1,758 research outputs found

    Hydrostatic and Physiologic Contributions to Intraocular Pressure Change During Postural Change

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    Many studies have observed that intraocular pressure (IOP) is dependent on tilt angle () during postural change. In this work, we aggregated 36 independent datasets from 30 published articles, representing 821 subjects, which reported data on IOP during postural change. From this data, we developed a generalized quantitative relationship between IOP and . We then compared the experimentally derived results to simulated predictions generated by our lumped parameter model of the eye, LPEye, considering only hydrostatic effects. The difference between the analytical and simulated values of IOP can be used to quantify the physiologic regulatory contribution

    A "Littlest Higgs" Model with Custodial SU(2) Symmetry

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    In this note, a ``littlest higgs'' model is presented which has an approximate custodial SU(2) symmetry. The model is based on the coset space SO(9)/(SO(5)Ă—SO(4))SO(9)/(SO(5)\times SO(4)). The light pseudo-goldstone bosons of the theory include a {\it single} higgs doublet below a TeV and a set of three SU(2)WSU(2)_W triplets and an electroweak singlet in the TeV range. All of these scalars obtain approximately custodial SU(2) preserving vacuum expectation values. This model addresses a defect in the earlier SO(5)Ă—SU(2)Ă—U(1)SO(5)\times SU(2)\times U(1) moose model, with the only extra complication being an extended top sector. Some of the precision electroweak observables are computed and do not deviate appreciably from Standard Model predictions. In an S-T oblique analysis, the dominant non-Standard Model contributions are the extended top sector and higgs doublet contributions. In conclusion, a wide range of higgs masses is allowed in a large region of parameter space consistent with naturalness, where large higgs masses requires some mild custodial SU(2) violation from the extended top sector.Comment: 22 pages + 8 figures; JHEP style, added references and extra discussion on size of T contributions, as well as some other minor clarifications. Version to appear in JHE

    Exact results for the reactivity of a single-file system

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    We derive analytical expressions for the reactivity of a Single-File System with fast diffusion and adsorption and desorption at one end. If the conversion reaction is fast, then the reactivity depends only very weakly on the system size, and the conversion is about 100%. If the reaction is slow, then the reactivity becomes proportional to the system size, the loading, and the reaction rate constant. If the system size increases the reactivity goes to the geometric mean of the reaction rate constant and the rate of adsorption and desorption. For large systems the number of nonconverted particles decreases exponentially with distance from the adsorption/desorption end.Comment: 4 pages, 2 figure

    Time of arrival through interacting environments: Tunneling processes

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    We discuss the propagation of wave packets through interacting environments. Such environments generally modify the dispersion relation or shape of the wave function. To study such effects in detail, we define the distribution function P_{X}(T), which describes the arrival time T of a packet at a detector located at point X. We calculate P_{X}(T) for wave packets traveling through a tunneling barrier and find that our results actually explain recent experiments. We compare our results with Nelson's stochastic interpretation of quantum mechanics and resolve a paradox previously apparent in Nelson's viewpoint about the tunneling time.Comment: Latex 19 pages, 11 eps figures, title modified, comments and references added, final versio

    Dynamic Image-Based Modelling of Kidney Branching Morphogenesis

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    Kidney branching morphogenesis has been studied extensively, but the mechanism that defines the branch points is still elusive. Here we obtained a 2D movie of kidney branching morphogenesis in culture to test different models of branching morphogenesis with physiological growth dynamics. We carried out image segmentation and calculated the displacement fields between the frames. The models were subsequently solved on the 2D domain, that was extracted from the movie. We find that Turing patterns are sensitive to the initial conditions when solved on the epithelial shapes. A previously proposed diffusion-dependent geometry effect allowed us to reproduce the growth fields reasonably well, both for an inhibitor of branching that was produced in the epithelium, and for an inducer of branching that was produced in the mesenchyme. The latter could be represented by Glial-derived neurotrophic factor (GDNF), which is expressed in the mesenchyme and induces outgrowth of ureteric branches. Considering that the Turing model represents the interaction between the GDNF and its receptor RET very well and that the model reproduces the relevant expression patterns in developing wildtype and mutant kidneys, it is well possible that a combination of the Turing mechanism and the geometry effect control branching morphogenesis

    Precision Electroweak Observables in the Minimal Moose Little Higgs Model

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    Little Higgs theories, in which the Higgs particle is realized as the pseudo-Goldstone boson of an approximate global chiral symmetry have generated much interest as possible alternatives to weak scale supersymmetry. In this paper we analyze precision electroweak observables in the Minimal Moose model and find that in order to be consistent with current experimental bounds, the gauge structure of this theory needs to be modified. We then look for viable regions of parameter space in the modified theory by calculating the various contributions to the S and T parameters.Comment: v2: 17 pages, 9 figures. Typeset in JHEP style. Added a references and two figures showing parameter space for each of two reference points. Corrected typo

    Microbiological assessments in a cut flower crop polytunnel field trial adopting soil covering and microbiocides for Fusarium wilt suppression

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    Publication history: Published online - 4 September 2020Cut flower Matthiola incana were raised by local commercial cultivators in a polytunnel. The field soil beds were either left uncovered as normal or covered with polythene sheets (except a hole for plant plug space). Average temperatures in the top 5 cm soil under cover dropped from 28 oC to 18 oC compared to its spiking up to 37 oC in uncovered counterparts. Microbiological analyses indicated that soil covering induced two log10 folds reduction of the wilt causal fungi Fusarium oxysporum and concomitantly increased one log10 fold wilt antagonistic natural soil inhabiting fungi populations. Standard dip/drench mixtures of commercial and local isolates microbiocides (bacteria) applied to M. incana plug roots improved plant health assessed by visible scores of the level of damage or wilt symptoms under soil covered treatments. Scanning electron microscopy, cultural and 16S rRNA PCR analyses revealed potent antifungal bacteria attached to the hyphal surfaces of F. oxysporum as ectosymbionts that may have implications for virulence regulation and host plants’ wilt disease control. Our microbiological data support the prospects of combining physiological and microbiological interventions upon covering the soil surface that offers the local horticulturists an evidence based sustainable means of Fusarium wilt control suppression in polytunnel crops.Department of Agriculture, Environment and Rural Affairs (DAERA) directed Evidence and Innovation project 16/3/11, and the support of a EU FP7–BIOFECTOR grant (JRR, CF, TM) for this stud

    Steady-State Properties of Single-File Systems with Conversion

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    We have used Monte-Carlo methods and analytical techniques to investigate the influence of the characteristic parameters, such as pipe length, diffusion, adsorption, desorption and reaction rate constants on the steady-state properties of Single-File Systems with a reaction. We looked at cases when all the sites are reactive and when only some of them are reactive. Comparisons between Mean-Field predictions and Monte-Carlo simulations for the occupancy profiles and reactivity are made. Substantial differences between Mean-Field and the simulations are found when rates of diffusion are high. Mean-Field results only include Single-File behavior by changing the diffusion rate constant, but it effectively allows passing of particles. Reactivity converges to a limit value if more reactive sites are added: sites in the middle of the system have little or no effect on the kinetics. Occupancy profiles show approximately exponential behavior from the ends to the middle of the system.Comment: 15 pages, 20 figure

    Two-domains bulklike Fermi surface of Ag films deposited onto Si(111)-(7x7)

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    Thick metallic silver films have been deposited onto Si(111)-(7x7) substrates at room temperature. Their electronic properties have been studied by using angle resolved photoelectron spectroscopy (ARPES). In addition to the electronic band dispersion along the high-symmetry directions, the Fermi surface topology of the grown films has been investigated. Using ARPES, the spectral weight distribution at the Fermi level throughout large portions of the reciprocal space has been determined at particular perpendicular electron-momentum values. Systematically, the contours of the Fermi surface of these films reflected a sixfold symmetry instead of the threefold symmetry of Ag single crystal. This loss of symmetry has been attributed to the fact that these films appear to be composed by two sets of domains rotated 60o^o from each other. Extra, photoemission features at the Fermi level were also detected, which have been attributed to the presence of surface states and \textit{sp}-quantum states. The dimensionality of the Fermi surface of these films has been analyzed studying the dependence of the Fermi surface contours with the incident photon energy. The behavior of these contours measured at particular points along the Ag Γ\GammaL high-symmetry direction puts forward the three-dimensional character of the electronic structure of the films investigated.Comment: 10 pages, 12 figures, submitted to Physical Review
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