria Regional de S??o Paulo Metropolitana dos Correios objetiva implementar melhoria em um dos seus principais processos: o atendimento nas ag??ncias. Dentro do contexto de gest??o pela qualidade total, destacamos o programa de ger??ncia da rotina e gerenciamento de melhorias (revis??o de processos), cujas ferramentas nortearam o nosso projeto. Nas ag??ncias, em decorr??ncia dos diversos produtos e servi??os que a ECT comercializa, faz-se necess??ria a gest??o das filas para que o tempo de espera excessivo n??o ocasione a insatisfa????o dos clientes. Com a implanta????o do pr??-atendimento em guich?? espec??fico, na ag??ncia Adolfina de Pinheiros, houve uma redu????o significativa do tempo de espera na fila, servindo como modelo para implanta????o em outras ag??ncias dos Correios. Al??m de atender ?? necessidade do cliente, estabelecida na matriz do QFD (Desdobramento da Fun????o Qualidade) do sistema de gest??o da qualidade da ECT, o projeto objetiva tornar a rotina de trabalho dos atendentes de guich?? mais f??cil, racional e produtiva

Avalia????o das pr??ticas de gest??o do conhecimento na ag??ncia nacional de telecomunica????es

A Gest??o do Conhecimento ?? de suma import??ncia para as organiza????es em que o conhecimento desempenha papel essencial. Nesses casos, o conhecimento afeta o trabalho e determina mudan??as irrevers??veis, tanto na vida das organiza????es como das pessoas que l?? trabalham. Este estudo analisa o processo de planejamento, implementa????o e desenvolvimento de pr??ticas de gest??o do conhecimento na Anatel, Ag??ncia Nacional de Telecomunica????es. ?? orientado por uma abordagem te??rica que foca, particularmente, na sociedade em rede (Castells, 1999) e nas dimens??es da Gest??o do Conhecimento (Angeloni, 2008). Um grupo de servidores da Anatel foi entrevistado e responderam a um question??rio com o objetivo de se avaliar sua familiaridade com pr??ticas de Gest??o do Conhecimento. A inclus??o da Gest??o do Conhecimento como t??pico da nova vers??o do Regimento Interno da Ag??ncia foi examinada, para verificar se representa passo estrat??gico para sua ado????o pela Ag??ncia. O estudo avalia a motiva????o para a ado????o da Gest??o do Conhecimento, investiga a ocorr??ncia de pr??ticas de Gest??o do Conhecimento na Anatel, bem como o est??gio de sua implementa????o e o alcance de sua ado????o entre os usu??rios da Ag??ncia e pela sociedade em geral. Finalmente, o estudo analisa se as iniciativas j?? tomadas para implementar a Gest??o do Conhecimento s??o consistentes com as diretrizes estabelecidas no novo Regimento Interno e se tais a????es s??o coordenadas de forma a promover a efic??cia da Gest??o do Conhecimento na Anatel

An??lise da estrutura organizacional da fiscaliza????o do transporte rodovi??rio na ag??ncia nacional de transportes terrestres

Fiscalizar a presta????o dos servi??os de transporte interestadual e internacional de passageiros e de transporte rodovi??rio de cargas ?? atribui????o da Superintend??ncia de Fiscaliza????o da Ag??ncia Nacional de Transportes Terrestres ??? ANTT. Esta pesquisa visa analisar a efici??ncia e efic??cia desta estrutura organizacional

Texto para discuss??o 18: ag??ncias executivas: estrat??gias de reforma administrativa

Este trabalho tem por objeto uma an??lise do projeto ag??ncias executivas, que ?? um dos projetos integrantes do plano diretor da Reforma do Aparelho do Estado (plano diretor). Trata-se, essencialmente, da implanta????o da reforma administrativa nas autarquias e funda????es p??blicas federais, que operam no Setor de Atividades Exclusivas do Estado

Ag??ncia itinerante

Trata-se de um instrumento de expans??o das a????es de atendimento do Banco do Nordeste, que permite ultrapassar os limites f??sicos das ag??ncias, de forma m??vel e flex??vel, visando o atendimento facilitado e in-loco de necessidades dos clientes-alvo, prestar orienta????o e operacionalizar neg??cios j?? demandados. Ocorre pelo deslocamento de funcion??rios das Ag??ncias, por um dia, para um dos munic??pios sob sua jurisdi????o. As visitas obedecem a um sistema de rod??zio, sempre priorizando as comunidades com maiores demandas. A Ag??ncia Itinerante ?? realizada em forte parceria com a Prefeitura do munic??pio, que cede um ponto de apoio, onde fica afixada a marca do Banco e o telefone do Cliente Consulta, facilitando o contato entre o Banco e seus clientes-alvo: os agentes produtivos. Iniciada em julho/97, j?? com 3.435 ocorr??ncias at?? 11.Set.98 e mais 491 previstas ainda para este ano, essa iniciativa contribui para ampliar a efetiva atua????o do Banco, pois ocorre em todo o Nordeste e norte de Minas Gerais, proporcionando maior visibilidade ?? empresa no cumprimento de sua miss??o

Programas de atendimento nas ag??ncias da ECT por portadores de defici??ncia f??sica

Desde o in??cio da d??cada de 1990, a Empresa Brasileira de Correios e Tel??grafos (ECT) tinha atingido o ponto m??ximo da sua capacidade de atendimento, sendo necess??rio criar alternativas para proporcionar maior conforto e rapidez aos seus usu??rios. A solu????o encontrada foi o Programa de atendimento nas ag??ncias por portadores de defici??ncia f??sica. Atrav??s deste programa, a ECT estabeleceu conv??nios com associa????es de deficientes f??sicos, viabilizando guich??s de ag??ncias totalmente operados por pessoas portadoras de defici??ncia f??sica. A grande inova????o foi o Conv??nio de Franquia Interna, onde os guich??s de ag??ncias pr??prias s??o franqueados ?? explora????o pelas Associa????es de Deficientes F??sicos. Com a iniciativa ampliou-se a capacidade de atendimento da ECT, conquistando-se maior efic??cia e efici??ncia, sem expans??o dos efetivos da empresa. Foram viabilizados novos neg??cios, em virtude da nova capacidade de atendimento