331 research outputs found

    Distribution and habitat partitioning of cetaceans (Mammalia: Cetartiodactyla) in the Bohol Sea, Philippines.

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    Understanding broad-scale species distribution and finer-scale ecological interactions is essential for conservation. We assessed species richness, distribution, habitat use and interspecific associations of cetacean in the Bohol Sea, Philippines. During 72 days of dedicated survey (2010 - 2013), we encountered 12 species of cetacean in 291 sightings, 16.8% of which involved mixed species. We used maximum entropy (MaxEnt) models to assess species’ habitat suitability and found slope and distance from the coast to be influential contributors to cetacean distribution. To explore habitat use, through foraging ecology and niche segregation of sympatric species, we compared behavioral budgets across species and found significant differences (chi-sq = 21.44; p-value = 0.044). We then used GLMs to determine the foraging likelihood in relation to oceanographic features, group size and presence of associated species. Results from model selection complimented those derived from MaxEnt. However, some inter-specific exclusion behavior might also occur. Overall, our study suggests that the Bohol Sea supports a high cetacean biodiversity while more complex inter-specific dynamics might further shape species’ ecological niches. These results highlight the importance of multi-species ecology and can be used to develop management actions

    Dolphin distribution and habitat suitability in North Western Australia: Applications and implications of a Broad-Scale, Non-targeted Dataset

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    Understanding species’ distribution patterns and the environmental and ecological interactions that drive them is fundamental for biodiversity conservation. Data deficiency exists in areas that are difficult to access, or where resources are limited. We use a broad-scale, non-targeted dataset to describe dolphin distribution and habitat suitability in remote north Western Australia, where there is a paucity of data to adequately inform species management. From 1,169 opportunistic dolphin sightings obtained from 10 dugong aerial surveys conducted over a four-year period, there were 661 Indo-Pacific bottlenose dolphin (Tursiops aduncus), 191 Australian humpback dolphin (Sousa sahulensis), nine Australian snubfin dolphin (Orcaella heinsohni), 16 Stenella sp., one killer whale (Orcinus orca), one false killer whale (Pseudorca crassidens), and 290 unidentified dolphin species sightings. Maximum Entropy (MaxEnt) habitat suitability models identified shallow intertidal areas around mainland coast, islands and shoals as important areas for humpback dolphins. In contrast, bottlenose dolphins are more likely to occur further offshore and at greater depths, suggesting niche partitioning between these two sympatric species. Bottlenose dolphin response to sea surface temperature is markedly different between seasons (positive in May; negative in October) and probably influenced by the Leeuwin Current, a prominent oceanographic feature. Our findings support broad marine spatial planning, impact assessment and the design of future surveys, which would benefit from the collection of high-resolution digital images for species identification verification. A substantial proportion of data were removed due to uncertainties resulting from non-targeted observations and this is likely to have reduced model performance. We highlight the importance of considering climatic and seasonal fluctuations in interpreting distribution patterns and species interactions in assuming habitat suitability

    The influence of halides in polyoxotitanate cages; dipole moment, splitting and expansion of d-orbitals and electron-electron repulsion

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    Metal-doped polyoxotitanate (M-POT) cages have been shown to be efficient single-source precursors to metal-doped titania [TiO2_2(M)] (state-of-the-art photocatalytic materials) as well as molecular models for the behaviour of dopant metal ions in bulk titania. Here we report the influence halide ions have on the optical and electronic properties of a series of halide-only, and cobalt halide-‘doped’ POT cages. In this combined experimental and computational study we show that halide ions can have several effects on the band gaps of halide-containing POT cages, influencing the dipole moment (hole–electron separation) and the structure of the valance band edge. Overall, the band gap behaviour stems from the effects of increasing orbital energy moving from F to I down Group 17, as well as crystal-field splitting of the d-orbitals, the potential effects of the Nephelauxetic influence of the halides and electron–electron repulsion.We thank the EPSRC (Doctoral Prize for P. D. M.), A*STAR Singapore (Scholarship for N. L.), the Studienstiftung des deutschen Volkes, Fonds of the Chemical Industry (S. H.) for funding. The authors would like to acknowledge the use of the EPSRC UK National Service for Computational Chemistry Software (NSCCS) at Imperial College London and contributions from its staff in carrying out this work

    Low energy expenditure and resting behaviour of humpback whale mother-calf pairs highlights conservation importance of sheltered breeding areas

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    Understanding the behaviour of humpback whale mother-calf pairs and the acoustic environment on their breeding grounds is fundamental to assessing the biological and ecological requirements needed to ensure a successful migration and survival of calves. Therefore, on a breeding/resting ground, Exmouth Gulf, Western Australia, we used animal-borne DTAGs to quantify the fine-scale behaviour and energetic expenditure of humpback whale mothers and calves, while sound recorders measured the acoustic environment. We show that: (i) lactating humpback whales keep their energy expenditure low by devoting a significant amount of time to rest, and their use of energy, inferred from respiration rates, is ~half than that of adults on their foraging grounds; (ii) lactating females mainly rest while stationary at shallow depths within reach of the hull of commercial ships, thus increasing the potential for ship strike collisions; (iii) the soundscape is dominated by biological sources; and (iv) even moderate increases of noise from vessels will decrease the communication range of humpback whales. Planned commercial infrastructure in Exmouth Gulf will cause a substantial increase in shipping traffic with the risk of ship strikes and acoustic disturbance potentially compromising energy reserves for the southern migration of humpback whales

    In Situ Characterisation of Permanent Magnetic Quadrupoles for focussing proton beams

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    High intensity laser driven proton beams are at present receiving much attention. The reasons for this are many but high on the list is the potential to produce compact accelerators. However two of the limitations of this technology is that unlike conventional nuclear RF accelerators lasers produce diverging beams with an exponential energy distribution. A number of different approaches have been attempted to monochromise these beams but it has become obvious that magnetic spectrometer technology developed over many years by nuclear physicists to transport and focus proton beams could play an important role for this purpose. This paper deals with the design and characterisation of a magnetic quadrupole system which will attempt to focus and transport laser-accelerated proton beams.Comment: 20 pages, 42 figure

    A [HN(BH═NH)2]2– Dianion, Isoelectronic with a ÎČ-Diketiminate

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    ProducciĂłn CientĂ­ficaThe 1:2 reaction of the Al(III) ÎČ-diketiminate dihydride [{DMPnacnac}AlH2] (DMPnacnac = HC{C(Me)N(2,6-Me2-C6H3)}2) (1) with ammonia–borane (NH3BH3) gives the new complex [{DMPnacnac}Al{NHBH)2NH}] (3), whose [HN(BHNH)2]2– dianion is isoelectronic with ÎČ-diketiminate anions.2019-03-15Ministerio de EconomĂ­a, Industria y Competitividad - Agencia Estatal de InvestigaciĂłn (AEI)European Research Council (ERC) and the European Social Fund (ESF)European Social Fund (ESF)RamĂłn y Cajal contract (RG-R, RYC-2015–19035

    Quasiperiodicity and non-computability in tilings

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    We study tilings of the plane that combine strong properties of different nature: combinatorial and algorithmic. We prove existence of a tile set that accepts only quasiperiodic and non-recursive tilings. Our construction is based on the fixed point construction; we improve this general technique and make it enforce the property of local regularity of tilings needed for quasiperiodicity. We prove also a stronger result: any effectively closed set can be recursively transformed into a tile set so that the Turing degrees of the resulted tilings consists exactly of the upper cone based on the Turing degrees of the later.Comment: v3: the version accepted to MFCS 201

    Pattern logics and auxiliary relations

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    A common theme in the study of logics over finite structures is adding auxiliary predicates to enhance expressiveness and convey additional information. Examples include adding an order or arith-metic for capturing complexity classes, or the power of real-life declarative languages. A recent trend is to add a data-value com-parison relation to words, trees, and graphs, for capturing modern data models such as XML and graph databases. Such additions often result in the loss of good properties of the underlying logic. Our goal is to show that such a loss can be avoided if we use pattern-based logics, standard in XML and graph data querying. The essence of such logics is that auxiliary relations are tested locally with respect to other relations in the structure. These logics are shown to admit strong versions of Hanf and Gaif-man locality theorems, which are used to prove a homomorphism preservation theorem, and a decidability result for the satisfiability problem. We discuss applications of these results to pattern logics over data forests, and consequently to querying XML data
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