626 research outputs found
Uso de ligas metálicas básicas em próteses sobre implantes: análise da adaptação marginal
The original protocol for implant prosthesis recommends the use of a gold framework for acrylic and ceramic prosthesis. However, due to its high cost, the use of alternative alloys is desired. This study compares the marginal accuracy of pre-made cylinders versus plastic cylinders cast with two different base metal casting alloys. Five samples each of (1) plastic cylinder cast in cobalt-chromium alloy, (2) plastic cylinder cast in nickel-chromium alloy, and (3) silver-palladium pre-made cylinder (control) were examined for marginal accuracy according to: (A) vertical gap; (B) horizontal gap and (C) horizontal gap depth at the abutment/cylinder interface. Data were submitted to statistical analysis (ANOVA and Student-Newman Keuls, pO protocolo para prótese sobre implantes recomenda o uso de uma infra-estrutura em ouro para próteses metalo-plásticas e metalo-cerâmicas. No entanto, devido ao seu alto custo, o uso de ligas alternativas é desejado. OBJETIVO: Este estudo compara a adaptação marginal de cilindros protéticos pré-fabricados e cilindros protéticos plásticos fundidos com dois tipos de ligas metálicas básicas. MATERIAL E MÉTODOS: 05 amostras de (1) cilindros plásticos fundidos em liga de cobalto cromo; (2) cilindros plásticos fundidos em liga de níquel cromo e (3) cilindros pré-fabricados com cinta metálica em paládio, foram examinados na interface intermediário/cilindro protético na análise de desajuste marginal, considerando-se (A) desajuste vertical, (B) desajuste horizontal e (C) profundidade de fenda. RESULTADOS: os valores médios para o desajuste vertical, horizontal e profundidade foram, respectivamente, 4,13µm, 14,5µm e 6,93µm para o cilindro pré-fabricado em paládio, 23,18µm, 33,2µm e 88µm para os cilindros plásticos fundidos em Níquel cromo e 25,6µm, 51,8µm e 114,54 µm para os cilindros fundidos em cobalto-cromo. CONCLUSÃO: não foram encontradas diferenças estatísticas entre os grupos fundidos (grupo 1 e 2), mas uma adaptação marginal significantemente superior foi observada com os cilindros pré-fabricados quando comparado aos cilindros plásticos fundidos com níquel-cromo e cobalto-cromo para todas as análises
Refining physical aspects of soil quality and soil health when exploring the effects of soil degradation and climate change on biomass production: an Italian case study
This study focuses on soil physical aspects of soil
quality and health with the objective to define procedures with worldwide
rather than only regional applicability, reflecting modern developments in
soil physical and agronomic research and addressing important questions
regarding possible effects of soil degradation and climate change. In
contrast to water and air, soils cannot, even after much research, be
characterized by a universally accepted quality definition and this hampers
the internal and external communication process. Soil quality expresses the
capacity of the soil to function. Biomass production is a primary function,
next to filtering and organic matter accumulation, and can be modeled with
soil–water–atmosphere–plant (SWAP) simulation models, as used in the
agronomic yield-gap program that defines potential yields (Yp) for any
location on earth determined by radiation, temperature and standardized crop
characteristics, assuming adequate water and nutrient supply and lack of
pests and diseases. The water-limited yield (Yw) reflects, in addition, the
often limited water availability at a particular location. Actual yields
(Ya) can be considered in relation to Yw to indicate yield gaps, to be
expressed in terms of the indicator (Ya/Yw)×100.
Soil data to calculate Yw for a given soil type (the genoform) should
consist of a range of soil properties as a function of past management
(various phenoforms) rather than as a single representative dataset. This way
a Yw-based characteristic soil quality range for every soil type is
defined, based on semipermanent soil properties. In this study effects of
subsoil compaction, overland flow following surface compaction and erosion
were simulated for six soil series in the Destra Sele area
in Italy, including effects of climate change. Recent proposals consider soil
health, which appeals more to people than soil quality and is now defined by
separate soil physical, chemical and biological indicators. Focusing on the
soil function biomass production, physical soil health at a given time of a
given type of soil can be expressed as a point (defined by a measured Ya)
on the defined soil quality range for that particular type of soil, thereby
defining the seriousness of the problem and the scope for improvement. The
six soils showed different behavior following the three types of land
degradation and projected climate change up to the year 2100. Effects are
expected to be major as reductions of biomass production of up to 50 %
appear likely under the scenarios. Rather than consider soil physical,
chemical and biological indicators separately, as proposed now elsewhere for
soil health, a sequential procedure is discussed, logically linking the
separate procedures.</p
Integration of rule-based ‘Expert Systems’ on RPAS capable of specific category operations within the U-space: An original mitigation strategy for operational safety risks
The use of RPAS for civil purposes is spreading across Europe and worldwide; Aviation Authorities are working to layout regulations to assure a safe and secure integration of RPAS with manned aircraft across both controlled and uncontrolled (below 500 Feet of altitude) airspace. Following the identification of a selection of safety risks potentially associated to RPAS Specific Category of operations, an original strategy of risks mitigation focused on rule-based ‘Expert Systems’, has been conceived and it is discussed in this work. The article recalls the main components of rule-based ‘Expert Systems’ that is the knowledge basis and the rules to instruct the ‘Expert system’. Then the work describes the implementation of the rules as statements derived from a safety risk matrix associated to RPAS capable of performing Specific Category operations within the U-space. Finally, the idea of integrating the ‘Expert System’ as a software module within RPAS functional architecture is presented and discussed. Such solution is deemed to be a valuable novelty for future implementations of advanced RPAS autopilots capable of recognizing and solving in flight/on ground operational safety risks in such a way to speed up the integration of RPAS into not segregated airspace and their market development
Resource Control for Synchronous Cooperative Threads
We develop new methods to statically bound the resources needed for the
execution of systems of concurrent, interactive threads. Our study is concerned
with a \emph{synchronous} model of interaction based on cooperative threads
whose execution proceeds in synchronous rounds called instants. Our
contribution is a system of compositional static analyses to guarantee that
each instant terminates and to bound the size of the values computed by the
system as a function of the size of its parameters at the beginning of the
instant. Our method generalises an approach designed for first-order functional
languages that relies on a combination of standard termination techniques for
term rewriting systems and an analysis of the size of the computed values based
on the notion of quasi-interpretation. We show that these two methods can be
combined to obtain an explicit polynomial bound on the resources needed for the
execution of the system during an instant. As a second contribution, we
introduce a virtual machine and a related bytecode thus producing a precise
description of the resources needed for the execution of a system. In this
context, we present a suitable control flow analysis that allows to formulte
the static analyses for resource control at byte code level
Prevalence of Mycobacterium avium subsp. paratuberculosis in milk and dairy cattle in Southern Italy; preliminary results
Paratuberculosis affects all ruminants worldwide. Mycobacterium avium subsp. paratuberculosis could have a role in human diseases like Crohn\u2019s. Some extra EU countries request importation of MAP-free products. Italy has not yet actualized a control program and the diffusion of the infection is still unknown in Southern Italy. The aim of this study was to evaluate the prevalence of the infection in five regions of Southern Italy. Bulk tank milk and in-line milk filters were sampled in 780 dairy cattle herds and respectively analyzed by ELISA and real time PCR. One hundred and fifty-five out of 780 herds (19.9%) were found positive by ELISA and/or real time PCR. Individual milk samples were then collected from all the producing animals of positive herds and from a selection of negative herds. The estimated prevalence varies from region to region between 2.8% and 5.5%. Our results indicate that the disease is widespread in the five regions. The observed prevalence could be underestimated
The Perigord black truffle responds to cold temperature with an extensive reprogramming of its transcriptional activity
International audienceThe Tuber melanosporum genome has been analysed with the aim of identifying and characterizing the genes involved in the environmental stress response. A whole genome array (7496 genes/probe) was used to verify the fungal transcriptional profiling upon a cold temperature period (7 days at 4 degrees C). A total of 423 genes resulted to be differentially expressed in a significant manner (>2.5-fold; p-value <0.05) in the mycelia exposed to cold, compared to the control ones: 187 of these genes were up-regulated, while 236 were down-regulated. Sixty-six and fifty-one percent, respectively, of the up- or down-regulated transcripts had no KOG classification and were clustered as unclassified proteins, which was the most abundant category in the both up- and down-regulated genes. A gene subset, containing a range of biological functions, was chosen to validate the microarray experiment through quantitative real time PCR (qRT-PCR). The analysis confirmed the array data for 16 out of 22 of the considered genes, confirming that a cold temperature period influences the truffle global gene expression. The expressed genes, which mostly resulted to be genes for heat shock proteins (HSPs) and genes involved in cell wall and lipid metabolism, could be involved in mechanisms, which are responsible for fungal adaptation. Since truffle ascomata develop during the winter period, we hypothesize that these differentially expressed genes may help the truffle to adapt to low temperatures and/or perceive environmental signals that regulate the fructification. (C) 2010 Elsevier Inc. All rights reserved
Sealing Capability and SEM Observation of the Implant-Abutment Interface
To evaluate the sealing capability of external hexagon implant systems and assess the marginal fit, two groups (n = 10 each) were employed: SIN (Sistema de Implantes Nacional, Brazil) and Osseotite, (Biomet 3i, USA). Sealing capability was determined by placing 0.7 μL of 1% acid-red solution in the implant wells before the torque of their respective abutments. Specimens were then placed into 2.5 mL vials filled with 1.3 mL of distilled water with the implant-abutment interface submerged. Three samples of 100 μL
water were collected at previously determinate times. The absorbance was measured with a spectrophotometer, and the data were analyzed by Two-way ANOVA (P < .05) and Tukey's test. Marginal fit was determined using SEM. Leakage was observed for both groups at all times and was significantly higher at 144 hrs. SEM analysis depicted gaps in the implant-abutment interface of both groups. Gaps in the implant-abutment interface were observed along with leakage increased at the 144 hrs evaluation period
Evaluations on hydrogen fuel cells as a source of energy for specific operations category civil RPAS systems
This paper is on the evaluation of hydrogen fuel cells as a mean to enhance RPAS systems
performances in terms of reachable range and endurance to integrate them into controlled airspaces operatively
and safely. Main steps to size a fuel cell system to feed electrical motors of a fixed wing RPAS capable of
specific operations category are described in this article. Then, a more extensive parametric model of a fuel cell
power line based on operative and safety requirements for medium range/medium endurance RPAS systems is
presented and discussed
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