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Author

Hong D. Vo

Other affiliations: Lund University
Bio: Hong D. Vo is an academic researcher from University of Queensland. The author has contributed to research in topics: Ballast & Decision support system. The author has an hindex of 4, co-authored 6 publications receiving 56 citations. Previous affiliations of Hong D. Vo include Lund University.

Papers
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Journal ArticleDOI
TL;DR: The results suggest that the birds are capable of estimating the width of the gap in relation to their wingspan with high precision and use precise, anticipatory, visually based judgements to control their flight in complex environments.
Abstract: When birds fly in cluttered environments, they must tailor their flight to the gaps that they traverse. We trained budgerigars, Melopsittacus undulatus, to fly through a vertically oriented gap of variable width, to investigate their ability to perform evasive manoeuvres during passage. When the gap was wider than their wingspan, the birds passed through it without interrupting their flight. When traversing narrower gaps, however, the birds interrupted their normal flight by raising their wings or tucking them against the body, to prevent contact with the flanking panels. Our results suggest that the birds are capable of estimating the width of the gap in relation to their wingspan with high precision: a mere 6% reduction in gap width causes a complete transition from normal flight to interrupted flight. Furthermore, birds with shorter wingspans display this transition at narrower gap widths. We conclude from our experiments that the birds are highly aware of their individual body size and use precise, anticipatory, visually based judgements to control their flight in complex environments.

34 citations

Journal ArticleDOI
TL;DR: The constancy of the approach speed suggests a simple means by which optic flow can be used to gauge the distance and width of the aperture, and guide wing closure, and the type of visual signals used by birds while negotiating cluttered environments are investigated.
Abstract: It is essential for birds to be agile and aware of their immediate environment, especially when flying through dense foliage. To investigate the type of visual signals and strategies used by birds while negotiating cluttered environments, we presented budgerigars with vertically oriented apertures of different widths. We find that, when flying through narrow apertures, birds execute their maneuvers in an anticipatory fashion, with wing closures, if necessary, occurring well in advance of the aperture. When passing through an aperture that is narrower than the wingspan, the birds close their wings at a specific, constant distance before the aperture, which is independent of aperture width. In these cases, the birds also fly significantly higher, possibly pre-compensating for the drop in altitude. The speed of approach is largely constant, and independent of the width of the aperture. The constancy of the approach speed suggests a simple means by which optic flow can be used to gauge the distance and width of the aperture, and guide wing closure.

13 citations

Journal ArticleDOI
TL;DR: The results suggest that the hybrid/polyploidy origin of parthenogenetic H. binoei has had surprisingly few negative fitness consequences and may have produced a broader overall niche for the species.
Abstract: Parthenogenesis often evolves in association with hybridization, but the associated ecological consequences are poorly understood. The Australian gecko Heteronotia binoei is unusual because triploid parthenogenesis evolved through reciprocal crosses between two sexual lineages, resulting in four possible cytonuclear genotypes. In this species complex, we compared the performance of these parthenogenetic genotypes with their sexual progenitors for a suite of physiological traits (metabolic rate, thermal tolerance, locomotor performance, and in vitro activity and gene sequence divergence of a cytonuclear metabolic pathway, cytochrome C oxidase). Mass-specific metabolic rate scaled differently with body mass for parthenogens and sexuals, while heat tolerance provided the only evidence for cytonuclear incompatibility in hybrid parthenogens. The most prominent phenotypic effects were attributable to nuclear genome dosage. Overall, our results suggest that the hybrid/polyploidy origin of parthenogenetic H. binoei has had surprisingly few negative fitness consequences and may have produced a broader overall niche for the species.

8 citations

Journal ArticleDOI
TL;DR: In this article, the authors report the development of a prototype tool for modeling the risks of spreading of non-indigenous invasive species via ballast water, which consists of two types of models: a 3D hydrodynamical model calculates the currents in the North Sea and Danish Straits, and an agent-based model estimates the dispersal of selected model organisms with the prevailing currents calculated by the model.
Abstract: We report the development of a prototype tool for modeling the risks of spreading of non-indigenous invasive species via ballast water. The tool constitutes of two types of models: a 3D hydrodynamical model calculates the currents in the North Sea and Danish Straits, and an agent-based model estimates the dispersal of selected model organisms with the prevailing currents calculated by the 3D hydrodynamical model. The analysis is concluded by a postprocessing activity, where scenarios of dispersal are combined into an interim estimate of connectivity within the study area. The latter can be used for assessment of potential risk associated with intentional or unintentional discharges of ballast water. We discuss how this prototype tool can be used for ballast water risk management and outline other functions and uses, e.g., in regard to ecosystem-based management and the implementation of the EU Marine Strategy Framework Directive.

6 citations

Posted ContentDOI
18 Mar 2022-bioRxiv
TL;DR: Dendritic sodium spikes in human and rat layer 2/3 pyramidal neurons could be generated across a similar wide input range, exhibited a similar frequency range of activation, and forward propagated with high fidelity to drive neuronal output.
Abstract: Dendritic computations signaled into neuronal output by the initiation and propagation of regenerative dendritic spikes are a feature of the electrical operation of rodent neocortical pyramidal neurons, that have a central role in neocortical circuit function. However, it remains poorly explored whether these mechanisms are operational in the human neocortex. To directly compare the dendritic computational properties of the most numerous class of pyramidal neuron in the human and rat neocortex we made simultaneous electrical recordings from the soma and apical dendrites of layer 2/3 pyramidal neurons maintained in acute brain slices of analogous cortical areas under identical experimental conditions. In both species correlated dendritic excitatory input led to the initiation of sodium channel-mediated dendritic spikes, which had stereotyped biophysical properties. Dendritic sodium spikes in human and rat layer 2/3 pyramidal neurons could be generated across a similar wide input range, exhibited a similar frequency range of activation, and forward propagated with high fidelity to drive neuronal output. Our findings therefore reveal that the dendritic computational properties of human layer 2/3 pyramidal neurons are phylogenetically conserved.

4 citations


Cited by
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Journal ArticleDOI
TL;DR: The aerial robot presented here for the first time was based on a quadrotor structure, which is capable of unique morphing performances based on an actuated elastic mechanism, which was able to pass through a narrow gap at a high forward speed by swiftly folding up the structure supporting its propellers.
Abstract: The aerial robot presented here for the first time was based on a quadrotor structure, which is capable of unique morphing performances based on an actuated elastic mechanism. Like birds, which are able to negotiate narrow apertures despite their relatively large wingspan, our Quad-Morphing robot was able to pass through a narrow gap at a high forward speed of 2.5 m.s− 1 by swiftly folding up the structure supporting its propellers. A control strategy was developed to deal with the loss of controllability on the roll axis resulting from the folding process, while keeping the robot stable until it has crossed the gap. In addition, a complete recovery procedure was also implemented to stabilize the robot after the unfolding process. A new metric was also used to quantify the gain in terms of the gap-crossing ability in comparison with that observed with classical quadrotors with rigid bodies. The performances of these morphing robots are presented, and experiments performed with a real flying robot passing through a small aperture by reducing its wingspan by 48% are described and discussed.

82 citations

Proceedings ArticleDOI
20 May 2019
TL;DR: A novel quadcopter design that uses passive rotary joints to enable rapid aerial morphing without the use of additional actuators is presented, and design rules are given that minimize transition time between configurations and maximize the available range of control inputs.
Abstract: This paper presents a novel quadcopter design that uses passive rotary joints to enable rapid aerial morphing without the use of additional actuators. The normally rigid connections between the arms of the quadcopter and the central body are replaced by sprung hinges that allow for the arms of the quadcopter to fold downward when low thrusts are produced by the propellers, resulting in a reduction of the largest dimension of the vehicle by approximately 50%. The ability of the vehicle to reduce its size during flight allows, e.g., for the traversal of gaps through which a non-morphing quadcopter could not pass. The vehicle is designed such that existing quadcopter controllers and trajectory generation algorithms can be used, provided that some additional constraints on the control inputs are met. The nonlinear dynamics of the system are presented, and design rules are given that minimize transition time between configurations and maximize the available range of control inputs. A method for performing gap traversal maneuvers is proposed and validated experimentally.

63 citations

Journal ArticleDOI
TL;DR: This research presents a set of multi-objective spatial tools for sea planning and environmental management in the Adriatic Sea Basin and concludes with an outlook towards the need for more integrated, multi-functional tools development for sea plans.

61 citations

Journal ArticleDOI
TL;DR: The different modes of meiosis and its deviations encountered in polyploid animals are reviewed, including gamete duplication, terminal fusion, central fusion, fusion of the first polar nucleus with the product of the second division, and premeiotic duplication followed by a normal meiosis.
Abstract: We review the different modes of meiosis and its deviations encountered in polyploid animals. Bisexual reproduction involving normal meiosis occurs in some allopolyploid frogs with variable degrees of polyploidy. Aberrant modes of bisexual reproduction include gynogenesis, where a sperm stimulates the egg to develop. The sperm may enter the egg but there is no fertilization and syngamy. In hybridogenesis, a genome is eliminated to produce haploid or diploid eggs or sperm. Ploidy can be elevated by fertilization with a haploid sperm in meiotic hybridogenesis, which elevates the ploidy of hybrid offspring such that they produce diploid gametes. Polyploids are then produced in the next generation. In kleptogenesis, females acquire full or partial genomes from their partners. In pre-equalizing hybrid meiosis, one genome is transmitted in the Mendelian fashion, while the other is transmitted clonally. Parthenogenetic animals have a very wide range of mechanisms for restoring or maintaining the mother's ploidy level, including gamete duplication, terminal fusion, central fusion, fusion of the first polar nucleus with the product of the first division, and premeiotic duplication followed by a normal meiosis. In apomictic parthenogenesis, meiosis is replaced by what is effectively mitotic cell division. The above modes have different evolutionary consequences, which are discussed. See also the sister article by Grandont et al. in this themed issue.

55 citations

Journal ArticleDOI
TL;DR: The results demonstrate surprisingly deep and geographically nested lineage diversity in the Australian monsoonal tropics, and drive home that deep phylogeographic structure is prevalent in tropical low‐dispersal taxa, even ones that are ubiquitous across geography and habitats.
Abstract: Multilocus phylogeography can uncover taxonomically unrecognized lineage diversity across complex biomes. The Australian monsoonal tropics include vast, ecologically intact savanna-woodland plains interspersed with ancient sandstone uplands. Although recognized in general for its high species richness and endemism, the biodiversity of the region remains underexplored due to its remoteness. This is despite a high rate of ongoing species discovery, especially in wetter regions and for rock-restricted taxa. To provide a baseline for ongoing comparative analyses, we tested for phylogeographic structure in an ecologically generalized and widespread taxon, the gecko Heteronotia binoei. We apply coalescent analyses to multilocus sequence data (mitochondrial DNA and eight nuclear DNA introns) from individuals sampled extensively and at fine scale across the region. The results demonstrate surprisingly deep and geographically nested lineage diversity. Several intra-specific clades previously shown to be endemic to the region were themselves found to contain multiple, short-range lineages. To infer landscapes with concentrations of unique phylogeographic diversity, we probabilistically estimate the ranges of lineages from point data and then, combining these estimates with the nDNA species tree, estimate phyloendemism across the region. Highest levels of phyloendemism occur in northern Top End, especially on islands, across the topographically complex Arnhem escarpment, and across the sandstone ranges of the western Gulf region. These results drive home that deep phylogeographic structure is prevalent in tropical low-dispersal taxa, even ones that are ubiquitous across geography and habitats.

48 citations