3,871 research outputs found
Effect of Tapper Ratio on a Car Rear Spoiler Performance
No full textThe increasing development of car modification and the lack of understanding on the function of using spoilers or rear wings on vehicles, underlies the research on the aerodynamic forces acting on cars. The influence of this aerodynamic device will produce a compressive force to the bottom of the vehicle or called downforce, where this force is greatly influenced by the CL (lift coefficient) value. The purpose of this study was to determine the effect of variations in the tapper ratio on the value of downforce and drag force on on single-element type spoilers made using a NACA 6412 airfoil. The research was conducted using the Computational Fluid Dynamic method using ANSYS Fluent software with steady state pressure based solver. In this study five variations of the tapper ratio were used, namely: 1:1; 1:0.5; 1:0.7; 0.5:1; and 0.7:1. The fluid properties used are adjusted to the climate and weather in general air conditions and at air flow speeds of 100 km/h. Based on the research conducted, it can be concluded that the highest lift coefficient value was achieved in the 1:1 tapper ratio variation which was equal to CL = -0.2275 and CD = 0.0195. The highest downforce value is achieved in the 1:1 tapper ratio variation that is equal to L = -107,529 N and the largest drag force value is also achieved in the 1: 1 tapper ratio variation that is equal to D = 9.2269 N. The best CL/CD results are obtained at the 1:05 tapper ratio variation with a value of 12.82
Effect of Tapper Ratio on a Car Rear Spoiler Performance
No full textThe increasing development of car modification and the lack of understanding on the function of using spoilers or rear wings on vehicles, underlies the research on the aerodynamic forces acting on cars. The influence of this aerodynamic device will produce a compressive force to the bottom of the vehicle or called downforce, where this force is greatly influenced by the CL (lift coefficient) value. The purpose of this study was to determine the effect of variations in the tapper ratio on the value of downforce and drag force on on single-element type spoilers made using a NACA 6412 airfoil. The research was conducted using the Computational Fluid Dynamic method using ANSYS Fluent software with steady state pressure based solver. In this study five variations of the tapper ratio were used, namely: 1:1; 1:0.5; 1:0.7; 0.5:1; and 0.7:1. The fluid properties used are adjusted to the climate and weather in general air conditions and at air flow speeds of 100 km/h. Based on the research conducted, it can be concluded that the highest lift coefficient value was achieved in the 1:1 tapper ratio variation which was equal to CL = -0.2275 and CD = 0.0195. The highest downforce value is achieved in the 1:1 tapper ratio variation that is equal to L = -107,529 N and the largest drag force value is also achieved in the 1: 1 tapper ratio variation that is equal to D = 9.2269 N. The best CL/CD results are obtained at the 1:05 tapper ratio variation with a value of 12.82
The systematic status of the lagoon periwinkle, <i>Littorina tenebrosa</i>
No full textEight samples of Littorina tenebrosa and L. saxatilis (Mollusca: Gastropoda) from Ireland and Britain, including pairs of each form from two locations in Ireland, were screened for genetic variation at 12 polymorphic enzyme loci using starch gel electrophoresis. Levels of polymorphism and heterozygosity were similar in L. tenebrosa and L. saxatilis, apart from a sample of L. tenebrosa from Britain which was less polymorphic than the Irish samples. No alleles were found to be unique to either form. Phylogenetic analysis using UPGMA showed that L. saxatilis and L. tenebrosa populations clustered as a monophyletic group. Nevertheless, the mean genetic distance between parapatric populations of L. saxatilis and L. tenebrosa (D=0.076) was similar to the mean for allopatric populations of either species (D=0.080). This indicates that there is a barrier to gene flow between the two forms Despite this, L. tenebrosa does not merit specific status since populations of this snail do not cluster as a distinct group, separate from L. saxatilis populations
Nicotinic acetylcholine receptor-mediated mechanisms in lung cancer
No full textDespite the known adverse health effects associated with tobacco use, over 45 million adults in the United States smoke. Cigarette smoking is the major etiologic factor associated with lung cancer. Cigarettes contain thousands of toxic chemicals, many of which are carcinogenic. Nicotine contributes directly to lung carcinogenesis through the activation of nicotinic acetylcholine receptors (nAChRs). nAChRs are ligand-gated ion channels, expressed in both normal and lung cancer cells, which mediate the proliferative, pro-survival, angiogenic, and metastatic effects of nicotine and its nitrosamine derivatives. The underlying molecular mechanisms involve increases in intracellular calcium levels and activation of cancer signal transduction pathways. In addition, acetylcholine (ACh) acts as an autocrine or paracrine growth factor in lung cancer. Other neurotransmitters and neuropeptides also activate similar growth loops. Recent genetic studies further support a role for nAChRs in the development of lung cancer. Several nAChR antagonists have been shown to inhibit lung cancer growth, suggesting that nAChRs may serve as valuable targets for biomarker-guided lung cancer interventions.Neuroscienc
Dopamine D2-receptor activation elicits akinesia, rigidity, catalepsy, and tremor in mice expressing hypersensitive {alpha}4 nicotinic receptors via a cholinergic-dependent mechanism
No full textRecent studies suggest that high-affinity neuronal nicotinic acetylcholine receptors (nAChRs) containing alpha4 and beta2 subunits (alpha4beta2*) functionally interact with G-protein-coupled dopamine (DA) D(2) receptors in basal ganglia. We hypothesized that if a functional interaction between these receptors exists, then mice expressing an M2 point mutation (Leu9'Ala) rendering alpha4 nAChRs hypersensitive to ACh may exhibit altered sensitivity to a D(2)-receptor agonist. When challenged with the D(2)R agonist, quinpirole (0.5-10 mg/kg), Leu9'Ala mice, but not wild-type (WT) littermates, developed severe, reversible motor impairment characterized by rigidity, catalepsy, akinesia, and tremor. While striatal DA tissue content, baseline release, and quinpirole-induced DA depletion did not differ between Leu9'Ala and WT mice, quinpirole dramatically increased activity of cholinergic striatal interneurons only in mutant animals, as measured by increased c-Fos expression in choline acetyltransferase (ChAT)-positive interneurons. Highlighting the importance of the cholinergic system in this mouse model, inhibiting the effects of ACh by blocking muscarinic receptors, or by selectively activating hypersensitive nAChRs with nicotine, rescued motor symptoms. This novel mouse model mimics the imbalance between striatal DA/ACh function associated with severe motor impairment in disorders such as Parkinson's disease, and the data suggest that a D(2)R-alpha4*-nAChR functional interaction regulates cholinergic interneuron activity
An evaluation of life cycle assessment and its application to the closed-loop recycling of carbon fibre reinforced polymers
No full textLife cycle assessment (LCA) is a valuable tool for establishing the environmental burdens of a composite material over its lifetime. It is therefore of importance to the composites industry as a material selection tool when determining the applicability of recycled composites in the component design phase. This review paper evaluates the LCA framework and its ability to accurately determine the benefits of closed-loop composite recycling, with the aim of aiding future material selection for recycled CFRP. LCA is a powerful tool for CFRP assessment when used in combination with an economic and technical component as covered by the integrated Life Cycle Engineering approach. The broad range of values available in LCA databases may prove an issue for cross comparison between studies and provide disparate results leading to impractical conclusions. The use phase offers the greatest potential for CFRP emissions savings in the transport sector; the advent of closed-loop recycling for CFRP may provide the multiple use phases required to breakeven on the significant energy burden of production or possibly provide net environmental savings gains over traditional materials
Allelic association discriminates draft orders
No full textA year ago there was hope that a finished sequence of the human genome would soon be publicly available and would give a more reliable locus order than an unconstrained radiation hybrid or genetic map. Alas, there are now different draft orders for each region, none of which may be correct because of gaps, uncertain polarity of contigs, and errors in assembly. Shortly before these drafts became available, we analysed allelic association (also called linkage disequilibrium, LD) in the FRAX region in a large sample of haplotypes (Ennis et al. 2000). We demonstrate here that this material discriminates among alternative draft orders. To express support for discrimination between two values of ?2 = ?2 ln L we use the Akaike criterion AIC = df[?2/min ?2?1]. Excluding premutations and full mutations at FMR1, all maps have 715 degrees of freedom (df) among 717 pairs of alleles after accepting L = 0 and estimating M, in the Malecot equation E(?) = Me d, where ? is the association between a pair of alleles at distance d. An AIC in excess of 2 provides evidence against a map with the larger ?2
Clonal myelopoiesis promotes adverse outcomes in chronic kidney disease
No full textWe sought to determine the relationship between age-related clonal hematopoiesis (CH) and chronic kidney disease (CKD). CH, defined as mosaic chromosome abnormalities (mCA) and/or driver mutations was identified in 5449 (2.9%) eligible UK Biobank participants (n = 190,487 median age = 58 years). CH was negatively associated with glomerular filtration rate estimated from cystatin-C (eGFR.cys; β = −0.75, P = 2.37 × 10
–4), but not with eGFR estimated from creatinine, and was specifically associated with CKD defined by eGFR.cys < 60 (OR = 1.02, P = 8.44 × 10
–8). In participants without prevalent myeloid neoplasms, eGFR.cys was associated with myeloid mCA (n = 148, β = −3.36, P = 0.01) and somatic driver mutations (n = 3241, β = −1.08, P = 6.25 × 10
–5) associated with myeloid neoplasia (myeloid CH), specifically mutations in CBL, TET2, JAK2, PPM1D and GNB1 but not DNMT3A or ASXL1. In participants with no history of cardiovascular disease or myeloid neoplasms, myeloid CH increased the risk of adverse outcomes in CKD (HR = 1.6, P = 0.002) compared to those without myeloid CH. Mendelian randomisation analysis provided suggestive evidence for a causal relationship between CH and CKD (P = 0.03). We conclude that CH, and specifically myeloid CH, is associated with CKD defined by eGFR.cys. Myeloid CH promotes adverse outcomes in CKD, highlighting the importance of the interaction between intrinsic and extrinsic factors to define the health risk associated with CH.
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Inherited common genetic polymorphisms are associated with tumour characteristics and treatment outcomes in young breast cancer patients
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