An integrated DC/DC converter with online monitoring of hot-carrier degradation

An integrated DC/DC converter with online monitoring of the degradation induced by hot-carrier stress (HCD) in new generation power LDMOS transistors is proposed. In particular, when a relatively high drain voltage is applied during on-state regime (switching phase), degradation mechanisms lead to an increase of the transistor on-resistance (RON). To this purpose, the converter is able to dynamically estimate the RON of the power LDMOS and to provide its value to the user during normal operation. The presented solution, developed in STMicroelectronics 90nm BCD technology, features a non-invasive current sensing and voltage sampling architecture, which is applied to a common DC/DC boost converter to evaluate the resistance of the power LDMOS. Without lack of generality, this specific sensing structure can be applied to any kind of converter, e.g. buck or buck-boost, as it does not require any change in the main conversion circuit

Endodontic Retreatment of Teeth With Uncertain Endodontic Prognosis Versus Dental Implants: 5-year Results From a Randomised Controlled Trial

PURPOSE. To ascertain whether it is better to endodontically retreat a previously endo-dontically treated tooth with periapical pathology and/or symptoms and an uncertain prognosis, or to replace the tooth with a single implant-supported crown. MATERIALS AND METHODS. Twenty patients requiring treatment of a previously endodon-tically treated tooth with periapical pathology and/or symptoms of endodontic origin and an uncertain prognosis, as judged by the recruiting investigator, were randomly allocated to endodontic retreatment (endo group; 10 patients) or tooth extraction and replacement with an implant-supported crown (implant group; 10 patients) according to a paral-lel-group design at a single centre. Patients were followed up to 5 years after treatment completion. Outcome measures were: procedure failure; complications; marginal bone level changes at both teeth and implants; radiographic endodontic success (teeth only); number of patient visits and days to complete treatment; chairside time; costs; and ae-sthetics, as assessed using the pink aesthetic score (PES) for the soft tissues and the white aesthetic score (WES) for the tooth/crown by independent assessors. RESULTS. One patient from the endo group dropped out. One endodontically retreated tooth fractured. There were no statistically significant differences in treatment failure between groups (difference in proportions = 0.1; 95% CI-0.18 to 0.35; P = 1.00). Three endo group patients had one complication each versus one complication in the implant group, the difference not being statistically significant (difference in proportions = 0.2; 95% CI-0.17 to 0.51; P = 0.582). The mean marginal bone levels at endo retreatment/implant insertion were 2.10 ± 0.66 mm for the endo and 0.05 ± 0.15 mm for the implant group. Five years after treatment completion, teeth lost on average 0.60 ± 0.96 mm and implants 0.56 ± 0.77 mm, the difference not being statistically significant (mean difference =-0.05 mm; 95% CI:-0.95 to 0.86; P = 0.914). Of the four teeth that originally showed periapical radiolucency, one was lost, two displayed complete healing, and one showed radiographic improvement. There were no statistically significant differences in the number of patient visits (endo = 6.7 ± 0.7; implant = 6.1 ± 0.7; mean difference = 0.6; 95% CI:-0.1 to 1.3 P = 0.106). However, it took significantly more days (endo = 61 ± 13.0; implant = 191.4 ± 75.0; mean difference =-130.4; 95% CI:-184.5 to-76.4; P < 0.001) but less chairside time (endo = 628 ± 41.4 min; implant = 328.5 ± 196.4 min; mean difference =-299.5; 95% CI:-441.3 to 1.0; P = < 0.001) to complete the rehabilitation. Implant treatment was significantly more expensive (endo = 1440 ± 549.7; implant = 2099 ± 170.3; mean difference = 659; 95% CI: 257.2 to 1060.8; P = 0.004). Five years after treatment completion, mean PES were 12.3 ± (1.3) and 8.9 ± 2.2 and mean WES were 8.1 ± 1.4 and 7.1 ± 1.7 in the endo group and implant group, respectively. Soft tissues aesthetics (PES) was significantly better at endodontically retreated teeth (mean difference-3.4; 95% CI-5.1 to-1.6; P (t-test) = 0.001), whereas no significant differences were observed between treatments in tooth aesthetics (WES) (mean difference =-1.0; 95% CI-2.6 to 0.5; P (t-test) = 0.178)

Machined Versus Cast Abutments for Single Dental Implants: A 3-year within-Patient Multicentre Randomized Controlled Trial

PURPOSE: To compare clinical outcomes of machined titanium abutments (machined group) versus cast cobalt-chrome abutments (cast group). MATERIALS AND METHODS: Thirty-one partially edentulous subjects received two single non-adjacent implant-supported crowns each at three centres. Three and a half months after implant placement, implants were randomized at impression taking to receive one machined and one cast abutment according to a within-patient study design. Four patients dropped out and one patient lost one implant before randomization, so only 26 patients had their implants randomized. Outcome measures were: prosthesis and implant failures, any complications, and radiographic peri-implant marginal bone level changes. Patients were followed up for 3 years after loading. RESULTS: After randomization, three patients dropped out. One implant failed and two crowns on cast abutments were lost, but differences in implant and prosthesis failures were not statistically different (McNemar test P = 1.000; difference in proportions = 0.04 and P = 0.500; difference in proportions = 0.08, respectively). Two minor complications occurred in the cast group versus one in the machined group, the difference not being statistically different (McNemar test P = 1.000; difference in proportions = 0.04; 95% CI 0.18 to 22.06). Both groups presented statistically significant peri-implant marginal bone loss from implant placement to 3 years after loading, respectively -0.72 ± 0.90 mm (P = 0.001) for machined and -0.60 ± 0.61 mm (P <0.001) for cast abutments, with no statistically significant differences between the two groups (mean difference -0.12 mm; 95% CI -0.57 to 0.34; P = 0.624). Both groups gradually lost marginal peri-implant bone from loading (baseline) to 3 years after loading, but this was not statistically significant; machined lost -0.05 ± 0.12 mm while cast lost -0.14 ± 0.11 mm, a difference that was not statistically significant (mean difference 0.06 mm; 95% CI -0.24 to 0.35; P = 0.708). CONCLUSIONS: The present clinical data suggest that implant prognosis up to 3 years after loading is not affected by the choice of machined or cast abutments

A first look at the Gargano (southern Italy) seismicity as seen by the local scale OTRIONS seismic network

OnApril 2013,alocal scale seismic network,namedOTRIONS, composed of twelve short period (1 Hz) three component seismometers, has been located in the northern part of the Apulia (Southern Italy). At each station, the acquisition systemallows the recording of data in situ and their real time transfer toa seismic laboratory located at the Dipartimento di Scienze della Terra e Geoambientali of Università di Bari "Aldo Moro". The preliminary real time detection and localization of the events is automatically realized by using the SeisComp3 software. In the first two months of data acquisition, the network recorded about one hundred low magnitude (ML<2) earthquakes. In that follows,wepresent the results of a study aimed at investigating the crustal structure of the Gargano promontory. To this aimweanalyzed the seismic events recorded in the area by the “Istituto Nazionale di Geofisica e Vulcanologia” (INGV) in the period 2006-2012 and the seismic events recorded by the OTRIONS network in the first two months of acquisition (march and april 2013). From the inversion of P and S travel times of INGV events we inferred a preliminary 3-layer Vp velocity model. The Moho is located at a depth of 27-30 km, in agreement with previous studies. A linearized inversion scheme that uses Velest (Kissling et al., 1994), allowed us to infer a 1D velocity model from the joint inversion of INGV and OTRIONS datasets of P and S travel times. On the whole, the number of earthquakes recorded by the OTRIONS seismic network is higher than 1200 in the period april,2013-march,2014

A first look at the Gargano (southern Italy) seismicity as seen by the local scale OTRIONS seismic network

On April 2013, a local scale seismic network, named OTRIONS, composed of twelve short period (1 Hz) three component seismometers, has been located in the northern part of the Apulia (southern Italy). In the first two months of data acquisition, the network recorded about one hundred very small (ML<2) magnitude earthquakes. A three-layer 1D VP velocity model was preliminarily computed, using the recordings of earthquakes occurred in the area in the period 2006-2012 and recorded by the national seismic network of INGV (Istituto Nazionale di Geofisica e Vulcanologia). This model was calibrated by means of a multi-scale approach, based on a global search of the minimum misfit between observed and theoretical travel times. At each step of the inversion, a grid-search technique was implemented to infer the elastic properties of the layers, by using HYPO71 to compute the forward models. In a further step, we used P and S travel times of both INGV and OTRIONS events to infer a minimum 1D VP velocity model, using a classical linearized inversion approach. Owing to the relatively small number of data and poor coverage of the area, in the inversion procedure, the VP/VS ratio was fixed to 1.82, as inferred from a modified Wadati diagram. The final 1D velocity model was obtained by averaging the inversion results arising from nine different initial velocity models. The inferred VP velocity model shows a gradual increase of P wave velocity with increasing the depth. The model is well constrained by data until to a depth of about 25-30 km

Shell morphology and sperm ultrastructure of Solen tehuelchusHanley, 1842 (Bivalvia: Solenidae): new taxonomic characters

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOSolen tehuelchus Hanley, 1842 is currently the only razor-clam reported from Brazilian waters. Although its shell is well known and similar to the other Solenoidea, their anatomical aspects are poorly studied. Recently some living specimens of S. tehuelchus were obtained from a Brazilian beach, allowing the removal of their testes for an ultrastructural analysis. In order to add a new anatomical feature for this species and provide a brief comparison between some related taxa, the shell and sperm ultrastructure were described in detail. The present study showed that characteristics of the spermatozoa of S. tehuelchus are similar to those of other solenids, although certain sperm ultrastructural characteristics such as a short acrosome with an electron-dense base and rounded nucleus are also similar to the species Tagelus plebeius (Lightfoot, 1786) (Solecurtidae). Herein, we have added new anatomic and taxonomic data hitherto unknown to science. The sperm morphology of S. tehuelchus, might in the near future bring new insights into the systematic of Solenidae.Solen tehuelchusHanley, 1842 is currently the only razor-clam reported from Brazilian waters. Although its shell is well known and similar to the other Solenoidea, their anatomical aspects are poorly studied. Recently some living specimens ofS. tehuelchus3427378FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO2010/15486-81106/2010sem informaçã

The Role of Frequency and Duty Cycle on the Gate Reliability of p-GaN HEMTs

In this letter, we present an extensive analysis on the role of both switching frequency (ranging from 100 kHz to 1 MHz) and duty cycle (from 10% to 90%) on the time-dependent gate breakdown of high electron mobility transistors (HEMTs) with Schottky metal to p-GaN gate. More specifically, results show how the gate lifetime of GaN HEMTs increases by reducing the frequency and the duty cycle of the stressing gate signal (VG). Such behavior is ascribed to the OFF-time, which is responsible to alter the electrostatic potential in the p-GaN layer during the rising phases of VG (from OFF- to ON-state). Findings of this analysis are useful both for further technology improvement and for GaN-based power circuit designers

Machined Versus Cast Abutments for Dental Implants: a 1-year Within-patient Multicentre Randomized Controlled Trial Assessing Marginal Seal Capacity and Outcomes

PURPOSE To compare clinical outcomes of machined titanium abutments (machined group) versus cast cobalt-chrome abutments (cast group) and to evaluate in vitro their implant fit. MATERIALS AND METHODS This study comprised two parts. In the in vitro part, the im-plant–abutment fit of 5 cast abutments and 5 machined abutments screwed on with a torque of 30 Ncm was qualitatively and quantitatively evaluated using micro-computed tomography (µ-CT) and AgNO3 to reveal connection gaps. In the clinical part, 31 partially edentulous subjects received two single non-adjacent implant-supported crowns at three centres. At impression taking, three and a half months after implant placement, implants were randomized to receive a machined or cast abutment according to a wi-thin-patient study design. Unfortunately, four patients dropped out and one patient lost one implant before randomization, so only 26 patients had their implants randomized. Outcome measures were: prosthesis and implant failures, any complications, and radiographic peri-implant marginal bone level changes. Patients were followed up to 1 year after loading. RESULTS The fit of the implant–abutment connection was assessed in vitro using µ-CT scans. No gaps were revealed at any of the machined or cast abutments tested. In the clinical part, after randomization, three patients dropped out, no implant failed, but one crown on a cast abutment was replaced. The between-group difference in prosthesis failure was not statistically different (McNemar chi-square test P = 1.0; difference in proportions = 0.039). One complication occurred in each group, the difference not being statistically different (McNemar test P = 1.000; difference in proportions = 0; 95% CI 0.06 to 15.99). Both groups presented statistically significant peri-implant marginal bone loss from implant placement to 1 year after loading, respectively-0.76 ± 1.01 mm for machined and-0.69 ± 0.82 mm for cast abutments, with no statistically significant differences between the two groups (mean difference 0.07 mm; 95% CI-0.54 to 0.67; P = 0.828). Both groups gradually lost marginal peri-implant bone from loading to 1 year after loading but this was not significantly different, respectively-0.06 ± 0.56 mm for machined and-0.10 ± 0.29 mm for cast abutments, with no statistically significant differences between the two groups (P = 0.739; mean difference 0.07 mm; 95% CI-0.12 to 0.16; P = 0.739). CONCLUSIONS Our clinical data suggests that implant prognosis up to 1 year after loading is not affected by using machined or cast abutments. In support of these findings, in vitro analysis proved that both types of abutments allow a tight fit with no gaps. The-refore, for the time being dentists should feel free to choose whichever type they prefer. However, these preliminary results need to be confirmed by larger trials with at least 10 years of follow-up