290 research outputs found
Penetration of Projectiles in Composite Laminates
This paper deals with the prediction of the penetration phenomenon of a cylindro-conical impactor on the ke;labepoxy-laminated composites using C eight-nded serendipity q&drilateral finite elementbased on first-order shear deformation theory (FSDT). Local as well as global deformations during impact is considered in the evaluation of indentation, penetration, and perforation phases. Local strainsduring impact have been evaluated using the hypothesis made from the available experimental observations of bulging during penetration. A detailed parametric study, considering various projectilesand target plate variables, has been carried out to find their effect on the response of the plate, and ballistic parameters, such as ballistic limit and absorbed energy
Effect of Heat Stress on Crossbred Dairy Cattle in Tropical Nepal: Impact on Blood Parameters
Chitwan district of Nepal has been known as the dairy kingdom of the country considering its strategic location andpotential to easily provision inputs and produce as well as market quality milk across the country. However, theclimate especially during summer has been a challenge to farmers that potentially compromise the daily milk yieldof cows. Therefore, sixteen crossbred dairy cattle were placed in a RCBD fashion to assess the impacts of cold waterbathing in ameliorating effect of heat stress on their performance and body physiology. Routine assessment of themicroclimate within the experimental shed and blood parameters was made. The results from the experimentinferred that frequency of bathing (none, once, twice or thrice a day) did not have any significant impact onHaemoglobin, Haematocrit, Sodium, Potassium, Chloride and Bicarbonate levels in the blood plasma(p>0.05). Inaddition, the animals did not exhibit any signs of physiological distress clinically either. A detailed study scopingtemperature humidity index and over a number of other milk and blood parameters are to be tested across a numberof other available breeds too in order for the researchers to come to a meaningful strategy to beat the heat stress
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Exploiting nonlinearities through geometric engineering to enhance the auxetic behaviour in re-entrant honeycomb metamaterials
Classical approaches to enhance auxeticity quite often involve exploring or designing newer architectures. In this work, simple geometrical features at the member level are engineered to exploit non-classical nonlinearities and improve the auxetic behaviour. The structural elements of the auxetic unit cell are here represented by thin strip-like beams, or thin-walled tubular beams. The resulting nonlinear stiffness enhances the auxeticity of the lattices, especially under large deformations. To quantify the influence of the proposed structural features on the resulting Poisson's ratio, we use here variational asymptotic method (VAM) and geometrically exact beam theory. The numerical examples reveal that 2D re-entrant type micro-structures made of thin strips exhibit an improvement in terms of auxetic behaviour under compression. For the auxetic unit cell with thin circular tubes as members, Brazier's effect associated with cross-sectional ovalisation improves the auxetic behaviour under tension; the enhancement is even more significant for the 3D re-entrant geometry. Thin strip-based auxetic unit cells were additively manufactured and tested under compression to verify the numerical observations. The experimentally measured values of the negative Poisson's ratio are in close agreement with the numerical results, revealing a 66% increase due to the nonlinearity. Simulation results showcase these alternative approaches to improve the auxetic behaviour through simple geometric engineering of the lattice ribs
A hierarchical latent response model for inferences about examinee engagement in terms of guessing and itemālevel nonāresponse
In lowāstakes assessments, test performance has few or no consequences for examinees themselves, so that examinees may not be fully engaged when answering the items. Instead of engaging in solution behaviour, disengaged examinees might randomly guess or generate no response at all. When ignored, examinee disengagement poses a severe threat to the validity of results obtained from lowāstakes assessments. Statistical modelling approaches in educational measurement have been proposed that account for nonāresponse or for guessing, but do not consider both types of disengaged behaviour simultaneously. We bring together research on modelling examinee engagement and research on missing values and present a hierarchical latent response model for identifying and modelling the processes associated with examinee disengagement jointly with the processes associated with engaged responses. To that end, we employ a mixture model that identifies disengagement at the itemābyāexaminee level by assuming different dataāgenerating processes underlying item responses and omissions, respectively, as well as response times associated with engaged and disengaged behaviour. By modelling examinee engagement with a latent response framework, the model allows assessing how examinee engagement relates to ability and speed as well as to identify items that are likely to evoke disengaged testātaking behaviour. An illustration of the model by means of an application to real data is presented
Forming a three-dimensional porous organic network via solid-state explosion of organic single crystals
Solid-state reaction of organic molecules holds a considerable advantage over liquid-phase processes in the manufacturing industry. However, the research progress in exploring this benefit is largely staggering, which leaves few liquid-phase systems to work with. Here, we show a synthetic protocol for the formation of a three-dimensional porous organic network via solid-state explosion of organic single crystals. The explosive reaction is realized by the Bergman reaction (cycloaromatization) of three enediyne groups on 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene. The origin of the explosion is systematically studied using single-crystal X-ray diffraction and differential scanning calorimetry, along with high-speed camera and density functional theory calculations. The results suggest that the solid-state explosion is triggered by an abrupt change in lattice energy induced by release of primer molecules in the 2,3,6,7,14,15-hexaethynyl-9,10-dihydro-9,10-[1,2]benzenoanthracene crystal lattice
Riverine plastic pollution from fisheries: Insights from the Ganges River system
This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordAbandoned, lost or otherwise discarded fishing gear represents a substantial proportion of global marine plastic pollution and can cause significant environmental and socio-economic impacts. Yet little is known about its presence in, and implications for, freshwater ecosystems or its downstream contribution to plastic pollution in the ocean. This study documents fishing gear-related debris in one of the world's largest plastic pollution contributing river catchments, the Ganges. Riverbank surveys conducted along the length of the river, from the coast in Bangladesh to the Himalaya in India, show that derelict fishing gear density increases with proximity to the sea. Fishing nets were the main gear type by volume and all samples examined for polymer type were plastic. Illegal gear types and restricted net mesh sizes were also recorded. Socio-economic surveys of fisher communities explored the behavioural drivers of plastic waste input from one of the world's largest inland fisheries and revealed short gear lifespans and high turnover rates, lack of appropriate end-of-life gear disposal methods and ineffective fisheries regulations. A biodiversity threat assessment identified the air-breathing aquatic vertebrate species most at risk of entanglement in, and impacts from, derelict fishing gear; namely species of threatened freshwater turtle and otter, and the endangered Ganges river dolphin. This research demonstrates a need for targeted and practical interventions to limit the input of fisheries-related plastic pollution to this major river system and ultimately, the global ocean. The approach used in this study could be replicated to examine the inputs, socio-economic drivers and ecological impacts of this previously uncharacterised but important source of plastic pollution in other major rivers worldwide.European CommissionEngineering and Physical Sciences Research Council (EPSRC
Economic evaluation of multiplex ligation-dependent probe amplification and karyotyping in prenatal diagnosis: a cost-minimization analysis
textabstractPurpose: To assess the cost-effectiveness of Multiplex Ligation-dependent Probe Amplification (MLPA, P095 kit) compared to karyotyping. Methods: A cost-minimization analysis alongside a nationwide prospective clinical study of 4,585 women undergoing amniocentesis on behalf of their age (ā„36Ā years), an increased risk following first trimester prenatal screening or parental anxiety. Results: Diagnostic accuracy of MLPA (P095 kit) was comparable to karyotyping (1.0 95% CI 0.999-1.0). Health-related quality of life did not differ between the strategies (summary physical health: mean difference 0.31, pĀ =Ā 0.82; summary mental health: mean difference 1.91, pĀ =Ā 0.22). Short-term costs were lower for MLPA: mean difference ā¬315.68 (bootstrap 95% CI ā¬315.63-315.74; -44.4%). The long-term costs were slightly higher for MLPA: mean difference ā¬76.42 (bootstrap 95% CI ā¬71.32-81.52; +8.6%). Total costs were on average ā¬240.13 (bootstrap 95% CI ā¬235.02-245.23; -14.9%) lower in favor of MLPA. Cost differences were sensitive to proportion of terminated pregnancies, sample throughput, individual choice and performance of tests in one laboratory, but not to failure rate or the exclusion of polluted samples. Conclusion: From an economic perspective, MLPA is the preferred prenatal diagnostic strategy in women who undergo amniocentesis on behalf of their age, following prenatal screening or parental anxiety
Single Cell Deposition and Patterning with a Robotic System
Integrating single-cell manipulation techniques in traditional and emerging biological culture systems is challenging. Microfabricated devices for single cell studies in particular often require cells to be spatially positioned at specific culture sites on the device surface. This paper presents a robotic micromanipulation system for pick-and-place positioning of single cells. By integrating computer vision and motion control algorithms, the system visually tracks a cell in real time and controls multiple positioning devices simultaneously to accurately pick up a single cell, transfer it to a desired substrate, and deposit it at a specified location. A traditional glass micropipette is used, and whole- and partial-cell aspiration techniques are investigated to manipulate single cells. Partially aspirating cells resulted in an operation speed of 15 seconds per cell and a 95% success rate. In contrast, the whole-cell aspiration method required 30 seconds per cell and achieved a success rate of 80%. The broad applicability of this robotic manipulation technique is demonstrated using multiple cell types on traditional substrates and on open-top microfabricated devices, without requiring modifications to device designs. Furthermore, we used this serial deposition process in conjunction with an established parallel cell manipulation technique to improve the efficiency of single cell capture from ā¼80% to 100%. Using a robotic micromanipulation system to position single cells on a substrate is demonstrated as an effective stand-alone or bolstering technology for single-cell studies, eliminating some of the drawbacks associated with standard single-cell handling and manipulation techniques
Clinical impact of additional findings detected by genome-wide non-invasive prenatal testing:Follow-up results of the TRIDENT-2 study
In the TRIDENT-2 study, all pregnant women in the Netherlands are offered genome-wide non-invasive prenatal testing (GW-NIPT) with a choice of receiving either full screening or screening solely for common trisomies. Previous data showed that GW-NIPT can reliably detect common trisomies in the general obstetric population and that this test can also detect other chromosomal abnormalities (additional findings). However, evidence regarding the clinical impact of screening for additional findings is lacking. Therefore, we present follow-up results of the TRIDENT-2 study to determine this clinical impact based on the laboratory and perinatal outcomes of cases with additional findings. Between April 2017 and April 2019, additional findings were detected in 402/110,739 pregnancies (0.36%). For 358 cases, the origin was proven to be either fetal (n = 79; 22.1%), (assumed) confined placental mosaicism (CPM) (n = 189; 52.8%), or maternal (n = 90; 25.1%). For the remaining 44 (10.9%), the origin of the aberration could not be determined. Most fetal chromosomal aberrations were pathogenic and associated with severe clinical phenotypes (61/79; 77.2%). For CPM cases, occurrence of pre-eclampsia (8.5% [16/189] vs 0.5% [754/159,924]; RR 18.5), and birth weigh
Delivering the WISE (Whole Systems Informing Self-Management Engagement) training package in primary care: learning from formative evaluation
Background: The WISE (Whole System Informing Self-management Engagement) approach encompasses creating, finding, and implementing appropriate self-care support for people with long-term conditions. A training package for primary care to introduce the approach was developed and underwent formative evaluation. This entailed exploring the acceptability of the WISE approach and its effectiveness in changing communication within consultations. The study aimed to refine the patient, practitioner, and patient level components of the WISE approach and translate the principles of WISE into an operational intervention deliverable through National Health Service training methods. Methods: Normalisation Process Theory provided a framework for development of the intervention. Practices were recruited from an inner city Primary Care Trust in NW England. All practice staff were expected to attend two afternoon training sessions. The training sessions were observed by members of the training team. Post-training audio recordings of consultations from each general practitioner and nurse in the practices were transcribed and read to provide a narrative overview of the incorporation of WISE skills and tools into consultations. Face-to-face semi-structured interviews were conducted with staff post-training. Results: Two practices out of 14 deemed eligible agreed to take part. Each practice attended two sessions, although a third session on consultation skills training was needed for one practice. Fifty-four post-training consultations were recorded from 15 clinicians. Two members of staff were interviewed at each practice. Significant elements of the training form and methods of delivery fitted contemporary practice. There were logistical problems in getting a whole practice to attend both sessions, and administrative staff founds some sections irrelevant. Clinicians reported problems incorporating some of the tools developed for WISE, and this was confirmed in the overview of consultations, with limited overt use of WISE tools and missed opportunities to address patients' self-management needs. Conclusions: The formative evaluation approach and attention to normalisation process theory allowed the training team to make adjustments to content and delivery and ensure appropriate staff attended each session. The content of the course was simplified and focussed more clearly on operationalising the WISE approach. The patient arm of the approach was strengthened by raising expectations of a change in approach to self-care support by their practice. <br/
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