A new fault-ride-through strategy for MTDC networks incorporating wind farms and modular multi-level converters

This paper presents a DC voltage control strategy for enhancing the fault-ride-through (FRT) capability of wind farms comprising of fully rated converter permanent magnet synchronous generators (FRC-PMSGs) connected to multi-terminal high voltage direct current (MT-HVDC) grids through modular multi-level converters (MMCs). The proposed FRT strategy is implemented on a master controller located in the offshore AC substation of each wind farm. The underlying issue addressed via the scheme relates to overvoltages in the HVDC links when the power transfer is disrupted due to faults occurring in the AC onshore grid. The corresponding Matlab/Simulinkr model has been validated using transient simulation, while the practical feasibility of the controller is demonstrated utilising Opal-RT© real-time hardware platform

Design of a Hybrid AC/DC Microgrid Using HOMER Pro: Case Study on an Islanded Residential Application

This paper is concerned with the design of an autonomous hybrid alternating current/direct current (AC/DC) microgrid for a community system, located on an island without the possibility of grid connection. It is comprised of photovoltaic (PV) arrays and a diesel generator, AC loads, and battery energy storage devices for ensuring uninterruptible power supply during prolonged periods of low sunshine. A multi-objective, non-derivative optimisation is considered in this residential application; the primary objective is the system cost minimisation, while it is also required that no load shedding is allowed. Additionally, the CO2 emissions are calculated to demonstrate the environmental benefit the proposed system offers. The commercial software, HOMER Pro, is utilised to identify the least-cost design among hundreds of options and simultaneously satisfy the secondary objective. A sensitivity analysis is also performed to evaluate design robustness against the uncertainty pertaining to fuel prices and PV generation. Finally, an assessment of the capabilities of the utilised optimisation platform is conducted, and a theoretical discussion sheds some light on the proposal for an enhanced design tool addressing the identified issues

Prevalence of sealants in relation to dental caries on the permanent molars of 12 and 15-year-old Greek adolescents. A national pathfinder survey

<p>Abstract</p> <p>Background</p> <p>The use of sealants as an effective measure for the prevention of pit and fissure caries in children has been well documented by several studies; either they are used on an individual or on a public health basis. In order to plan and establish a national preventive program with sealants in a community, it is mandatory to know the epidemiological pattern of caries along with other variables influencing their use and effectiveness. Aims: To assess the utilization and distribution pattern of pit and fissure sealants on the first and second permanent molars of Greek adolescents and to evaluate whether the existing usage of sealants and some socio-demographic factors are correlated to caries prevalence on the population examined</p> <p>Methods</p> <p>A stratified cluster sample of 2481 Greek adolescents was selected according to WHO guidelines (1224 twelve and 1,257 fifteen-year-old), living in urban and rural areas in 11 districts within the country. Five calibrated examiners carried out clinical examinations, recording caries experience at the dentine threshold (BASCD criteria) and presence or absence of sealants along with Socio-demographic indicators associated with oral health. Mann Whitney and Pearson's chi-square non parametric tests were utilized for assessing the data. The level of significance was p < 0.05.</p> <p>Results</p> <p>Sealants utilization varied considerably within the different districts, with 8,3% of the 12 and 8,0% of the 15-year-old adolescents having at least one sealed molar. Sealants reduced DMFS scores by 11% in the 12-year-olds and by 24% in the 15-year-olds, while 15-year-old adolescents from rural areas had a statistically significant (p = 0.002) less chance of having sealants (71%) compared to children from urban areas. Girls had higher chance to receive sealants in both age groups (26% for the 12 and 19% for the 15-year-old) as well as patients that visited the dentist for prevention compared to those visiting the dentist because they thought they needed a restoration or because they were in pain.</p> <p>Conclusions</p> <p>The finding that sealants reduced DMFS scores despite their very low utilization, along with the high prevalence of dental caries found on the occlusal surfaces of the posterior teeth of Greek adolescents, is calling for a national preventive program with sealants which could eliminate caries to a larger extent.</p

The role of empathy in psychoanalytic psychotherapy: A historical exploration

Empathy is one of the most consistent outcome predictors in contemporary psychotherapy research. The function of empathy is particularly important for the development of a positive therapeutic relationship: patients report positive therapeutic experiences when they feel understood, safe, and able to disclose personal information to their therapists. Despite its clear significance in the consulting room and psychotherapy research, there is no single, consensual definition of empathy. This can be accounted by the complex and multi-faceted nature of empathy, as well as the ambiguous and conflicting literature surrounding it. This paper provides a historical exploration of empathy and its impact on the therapeutic relationship across the most influential psychoanalytic psychotherapies: classic psychoanalysis, person-centered therapy and self-psychology. By comparing the three clinical schools of thought, the paper identifies significant differences in the function of transference and therapist’s role. Then, drawing on the different clinical uses of empathy, the paper argues that the earlier uses of empathy (most notably through Jaspers’ and Freud’s writings) are limited to its epistemological (intellectual or cognitive) features, whilst person-centered and self-psychology therapies capitalise on its affective qualities. Finally, the paper provides a rationale for further study of the overarching features of empathy in contemporary psychotherapy research

Dental sealant knowledge, opinion, values and practice of Spanish dentists

[Background] Multiple guidelines and systematic reviews recommend sealant use to reduce caries risk. Yet, multiple reports also indicate that sealants are significantly underutilized. This study examined the knowledge, opinions, values, and practice (KOVP) of dentists concerning sealant use in the southwest region of Andalusia, Spain. This is a prelude to the generation of a regional plan for improving children’s oral health in Andalusia.[Methods] The survey’s target population was dentists working in western Andalusia, equally distributed in the provinces of Seville, Cadiz, and Huelva (N=2,047). A convenience sample of meeting participants and meeting participant email lists (N=400) were solicited from the annual course on Community and Pediatric Dentistry. This course is required for all public health sector dentists, and is open to all private sector dentists. Information on the dentist’s KOVP of sealants was collected using four-part questionnaire with 31, 5-point Likert-scaled questions.[Results] The survey population demographics included 190 men (48%) and 206 women (52%) with an average clinical experience of 10.6 (± 8.4) years and 9.3 (± 7.5) years, respectively. A significant sex difference was observed in the distribution of place of work (urban/suburb) (p=0.001), but no sex differences between working sector (public/private). The mean ± SD values for each of the four KOVP sections for pit and fissure sealants were: knowledge = 3.57 ± 0.47; opinion = 2.48 ± 0.47; value = 2.74 ± 0.52; and practice = 3.48 ± 0.50. No sex differences were found in KOVP (all p >0.4). Independent of sex: knowledge statistically differed by years of experience and place of work; opinion statistically differed by years of experience and sector; and practice statistically differed by years of experience and sector. Less experienced dentists tended to have slightly higher scores (~0.25 on a Likert 1–5 scale). Statistically significant correlations were found between knowledge and practice (r=0.44, p=0.00) and between opinion and value (r=0.35, p=0.00).[Conclusions] The results suggest that, similar to other countries, Andalusian dentists know that sealants are effective, have neutral to positive attitudes toward sealants; though, based on epidemiological studies, underuse sealants. Therefore, methods other than classical behavior change (eg: financial or legal mechanisms) will be required to change practice patterns aimed at improving children's oral health.We acknowledge the following sources for invaluable financial support NIMHD 1 R34 DE022272 (NIH2385) and NIDCR 1 U24 MD006964

The catatonic dilemma expanded

Catatonia is a common syndrome that was first described in the literature by Karl Kahlbaum in 1874. The literature is still developing and remains unclear on many issues, especially classification, diagnosis, and pathophysiology. Clinicians caring for psychiatric patients with catatonic syndromes continue to face many dilemmas in diagnosis and treatment. We discuss many of the common problems encountered in the care of a catatonic patient, and discuss each problem with a review of the literature. Focus is on practical aspects of classification, epidemiology, differential diagnosis, treatment, medical comorbidity, cognition, emotion, prognosis, and areas for future research in catatonic syndromes

The relationship between subtypes of depression and cardiovascular disease: a systematic review of biological models

A compelling association has been observed between cardiovascular disease (CVD) and depression, suggesting individuals with depression to be at significantly higher risk for CVD and CVD-related mortality. Systemic immune activation, hypothalamic–pituitary–adrenal (HPA) axis hyperactivity, arterial stiffness and endothelial dysfunction have been frequently implicated in this relationship. Although a differential epidemiological association between CVD and depression subtypes is evident, it has not been determined if this indicates subtype specific biological mechanisms. A comprehensive systematic literature search was conducted using PubMed and PsycINFO databases yielding 147 articles for this review. A complex pattern of systemic immune activation, endothelial dysfunction and HPA axis hyperactivity is suggestive of the biological relationship between CVD and depression subtypes. The findings of this review suggest that diagnostic subtypes rather than a unifying model of depression should be considered when investigating the bidirectional biological relationship between CVD and depression. The suggested model of a subtype-specific biological relationship between depression and CVDs has implications for future research and possibly for diagnostic and therapeutic processes