P4DM: Measure the Link Delay with P4.

Network management strategies depend on a timely and accurate knowledge of the network performance measures. Among these, one of the most relevant is the delay of the links, which unfortunately is not easy to measure with accuracy, especially when considering multi-hop paths. This is a classical networking problem, for which several solutions have been proposed. Nonetheless, we argue in this manuscript that there is still some room for improving accuracy and effectiveness in the measurement. This paper proposes a new solution based on the exploitation of the P4 data plane programming language. The basic idea is to handle lightweight probe packets that are forged ad-hoc at the edge of a link and processed at the other edge. Hosts generate the probe packets that are then exploited by the P4 programs in the switches to implement the measure. This approach provides an accurate and reliable measure of the link transit time, also effective in multi-hop links. In this latter case, we show that the measurement is not influenced much by the packet loss when the network is overloaded, thus providing more reliable results with respect to more conventional tools such as the classical ping utility. The manuscript explains the proposed P4 solution; then, it provides a comparison with several other approaches found in the literature, showing that outperform most of them, and finally show the behavior of the proposed methodology when facing a multi hop network path on a congested network to prove its robustness.

Microservice security: a systematic literature review.

Microservices is an emerging paradigm for developing distributed systems. With their widespread adoption, more and more work investigated the relation between microservices and security. Alas, the literature on this subject does not form a well-defined corpus: it is spread over many venues and composed of contributions mainly addressing specific scenarios or needs. In this work, we conduct a systematic review of the field, gathering 290 relevant publications-at the time of writing, the largest curated dataset on the topic. We analyse our dataset along two lines: (a) quantitatively, through publication metadata, which allows us to chart publication outlets, communities, approaches, and tackled issues; (b) qualitatively, through 20 research questions used to provide an aggregated overview of the literature and to spot gaps left open. We summarise our analyses in the conclusion in the form of a call for action to address the main open challenges.

Laser-Treated Titanium Implants: An In Vivo Histomorphometric and Biomechanical Analysis.

PURPOSE: The aim of the present histological and biomechanical analysis was to compare, in vivo, the strength and quality of osseointegration between a laser-treated implant surface and a standard machined surface. MATERIAL AND METHODS: Customized titanium implants, having 2 different surfaces, were used. Implants were longitudinally split in the 2 surfaces: one side was laser treated and the opposite one had a machined surface. Eight implants were inserted in the iliac crest of 2 sheep: 4 with a split laser and machined surfaces, 2 with a completely laser-treated surface, and 2 with fully machined surfaces. The animals were killed 8 weeks after the placement of implants. The histomorphometric and biomechanical parameters calculated for each surface were the bone-implant contact (%BIC) and the reverse torque value (RTV) RESULTS:: The RTV of the laser-treated implants were about 3-fold higher than that of the machined implants. The histomorphometric results showed a significant difference of %BIC around 30% between the laser surfaces compared to the machined ones. CONCLUSIONS: The present study showed that laser surface treatment induces better osteointegration than machined surface. The laser-treated surface seems to be able to increase the osseointegration amount in respect to the machined implants.

Morphological Aspect and iNOS and Bax Expression Modification in Bone Tissue Around Dental Implants Positioned Using Piezoelectric Bone Surgery Versus Conventional Drill Technique.

BACKGROUND: The aim of this work is to evaluate differences occurring in bone tissue around dental implants positioned using piezoelectric or conventional drill technique. METHODS: Twenty-four implants were inserted bilaterally in the iliac crest of 6 sheep after site preparation through a piezoelectric instrument (Test) or after site preparation through conventional drill technique with rotary instruments (Control). Animals were randomly divided to be euthanized at 15 and 30 days post-intervention (p.i.); peri-implant bone samples were withdrawn and processed for histological analysis and immunohistochemical evaluation of iNOS and Bax expression. RESULTS: Active remodeling phenomena in both Test and Control samples are showed at 15 days p.i., while at 30 days p.i., the overall organization of the peri-implant bone resembles native bone tissue. Immunohistochemical evaluation reveals a statistically significant increase of both iNOS and Bax expression at 15 days p.i. compared to samples obtained 30 days p.i. and to native bone. At both healing times, a higher but not statistically significant iNOS and Bax expression is recorded in samples from Control compared to Test Group. CONCLUSION: Even if the insertion protocol does not seem to significantly interfere with the long-term healing process, implant site preparation through the piezoelectric bone surgery technique may allow a reduction of peri-implant bone tissue inflammation and support a more rapid bone tissue healing phase.

Primary stability, insertion torque, and bone density of conical implants with internal hexagon: is there a relationship?

Between implants and peri-implant bone, there should be a minimum gap, without micromotions over a threshold, which could cause resorption and fibrosis. The higher the implant insertion torque, the higher will be the initial stability. The aim was to evaluate in vitro the correlation between micromotions and insertion torque of implants in bone of different densities. The test was performed on bovine bone of hard, medium, and soft density: 150 implants were used, 10 for each torque (20, 35, 45, 70, and 100 N/cm). Samples were fixed on a loading device. On each sample, we applied a 25-N horizontal force. Insertion torque and micromotions are statistically correlated. In soft bone with an insertion force of 20 and 35 N/cm, the micromotion resulted significantly over the risk threshold, which was not found with an insertion force of 45 and 70 N/cm and in hard and medium bones with any insertion torque. The increase in insertion torque reduces the amount of micromotions between implant and bone. Therefore, the immediate loading may be considered a valid therapeutic choice, even in low-density bone, as long as at least 45 N/cm of insertion torque is reached.

New laser-treated implant surfaces: a histologic and histomorphometric pilot study in rabbits.

PURPOSE: The purpose of this study was to confirm the validity of laser treated implant surfaces, with regard to high superficial purity preservation and to extremely regular and uniform roughness surfaces. METHODS: In this in vivo study, seven different laser treated implant surfaces were analyzed. A diode-pumped solid state source laser, in a Q-Switch output mode, was used at various wavelengths, which were chosen to generate surface irregularities of varying diameter, depth and pitch. Twenty one implants were placed in 11 New Zealand rabbits. Eight weeks after surgery, implants were harvested for histometric analysis: total, threads and body bone-to-implant, and bone-to-implant contacts were measured. The morphologic analysis of the surface was carried out using a Scanning Electron Microscope. RESULTS: Average bone-implant contact values were approximately 50% for all tested surfaces. Both total and threads values, within the same processing pattern group, had a high variance. Bone-implant contact thread and body variances were different, so that is possible that laser beam angle is able to modify the superficial roughness and thus the histological response. CONCLUSIONS: Implants provided with pores of 20 and 25 µm achieved more than satisfactory bone-implant contact partial peaks. Further statistically significant experiments are needed in order to study, in depth, these surfaces.

Primary stability, insertion torque and bone density of cylindric implant ad modum Branemark: is there a relationship? An in vitro study.

OBJECTIVES: Protocols of immediate loading have been reported in several studies. It has also been demonstrated that the cause of failure of immediate loaded implants is due to the micromotion on the bone-implant interface induced by immediate loading. There should be a minimum gap between the implant and the peri-implant bone, without micromotions occurring above a definite threshold risk as they induce bone resorption and fibrosis around the implant. Measurement of the torque necessary to insert an implant in the bone is a parameter for measuring initial stability. The higher the implant insertion torque, the higher the initial stability attained. The aim of this study was to evaluate in vitro the correlation between the micromotion of cylindric screw implants ad modum Branemark and the insertion torque in bone of different densities. MATERIAL AND METHODS: The test was carried out on 2 × 2 cm samples of fresh bovine bone of three different densities: hard (H), medium (M) and soft (S). One hundred and fifty hexa implants ad modum Branemark were used, 3.75 mm in diameter and 9 mm long. To screw in the implants, a customized manual key was used, controlled digitally to evaluate the peak insertion torques. Ten implants were prepared for each torque (20, 35, 45, 70 and 100 N/cm). The bone sample was then fixed on a loading device, which allowed evaluating the micromotion. On each sample, we applied a 25 N horizontal force. RESULTS: The results indicate that the peak insertion torque and the implant micromotion are statistically correlated, and statistically significant differences in H and M bone were found compared with S bone. In S bone, we noted a micromotion significantly higher than the risk threshold, and it was not possible to reach peak insertion torque above 35 N/cm. In H and M bone, the micromotion is below the threshold of all insertion torques. CONCLUSIONS: Increasing the peak insertion torque, we can reduce the extent of the micromotion between the implant and the bone when submitted to lateral forces in vitro. In soft bone, the micromotion was always high; hence, immediate loading of implants in low-density bone should be evaluated with care.

Implant micromotion is related to peak insertion torque and bone density.

OBJECTIVES: Measuring peak insertion torque in relation to different bone densities, the present study seeks to determine whether micromotion at the interface is related to primary stability achieved by increasing insertion torque. MATERIAL AND METHODS: A total of 120 Ti-Bone implants were placed in fresh bovine bone samples representing three density categories: hard, normal and soft (HNS). Five groups of peak insertion torque (20, 35, 45, 70 and 100 N/cm) were evaluated in the three bone density categories noted. Customized electronic equipment connected to a PC was used to register the peak and other insertion torque data. A loading device, consisting of a digital force gauge and a digital micrometer, was used to measure the micromovements of the implant during the application of 20, 25 and 30 N lateral forces. The data were analyzed for statistical significance by ANOVA and Spearman's rank correlation coefficient tests. RESULTS: A statistically significant difference between implant micromobility placed with different levels of torque and in different bone densities was demonstrated by ANOVA. Spearman's rank correlation coefficient showed a high dependency between the peak insertion torque and the observed micromovement. Particularly, in soft bone, it was not possible to achieve more than 35 N/cm of peak insertion torque. CONCLUSIONS: Results showed that increasing the peak insertion torque reduces the level of implant micromotion. In addition, micromotion in soft bone was found to be consistently high, which could lead to the failure of osseointegration. Thus, immediate functional loading of implants in soft bone should be considered with caution.