Variation of Important Non-Dimensional Numbers During Bubble Growth at Nucleation Site in Microchannels

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Two phase flow initiates at Onset of Nucleate Boiling, where the first bubble emerges in the downstream flow direction. Bubble nucleation and growth in microchannel heat sinks is very conspicuous phase as the growing bubble can completely block the flow cross-section area at high heat flux. Hence, microchannels are more susceptible to flow boiling instability. In this paper effort has been put to study the bubble dynamics during bubble growth at nucleation site for microchannel in terms of non-dimensional energy ratio numbers and their variation from bubble inception until departure. New non dimensional energy ratio is also proposed, which can be useful to differentiate inertia controlled and thermal diffusion controlled region during bubble growth at nucleation site

Expression profiling of Castanea genes during resistant and susceptible interactions with the Oomycete pathogen Phytophthora cinnamomi reveal possible mechanisms of immunity

The most dangerous pathogen affecting the production of chestnuts is Phytophthora cinnamomi a hemibiotrophic that causes root rot, also known as ink disease. Little information has been acquired in chestnut on the molecular defense strategies against this pathogen. The expression of eight candidate genes potentially involved in the defense to P. cinnamomi was quantified by digital PCR in Castanea genotypes showing different susceptibility to the pathogen. Seven of the eight candidate genes displayed differentially expressed levels depending on genotype and time-point after inoculation. Cast_Gnk2-like revealed to be the most expressed gene across all experiments and the one that best discriminates between susceptible and resistant genotypes. Our data suggest that the pre-formed defenses are crucial for the resistance of C. crenata to P. cinnamomi. A lower and delayed expression of the eight studied genes was found in the susceptible Castanea sativa, which may be related with the establishment and spread of the disease in this species. A working model integrating the obtained results is presentedinfo:eu-repo/semantics/publishedVersio

Experimental Microbial Evolution of Extremophiles

Experimental microbial evolutions (EME) involves studying closely a microbial population after it has been through a large number of generations under controlled conditions (Kussell 2013). Adaptive laboratory evolution (ALE) selects for fitness under experimentally imposed conditions (Bennett and Hughes 2009; Dragosits and Mattanovich 2013). However, experimental evolution studies focusing on the contributions of genetic drift and natural mutation rates to evolution are conducted under non-selective conditions to avoid changes imposed by selection (Hindré et al. 2012). To understand the application of experimental evolutionary methods to extremophiles it is essential to consider the recent growth in this field over the last decade using model non-extremophilic microorganisms. This growth reflects both a greater appreciation of the power of experimental evolution for testing evolutionary hypotheses and, especially recently, the new power of genomic methods for analyzing changes in experimentally evolved lineages. Since many crucial processes are driven by microorganisms in nature, it is essential to understand and appreciate how microbial communities function, particularly with relevance to selection. However, many theories developed to understand microbial ecological patterns focus on the distribution and the structure of diversity within a microbial population comprised of single species (Prosser et al. 2007). Therefore an understanding of the concept of species is needed. A common definition of species using a genetic concept is a group of interbreeding individuals that is isolated from other such groups by barriers of recombination (Prosser et al. 2007). An alternative ecological species concept defines a species as set of individuals that can be considered identical in all relevant ecological traits (Cohan 2001). This is particularly important because of the abundance and deep phylogenetic complexity of microbial communities. Cohan postulated that “bacteria occupy discrete niches and that periodic selection will purge genetic variation within each niche without preventing divergence between the inhabitants of different niches”. The importance of gene exchange mechanisms likely in bacteria and archaea and therefore extremophiles, arises from the fact that their genomes are divided into two distinct parts, the core genome and the accessory genome (Cohan 2001). The core genome consists of genes that are crucial for the functioning of an organism and the accessory genome consists of genes that are capable of adapting to the changing ecosystem through gain and loss of function. Strains that belong to the same species can differ in the composition of accessory genes and therefore their capability to adapt to changing ecosystems (Cohan 2001; Tettelin et al. 2005; Gill et al. 2005). Additional ecological diversity exists in plasmids, transposons and pathogenicity islands as they can be easily shared in a favorable environment but still be absent in the same species found elsewhere (Wertz et al. 2003). This poses a major challenge for studying ALE and community microbial ecology indicating a continued need to develop a fitting theory that connects the fluid nature of microbial communities to their ecology (Wertz et al. 2003; Coleman et al. 2006). Understanding the nature and contribution of different processes that determine the frequencies of genes in any population is the biggest concern in population and evolutionary genetics (Prosser et al. 2007) and it is critical for an understanding of experimental evolution

Investigating the Aetiology of Telangiectatic Matting

IntroductionTelangiectatic matting (TM) is a morphological description referring to vessels with a small diameter of less than 0.2 mm that can appear sporadically or in well-defined patches (hence the term ‘matting’) primarily on the lower limbs. The aetiology underlying TM remains uncertain however angiogenic and inflammatory mechanisms are believed to play a pathogenic role. The aim of this study was to investigate the pathogenesis of TM and identify possible risk factors. MethodsThis study had two parts. The clinical records of consecutive patients were retrospectively analysed to identify risk factors for TM. In the second part, the haemostatic and coagulation profile of 12 patients with TM were analysed and compared with 12 controls using standard coagulation tests, platelet function and a global assay of coagulation namely rotational thromboelastometry (ROTEM).ResultsIn 352 consecutive patients presenting to a phlebology practice, 25 patients had TM (7.1%). All 25 patients were female with the median age of 45 (27-57) years. A comprehensive medical history was taken. Amongst 27 possible risk factors assessed, statistically significant associations included recurrent epistaxis, easy bruising, hypersensitivity (eczema, hives, hay fever, rhinitis), previous treatment with sclerotherapy or vascular laser for lower limb veins and a family history of telangiectasias. The haemostatic and coagulation profile of patients with TM did not differ significantly from those without TM.ConclusionTM is associated with both hypersensitivity and a bleeding tendency. Our study revealed no significant increase in the incidence of haemostatic abnormalities in patients with TM compared with the control group. Given the significant association with hypersensitivity disorders we believe underlying mast cell hyperreactivity may contribute to both hypersensitivity and a bleeding tendency and predispose patients to TM. Further research studying mast cell activity is warranted to establish a definite link

Study of Score Fusion and Quality Weighting in the Bio-Secure DS2 Database

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