Wave attenuation and dispersion due to floating ice covers

Experiments investigating the attenuation and dispersion of surface waves in a variety of ice covers are performed using a refrigerated wave flume. The ice conditions tested in the experiments cover naturally occurring combinations of continuous, fragmented, pancake and grease ice. Attenuation rates are shown to be a function of ice thickness, wave frequency, and the general rigidity of the ice cover. Dispersion changes were minor except for large wavelength increases when continuous covers were tested. Results are verified and compared with existing literature to show the extended range of investigation in terms of incident wave frequency and ice conditions

Positivity and conservation of superenergy tensors

Two essential properties of energy-momentum tensors T_{\mu\nu} are their positivity and conservation. This is mathematically formalized by, respectively, an energy condition, as the dominant energy condition, and the vanishing of their divergence \nabla^\mu T_{\mu\nu}=0. The classical Bel and Bel-Robinson superenergy tensors, generated from the Riemann and Weyl tensors, respectively, are rank-4 tensors. But they share these two properties with energy momentum tensors: the Dominant Property (DP) and the divergence-free property in the absence of sources (vacuum). Senovilla defined a universal algebraic construction which generates a basic superenergy tensor T{A} from any arbitrary tensor A. In this construction the seed tensor A is structured as an r-fold multivector, which can always be done. The most important feature of the basic superenergy tensors is that they satisfy automatically the DP, independently of the generating tensor A. In a previous paper we presented a more compact definition of T{A} using the r-fold Clifford algebra. This form for the superenergy tensors allowed to obtain an easy proof of the DP valid for any dimension. In this paper we include this proof. We explain which new elements appear when we consider the tensor T{A} generated by a non-degree-defined r-fold multivector A and how orthogonal Lorentz transformations and bilinear observables of spinor fields are included as particular cases of superenergy tensors. We find some sufficient conditions for the seed tensor A, which guarantee that the generated tensor T{A} is divergence-free. These sufficient conditions are satisfied by some physical fields, which are presented as examples.Comment: 19 pages, no figures. Language and minor changes. Published versio

Clinical Case of Huge Congenital Hypertrophy of the Retinal Pigment Epithelium Labeled as Choroidal Melanoma

A case of a 48-year-old woman who was referred to an Ocular Oncology Unit with a suspected choroidal melanoma diagnosis in her left eye, which final diagnosis was a congenital hypertrophy of the retinal pigment epithelium (CHRPE). No evidence of other ocular or general condition findings has been reported. Diagnostic, as well as the risks of malignancy, are discussed. We highlight the importance of performing an appropriate differential diagnosis of a large pigmented lesion detected on routine ocular examination due to the implications for the patient

A phase-shift-periodic parallel boundary condition for low-magnetic-shear scenarios

We formulate a generalized periodic boundary condition as a limit of the standard twist-and-shift parallel boundary condition that is suitable for simulations of plasmas with low magnetic shear. This is done by applying a phase shift in the binormal direction when crossing the parallel boundary. While this phase shift can be set to zero without loss of generality in the local flux-tube limit when employing the twist-and-shift boundary condition, we show that this is not the most general case when employing periodic parallel boundaries, and may not even be the most desirable. A non-zero phase shift can be used to avoid the convective cells that plague simulations of the three-dimensional Hasegawa-Wakatani system, and is shown to have measurable effects in periodic low-magnetic-shear gyrokinetic simulations. We propose a numerical program where a sampling of periodic simulations at random pseudo-irrational flux surfaces are used to determine physical observables in a statistical sense. This approach can serve as an alternative to applying the twist-and-shift boundary condition to low-magnetic-shear scenarios which, while more straightforward, can be computationally demanding.Comment: 4 figures, 1 tabl

Editorial: Advances in Power-to-X: Processes, Systems, and Deployment

[No abstract available

Propiedades morfológicas y estructurales de recubrimientos nitruro de titanio aluminio producidos por magnetron sputtering tríodo

TixAl1-xN coatings were grown using the triode magnetron sputtering technique varying the bias voltage between -40 V and -150V. The influence of bias voltage on structural and morphological properties was analyzed by means of energy dispersive spectroscopLos recubrimientos TixAl1-xN se cultivaron usando la técnica de pulverización catódica con magnetrón triodo, variando el voltaje de polarización entre -40 V y -150V. La influencia del voltaje de polarización en las propiedades estructurales y morfológica

Methods employed in optical emission spectroscopy analysis: a review

In this work, different methods employed for the analysis of emission spectra are presented -- The proposal is to calculate the excitation temperature (Texc), electronic temperature (Te) and electron density (ne) for several plasma techniques used in the growth of thin films -- Some of these techniques include magnetron sputtering and arc discharges -- Initially, some fundamental physical principles that support the Optical Emission Spectroscopy (OES) technique are described; then, some rules to consider during the spectral analysis to avoid ambiguities are listed -- Finally, some of the more frequently used spectroscopic methods for determining the physical properties of plasma are describe

Energy-restricted diets based on a distinct food selection affecting the glycemic index induce different weight loss and oxidative response

Background and aims: Low glycemic index (GI) based diets could influence the accompanying physiological adaptations to energy restriction in the treatment of obesity. It was aimed to investigate the effects of two energy-restricted diets with different food distribution and GI values on weight loss and energy metabolism in the nutritional treatment of obesity. Subjects and Methods: Participants (n=32;BMI:32.5±4.3kg/m2) were randomly assigned to follow two energy-restricted diets with higher-GI or lower-GI for 8 weeks. The energy restriction was -30% in relation to energy expenditure. Anthropometry, energy expenditure and mitochondrial oxidation were assessed at baseline and at the endpoint of the intervention. Body weight was also measured one year after the treatment. The work was approved by the ethical committees of the University of Navarra (54/2006).Results: Volunteers consuming the lower-GI diet showed a significantly higher weight loss than their counterparts (-5.3±2.6% vs -7.5±2.9%;p=0.032), although the decrease in resting energy expenditure (REE) was similar between groups (p=0.783). Mitochondrial oxidation was significantly affected by the type of diet (p=0.001), being activated after the lower-GI treatment (p=0.022). Interestingly, one year after the nutritional intervention weight regain was only statistically significant in the higher-GI group (p=0.033).Conclusions: Lower-GI energy-restricted diets achieved through a specific differential food selection can improve the energy adaptations during obesity treatment, favouring weight loss and probably weight maintenance compared with higher-GI hypocaloric diets

Sea turtle (Reptilia, Testudines) diversity and occurrence in the Azores Archipelago (NE Atlantic)

BACKGROUND: Six species of marine turtles occur in the Azores Archipelago. The loggerhead, Caretta caretta (Linnaeus, 1758), is by far the most common species and is being constantly monitored and tagged by a joint project between the University of the Azores and the University of Florida since 1989. With the implementation of the tuna fishery observers (for dolphin safe seals), an increment of sea turtle reports has been verified as expected. The leather back turtle, Dermochelys coriacea (Vandelli, 1761) is the second most observed species in the Azores' EEZ, a fact probably also linked to the tuna fishery observation programme. All other species are occasional/vagrant albeit the green turtle, Chelonia mydas (Linnaeus, 1758) is more commonly seen than the others. Historically, sea turtles were occasionally taken for food in specific fishing villages and ports. Since 1986, sea turtles, as well as all marine mammals, are fully protected in the Azores although human-related activities (e.g. plastics, discarded fishing gear) do generate serious injuries and deaths. NEW INFORMATION: In this paper, we update sea turtle species' checklist for the Azores and give detailed geographic coordinates on their known occurrences.FUNDING: Funding Institutions: AZORESBIOPORTAL – PORBIOTA (Azores PO 2020 - ACORES-01-0145-FEDER-000072). This project was financed by FEDER in 85% and by Azorean Public funds by 15% through Operational Program Azores 2020. This work is also funded by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT - Portuguese Foundation for Science and Technology under the Research Infrastructure PORBIOTA - Portuguese E-Infrastructure for Information and Research on Biodiversity, project number POCI-01-0145-FEDER-022127. For the period 2022-2023- Portal da Biodiversidade dos Açores (2022-2023) - PO Azores Project - M1.1.A/INFRAEST CIENT/001/2022. OPEN ACCESS will be supported by the project FCT-UIDB/00329/2020-2024 (Thematic Line 1 – integrated ecological assessment of environmental change on biodiversity).info:eu-repo/semantics/publishedVersio