To perform vector control of single-inverter dual induction motors, drives are standardly equipped with current and position sensors. In medium-power railway applications, a shaft encoder is usually ...mounted on each motor, and the inverter output current is measured using two current sensors. Yet, this configuration features some disadvantages. First, torque-sharing cannot be computed because stator current of each motor is unknown. Similarly, saliency extraction of each motor is not achievable since individual current drawn by each motor is not measured. An option that achieves torque-sharing calculation is to attach two current sensors to each motor, provided that both rotor positions are known. However, industrial inverter/control platforms considered offer a maximum of three input channels for current sensors. Besides, some industry fields tend towards encoderless speed control. Therefore, this paper proposes to use three current sensors in total and no shaft encoders. Thanks to a special current sensor arrangement and a voltage step excitation method, saliency-based encoderless control is achieved. In addition, a method is presented to estimate torque-sharing. Experimental measurements, taken on a dual induction motor test bench, will show the capability of the proposed methodology to identify individual loading as well as excellent encoderless control performance.
Aim
There are no nationally representative epidemiological studies available reporting on the different recession types according to the 2018 classification system or focusing on the aesthetic zone. ...The aims of this cross‐sectional study were (a) to provide estimates on the prevalence, severity and extent of mid‐buccal GRs according to the 2018 classification and (b) to identify their risk indicators in the adult U.S. population from the NHANES database.
Materials and Methods
Data from 10,676 subjects, representative of 143.8 millions of adults, were retrieved from the NHANES 2009–2014 database. GR prevalence was defined as the presence of at least one mid‐buccal GR ≥1 mm. GRs were categorized following the 2018 World Workshop classification system (RT1, RT2, RT3) and according to different severity cut‐offs. An analysis for GR risk indicators was also performed, selecting subjects without periodontitis.
Results
The patient‐level prevalence of mid‐buccal GRs (all types) was 91.6%, while it decreased to 70.7% when considering only the aesthetic zone. When focusing on RT1 GRs, the patient‐level prevalence (whole mouth) was 12.4%, while it was 5.8% considering only the aesthetic zone. The majority of RT1 GRs were considered as mild (1–2 mm). The whole‐mouth patient‐level prevalence of RT2 and RT3 GRs was 88.8% and 55.0%, respectively. Age (35–49 years), gender (female), ethnicity (non–Hispanic Whites), last dental visit (>6 months before), tooth type (incisors) and the arch (mandible) resulted as risk indicators associated with the presence of RT1 GR.
Conclusions
Mid‐buccal GRs affect almost the entire US population. Age, gender, ethnicity, dental care exposure, tooth type and arch were identified as risk indicators for RT1 GRs.
Aim
The primary aim of this systematic review was to evaluate the effect of various techniques used for vertical ridge augmentation on clinical vertical bone gain.
Material and Methods
A protocol was ...developed to answer the following focused question: “In patients with vertical alveolar ridge deficiencies, how effective are different augmentation procedures for clinical alveolar ridge gain?” Randomized and controlled clinical trials and prospective and retrospective case series were included, and meta‐analyses were performed to evaluate vertical bone gain based on the type of procedure and to compare bone gains in controlled studies.
Results
Thirty‐six publications were included. Results demonstrated a significant vertical bone gain for all treatment approaches (n = 33; weighted mean effect = 4.16 mm; 95% CI 3.72–4.61; p < 0.001). Clinical vertical bone gain and complications rate varied among the different procedures, with a weighted mean gain of 8.04 mm and complications rate of 47.3% for distraction osteogenesis, 4.18 mm and 12.1% for guided bone regeneration (GBR), and 3.46 mm and 23.9% for bone blocks. In comparative studies, GBR achieved a significant greater bone gain when compared to bone blocks (n = 3; weighted mean difference = 1.34 mm; 95% CI 0.76–1.91; p < 0.001).
Conclusions
Vertical ridge augmentation is a feasible and effective therapy for the reconstruction of deficient alveolar ridges, although complications are common.
Some induction motors present saliencies that periodically modify the air-gap flux following a sinusoidal shape. Consequently, these modulations are reflected in the transient leakage inductance. ...Therefore, transient leakage inductance can be expressed as a constant term or offset, which comes from the symmetrical machine, plus all motor saliency sinusoids, modulated by the mentioned saliencies. Since saliencies are linked to the rotor position or flux, calculation of transient leakage inductance enables encoderless vector control. A way to calculate transient leakage inductance is to excite the machine with voltage steps and estimate the resulting phase current slopes since they are inversely proportional to phase transient inductance. For creating a vector, only the three current slopes resulting from a single active state are sufficient. The vector sum of the three current slopes leads to the so-called saliency-offset vector, which is a vector composed of an offset, which is created due to the contribution of the transient inductance offset, plus several saliency phasors, superposed to the offset. To access saliencies, it is critical to accurately identify the offset of the saliency-offset vector, especially in induction motors since offset is much bigger than saliencies. This article presents an advanced signal processing scheme that identifies the offset in the saliency-offset vector, assuming offset amplitude differsdepending on the voltage step applied. Using a feedforward scheme, the offset is eliminated, leading to a saliency vector where rotor slotting can be extracted from. A novel excitation is proposed to reduce additional current distortions coming from the one-active excitation.
In this work, we have reported the vapor liquid equilibria (VLE) data for the binary mixtures containing {2-(2-ethoxyethoxy)ethanol (1) + 1-propanol, 2-propanol, 1-butanol, or 2-butanol (2)}. All ...the VLE measurements were conducted at temperatures ranging between (273.15 to 363.15) K over the whole composition range. The NRTL and UNIQUAC models were used to correlate the VLE experimental data. Furthermore, experimental measurements of densities, sound velocities, and refractive indices were measured for aforementioned binary mixtures at atmospheric pressure and at T = (293.15, 303.15, 313.15, and 323.15) K. By utilizing the experimental results, the excess/deviation functions were calculated and fitted to the Redlich–Kister polynomial equation.
The aim of this paper is to provide an assessment of the benefits and costs of the deployment of RES-E, electricity from renewable energy sources (RES-E) in Spain between 2002 and 2011. The benefits ...refer to reductions of CO₂ emissions and fossil-fuel imports. These are compared to the costs of public support for RES-E deployment granted through the feed-in-tariff system (FIT). Three different methods have been applied for this purpose: the operative margin factor, the build margin factor and a combination of both. The results show that the benefits of RES-E promotion have outweighed the overall costs of RES-E deployment, although significant variation can be observed across technologies. While those benefits have been higher than the costs for on-shore wind and small hydro, this is not the case with the solar technologies. The costs have been significantly higher than the benefits in the case of solar photovoltaics and slightly higher in the case of solar thermoelectric.
Emergency medical technicians (EMTs) are essential health care workers (HCWs). Although they play an extraordinary role during the COVID-19 pandemic, they are mostly exposed to various occupational ...health and safety risks that have significantly impacted their mental health, giving rise to symptoms, such as stress and burnout.
This study aimed to assess the perceived levels of stress and burnout amongst EMTs in relation to their socio-demographic characteristics and to explore the associations between their stress and burnout levels during the COVID-19 pandemic.
This work is an observational cross-sectional design study conducted between 29 March and 30 April 2021, with a convenience sample of 280 Spanish EMTs yielding a response rate of 28%. The online survey had 42 items that aimed to determine participants' socio-demographic characteristics, the Perceived Stress Scale (PSS) and the Maslach Burnout Inventory (MBI).
The results showed that more than half of the EMTs (53%) perceived a moderate stress level, 37% perceived moderate levels of emotional exhaustion (EE) and 40% had moderate levels of depersonalization (DP). Furthermore, 48% had low levels of personal accomplishment (PA). Gender, age, having personal protective equipment (PPE) and experiencing fear of infection were statistically significant areas where participants experienced greater stress (p < 0.05). A positive correlation between stress, EE and DP and a negative correlation between stress and the PA subdimension of burnout were found.
The COVID-19 pandemic had a tremendous impact on the mental health of ambulance EMTs. Further studies building on this study and others on the psychological status of EMTs before the pandemic and follow-up during the pandemic, as well as deeper investigations on their work conditions, are needed to facilitate the implementation of various interventions. Such efforts can mitigate the negative impacts of the pandemic on their mental health, and prepare them for future disasters.
KEY MESSAGE
The COVID-19 pandemic has affected the lives of the majority of the world's population. In particular, it has impacted the mental health of various communities, including HCWs. Highly stressful and insecure work conditions have placed frontline HCWs at a high risk of psychological distress, making them victims and service providers simultaneously.
Periodontitis is a ubiquitous and irreversible inflammatory condition and represents a significant public health burden. Severe periodontitis affects over 11% of adults, is a major cause of tooth ...loss impacting negatively upon speech, nutrition, quality of life and self‐esteem, and has systemic inflammatory consequences. Periodontitis is preventable and treatment leads to reduced rates of tooth loss and improved quality of life. However, successful treatment necessitates behaviour change in patients to address lifestyle risk factors (e.g. smoking) and, most importantly, to attain and sustain high standards of daily plaque removal, lifelong. While mechanical plaque removal remains the bedrock of successful periodontal disease management, in high‐risk patients it appears that the critical threshold for plaque accumulation to trigger periodontitis is low, and such patients may benefit from adjunctive agents for primary prevention of periodontitis.
Aim
The aims of this working group were to systematically review the evidence for primary prevention of periodontitis by preventing gingivitis via four approaches: 1) the efficacy of mechanical self‐administered plaque control regimes; 2) the efficacy of self‐administered inter‐dental mechanical plaque control; 3) the efficacy of adjunctive chemical plaque control; and 4) anti‐inflammatory (sole or adjunctive) approaches.
Methods
Two meta‐reviews (mechanical plaque removal) and two traditional systematic reviews (chemical plaque control/anti‐inflammatory agents) formed the basis of this consensus.
Results
Data support the belief that professionally administered plaque control significantly improves gingival inflammation and lowers plaque scores, with some evidence that reinforcement of oral hygiene provides further benefit. Re‐chargeable power toothbrushes provide small but statistically significant additional reductions in gingival inflammation and plaque levels. Flossing cannot be recommended other than for sites of gingival and periodontal health, where inter‐dental brushes (IDBs) will not pass through the interproximal area without trauma. Otherwise, IDBs are the device of choice for interproximal plaque removal. Use of local or systemic anti‐inflammatory agents in the management of gingivitis has no robust evidence base. We support the almost universal recommendations that all people should brush their teeth twice a day for at least 2 min. with fluoridated dentifrice. Expert opinion is that for periodontitis patients 2 min. is likely to be insufficient, especially when considering the need for additional use of inter‐dental cleaning devices. In patients with gingivitis once daily inter‐dental cleaning is recommended and the adjunctive use of chemical plaque control agents offers advantages in this group.
Background and Aims
To review the regenerative technologies used in bone regeneration: bone grafts, barrier membranes, bioactive factors and cell therapies.
Material and Methods
Four background ...review publications served to elaborate this consensus report.
Results and Conclusions
Biomaterials used as bone grafts must meet specific requirements: biocompatibility, porosity, osteoconductivity, osteoinductivity, surface properties, biodegradability, mechanical properties, angiogenicity, handling and manufacturing processes. Currently used biomaterials have demonstrated advantages and limitations based on the fulfilment of these requirements. Similarly, membranes for guided bone regeneration (GBR) must fulfil specific properties and potential biological mechanisms to improve their clinical applicability. Pre‐clinical and clinical studies have evaluated the added effect of bone morphogenetic proteins (mainly BMP‐2) and autologous platelet concentrates (APCs) when used as bioactive agents to enhance bone regeneration. Three main approaches using cell therapies to enhance bone regeneration have been evaluated: (a) “minimally manipulated” whole tissue fractions; (b) ex vivo expanded “uncommitted” stem/progenitor cells; and (c) ex vivo expanded “committed” bone‐/periosteum‐derived cells. Based on the evidence from clinical trials, transplantation of cells, most commonly whole bone marrow aspirates (BMA) or bone marrow aspirate concentrations (BMAC), in combination with biomaterial scaffolds has demonstrated an additional effect in sinus augmentation and horizontal ridge augmentation, and comparable bone regeneration to autogenous bone in alveolar cleft repair.
In cooperative property rights systems, workers jointly own and manage production, whereas in outside-ownership systems, an owner contracts workers. Despite a rich literature on how the allocation of ...property rights matters for specialization, efficiency, and equity, little causal evidence exists. During a land reform in El Salvador in 1980, the military government reorganized properties owned by individuals with cumulative landholdings over 500 hectares into cooperatives; properties below this threshold remained as outside-owned properties. Using the discontinuous probability of cooperative formation, I provide evidence on the effects of cooperative property rights relative to outside ownership on specialization, productivity, and worker equity.
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