The effects of powder processing parameters on the microstructure and energy absorption characteristics of low voltage ZnO varistors

The effect of comminution techniques used during the powder preparation stage of zinc oxide varistor powder was studied. The continual requirement for downsizing in electronic components combined with improved performance, demand greater understanding of the parameters influencing the required characteristics. Improvements in energy absorption capability of low voltage zinc oxide varistors are highly desirable from both a commercial and end product performance perspective. Enhanced energy absorption capability can be used to upgrade the rating of an existing varistor form factor capable of suppressing larger transients (Product capability enhancement) or alternatively reducing the part dimensions (Cost improvements). Current commercial applications for zinc oxide varistors demand energy performance improvements especially in automotive and telecommunications applications, where dimensions and costs as well as high reliability are imperative to compete in the world marketplace. The physics of energy absorption indicates that in order to improve this, improvements must be made in thermal properties, material processing and testing. Materials parameters of interest include, uniform density, chemical homogeneity and grain size. A high degree of chemical homogeneity in the oxide powder mix prior to pressing and densification is required, in particular, particle size distributions of the oxide dopants and zinc oxide -oxide dopant mixture with maximum values < ljum are highly desirable. Varistors manufactured by the conventional ceramic process use comminution to achieve particle size reduction of oxide dopants, prior to their addition to the zinc oxide slip. This work compares the effects of using eight combinations of milling-mixing techniques on the particle size distribution of oxide dopants and the full formula slip, and examines the microstructural properties of the densified parts using scanning electron microscopy (SEM), and compares the energy absorption capabilities of the devices produced by each technique. The four comminution techniques studied were, Ball, Vibratory, Turbula, and Attrition milling. Shear mixing was used as in the conventional manufacturing process to mix the oxide dopants and zinc oxide. The work has shown that attrition milling is the most efficient comminution technique, reducing particle size distribution averages to well below ljum in less than two hours, compared to the other techniques which, regardless of milling time could not achieve the sub micron size distribution averages. In all samples where comminution versus shear mixing was used to mix-mill the oxide dopants and zinc oxide together, the energy capability was always considerably improved over the samples where shear mixing alone was used. This work has also identified Vibratory milling of oxide dopants followed by attrition milling of the oxide dopants and zinc oxide together, gave 12% better average energy absorption capability performance over the conventional technique. (Ball milling followed by shear mixing

On the development of perfectionism: The longitudinal role of academic achievement and academic efficacy

Objective: Although perfectionism is a prominent personality disposition, only a few longitudinal studies have investigated how perfectionism develops. Theoretical models and qualitative studies have posited that academic success is a developmental antecedent of perfectionism. Yet, quantitative studies tend to interpret the cross-sectional relationships as academic success being an outcome of perfectionism. In light of these gaps in the literature, the present study was the first to investigate the longitudinal relationships between perfectionistic strivings, perfectionistic concerns, academic achievement, and academic efficacy examining academic success as an antecedent of perfectionism. Method: The study examined 487 adolescents (aged 12-19 years, 54% female) using a crosslagged longitudinal design with three time points spaced 4-5 months apart. Results: Results showed that academic achievement predicted relative increases in both perfectionistic strivings and perfectionistic concerns, even when including academic efficacy. In addition, academic efficacy predicted relative increases in perfectionistic strivings. Discussion: This is the first study to show that academic achievement is a common factor in the development of perfectionistic strivings and perfectionistic concerns, whereas academic efficacy plays a role only in the development of perfectionistic strivings. Conclusions: Implications of the findings for the development of perfectionism are discussed

OpenFermion: The Electronic Structure Package for Quantum Computers

Quantum simulation of chemistry and materials is predicted to be an important application for both near-term and fault-tolerant quantum devices. However, at present, developing and studying algorithms for these problems can be difficult due to the prohibitive amount of domain knowledge required in both the area of chemistry and quantum algorithms. To help bridge this gap and open the field to more researchers, we have developed the OpenFermion software package (www.openfermion.org). OpenFermion is an open-source software library written largely in Python under an Apache 2.0 license, aimed at enabling the simulation of fermionic models and quantum chemistry problems on quantum hardware. Beginning with an interface to common electronic structure packages, it simplifies the translation between a molecular specification and a quantum circuit for solving or studying the electronic structure problem on a quantum computer, minimizing the amount of domain expertise required to enter the field. The package is designed to be extensible and robust, maintaining high software standards in documentation and testing. This release paper outlines the key motivations behind design choices in OpenFermion and discusses some basic OpenFermion functionality which we believe will aid the community in the development of better quantum algorithms and tools for this exciting area of research.Comment: 22 page

Development of perfectionism in junior athletes: A three-sample study of coach and parental pressure

Perfectionism predicts cognitions, emotions, and behaviors in sport. Nonetheless, our understanding of the factors that influence its development is limited. We sought to address this issue by examining the role of coach and parental pressure in the development of perfectionism in sport. Using three samples of junior athletes (16-19 years; cross-sectional: N = 212; 3-month longitudinal: N = 101; 6-month longitudinal: N = 110), we examined relations between coach pressure to be perfect, parental pressure to be perfect, perfectionistic strivings, and perfectionistic concerns. Mini meta-analysis of the combined cross-sectional data (N = 423) showed that both coach pressure and parental pressure were positively correlated with perfectionistic strivings and perfectionistic concerns. In contrast, longitudinal analyses showed that only coach pressure predicted increased perfectionistic strivings and perfectionistic concerns over time. Overall, our findings provide preliminary evidence that coaches may play a more important role in the development of junior athletes’ perfectionism than parents

Effects of antiplatelet therapy on stroke risk by brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases: subgroup analyses of the RESTART randomised, open-label trial

Background Findings from the RESTART trial suggest that starting antiplatelet therapy might reduce the risk of recurrent symptomatic intracerebral haemorrhage compared with avoiding antiplatelet therapy. Brain imaging features of intracerebral haemorrhage and cerebral small vessel diseases (such as cerebral microbleeds) are associated with greater risks of recurrent intracerebral haemorrhage. We did subgroup analyses of the RESTART trial to explore whether these brain imaging features modify the effects of antiplatelet therapy

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Background: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

Background: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. Methods: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). Findings: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29–146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0– 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25–1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39–1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65–1·60]; p=0·92). Interpretation: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention

Effects of antiplatelet therapy after stroke due to intracerebral haemorrhage (RESTART): a randomised, open-label trial

BACKGROUND: Antiplatelet therapy reduces the risk of major vascular events for people with occlusive vascular disease, although it might increase the risk of intracranial haemorrhage. Patients surviving the commonest subtype of intracranial haemorrhage, intracerebral haemorrhage, are at risk of both haemorrhagic and occlusive vascular events, but whether antiplatelet therapy can be used safely is unclear. We aimed to estimate the relative and absolute effects of antiplatelet therapy on recurrent intracerebral haemorrhage and whether this risk might exceed any reduction of occlusive vascular events. METHODS: The REstart or STop Antithrombotics Randomised Trial (RESTART) was a prospective, randomised, open-label, blinded endpoint, parallel-group trial at 122 hospitals in the UK. We recruited adults (≥18 years) who were taking antithrombotic (antiplatelet or anticoagulant) therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage, discontinued antithrombotic therapy, and survived for 24 h. Computerised randomisation incorporating minimisation allocated participants (1:1) to start or avoid antiplatelet therapy. We followed participants for the primary outcome (recurrent symptomatic intracerebral haemorrhage) for up to 5 years. We analysed data from all randomised participants using Cox proportional hazards regression, adjusted for minimisation covariates. This trial is registered with ISRCTN (number ISRCTN71907627). FINDINGS: Between May 22, 2013, and May 31, 2018, 537 participants were recruited a median of 76 days (IQR 29-146) after intracerebral haemorrhage onset: 268 were assigned to start and 269 (one withdrew) to avoid antiplatelet therapy. Participants were followed for a median of 2·0 years (IQR [1·0- 3·0]; completeness 99·3%). 12 (4%) of 268 participants allocated to antiplatelet therapy had recurrence of intracerebral haemorrhage compared with 23 (9%) of 268 participants allocated to avoid antiplatelet therapy (adjusted hazard ratio 0·51 [95% CI 0·25-1·03]; p=0·060). 18 (7%) participants allocated to antiplatelet therapy experienced major haemorrhagic events compared with 25 (9%) participants allocated to avoid antiplatelet therapy (0·71 [0·39-1·30]; p=0·27), and 39 [15%] participants allocated to antiplatelet therapy had major occlusive vascular events compared with 38 [14%] allocated to avoid antiplatelet therapy (1·02 [0·65-1·60]; p=0·92). INTERPRETATION: These results exclude all but a very modest increase in the risk of recurrent intracerebral haemorrhage with antiplatelet therapy for patients on antithrombotic therapy for the prevention of occlusive vascular disease when they developed intracerebral haemorrhage. The risk of recurrent intracerebral haemorrhage is probably too small to exceed the established benefits of antiplatelet therapy for secondary prevention. FUNDING: British Heart Foundation

On the development of perfectionism in adolescence: Perceived parental expectations predict longitudinal increases in socially prescribed perfectionism

Adolescence is regarded a key period when individual differences in perfectionism develop. Yet, so far only a few longitudinal studies have investigated the development of perfectionism in adolescents. Using a longitudinal correlational design with 381 adolescents aged 15-19 years, the present study investigated whether perceived parental expectations and criticism predicted longitudinal increases in self-oriented and socially prescribed perfectionism over 7-9 months. Results showed that perceived parental expectations predicted longitudinal increases in socially prescribed perfectionism: Adolescents who perceived that their parents had high expectations of them at Time 1, showed increased socially prescribed perfectionism from Time 1 to Time 2 compared to adolescents who did not perceive their parents’ having such high expectations. No such effect was found for self-oriented perfectionism. The findings provide supportive evidence for the social expectations model of the development of perfectionism regarding socially prescribed perfectionism, but not self-oriented perfectionism. Implications of this finding for the understanding of the development of perfectionism and future studies are discussed

Nutritional abrogation of photoimmunosuppression: In vivo investigations

Skin cancer is a major public health concern, and the primary aetiological factor in the majority of skin cancers is ultraviolet radiation (UVR) exposure. UVR not only induces potentially mutagenic DNA damage but also suppresses cell-mediated immunity (CMI), allowing cancerous cells to escape destruction and progress to tumours. A considerable proportion of an individual\u27s annual sun exposure is obtained outside the vacation period when topical and physical measures for photoprotection are irregularly used. Certain nutrients could provide an adjunctive protective role, and evidence is accruing from experimental studies to support their use in abrogation of photoimmunosuppression. Moreover, developments in clinical research methods to evaluate impact of solar-simulated radiation on cutaneous CMI allow the immune protective potential of nutritional agents to be examined in humans in vivo. This article summarises the mediation of CMI and its suppression by UVR, evaluates the methodology for quantitative assessment in vivo, reviews the human studies reported on nutritional abrogation of photoimmunosuppression including recent randomized controlled trials and discusses the mechanisms of photoprotection by the nutrients. This includes, in addition to antioxidants, novel studies of omega-3 polyunsaturated fatty acids and nicotinamide