22 research outputs found

    Reframing Kurtz’s Painting: Colonial Legacies and Minority Rights in Ethnically Divided Societies

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    Minority rights constitute some of the most normatively and economically important human rights. Although the political science and legal literatures have proffered a number of constitutional and institutional design solutions to address the protection of minority rights, these solutions are characterized by a noticeable neglect of, and lack of sensitivity to, historical processes. This Article addresses that gap in the literature by developing a causal argument that explains diverging practices of minority rights protections as functions of colonial governments’ variegated institutional practices with respect to particular ethnic groups. Specifically, this Article argues that in instances where colonial governments politicize and institutionalize ethnic hegemony in the pre-independence period, an institutional legacy is created that leads to lower levels of minority rights protections. Conversely, a uniform treatment and depoliticization of ethnicity prior to independence ultimately minimizes ethnic cleavages post-independence and consequently causes higher levels of minority rights protections. Through a highly structured comparative historical analysis of Botswana and Ghana, this Article builds on a new and exciting research agenda that focuses on the role of long-term historio-structural and institutional influences on human rights performance and makes important empirical contributions by eschewing traditional methodologies that focus on single case studies that are largely descriptive in their analyses. Ultimately, this Article highlights both the strength of a historical approach to understanding current variations in minority rights protections and the varied institutional responses within a specific colonial government

    A survey for variable young stars with small telescopes: II - mapping a protoplanetary disc with stable structures at 0.15 au

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    The HOYS citizen science project conducts long term, multifilter, high cadence monitoring of large YSO samples with a wide variety of professional and amateur telescopes. We present the analysis of the light curve of V1490 Cyg in the Pelican Nebula. We show that colour terms in the diverse photometric data can be calibrated out to achieve a median photometric accuracy of 0.02 mag in broadband filters, allowing detailed investigations into a variety of variability amplitudes over timescales from hours to several years. Using Gaia DR2 we estimate the distance to the Pelican Nebula to be 870 +70 −55 pc. V1490 Cyg is a quasi-periodic dipper with a period of 31.447 ± 0.011 d. The obscuring dust has homogeneous properties, and grains larger than those typical in the ISM. Larger variability on short timescales is observed in U and Rc−Hα, with U-amplitudes reaching 3 mag on timescales of hours, indicating the source is accreting. The Hα equivalent width and NIR/MIR colours place V1490 Cyg between CTTS/WTTS and transition disk objects. The material responsible for the dipping is located in a warped inner disk, about 0.15 AU from the star. This mass reservoir can be filled and emptied on time scales shorter than the period at a rate of up to 10−10 Mïżœ/yr, consistent with low levels of accretion in other T Tauri stars. Most likely the warp at this separation from the star is induced by a protoplanet in the inner accretion disk. However, we cannot fully rule out the possibility of an AA Tau-like warp, or occultations by the Hill sphere around a forming planet

    Petrosal and Bony Labyrinth Morphology Supports Paraphyly of Elephantulus Within Macroscelididae (Mammalia, Afrotheria)

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    International audienceInterest in the phylogeny of Macroscelididae(sengis or elephant shrews) has been prompted by molecularstudies indicating thatElephantulus rozetiis best placed asthe sister group ofPetrodromus tetradactylus(this cladebeing in turn the sister taxon toMacroscelides proboscideus)than among other species of the genusElephantulus. Untilnow, no discrete morphological characters have been pro-posed to support the grouping ofE. rozeti,Petrodromus, andMacroscelidesinto this single so-called‘Panelephantulus’clade. Here, we employedÎŒCT scanning in order to investi-gate the petrosal and bony labyrinth (bony capsule of theinner ear) morphology of most species of extantMacroscelididae. We performed a cladistic analysis on eartraits and found that despite some convergences (e.g.,concerning the bony arterial canals inMacroscelidesandRhynchocyon) the middle and inner ear morphology fur-nishes significant support for the‘Panelephantulus’clade.In our analysis, this clade is unambigously supported by thepresence of a fully ossified stapediofacial tube. Two addi-tional characters (the presence of a bony septum at the mouthof the fenestra cochleae dividing the D3 sinus into twodistinct cavities and the absence of an accessory lateralpneumatic fossa) could also support‘Panelephantulus.’These newly discovered morphological characters supportthe molecular phylogenies published and highlight the im-portance of coding hitherto difficult to sample morphologieswithin cladistic analyses using micro-CT techniques.Taxonomic implications are briefly discussed

    Jaw anatomy of Potamogale velox (Tenrecidae, Afrotheria) with a focus on cranial arteries and the coronoid canal in mammals

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    Afrotheria is a strongly supported clade within placental mammals, but morphological synapomorphies for the entire group have only recently come to light. Soft tissue characters represent an underutilized source of data for phylogenetic analysis, but nonetheless provide features shared by some or all members of Afrotheria. Here, we investigate the developmental anatomy of Potamogale velox (Tenrecidae) with histological and computerized tomographic data at different ontogenetic ages, combined with osteological data from other mammals, to investigate patterns of cranial arterial supply and the distribution of the coronoid canal. Potamogale is atypical among placental mammals in exhibiting a small superior stapedial artery, a primary supply of the posterior auricular by the posterior stapedial artery, and the development of vascular plexuses (possibly with relevance for heat exchange) in the posterior and dorsal regions of its neck. In addition, the posterior aspect of Meckel’s cartilage increases its medial deflection in larger embryonic specimens as the mandibular condyle extends mediolaterally during embryogenesis. We also map the distribution of the coronoid canal across mammals, and discuss potential confusion of this feature with alveoli of the posterior teeth. The widespread distribution of the coronoid canal among living and fossil proboscideans, sirenians, and hyracoids supports previous interpretations that a patent coronoid canal is a synapomorphy of paenungulates, but not afrotherians as a whole

    Assessment of the mechanical role of cranial sutures in the mammalian skull: Computational biomechanical modelling of the rat skull

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    Cranial sutures are fibrocellular joints between the skull bones that are progressively replaced with bone throughout ontogeny, facilitating growth and cranial shape change. This transition from soft tissue to bone is reflected in the biomechanical properties of the craniofacial complex. However, the mechanical significance of cranial sutures has only been explored at a few localised areas within the mammalian skull, and as such our understanding of suture function in overall skull biomechanics is still limited. Here, we sought to determine how the overall strain environment is affected by the complex network of cranial sutures in the mammal skull. We combined two computational biomechanical methods, multibody dynamics analysis and finite element analysis, to simulate biting in a rat skull and compared models with and without cranial sutures. Our results show that including complex sutures in the rat model does not substantially change overall strain gradients across the cranium, particularly strain magnitudes in the bones overlying the brain. However, local variations in strain magnitudes and patterns can be observed in areas close to the sutures. These results show that, during feeding, sutures may be more important in some regions than others. Sutures should therefore be included in models that require accurate local strain magnitudes and patterns of cranial strain, particularly if models are developed for analysis of specific regions, such as the temporomandibular joint or zygomatic arch. Our results suggest that, for mammalian skulls, cranial sutures might be more important for allowing brain expansion during growth than redistributing biting loads across the cranium in adults

    Assessment of the mechanical role of cranial sutures in the mammalian skull: Computational biomechanical modelling of the rat skull.

    No full text
    Cranial sutures are fibrocellular joints between the skull bones that are progressively replaced with bone throughout ontogeny, facilitating growth and cranial shape change. This transition from soft tissue to bone is reflected in the biomechanical properties of the craniofacial complex. However, the mechanical significance of cranial sutures has only been explored at a few localised areas within the mammalian skull, and as such our understanding of suture function in overall skull biomechanics is still limited. Here, we sought to determine how the overall strain environment is affected by the complex network of cranial sutures in the mammal skull. We combined two computational biomechanical methods, multibody dynamics analysis and finite element analysis, to simulate biting in a rat skull and compared models with and without cranial sutures. Our results show that including complex sutures in the rat model does not substantially change overall strain gradients across the cranium, particularly strain magnitudes in the bones overlying the brain. However, local variations in strain magnitudes and patterns can be observed in areas close to the sutures. These results show that, during feeding, sutures may be more important in some regions than others. Sutures should therefore be included in models that require accurate local strain magnitudes and patterns of cranial strain, particularly if models are developed for analysis of specific regions, such as the temporomandibular joint or zygomatic arch. Our results suggest that, for mammalian skulls, cranial sutures might be more important for allowing brain expansion during growth than redistributing biting loads across the cranium in adults

    Dietary specializations and diversity in feeding ecology of the earliest stem mammals

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    The origin and radiation of mammals are key events in the history of life, with fossils placing the origin at 220 million years ago, in the Late Triassic period1. The earliest mammals, representing the first 50 million years of their evolution and including the most basal taxa, are widely considered to be generalized insectivores1, 2. This implies that the first phase of the mammalian radiation—associated with the appearance in the fossil record of important innovations such as heterodont dentition, diphyodonty and the dentary–squamosal jaw joint1, 3—was decoupled from ecomorphological diversification2, 4. Finds of exceptionally complete specimens of later Mesozoic mammals have revealed greater ecomorphological diversity than previously suspected, including adaptations for swimming, burrowing, digging and even gliding2, 5, 6, but such well-preserved fossils of earlier mammals do not exist1, and robust analysis of their ecomorphological diversity has previously been lacking. Here we present the results of an integrated analysis, using synchrotron X-ray tomography and analyses of biomechanics, finite element models and tooth microwear textures. We find significant differences in function and dietary ecology between two of the earliest mammaliaform taxa, Morganucodon and Kuehneotherium—taxa that are central to the debate on mammalian evolution. Morganucodon possessed comparatively more forceful and robust jaws and consumed ‘harder’ prey, comparable to extant small-bodied mammals that eat considerable amounts of coleopterans. Kuehneotherium ingested a diet comparable to extant mixed feeders and specialists on ‘soft’ prey such as lepidopterans. Our results reveal previously hidden trophic specialization at the base of the mammalian radiation; hence even the earliest mammaliaforms were beginning to diversify—morphologically, functionally and ecologically. In contrast to the prevailing view2, 4, this pattern suggests that lineage splitting during the earliest stages of mammalian evolution was associated with ecomorphological specialization and niche partitioning
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