3,358 research outputs found

    High-precision gravimetric survey in support of lunar laser ranging at Haleakala, Maui, 1976 - 1978

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    The planning, observations and adjustment of high-precision gravity survey networks established on the islands of Maui and Oahu as part of the geodetic-geophysical program in support of lunar laser ranging at Haleakala, Maui, Hawaii are described. The gravity survey networks include 43 independently measured gravity differences along the gravity calibration line from Kahului Airport to the summit of Mt. Haleakala, together with some key points close to tidal gauges on Maui, and 40 gravity differences within metropolitan Honolulu. The results of the 1976-1978 survey are compared with surveys made in 1961 and in 1964-1965. All final gravity values are given in the system of the international gravity standardization net 1971 (IGSN 71); values are obtained by subtracting 14.57 mgal from the Potsdam value at the gravity base station at the Hickam Air Force Base, Honolulu

    Refraction effect in satellite tracking

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    Refraction effect in satellite tracking in earths atmospher

    Interface Equations for Capillary Rise in Random Environment

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    We consider the influence of quenched noise upon interface dynamics in 2D and 3D capillary rise with rough walls by using phase-field approach, where the local conservation of mass in the bulk is explicitly included. In the 2D case the disorder is assumed to be in the effective mobility coefficient, while in the 3D case we explicitly consider the influence of locally fluctuating geometry along a solid wall using a generalized curvilinear coordinate transformation. To obtain the equations of motion for meniscus and contact lines, we develop a systematic projection formalism which allows inclusion of disorder. Using this formalism, we derive linearized equations of motion for the meniscus and contact line variables, which become local in the Fourier space representation. These dispersion relations contain effective noise that is linearly proportional to the velocity. The deterministic parts of our dispersion relations agree with results obtained from other similar studies in the proper limits. However, the forms of the noise terms derived here are quantitatively different from the other studies

    A study of the degree to which satellite- derived gravitational data can be related to the anomalous surface gravity field and other anomalous geophysical parameters Final report

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    Satellite-derived gravitational data related to anomalous surface gravity field and other geophysical parameters of Solomon Islands are

    Increasing melanism along a latitudinal gradient in a widespread amphibian: local adaptation, ontogenic or environmental plasticity?

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    <p>Abstract</p> <p>Background</p> <p>The thermal benefits of melanism in ectothermic animals are widely recognized, but relatively little is known about population differentiation in the degree of melanism along thermal gradients, and the relative contributions of genetic <it>vs. </it>environmental components into the level of melanism expressed. We investigated variation in the degree of melanism in the common frog (<it>Rana temporaria</it>; an active heliotherm thermoregulator) by comparing the degree of melanism (i) among twelve populations spanning over 1500 km long latitudinal gradient across the Scandinavian Peninsula and (ii) between two populations from latitudinal extremes subjected to larval temperature treatments in a common garden experiment.</p> <p>Results</p> <p>We found that the degree of melanism increased steeply in the wild as a function of latitude. Comparison of the degree of population differentiation in melanism (<it>P<sub>ST</sub></it>) and neutral marker loci (<it>F<sub>ST</sub></it>) revealed that the <it>P<sub>ST </sub></it> ><it>F<sub>ST</sub></it>, indicating that the differences cannot be explained by random genetic drift alone. However, the latitudinal trend observed in the wild was not present in the common garden data, suggesting that the cline in nature is not attributable to direct genetic differences.</p> <p>Conclusions</p> <p>As straightforward local adaptation can be ruled out, the observed trend is likely to result from environment-driven phenotypic plasticity or ontogenetic plasticity coupled with population differences in age structure. In general, our results provide an example how phenotypic plasticity or even plain ontogeny can drive latitudinal clines and result in patterns perfectly matching the genetic differences expected under adaptive hypotheses.</p

    Protein Adsorption and Its Effects on Electroanalytical Performance of Nanocellulose/Carbon Nanotube Composite Electrodes

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    Protein fouling is a critical issue in the development of electrochemical sensors for medical applications, as it can significantly impact their sensitivity, stability, and reliability. Modifying planar electrodes with conductive nanomaterials that possess a high surface area, such as carbon nanotubes (CNTs), has been shown to significantly improve fouling resistance and sensitivity. However, the inherent hydrophobicity of CNTs and their poor dispersibility in solvents pose challenges in optimizing such electrode architectures for maximum sensitivity. Fortunately, nanocellulosic materials offer an efficient and sustainable approach to achieving effective functional and hybrid nanoscale architectures by enabling stable aqueous dispersions of carbon nanomaterials. Additionally, the inherent hygroscopicity and fouling-resistant nature of nanocellulosic materials can provide superior functionalities in such composites. In this study, we evaluate the fouling behavior of two nanocellulose (NC)/multiwalled carbon nanotube (MWCNT) composite electrode systems: one using sulfated cellulose nanofibers and another using sulfated cellulose nanocrystals. We compare these composites to commercial MWCNT electrodes without nanocellulose and analyze their behavior in physiologically relevant fouling environments of varying complexity using common outer- and inner-sphere redox probes. Additionally, we use quartz crystal microgravimetry with dissipation monitoring (QCM-D) to investigate the behavior of amorphous carbon surfaces and nanocellulosic materials in fouling environments. Our results demonstrate that the NC/MWCNT composite electrodes provide significant advantages for measurement reliability, sensitivity, and selectivity over only MWCNT-based electrodes, even in complex physiological monitoring environments such as human plasma.</p

    Dynamics and Kinetic Roughening of Interfaces in Two-Dimensional Forced Wetting

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    We consider the dynamics and kinetic roughening of wetting fronts in the case of forced wetting driven by a constant mass flux into a 2D disordered medium. We employ a coarse-grained phase field model with local conservation of density, which has been developed earlier for spontaneous imbibition driven by a capillary forces. The forced flow creates interfaces that propagate at a constant average velocity. We first derive a linearized equation of motion for the interface fluctuations using projection methods. From this we extract a time-independent crossover length őĺ√ó\xi_\times, which separates two regimes of dissipative behavior and governs the kinetic roughening of the interfaces by giving an upper cutoff for the extent of the fluctuations. By numerically integrating the phase field model, we find that the interfaces are superrough with a roughness exponent of Ōá=1.35¬Ī0.05\chi = 1.35 \pm 0.05, a growth exponent of ő≤=0.50¬Ī0.02\beta = 0.50 \pm 0.02, and őĺ√ó‚ąľv‚ąí1/2\xi_\times \sim v^{-1/2} as a function of the velocity. These results are in good agreement with recent experiments on Hele-Shaw cells. We also make a direct numerical comparison between the solutions of the full phase field model and the corresponding linearized interface equation. Good agreement is found in spatial correlations, while the temporal correlations in the two models are somewhat different.Comment: 9 pages, 4 figures, submitted to Eur.Phys.J.
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