The Eckert number phenomenon: experimental investigations on the heat transfer from a moving wall in the case of a rotating cylinder

The Eckert number phenomenon was investigated theoretically by Geropp in 1969 and describes a reversal in heat transfer from a moving wall at an Eckert number Ec ≈ 1. In this report the Eckert number phenomenon is confirmed experimentally for the first time. For that purpose the heat transfer from a heated, vertically rotating cylinder in a crossflow was investigated. In order to perform the experiments in a range where the predicted phenomenon occurs, extreme rotational speeds were necessary. A heating concept had to be developed which allowed an input of heating power independent of the speed and which therefore had to be contact-free. The results show, among other things, that the temperature difference between the wall and the surrounding fluid has a significant effect on the predicted reversal of heat transfer at the wall. Moreover, maximum heat transfer occurs at an Eckert number Ec ≈ 0.3, which is of great importance for the cooling of hot surfaces in a gas-flow

Stirling-cycle heat-pumps and refrigerators – a realistic alternative?

Concerns about the environmental impact of refrigerants used in vapour-compression heatpumps and refrigerators, have prompted the Stirling-Cycle Research Group at the University of Canterbury to investigate the feasibility of low-cost Stirling-cycle machines that use air as the refrigerant. Such machines theoretically have the highest efficiency possible for any practical thermodynamic system, and thus provide a tempting alternative to traditional vapourcompression technology. This paper outlines the working principles of Stirling-cycle heat-pumps and refrigerators, and describes some of the work performed at Canterbury University. Some of the heat-pump development programme results are also presented, and briefly discussed

Stroke genetics: prospects for personalized medicine.

Epidemiologic evidence supports a genetic predisposition to stroke. Recent advances, primarily using the genome-wide association study approach, are transforming what we know about the genetics of multifactorial stroke, and are identifying novel stroke genes. The current findings are consistent with different stroke subtypes having different genetic architecture. These discoveries may identify novel pathways involved in stroke pathogenesis, and suggest new treatment approaches. However, the already identified genetic variants explain only a small proportion of overall stroke risk, and therefore are not currently useful in predicting risk for the individual patient. Such risk prediction may become a reality as identification of a greater number of stroke risk variants that explain the majority of genetic risk proceeds, and perhaps when information on rare variants, identified by whole-genome sequencing, is also incorporated into risk algorithms. Pharmacogenomics may offer the potential for earlier implementation of 'personalized genetic' medicine. Genetic variants affecting clopidogrel and warfarin metabolism may identify non-responders and reduce side-effects, but these approaches have not yet been widely adopted in clinical practice

Genetic risk factors for ischaemic stroke and its subtypes (the METASTROKE Collaboration): a meta-analysis of genome-wide association studies

<p>Background - Various genome-wide association studies (GWAS) have been done in ischaemic stroke, identifying a few loci associated with the disease, but sample sizes have been 3500 cases or less. We established the METASTROKE collaboration with the aim of validating associations from previous GWAS and identifying novel genetic associations through meta-analysis of GWAS datasets for ischaemic stroke and its subtypes.</p> <p>Methods - We meta-analysed data from 15 ischaemic stroke cohorts with a total of 12 389 individuals with ischaemic stroke and 62 004 controls, all of European ancestry. For the associations reaching genome-wide significance in METASTROKE, we did a further analysis, conditioning on the lead single nucleotide polymorphism in every associated region. Replication of novel suggestive signals was done in 13 347 cases and 29 083 controls.</p> <p>Findings - We verified previous associations for cardioembolic stroke near PITX2 (p=2·8×10−16) and ZFHX3 (p=2·28×10−8), and for large-vessel stroke at a 9p21 locus (p=3·32×10−5) and HDAC9 (p=2·03×10−12). Additionally, we verified that all associations were subtype specific. Conditional analysis in the three regions for which the associations reached genome-wide significance (PITX2, ZFHX3, and HDAC9) indicated that all the signal in each region could be attributed to one risk haplotype. We also identified 12 potentially novel loci at p<5×10−6. However, we were unable to replicate any of these novel associations in the replication cohort.</p> <p>Interpretation - Our results show that, although genetic variants can be detected in patients with ischaemic stroke when compared with controls, all associations we were able to confirm are specific to a stroke subtype. This finding has two implications. First, to maximise success of genetic studies in ischaemic stroke, detailed stroke subtyping is required. Second, different genetic pathophysiological mechanisms seem to be associated with different stroke subtypes.</p&gt

Genome-wide association study identifies a variant in HDAC9 associated with large vessel ischemic stroke

Genetic factors have been implicated in stroke risk but few replicated associations have been reported. We conducted a genome-wide association study (GWAS) in ischemic stroke and its subtypes in 3,548 cases and 5,972 controls, all of European ancestry. Replication of potential signals was performed in 5,859 cases and 6,281 controls. We replicated reported associations between variants close to PITX2 and ZFHX3 with cardioembolic stroke, and a 9p21 locus with large vessel stroke. We identified a novel association for a SNP within the histone deacetylase 9(HDAC9) gene on chromosome 7p21.1 which was associated with large vessel stroke including additional replication in a further 735 cases and 28583 controls (rs11984041, combined P = 1.87×10−11, OR=1.42 (95% CI) 1.28-1.57). All four loci exhibit evidence for heterogeneity of effect across the stroke subtypes, with some, and possibly all, affecting risk for only one subtype. This suggests differing genetic architectures for different stroke subtypes

An Amish founder variant consolidates disruption of CEP55 as a cause of hydranencephaly and renal dysplasia

This is the author accepted manuscript. The final version is available from Springer Nature via the DOI in this record.The centrosomal protein 55 kDa (CEP55 (OMIM 610000)) plays a fundamental role in cell cycle regulation and cytokinesis. However, the precise role of CEP55 in human embryonic growth and development is yet to be fully defined. Here we identified a novel homozygous founder frameshift variant in CEP55, present at low frequency in the Amish community, in two siblings presenting with a lethal foetal disorder. The features of the condition are reminiscent of a Meckel-like syndrome comprising of Potter sequence, hydranencephaly, and cystic dysplastic kidneys. These findings, considered alongside two recent studies of single families reporting loss of function candidate variants in CEP55, confirm disruption of CEP55 function as a cause of this clinical spectrum and enable us to delineate the cardinal clinical features of this disorder, providing important new insights into early human development.Medical Research CouncilNewlife Foundation for disabled childre

Application of Flexible Bronchoscopy in Inhalation Lung Injury

Background: As acute inhalational injury is an uncommon presentation to most institutions, a standard approach to its assessment and management, especially using flexible bronchoscopy, has not received significant attention. Methods: The objective of this study is to evaluate the value of using flexible bronchoscopy as part of the evaluation and management of patients with inhalational lung injury. Twenty-three cases of inhalational lung injury were treated in our three hospitals after a fire in a residential building. The twenty cases that underwent bronchoscopy as part of their management are included in this analysis. After admission, the first bronchoscopy was conducted within 18-72 hours post inhalational injury. G2-level patients were reexamined 24 hours after the first bronchoscopy, while G1-level patients were reexamined 72 hours later. Subsequently, all patients were re-examined every 2-3 days until recovered or until only tunica mucosa bronchi congestion was identified by bronchoscopy. Results: Twenty patients had airway injury diagnosed by bronchoscopy including burns to the larynx and glottis or large airways. Bronchoscopic classification of the inhalation injury was performed, identifying 12 cases of grade G1 changes and 8 cases of grade G2. The airway injury in the 12 cases of grade G1 patients demonstrated recovery in 2-8 days, in the airway injury of the 8 cases of grade G2 patients had a prolonged recovery with airway injury improving in 6-21 days averaged. The difference in recovery time between the two groups was significant (P Conclusions: The use of flexible bronchoscopy has great value in the diagnosis of inhalational injury without any complications. Its use should be incorporated into clinical practice

Unravelling the Genetics of Ischaemic Stroke

Hugh Markus discusses genetic factors in stroke risk, and emphasizes the importance of large sample studies and rigorous replication of results in genetic stroke research

Mechanisms and treatment of ischaemic stroke: insights from genetic associations

The precise pathophysiology of ischaemic stroke is unclear, and a greater understanding of the different mechanisms that underlie large-artery, cardioembolic and lacunar ischaemic stroke subtypes would enable the development of more-effective, subtype-specific therapies. Genome-wide association studies (GWASs) are identifying novel genetic variants that associate with the risk of stroke. These associations provide insight into the pathophysiological mechanisms, and present opportunities for novel therapeutic approaches. In this Review, we summarize the genetic variants that have been linked to ischaemic stroke in GWASs to date and discuss the implications of these associations for both our understanding and treatment of ischaemic stroke. The majority of genetic variants identified are associated with specific subtypes of ischaemic stroke, implying that these subtypes have distinct genetic architectures and pathophysiological mechanisms. The findings from the GWASs highlight the need to consider whether therapies should be subtype-specific. Further GWASs that include large cohorts are likely to provide further insights, and emerging technologies will complement and build on the GWAS findings

Experimental study of extended timescale dynamics of a plasma wakefield driven by a self-modulated proton bunch

Plasma wakefield dynamics over timescales up to 800 ps, approximately 100 plasma periods, are studied experimentally at the Advanced Wakefield Experiment (AWAKE). The development of the longitudinal wakefield amplitude driven by a self-modulated proton bunch is measured using the external injection of witness electrons that sample the fields. In simulation, resonant excitation of the wakefield causes plasma electron trajectory crossing, resulting in the development of a potential outside the plasma boundary as electrons are transversely ejected. Trends consistent with the presence of this potential are experimentally measured and their dependence on wakefield amplitude are studied via seed laser timing scans and electron injection delay scan