Influence of topography on tide propagation and amplification in semi-enclosed basins

An idealized model for tide propagation and amplification in semi-enclosed rectangular basins is presented, accounting for depth differences by a combination of longitudinal and lateral topographic steps. The basin geometry is formed by several adjacent compartments of identical width, each having either a uniform depth or two depths separated by a transverse topographic step. The problem is forced by an incoming Kelvin wave at the open end, while allowing waves to radiate outward. The solution in each compartment is written as the superposition of (semi)-analytical wave solutions in an infinite channel, individually satisfying the depth-averaged linear shallow water equations on the f plane, including bottom friction. A collocation technique is employed to satisfy continuity of elevation and flux across the longitudinal topographic steps between the compartments. The model results show that the tidal wave in shallow parts displays slower propagation, enhanced dissipation and amplified amplitudes. This reveals a resonance mechanism, occurring when\ud the length of the shallow end is roughly an odd multiple of the quarter Kelvin wavelength. Alternatively, for sufficiently wide basins, also Poincaré waves may become resonant. A transverse step implies different wavelengths of the incoming and reflected Kelvin wave, leading to increased amplitudes in shallow regions and a shift of amphidromic points in the direction of the deeper part. Including the shallow parts near the basin’s closed end (thus capturing the Kelvin resonance mechanism) is essential to reproduce semi-diurnal and diurnal\ud tide observations in the Gulf of California, the Adriatic Sea and the Persian Gulf

The Hyalella (Crustacea: Amphipoda) species cloud of the ancient Lake Titicaca originated from multiple colonizations

The final publication is available at Elsevier via https://doi.org/10.1016/j.ympev.2018.03.004. © 2018. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/Ancient lakes are renowned for their exceptional diversity of endemic species. As model systems for the study of sympatric speciation, it is necessary to understand whether a given hypothesized species flock is of monophyletic or polyphyletic origin. Here, we present the first molecular characterization of the Hyalella (Crustacea: Amphipoda) species complex of Lake Titicaca, using COI and 28S DNA sequences, including samples from the connected Small and Large Lakes that comprise Lake Titicaca as well as from a broader survey of southern South American sites. At least five evolutionarily distant lineages are present within Lake Titicaca, which were estimated to have diverged from one another 12–20 MYA. These major lineages are dispersed throughout the broader South American Hyalella phylogeny, with each lineage representing at least one independent colonization of the lake. Moreover, complex genetic relationships are revealed between Lake Titicaca individuals and those from surrounding water bodies, which may be explained by repeated dispersal into and out of the lake, combined with parallel intralacustrine diversification within two separate clades. Although further work in deeper waters will be required to determine the number of species present and modes of diversification, our results strongly indicate that this amphipod species cloud is polyphyletic with a complex geographic history.Natural Sciences and Engineering Research Council || Discovery Grant 2012-327509Natural Sciences and Engineering Research Council || Discovery Grant 386591-2010Natural Sciences and Engineering Research Council || Undergraduate Student Research AwardsNatural Sciences and Engineering Research Council || Postdoctoral FellowshipCatholic University of Temuco, Research Direction || Limnology Project DGI-DCA 2007-01, Project MECESUP UCT 080

Body water distribution in severe obesity and its assessment from eight-polar bioelectrical impedance analysis

Objective: To measure body water distribution and to evaluate the accuracy of eight-polar bioelectrical impedance analysis (BIA) for the assessment of total body water (TBW) and extracellular water (ECW) in severe obesity. Design: Cross-sectional study. Setting: Obesity clinic. Subjects: In all, 75 women aged 18-66y, 25 with body mass index (BMI) between 19.1 and 29.9 kg/m2 (ie not obese), 25 with BMI between 30.0 and 39.9 kg/m2 (ie class I and II obese), and 25 with BMI between 40.0 and 48.2 kg/m2 (ie class III obese). Methods: TBW and ECW were measured by 2H20 and Br dilution. Body resistance (R) was obtained by summing the resistances of arms, trunk and legs as measured by eight-polar BIA (InBody 3.0, Biospace, Seoul, Korea). The resistance index at a frequency of x kHz (RIx) was calculated as height 2/Rx. Results: ECW : TBW was similar in women with class III (46 ± 3%, mean ± s.d.) and class I-II obesity (45 ± 3%) but higher than in nonobese women (39 ± 3%, P<0.05). In a random subsample of 37 subjects, RI500 explained 82% of TBW variance (P<0.0001) and cross-validation of the obtained algorithm in the remaining 38 subjects gave a percent root mean square error (RMSE%) of 5% and a pure error (PE) of 2.11. In the same subjects, RIs explained 87% of ECW variance (P<0.0001) and cross-validation of the obtained algorithm gave a RMSE% of 8% and a PE of 1.4 I. The contribution of weight and BMI to the prediction of TBW and ECW was nil or negligible on practical grounds. Conclusions: ECW : TBW is similar in women with class I-II and class III obesity up to BMI values of 48.2 kg/m2. Eight-polar BIA offers accurate estimates of TBW and ECW in women with a wide range of BMI (19.1-48.2 kg/m2) without the need of population-specific formulae. © 2005 Nature Publishing Group. All rights reserved

MRI relaxation properties of water-soluble apoferritin-encapsulated gadolinium oxide-hydroxide nanoparticles

We have prepared water-soluble gadolinium oxide nanoparticles that show potential as MRI contrast agents. The particles were built into the apoferritin cavity and have an average size of 5 nm. After seven days a loss of 5% of Gd was detected compared with the as-prepared samples; after that the Gd remained constant and stabilized inside the apoferritin, indicating that the apoferritin capsid acts as a Gd store, avoiding metal delivery and consequent toxicity. The NMR longitudinal and transverse relaxivities resulted about 10 and 70 times higher than the ones of clinically approved paramagnetic Gd-chelates, thus indicating the possible route for synthesizing a novel class of MRI contrast agents