Browsing by Author "Munoz, Francisco"

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    Energetics and the magnetic state of Mn2 adsorbed on Au(111): Dimer bond distance dependence
    (2016) Lopez Moreno, S.; Mejía López, José Félix; Munoz, Francisco; Calles, A.; Moran Lopez, J.L.
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    First-Principles Identification of Single Photon Emitters Based on Carbon Clusters in Hexagonal Boron Nitride
    (2021) Jara, Cesar; Rauch, Tomas; Botti, Silvana; Marques, Miguel A. L.; Norambuena, Ariel; Coto, Raul; Castellanos-Aguila, J. E.; Maze, Jeronimo R.; Munoz, Francisco
    A recent study associates carbon with single photon emitters (SPEs) in hexagonal boron nitride (h-BN). This observation, together with the high mobility of carbon in h-BN, suggests the existence of SPEs based on carbon clusters. Here, by means of density functional theory calculations, we studied clusters of substitutional carbon atoms up to tetramers in h-BN. Two different conformations of neutral carbon trimers have zero-point line energies and shifts of the phonon sideband compatible with typical photoluminescence spectra. Moreover, some conformations of two small C clusters next to each other result in photoluminescence spectra similar to those found in the experiments. We also showed that vacancies are unable to reproduce the typical features of the phonon sideband observed in most measurements because of the large spectral weight of low-energy breathing modes, ubiquitous in such defects.
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    Improving Trapping Efficiency for Control of American Mink (Neovison vison) in Patagonia
    (2022) Medina-Vogel, Gonzalo; Munoz, Francisco; Moeggenberg, Meredith; Calvo-Mac, Carlos; Barros-Lama, Macarena; Ulloa, Nickolas; Pons, Daniel J.; Clapperton, B. Kay
    Simple Summary Two main challenges to control invasive mammals are to maximize campaign efficacy and cost-effectiveness, and to avoid trapping other species. We designed and tested new protocols to address those challenges to control alien American mink in southern Chile. We recommend the use of the GMV-13 variant of collapsible wire cage with scent gland lure, as they are smaller, cheaper, easier to transport and effective at catching female mink and reducing the possibility of trapping native species. Trapping campaigns using GMV-13 should be conducted principally during summer, with a 200-m trap spacing, for up to 6 days before moving traps to a new site, with a combination of three days with female scent gland lure followed by three days with male scent gland lure. Our modelling reveals that this should result in the removal of at least 70% of the local estimated discrete mink population within the area covered by each transect. Two main challenges when controlling alien American mink (Neovison vison) in Patagonia are to maximize campaign efficacy and cost-effectiveness and to avoid trapping native species. We designed and tested new variants of collapsible wire box traps, compared the efficacy of a food-based bait and a scent lure and compared catch rates in different seasons of the year. We used the data to model the efficiency rate of the trapping and to determine the trapping effort required to remove 70-90% of the estimated discrete mink population. Between January 2018 and March 2021, we operated 59 trapping transects over 103 three-day trapping periods in southern Chile. Traps were first baited with canned fish, and afterwards with mink anal gland lure. We compared the efficacy of mink capture with that of our previous study. We trapped 196 mink (125 males, 71 females), with most captures in summer. The medium-sized GMV-18 trap caught more male mink, but the more compact GMV-13 caught fewer non-target rodents and no native mammals. The scent lure was more successful than the canned fish when the previous campaign's data were included in the analysis. There was also a significant improvement in the proportion of female mink trapped and reduced labour compared with our previous campaign that used larger traps, fish bait and 400-500 m trap spacings. We caught relatively more females than males after the third night of trapping on a transect. Our data analysis supports the use of the GMV-13 variant of wire cage trap as the best trap size: it is effective on female mink, small, cheap and easy to transport. Combined with mink anal scent lure, it reduces the possibility of trapping native species compared with other traps tested in Chile. As the most efficient method for removing at least 70% of the estimated discrete mink population within the area covered by each trap transect in southern Chile tested to date, we recommend trapping campaigns using GMV-13 during summer, with a 200-m trap spacing, for up to 6 days before moving traps to a new site, with a combination of three days with a female scent gland lure, followed by three days with a male scent gland lure.
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    Kelp and dolphin gulls cause perineal wounds in South American fur seal pups (Arctocephalus australis) at Guafo Island, Chilean Patagonia
    (ROYAL SOC, 2017) Seguel, Mauricio; Munoz, Francisco; Montalva, Felipe; Perez Venegas, Diego; Paves, Hector; Gottdenker, Nicole
    During five reproductive seasons, we documented the presence, extent and origin of perineal wounds in South American fur seal pups (Arctocephalus australis) on Guafo Island, Northern Chilean Patagonia. The seasonal prevalence of perineal wounds ranged from 5 to 9%, and new cases were more common at the end of the breeding season ( February), when pups were on average two months old and were actively expelling hookworms ( pUncinaria sp). Histologically, wounds corresponded to marked ulcerative lymphoplasmacytic and histiocytic dermatitis with granulation tissue and mixed bacterial colonies. In 2015 and 2017, kelp gulls (Larus dominicanus) and dolphin gulls (Leucophaeus scoresbii) were observed picking and wounding the perineal area of marked pups. This behaviour occurred more frequently after the pups' defecation, when sea gulls engaged in consumption of pups' faeces. The affected pups usually had moderate to marked hookworm infections along with bloody diarrhoea and anaemia. Pups with severe wounds (23% of affected animals) had swollen perineal areas and signs of secondary systemic bacterial infection. We propose that seagulls on Guafo Island have learned to consume remains of blood and parasites in the faeces of pups affected by hookworm infection, causing perineal wounds during this process. We conclude that this perineal wounding is an unintentional, occasional negative effect of an otherwise commensal gull-fur seal relationship.
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    Liquidity and firm investment: Evidence for Latin America
    (ELSEVIER, 2013) Munoz, Francisco
    This paper explores the relationship between firms' investment and stock market liquidity. Using a panel of Latin American firms, I find evidence that a higher trading volume and a higher industry-adjusted trading volume are associated with higher firm investment (PPE, Total Assets, and Inventory). This relationship is higher in episodes where the firm decides to issue shares, and it is also greater for firms with tighter financial constraints and better investment opportunities. This evidence is consistent with a mispricing channel, where firms issue and invest the proceeds to take advantage of low cost of capital, or with a cost channel, where liquidity is associated with lower issuance costs. Also, it is less related with an informational channel, where a liquid market helps a manager to take more efficient decisions, since this channel does not necessarily predict an increase in investment, but only more efficient investment. (C) 2012 Elsevier B.V. All rights reserved.
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    Spin-active single photon emitters in hexagonal boron nitride from carbon-based defects
    (2023) Pinilla, Fernanda; Vasquez, Nicolas; Chacon, Ignacio; Maze, Jeronimo R.; Cardenas, Carlos; Munoz, Francisco
    Most single photon emitters in hexagonal boron nitride have been identified as carbon substitutional defects, forming donor-acceptor systems. Unlike the most studied bulk emitters (i.e. color centers in diamond), these defects have no net spin, or have a single unpaired spin. By means of density functional calculations, we show that two non-adjacent carbon substitutional defects of the same type (i.e. C-B-C-B, and C-N-C-N), can have a triplet groundstate. In particular, one of such defects has a zero phonon line energy of 2.5 eV, and its triplet state is nearly 0.5 eV more stable than its singlet. The mechanism behind the destabilization of the singlet state is related to a larger electrostatic repulsion of a symmetric wave function in a charged lattice.
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    Wnt-5 alpha increases NO and modulates NMDA receptor in rat hippocampal neurons
    (2014) Munoz, Francisco; Godoy Zeballos, Juan Alejandro; Cerpa Nebott, Waldo Francisco; Poblete, I.; García-Huidobro Toro, Juan Pablo; Inestrosa Cantín, Nibaldo