1,272 research outputs found

    To clean or not to clean? A critical review of beach cleaning methods and impacts

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    Cleaning is a fundamental concern of beach managers in many destinations as well as an important requirement in beach quality awards. However, it has been largely neglected in the literature. This paper provides an overview of empirical studies on beach cleaning and analyzes cleaning-related requirements of 11 beach awards that generate controversy in the literature. This study comments on key aspects of beach cleaning, resolves various misconceptions, and provides new perspectives by integrating related topics drawn from a wide range of literature. The arguments based on both the ecological and tourism managerial perspectives are presented, indicating the gaps and proposing research solutions. The paper calls for empirical studies with regard to the efficiency of different cleaning approaches on beaches with varying levels of use intensity and for methodological designs that separate the impacts of mechanical grooming from those of trampling, dune destruction, shore armoring, artificial lighting, among others

    On local and global aspects of the 1:4 resonance in the conservative cubic Hénon maps

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    We study the 1:4 resonance for the conservative cubic Henon maps C6 with positive and negative cubic terms. These maps show up different bifurcation structures both for fixed points with eigenvalues 6i and for 4-periodic orbits. While for C-, the 1:4 resonance unfolding has the so-called Arnold degeneracy [the first Birkhoff twist coefficient equals (in absolute value) to the first resonant term coefficient], the map Cþ has a different type of degeneracy because the resonant term can vanish. In the last case, non-symmetric points are created and destroyed at pitchfork bifurcations and, as a result of global bifurcations, the 1:4 resonant chain of islands rotates by p/4. For both maps, several bifurcations are detected and illustrated

    Evaluation of the Implementation of K4 Coverage Services at Harapan and Waibu Health Centers in the Jayapura Regency

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    Background: K4 coverage (fourth visit) is the number of pregnant women who have received ANC services following the service provisions according to the recommended schedule for each trimester during pregnancy compared to the target number of pregnant women in a work area over a period of one year. According to the profile data from the Jayapura Regency Health Office, the number of K4 visits in 2020 was 69.2% and there was an increase in 2021 of 77.7%, below the provincial target of 95%. Objectives: The purpose of this study was to evaluate the implementation of K4 coverage services at Harapan Health Center and Waibu Health Center in terms of input, process, output, and external factors. Methods: This type of research is qualitative with a case study approach. There were 9 informants in this study consisting of staff from the Health Office, health workers at the Waibu and Harapan Health Centers, and pregnant women from the working areas of each Health Center. Data was collected by in-depth interviews using a list of questions and document study. Result: The results of the research on service inputs for K4 coverage at the Harapan Health Center had no problems, while at the Waibu Health Center there was a lack of human resources, complete and adequate infrastructure, and funding that had not been allocated properly. The process flow for K4 coverage services at the Health Center is appropriate. The output that has not been achieved is due to the uncertainty in predicting the targeting of pregnant women. External factors of geography, demography and support also have an influence on K4 coverage services

    Rotation and pulsation in Ap stars: first light results from TESS sectors 1 and 2

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    We present the first results from the Transiting Exoplanet Survey Satellite (TESS) on the rotational and pulsational variability of magnetic chemically peculiar A-type stars. We analyse TESS 2-min cadence data from sectors 1 and 2 on a sample of 83 stars. Five new rapidly oscillating Ap (roAp) stars are announced. One of these pulsates with periods around 4.7 min, making it the shortest period roAp star known to date. Four out of the five new roAp stars are multiperiodic. Three of these, and the singly-periodic one show the presence of rotational mode splitting. Individual frequencies are provided in all cases. In addition, seven previously known roAp stars are analysed. Additional modes of oscillation are found in some stars, while in others we are able to distinguish the true pulsations from possible aliases present in the ground-based data. We find that the pulsation amplitude in the TESS filter is typically a factor 6 smaller than that in the B filter which is usually used for ground-based observations. For four roAp stars we set constraints on the inclination angle and magnetic obliquity, through the application of the oblique pulsator model. We also confirm the absence of roAp-type pulsations down to amplitude limits of 6 and 13 micromag, respectively, in two of the best characterised non-oscillating Ap (noAp) stars. We announce 27 new rotational variables along with their rotation periods, and provide different rotation periods for seven other stars. Finally, we discuss how these results challenge state-of-the-art pulsation models for roAp stars.We thank the referee for very detailed and useful comments to the original manuscript. This work was supported by FCT - Fundação para a Ciência e a Tecnologia through national funds and by FEDER through COMPETE2020 - Programa Operacional Competitividade e Internacionalização by these grants: UID/FIS/04434/2019, PTDC/FIS-AST/30389/2017 & POCI-01- 0145-FEDER-030389. MC is supported in the form of work contract funded by national funds through FCT. Funding for the Stellar Astrophysics Centre is provided by The Danish National Research Foundation (Grant agreement no.: DNRF106). DLH and DWK acknowledge financial support from the Science and Technology Facilities Council (STFC) via grant ST/M000877/1. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium). Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement. LFM acknowledges support from the UNAM by the way of DGAPA project PAPIIT IN100918. The research leading to these results has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation programme (grant agreement N 670519: MAMSIE) and from the Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO) under the grant agreement G0H5416N (ERC Opvangproject). MS acknowledges the financial support of Postdoc@MUNI project CZ.02.2.69/0.0/0.0/16 027/0008360. EN acknowledges the Polish National Science Center grants no.2014/13/B/ST9/00902. JCS acknowledges funding support from Spanish public funds for research under projects ESP2017-87676-2-2 and ESP2015- 65712-C5-5-R, and from project RYC-2012-09913 under the ‘Ramón y Cajal’ program of the Spanish Ministry of Science and Education. AGH acknowledges funding support from Spanish public funds for research under projects ESP2017-87676-2-2 and ESP2015-65712-C5-5-R of the Spanish Ministry of Science and Education. A´ S, ZsB, and RSz acknowledge the financial support of the GINOP-2.3.2-15-2016- 00003, K-115709, K-113117, K-119517 and PD-123910 grants of the Hungarian National Research, Development and Innovation Office (NKFIH), and the Lendület Program of the Hungarian Academy of Sciences, project No. LP2018-7/2018. GH has been supported by the Polish NCN grant 2015/18/A/ST9/00578. MLM acknowledges funding support from Spanish public funds for research under project ESP2015- 65712-C5-3-R. JPG acknowledges funding support from Spanish public funds for research under project ESP2017-87676-C5-5-R. MLM and JPG also acknowledges funding support from the State Agency for Research of the Spanish MCIU through the ”Center of Excellence Severo Ochoa” award for the Instituto de Astrofísica de Andalucía (SEV-2017-0709). IS acknowledges funding support of NSF under projects DN 08-1/2016 and DN 18/13-12.12.2017. P. Kołaczek-Szymański acknowledges support from the NCN grant no. 2016/21/B/ST9/01126. This paper includes data collected by the TESS mission. Funding for the TESS mission is provided by the NASA Explorer Program

    Dating young open clusters using delta Scuti stars. Results for Trumpler 10 and Praesepe

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    Aims. The main goal of this work is to date young open clusters using δ\delta Sct stars. Seismic indices such as the large separation and the frequency at maximum power can help to constrain the models to better characterise the stars. We propose a reliable method to identify some radial modes, which gives us greater confidence in the constrained models. Methods. We extract the frequency content of a sample of δ\delta Sct stars belonging to the same open cluster. We estimate the low-order large separation by means of different techniques and the frequency at maximum power for each member of the sample. We use a grid of models built with the typical parameters of δ\delta Sct stars, including mass, metallicity and rotation as independent variables, and determine the oscillation modes. We select the observed frequencies whose ratios match those of the models. Once we find a range of radial modes matching the observed frequencies, mainly the fundamental mode, we add it to the other seismic parameters to derive the stellar age. Assuming star groups have similar chemistry and age, we estimate their mean age by computing a weighted probability density function fit to the age distribution of the seismically constrained models. Results. We estimate the age of Trumpler 10 to be 3020+3030_{-20}{+30} Myr, and that of Praesepe to be 580±230580 \pm 230 Myr. In this latter case, we find two apparent populations of δ\delta Sct stars in the same cluster, one at 510±140510 \pm 140 Myr and another at 890±140890 \pm 140 Myr. This may be due to two different formation events, different rotational velocities of the members in our sample of stars (as rapid rotation may modify the observed large separation), or to membership of unresolved binary systems.Comment: 20 pages, 25 figure, uses the open-source code MultiModes (see https://github.com/davidpamos/MultiModes). It will be published in A&

    De la función de riesgos : una aproximación a los riesgos del balance

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    Artículo de revistaEn el presente artículo se hace una revisión de los conceptos generales de la gestión de riesgos. Se describe un área de riesgos en una institución de ámbito global. A continuación, se describen los factores de riesgo involucrados en la gestión del balance, abordando brevemente el problema de la asignación de capital económico y la necesidad de contar con un sistema de tasas de transferencia. Luego, la discusión se centra en los principales factores de riesgo del balance, para después abordar las principales medidas estáticas y dinámicas relevantes a la gestión del riesgo. La medición y control del riesgo de liquidez del balance se tratan en una sección aparte. Finalmente, se presenta, como ejemplo práctico, la aplicación de una metodología desarrollada para el tratamiento de depósitos de clientes sin vencimiento definido

    Evidence for a black hole in the historical X-ray transient A 1524-61 (=KY TrA)

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    We present VLT spectroscopy, high-resolution imaging and time-resolved photometry of KY TrA, the optical counterpart to the X-ray binary A 1524-61. We perform a refined astrometry of the field, yielding improved coordinates for KY TrA and the field star interloper of similar optical brightness that we locate 0.64±0.040.64 \pm 0.04 arcsec SE. From the spectroscopy, we refine the radial velocity semi-amplitude of the donor star to K2=501±52K_2 = 501 \pm 52 km s1^{-1} by employing the correlation between this parameter and the full-width at half-maximum of the Hα\alpha emission line. The rr-band light curve shows an ellipsoidal-like modulation with a likely orbital period of 0.26±0.010.26 \pm 0.01 d (6.24±0.246.24 \pm 0.24 h). These numbers imply a mass function f(M1)=3.2±1.0f(M_1) = 3.2 \pm 1.0 M_\odot. The KY TrA de-reddened quiescent colour (ri)0=0.27±0.08(r-i)_0 = 0.27 \pm 0.08 is consistent with a donor star of spectral type K2 or later, in case of significant accretion disc light contribution to the optical continuum. The colour allows us to place a very conservative upper limit on the companion star mass, M20.94M_2 \leq 0.94 M_\odot, and, in turn, on the binary mass ratio, q=M2/M10.31q = M_2/M_1 \leq 0.31. By exploiting the correlation between the binary inclination and the depth of the Hα\alpha line trough, we establish i=57±13i = 57 \pm 13 deg. All these values lead to a compact object and donor mass of M1=5.82.4+3.0M_1 = 5.8^{+3.0}_{-2.4} M_\odot and M2=0.5±0.3M_2 = 0.5 \pm 0.3 M_\odot, respectively, thus confirming the black hole nature of the accreting object. In addition, we estimate a distance toward the system of 8.0±0.98.0 \pm 0.9 kpc.Comment: 7 pages, 5 figure
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