Compensation for Uneven Surfaces When Building Laser Deposited Structures

Direct Laser Deposition (DLD) is a blown-powder laser deposition process that can be used to quickly produce, modify or repair fully-dense metallic parts by a layered manufacturing method. However, uneven substrate surfaces often cause variation in the deposited layer which is magnified by succeeding layers. Research carried out at the University of Liverpool has resulted in a non-feedback layer height controlling process based on controlling the shape of the powder streams emitted from a four-port side feed nozzle. This method limits deposited layer height by causing a sharp reduction of catchment efficiency in the vertical plane at a fixed distance from the powder feed nozzle, and is therefore capable of depositing a consistent layer height in spite of power, powder flow or process velocity variation. This paper demonstrates how this method of layer height control can compensate for irregular substrate surfaces in the production of accurate DLD parts.Mechanical Engineerin

Mesoscale Adjustments within the Planetary Boundary Layer in Tropical and Extratropical Environments

A series of three papers comprised the research completed for this dissertation study. Each contribution examined mesoscale processes that occurred within the planetary boundary layer in the context of the chosen avenue of research. The premise of paper one centered on the daytime growth of the convective mixed layer over the continental mid-latitudes for the application of smoke management from wildland fire. An evaluation of the most robust practical technique for mixed-layer height estimation was performed using numerical model simulations and space-based lidar retrievals. Results revealed that daytime mixed-layer growth corresponded with the excitation of the turbulent kinetic energy (TKE) and layer height was best determined where the dissipation of TKE occurred in the vertical. Papers two and three were completed as a two-part series where emphasis was placed on the boundary layer dynamics associated with the precursor environment wherein Hurricane Sandy (October 2012) developed. And although greater attention was paid to the localized mesoscale dynamics, evaluation of the larger-scale influence was also examined across the entire northern hemisphere weeks in advance. Results from two mesoscale model simulations, a control run and no-terrain experiment, show that the precursor environment is highly influential to its developmental fate. In the case of Sandy, the surrounding orography imposed constraints on the environmental mass field such that a low-level curved momentum channel was produced upstream of the incipient disturbance (on its southwestern side) wherein vorticity generation was maximized and wrapped into the vortex inflow region. The latter westerly momentum also converged with a secondary low-level southerly jet feature that emanated into the vortex inflow region. Model results were evaluated against a suite of satellite data including composite brightness imagery, scatterometer surface wind data, space-based lidar retrievals, and Best Track data (on storm track, mean sea level pressure, and maximum tangential wind speed) from the National Hurricane Center database

A Demonstration Study of the Quiet Time Transcendental Meditation Program

This manuscript presents a demonstration study of Quiet Time (QT), a classroom-based Transcendental Meditation intervention. The aim of the study is to assess the feasibility of implementing and evaluating QT in two pilot settings in the United Kingdom and Ireland. This study contributes to the field by targeting middle childhood, testing efficiency in two settings operating under different educational systems, and including a large array of measures. First, teacher and pupil engagement with QT was assessed. Second, the feasibility of using a quasi-experimental design and a wide range of instruments to measure changes in pupil outcomes before and after the intervention was assessed. This allows us to obtain information about which instruments might be feasible to administer and most sensitive to change. The first setting included 89 students from a primary school in the United Kingdom: those in sixth grade received the QT intervention, while those in fifth grade practiced meditation using the Headspace application. The second setting included 100 fifth- and sixth-grade students from two schools in Ireland: one received the QT intervention, the other served as a control. Recruitment and retention rates were high in both settings, and the intervention was feasible and accepted by students, parents and teachers. Implementation fidelity was lower in the United Kingdom setting where delivery started later in the school year and the practice was affected by preparation for the Standard Assessment Tests. These results show that QT may be feasibly delivered in school settings, and suggest the use of a compact battery of tests to measure impact. We find suggestive evidence that the intervention affected executive function as children who practiced QT showed improved working memory in both settings. In the Irish setting, pupils in the QT group had improved ability to control responses. These results have implications for future studies by a) demonstrating that implementation fidelity is highly context dependent and b) providing suggestive evidence of the malleability of children’s skills in middle childhood. The results of this demonstration study will be used to inform a larger RCT of the QT intervention

Feasibility, Acceptability, and Initial Effects of the Quiet Time transcendental meditation program: Evidence from two school pilots

This paper assesses for the first time the feasibility, acceptability and preliminary impacts of Quiet Time (QT), a classroom-based Transcendental Meditation intervention that has been shown to be effective in other settings, in the UK and Ireland. The first study, implemented in a London primary school, included 89 children: those in sixth grade received the QT intervention, while those in fifth grade practiced meditation using the Headspace application. The second study, implemented in Donegal, included 100 fifth- and sixth-grade children from two schools: one received the QT intervention, the other served as a control. Feasibility outcomes included recruitment, programme delivery, and data collection at two timepoints. Acceptability outcomes included satisfaction reports. Outcomes at baseline and follow-up included measures of social skills and preferences, executive function, mental health and socio-emotional well-being, and academic achievement. Recruitment and retention rates were high in both pilots, and the results indicate that the intervention, when implemented with fidelity, is feasible and accepted by children, parents and teachers. Implementation fidelity was lower in the London pilot where delivery started later in the school year and the practice was affected by preparation for the Standard Assessment Tests. We find suggestive evidence that the intervention affected certain dimensions of children’s skills. The children who practiced QT showed improved working memory in both pilots. In the Irish pilot, pupils in the QT group had improved executive functioning; and girls showed improved emotional skills. These results suggest that QT may be feasibly delivered in school settings, it is well accepted, and may yield attention and emotional benefits, especially for girls, when implemented on a regular basis by trained teachers

Ultrafast laser parallel microdrilling using multiple annular beams generated by a spatial light modulator

Ultrafast laser parallel microdrilling using diffractive multiple annular beam patterns is demonstrated in this paper. The annular beam was generated by diffractive axicon computer generated holograms (CGHs) using a spatial light modulator. The diameter of the annular beam can be easily adjusted by varying the radius of the smallest ring in the axicon. Multiple annular beams with arbitrary arrangement and multiple annular beam arrays were generated by superimposing an axicon CGH onto a grating and lenses algorithm calculated multi-beam CGH and a binary Dammann grating CGH, respectively. Microholes were drilled through a 0.03 mm thick stainless steel foil using the multiple annular beams. By avoiding huge laser output attenuation and mechanical annular scanning, the processing is ~200 times faster than the normal single beam processing

Influence of contrast media dose and osmolality on the diagnostic performance of contrast fractional flow reserve

Background—Contrast fractional flow reserve (cFFR) is a method for assessing functional significance of coronary stenoses, which is more accurate than resting indices and does not require adenosine. However, contrast media volume and osmolality may affect the degree of hyperemia and therefore diagnostic performance. Methods and Results—cFFR, instantaneous wave–free ratio, distal pressure/aortic pressure at rest, and FFR were measured in 763 patients from 12 centers. We compared the diagnostic performance of cFFR between patients receiving low or iso-osmolality contrast (n=574 versus 189) and low or high contrast volume (n=341 versus 422) using FFR≤0.80 as a reference standard. The sensitivity, specificity, and overall accuracy of cFFR for the low versus iso-osmolality groups were 73%, 93%, and 85% versus 87%, 90%, and 89%, and for the low versus high contrast volume groups were 69%, 99%, and 83% versus 82%, 93%, and 88%. By receiver operating characteristics (ROC) analysis, cFFR provided better diagnostic performance than resting indices regardless of contrast osmolality and volume (P<0.001 for all groups). There was no significant difference between the area under the curve of cFFR in the low- and iso-osmolality groups (0.938 versus 0.957; P=0.40) and in the low- and high-volume groups (0.939 versus 0.949; P=0.61). Multivariable logistic regression analysis showed that neither contrast osmolality nor volume affected the overall accuracy of cFFR; however, both affected the sensitivity and specificity. Conclusions—The overall accuracy of cFFR is greater than instantaneous wave–free ratio and distal pressure/aortic pressure and not significantly affected by contrast volume and osmolality. However, contrast volume and osmolality do affect the sensitivity and specificity of cFFR

Polyurea-Functionalized Multiwalled Carbon Nanotubes

An in situ polycondensation approach was applied to functionalize multiwalled carbon nanotubes (MWNTs), resulting in various linear or hyperbranched polycondensed polymers [e.g., polyureas, polyurethanes, and poly(urea-urethane)-bonded carbon nanotubes]. The quantity of the grafted polymer can be easily controlled by the feed ratio of monomers. As a typical example, the polyurea-functionalized MWNTs were measured and characterized in detail. The oxidized MWNTs (MWNT-COOH) were converted into acyl chloride-functionalized MWNTs (MWNT-COCl) by reaction with neat thionyl chloride (SOCl2). MWNT-COCl was reacted with excess 1,6-diaminohexane, affording amino-functionalized MWNTs (MWNT-NH2). In the presence of MWNT-NH2, the polyurea was covalently coated onto the surfaces of the nanotube by in situ polycondensation of diisocyanate [e.g., 4,4‘-methylenebis(phenylisocyanate)] and 1,6-diaminohexane, followed by the removal of free polymer via repeated filtering and solvent washing. The coated polyurea content can be controlled to some extent by adjusting the feed ratio of the isocyanato and amino groups. The structure and morphology of the resulting nanocomposites were characterized by FTIR, NMR, Raman, confocal Raman, TEM, EDS, and SEM measurements. The polyurea-coated MWNTs showed interesting self-assembled flat- or flowerlike morphologies in the solid state. The signals corresponding to that of the D and G bands of the carbon nanotubes were strongly attenuated after polyurea was chemically tethered to the MWNT surfaces. Comparative experiments showed that the grafted polymer species and structures have a strong effect on the Raman signals of polymer-functionalized MWNTs

Effectiveness of testing, contact tracing and isolation interventions among the general population on reducing transmission of SARS-CoV-2: a systematic review

We conducted a systematic literature review of general population testing, contact tracing, case isolation and contact quarantine interventions to assess their effectiveness in reducing SARS-CoV-2 transmission, as implemented in real-world settings. We designed a broad search strategy and aimed to identify peer-reviewed studies of any design provided there was a quantitative measure of effectiveness on a transmission outcome. Studies that assessed the effect of testing or diagnosis on disease outcomes via treatment, but did not assess a transmission outcome, were not included. We focused on interventions implemented among the general population rather than in specific settings; these were from anywhere in the world and published any time after 1 January 2020 until the end of 2022. From 26 720 titles and abstracts, 1181 were reviewed as full text, and 25 met our inclusion criteria. These 25 studies included one randomized control trial (RCT) and the remaining 24 analysed empirical data and made some attempt to control for confounding. Studies included were categorized by the type of intervention: contact tracing (seven studies); specific testing strategies (12 studies); strategies for isolating cases/contacts (four studies); and 'test, trace, isolate' (TTI) as a part of a package of interventions (two studies). None of the 25 studies were rated at low risk of bias and many were rated as serious risk of bias, particularly due to the likely presence of uncontrolled confounding factors, which was a major challenge in assessing the independent effects of TTI in observational studies. These confounding factors are to be expected from observational studies during an on-going pandemic, when the emphasis was on reducing the epidemic burden rather than trial design. Findings from these 25 studies suggested an important public health role for testing followed by isolation, especially where mass and serial testing was used to reduce transmission. Some of the most compelling analyses came from examining fine-grained within-country data on contact tracing; while broader studies which compared behaviour between countries also often found TTI led to reduced transmission and mortality, this was not universal. There was limited evidence for the benefit of isolation of cases/contacts away from the home environment. One study, an RCT, showed that daily testing of contacts could be a viable strategy to replace lengthy quarantine of contacts. Based on the scarcity of robust empirical evidence, we were not able to draw any firm quantitative conclusions about the quantitative impact of TTI interventions in different epidemic contexts. While the majority of studies found that testing, tracing and isolation reduced transmission, evidence for the scale of this impact is only available for specific scenarios and hence is not necessarily generalizable. Our review therefore emphasizes the need to conduct robust experimental studies that help inform the likely quantitative impact of different TTI interventions on transmission and their optimal design. Work is needed to support such studies in the context of future emerging epidemics, along with assessments of the cost-effectiveness of TTI interventions, which was beyond the scope of this review but will be critical to decision-making. This article is part of the theme issue 'The effectiveness of non-pharmaceutical interventions on the COVID-19 pandemic: the evidence'

Multidimensional collaboration; reflections on action research in a clinical context

This paper reflects on the challenges and benefits of multidimensional collaboration in an action research study to evaluate and improve preoperative education for patients awaiting colorectal surgery. Three cycles of planning, acting,observing and reflecting were designed to evaluate practice and implement change in this interactive setting, calling for specific and distinct collaborations. Data collection includes: observing educational interactions; administering patient evaluation questionnaires; interviewing healthcare staff, patients and carers; patient and carer focus groups; and examining written and audiovisual educational materials. The study revolves around and depends on multi-dimensional collaborations. Reflecting on these collaborations highlights the diversity of perspectives held by all those engaged in the study and enhances the action research lessons. Successfully maintaining the collaborations recognises the need for negotiation, inclusivity, comprehension, brokerage,and problem-solving. Managing the potential tensions is crucial to the successful implementation of changes introduced to practice and thus has important implications for patients’ well-being. This paper describes the experiences from an action research project involving new and specific collaborations, focusing on a particular healthcare setting. It exemplifies the challenges of the collaborative action research process and examines how both researchers and practitioners might reflect on the translation of theory into educational practices within a hospital colorectal department. Despite its context-specific features, the reflections on the types of challenges faced and lessons learned provide implications for action researchers in diverse healthcare settings across the world

The response of leptin, interleukin-6 and fat oxidation to feeding in weight-losing patients with pancreatic cancer

At baseline, weight-losing pancreatic cancer patients (n=7) had lower leptin (P<0.05) but higher cortisol, interleukin-6, resting energy expenditure and fat oxidation than healthy subjects (n=6, P<0.05). Over a 4 h feeding period, the areas under the curve for glucose, cortisol and interleukin-6 were greater (P<0.05), but less for leptin in the cancer group (P<0.05). Therefore, it would appear that low leptin concentrations, increased fat oxidation and insulin resistance are associated with increased concentrations of cortisol and interleukin-6 in weight-losing patients with pancreatic cancer