1,167 research outputs found
Influence of the Antithrombotic Therapy in the Healing of Simple Post-Extraction Sockets: A Randomized Clinical Trial
Background: An adequate blood supply plays a leading role in the healing process of the post-extractive socket; its coagulation leads to fibrin clot formation, which acts as a physical barrier able to prevent postoperative bleeding and microbial infection. The purpose of this study was to evaluate the effectiveness of antiaggregant drugs in healing post-extraction sockets compared to natural wound healing. Methods: This was a single-center prospective clinical trial. Extraction sockets allocated in healthy patients and in patients assuming antiplatelet drugs were considered. Thirty consecutive patients under (treated with/in treatment with) oral antiplatelet treatment were enrolled in the test group. In order to provide a control group, 30 consecutive patients meeting all the exclusion and inclusion criteria were enrolled. The extraction of the mono-radicular tooth was atraumatically performed without gingivoplasty or osteotomy procedures that could influence the healing process. Photographs were obtained before and immediately after surgery and at 3-, 7-, 14-and 28-days follow-up. Results: All patients assumed the prescribed therapy and their postoperative recovery was uneventful without any kind of post-extractive complications. The results of inter-group comparison show that on the third and seventh days of follow-up, the antiplatelet group expressed a statistically significant higher level of healing compared to the control group (p < 0.05), while no statistically significant differences were recorded at 14-and 28-days follow-up. Conclusions: Patients treated with antiplatelet agents seemed to show that this therapy can positively affect the healing process after tooth extractions
Introduction of seismic source directivity on hazard map
The seismic hazard maps are mainly influenced by the uncertainty associated to the ground motion predictive equation (GMPE). This uncertainty represents the unexplained part of the ground motion and it is mostly related to the choice of the model’s variables. In fact the representation of the ground motion through the GMPEs is simple compared to the complexity of the physical process involved: if only the magnitude and distance are taken into account, GMPEs predicts isoseismals curves that are expected to be isotropic around the hypocenter or along the fault. Instead, the presence of a fault plane across which a process of failure in shear develops makes this general formulation reliable only on average. In fact this failure is responsible of an asymmetry in the seismic radiation known, since Ben-Menhaem (PhD1961), as directivity effect. While the general knowledge of the earthquakes is treated explicitly in the empirical prediction, specific trends like the directivity effects are hidden in the uncertainty sigma. A way to reduce the sigma is therefore to refine the seismic seismic source description inside the GMPEs (e.g. NGA project, Power et al, Earthquake Spectra, 2008).
In this framework we propose a strategy to introduce the directivity in the GMPEs and to study its effect on uncertainties and on hazard maps. For this purpose, we have used two different directivity models acting on the GMPE as corrective factors: one proposed by Somerville et al. (Seis.Res.Lett.1997) and the other one proposed by Spudich and Chiou (Earthquake Spectra 2008).The first factor depends on geometrical parameters and comes from theoretical deduction. The second one includes many source parameters and it is a hybrid factor, which functional formulation is deduced from the theory, calibrated on synthetic simulations and scaled on data.
The classic hazard equation is then adapted in order to increase the number of source parameters (i.e. adding one integral over the parametric space for each new variable involved) and taking into account the corrective factors for directivity (Spagnuolo, PhD2010). We present the comparisons of hazard maps depending on the directivity factor and on the probability density functions of the fault strike and of the rupture “laterality”
Preliminary estimates of tritium permeation and retention in the first wall of DEMO due to ion bombardment
Tritium self-sufficiency presents a critical engineering challenge for DEMO, requiring efficient breeding and extraction systems, as well as minimizing tritium losses to the surrounding systems, such as plasma-facing components, vacuum vessel, cooling system, etc. Structural and plasma-facing components will act as a tritium sink, as tritium will be accumulated in the bulk of these components due to energetic particle bombardment and may permeate out of the vacuum system. The design of the plasma-facing components will consequently directly influence the plant lifetime, operational safety and cost of any future power plant. Therefore, modeling of tritium retention and permeation in these components is required for the engineering designs of the tritium breeding and safety systems. In this work, the diffusion-transport code TESSIM-X is benchmarked against the well-established TMAP7 code and a comparison with a simplified DEMO-relevant test case is performed. The use of either code for modeling of DEMO conditions is discussed. Following this, TESSIM-X is used to provide a preliminary assessment of tritium permeation and retention in the DEMO first wall, based on the current WCLL (Water Cooled Lithium Lead) and HCPB (Helium Cooled Pebble Bed) breeding blanket designs
Structural assessment of the EU-DEMO water-cooled lead lithium central outboard blanket segment adopting the sub-modelling technique
The development of a sound conceptual design of the Water-Cooled Lead Lithium Breeding Blanket (WCLL BB) is pivotal to make a breakthrough towards the selection of the driver blanket concept for the EU-DEMO. To achieve this goal, an intense research campaign has been performed at the University of Palermo, in cooperation with ENEA Brasimone, under the umbrella of EUROfusion. In this paper, structural analyses of different poloidal regions of the WCLL BB Central Outboard Blanket (COB) segment are reported. In particular, starting from the results of the thermo-mechanical analysis of the whole WCLL BB COB segment, the sub-modelling technique has been applied to the most significant poloidal regions, located at the top, middle and bottom of the segment. The aim is to focus on the stress field locally arising under purposely selected steady-state nominal and accidental loading scenarios. The nominal BB operating conditions, as well as steady-state scenarios derived from both the in-box LOCA and Vertical Plasma Disruption accidents have been considered. Thanks to the sub-modelling approach, the deformative action of the entire segment can be imposed at the boundaries of each local model to realistically assess its structural performances. Moreover, each local model reproduces structural details not included in the global one, such as the Segment Box (SB) cooling channels. Then, the structural behaviour of the selected regions has been assessed in compliance with the RCC-MRx code. The obtained results highlighted that the structural behaviour predicted by the whole segment analysis is similar to that predicted by sub-modelling calculations within the Stiffening Plates, whereas the application of the sub-modelling is a must to investigate in detail the SB structural performances. In addition, results indicate that the BB attachments should be revised, as they contribute to produce the WCLL COB large deformation originating excessive stresses, mainly within the equatorial region
Validation of multi-physics integrated procedure for the HCPB breeding blanket
The wide range of requirements and constraints involved in the design of nuclear components for fusion reactors makes the development of multi-physics analysis procedures of utmost importance. In the framework of the European DEMO project, the Karlsruhe Institute of Technology (KIT) is dedicating several efforts to the development of a multi-physics analysis tool allowing the characterization of breeding blanket design points which are consistent from the neutronic, thermal-hydraulic and thermal-mechanical points of view. In particular, a procedure developed at KIT is characterized by the implementation of analysis software only. A preliminary step for the validation of such a procedure has been accomplished using a dedicated model of the DEMO Helium Cooled Pebble Bed Blanket 4th outboard module. A global model representative of nuclear irradiation in DEMO and two local models have been set up. Nuclear power deposition and the spatial distribution of its volumetric density have been calculated using Monte Carlo N-Particle transport code for the aforementioned models and compared in order to validate the procedure set up. The outcomes of this comparative study are herein presented and critically discussed
Variability of kinematic source parameters and its implication on the choice of the design scenario
Near-fault seismic recordings for recent earthquakes (Chi Chi earthquake,
1999, and Parkfield earthquake, 2004) show the high spatial heterogeneity
of ground motion. This variability is controlled by fault geometry, rupture complexity,
and also by wave propagation and site effects. Nowadays, the number of available
records in the near-source region is still not enough to infer a robust parameterization
of the ground motion and to retrieve multiparametric predictive equations valid at
close distances from the fault. The use of a synthetic approach may help to overcome
this limitation and to study the strong ground motion variability. In this article we
focus on ground-motion dependence on different earthquakes breaking the same fault,
as it has been rarely recorded by instruments. We model seismic scenarios from different
rupture models of a fault similar to the 1980 Irpinia, Italy, earthquake source
(Mw 6.9). A discrete wavenumber/finite element technique is used to compute fullwave
displacement and velocity time series in the low-frequency band (up to 2 Hz).
We investigate the variability of the ground motion as a function of different
source parameters (rupture velocity, slip distribution, nucleation point, and source
time function), whose values depend on the state of knowledge of the physical model
driving the process. The probability density functions of the simulated ground-motion
parameters, such as displacement response spectrum and peak ground velocity, are
used to identify particular scenarios that match specific engineering requests
Energy Scheduling and Performance Evaluation of an e-Vehicle Charging Station
This paper proposes an energy management system (EMS) for a photovoltaic (PV) grid-connected charging station with a battery energy storage system (BESS). The main objective of this EMS is to manage the energy delivered to the electric vehicle (EV), considering the price and (Formula presented.) emissions due to the grid’s connection. Thus, we present a multi-objective two-stage optimization to reduce the impact of the charging station on the environment, as well as the costs. The first stage of the optimization provides an energy schedule, taking into account the PV forecast, the hourly grid’s (Formula presented.) emissions factor, the electricity price, and the initial state of charge of the BESS. The output from this first stage corresponds to the maximum power permitted to be delivered to the EV by the grid. Then, the second stage of the optimization is based on model predictive control that looks to manage the energy flow from the grid, the PV, and the BESS. The proposed EMS is validated using an actual PV/BESS charging station located at the University of Trieste, Italy. Then, this paper presents an analysis of the performance of the charging station under the new EMS considering three main aspects, economic, environmental, and energy, for one month of data. The results show that due to the proposed optimization, the new energy profile guarantees a reduction of 32% in emissions and 29% in energy costs
Variability of kinematic source parameters and its implication on the choice of the design scenario
Near-fault seismic recordings for recent earthquakes (Chi Chi earthquake, 1999; Parkfield earthquake, 2004) show the high spatial heterogeneity of ground motion. This variability is controlled by fault geometry, rupture complexity, and also by wave propagation and site effects.
Nowadays, the number of available records in near-source region is still not enough to infer a robust parameterization of the ground motion and to retrieve multi-parametric predictive equations valid at
close distances from the fault. The use of a synthetic approach may help to overcome this limitation and to study the strong ground motion variability. In this paper we focus on ground-motion dependence on different earthquakes breaking the same fault, as it has been rarely recorded by instruments. We model seismic scenarios from different rupture models of a fault similar to the
1980 Irpinia, Italy, earthquake source (Mw 6.9). A discrete wavenumber-finite element technique is used to compute full-wave displacement and velocity time series in the low-frequency band (up to 2 Hz).
We investigate the variability of the ground motion as a function of different source parameters (rupture velocity, slip distribution, nucleation point, source time function), whose values depend on the state of knowledge of the physical model driving the process. The probability density functions of the simulated ground motion parameters, such as displacement response spectrum (SD) and peak ground velocity (PGV), have been used to identify particular scenarios that match specific engineering requests
Minimization of Adverse Effects Associated with Dental Alloys
Metal alloys are one of the most popular materials used in current dental practice. In the oral cavity, metal structures are exposed to various mechanical and chemical factors. Consequently, metal ions are released into the oral fluid, which may negatively affect the surrounding tissues and even internal organs. Adverse effects associated with metallic oral appliances may have various local and systemic manifestations, such as mouth burning, potentially malignant oral lesions, and local or systemic hypersensitivity. However, clear diagnostic criteria and treatment guidelines for adverse effects associated with dental alloys have not been developed yet. The present comprehensive literature review aims (1) to summarize the current information related to possible side effects of metallic oral appliances; (2) to analyze the risk factors aggravating the negative effects of dental alloys; and (3) to develop recommendations for diagnosis, management, and prevention of pathological conditions associated with metallic oral appliances
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