63,353 research outputs found

    Learning on the Halfshell

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    Aluminium or copper substrate panel for selective absorption of solar energy

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    A method for making panels which selectively absorb solar energy is disclosed. The panels are comprised of an aluminum substrate, a layer of zinc thereon, a layer of nickel over the zinc layer and an outer layer of solar energy absorbing nickel oxide or a copper substrate with a layer of nickel thereon and a layer of solar energy absorbing nickel oxide distal from the copper substrate

    Method for making an aluminum or copper substrate panel for selective absorption of solar energy

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    A panel is described for selectively absorbing solar energy comprising an aluminum substrate. A zinc layer was covered by a layer of nickel and an outer layer of solar energy absorbing nickel oxide or a copper substrate with a nickel layer. A layer of solar energy absorbing nickel oxide distal from the copper substrate was included. A method for making these panels is disclosed

    Impact of dynamical chiral symmetry breaking on meson structure and interactions

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    We provide a glimpse of recent progress in meson physics made via QCD's Dyson-Schwinger equations with: a perspective on confinement and dynamical chiral symmetry breaking (DCSB); a pre'cis on the physics of in-hadron condensates; results for the masses of the \pi, \sigma, \rho, a_1 mesons and their first-radial excitations; and an illustration of the impact of DCSB on the pion form factor.Comment: 6 pages, 3 figures, 1 table. Contribution to Proceedings of the 11th International Workshop on Meson Production, Properties and Interaction, Uniwersytet Jagiellonski, Instytut Fizyki, Krakow, Poland, 10-15 June 201

    An Expansion Term In Hamilton's Equations

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    For any given spacetime the choice of time coordinate is undetermined. A particular choice is the absolute time associated with a preferred vector field. Using the absolute time Hamilton's equations are (δHc)/(δq)=π˙+Θπ,- (\delta H_{c})/(\delta q)=\dot{\pi}+\Theta\pi, + (\delta H_{c})/(\delta \pi)=\dot{q},where, where \Theta = V^{a}_{.;a}istheexpansionofthevectorfield.Thusthereisahithertounnoticedtermintheexpansionofthepreferredvectorfield.Hamiltonsequationscanbeusedtodescribefluidmotion.Inthiscasetheabsolutetimeisthetimeassociatedwiththefluidscomovingvector.Asmeasuredbythisabsolutetimetheexpansiontermispresent.Similarlyincosmology,eachobserverhasacomovingvectorandHamiltonsequationsagainhaveanexpansionterm.ItisnecessarytoincludetheexpansiontermtoquantizesystemssuchastheabovebythecanonicalmethodofreplacingDiracbracketsbycommutators.Hamiltonsequationsinthisformdonothaveacorrespondingsympleticform.Replacingtheexpansionbyaparticlenumber is the expansion of the vector field. Thus there is a hitherto unnoticed term in the expansion of the preferred vector field. Hamilton's equations can be used to describe fluid motion. In this case the absolute time is the time associated with the fluid's co-moving vector. As measured by this absolute time the expansion term is present. Similarly in cosmology, each observer has a co-moving vector and Hamilton's equations again have an expansion term. It is necessary to include the expansion term to quantize systems such as the above by the canonical method of replacing Dirac brackets by commutators. Hamilton's equations in this form do not have a corresponding sympletic form. Replacing the expansion by a particle number N\equiv exp(-\int\Theta d \ta)andintroducingtheparticlenumbersconjugatemomentum and introducing the particle numbers conjugate momentum \pi^{N}thestandardsympleticformcanberecoveredwithtwoextrafieldsNand the standard sympletic form can be recovered with two extra fields N and \pi^N$. Briefly the possibility of a non-standard sympletic form and the further possibility of there being a non-zero Finsler curvature corresponding to this are looked at.Comment: 10 page

    Effects of the roller feed ratio on wrinkling failure in conventional spinning of a cylindrical cup

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    In this study, wrinkling failure in conventional spinning of a cylindrical cup has been investigated by using both finite element (FE) analysis and experimental methods. FE simulation models of a spinning experiment have been developed using the explicit finite element solution method provided by the software Abaqus. The severity of wrinkles is quantified by calculating the standard deviation of the radial coordinates of element nodes on the edge of the workpiece obtained from the FE models. The results show that the severity of wrinkles tends to increase when increasing the roller feed ratio. A forming limit study for wrinkling has been carried out and shows that there is a feed ratio limit beyond which the wrinkling failure will take place. Provided that the feed ratio is kept below this limit, the wrinkling failure can be prevented. It is believed that high compressive tangential stresses in the local forming zone are the causes of the wrinkling failure. Furthermore, the computational performance of the solid and shell elements in simulating the spinning process are examined and the tool forces obtained from wrinkling and wrinkle-free models are compared. Finally, the effects of the feed ratio on variations of the wall thickness of the spun cylindrical cup are investigated. </jats:p

    Prevalence of working smoke alarms in local authority inner city housing: randomised controlled trial

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    Objectives To identify which type of smoke alarm is most likely to remain working in local authority inner city housing, and to identify an alarm tolerated in households with smokers. Design Randomised controlled trial. Setting Two local authority housing estates in inner London. Participants 2145 households. Intervention Installation of one of five types of smoke alarm (ionisation sensor with a zinc battery; ionisation sensor with a zinc battery and pause button; ionisation sensor with a lithium battery and pause button; optical sensor with a lithium battery; or optical sensor with a zinc battery). Main outcome measure Percentage of homes with any working alarm and percentage in which the alarm installed for this study was working after 15 months. Results 54.4% (1166/2145) of all households and 45.9% (465/1012) of households occupied by smokers had a working smoke alarm. Ionisation sensor, lithium battery, and there being a smoker in the household were independently associated with whether an alarm was working (adjusted odds ratios 2.24 (95% confidence interval 1.75 to 2.87), 2.20 (1.77 to 2.75), and 0.62 (0.52 to 0.74)). The most common reasons for non-function were missing battery (19%), missing alarm (17%), and battery disconnected (4%). Conclusions Nearly half of the alarms installed were not working when tested 15 months later. Type of alarm and power source are important determinants of whether a household had a working alarm

    Decellularised cartilage ECM culture coatings drive rapid and robust chondrogenic differentiation of human periosteal cells

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    The control of cell behaviour in an effort to create highly homogeneous cultures is becoming an area of intense research, both to elucidate fundamental biology and for regenerative applications. The extracellular matrix (ECM) controls many cellular processes in vivo, and as such is a rich source of cues that may be translated in vitro. Herein, we describe the creation of cell culture coatings from porcine decellularised hyaline cartilage through enzymatic digestion. Surprisingly, heat-mediated sterilisation created a coating with the capacity to rapidly and robustly induce chondrogenic differentiation of human periosteal cells. This differentiation was validated through the alteration of cell phenotype from a fibroblastic to a cuboidal/cobblestone chondrocyte-like appearance. Moreover, chondrogenic gene expression further supported this observation, where cells cultured on heat sterilised ECM-coated plastic displayed higher expression of COL2A1, ACAN and PRG4 (p 0.05) compared to non-coated plastic cultures. Interestingly, COL2A1 and ACAN expression in this context were sensitive to initial cell density; however, SOX9 expression appeared to be mainly driven by the coating independent of seeding density. The creation of a highly chondrogenic coating may provide a cost-effective solution for the differentiation and/or expansion of human chondrocytes aimed towards cartilage repair strategies
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