14,922 research outputs found
Chord Label Personalization through Deep Learning of Integrated Harmonic Interval-based Representations
The increasing accuracy of automatic chord estimation systems, the
availability of vast amounts of heterogeneous reference annotations, and
insights from annotator subjectivity research make chord label personalization
increasingly important. Nevertheless, automatic chord estimation systems are
historically exclusively trained and evaluated on a single reference
annotation. We introduce a first approach to automatic chord label
personalization by modeling subjectivity through deep learning of a harmonic
interval-based chord label representation. After integrating these
representations from multiple annotators, we can accurately personalize chord
labels for individual annotators from a single model and the annotators' chord
label vocabulary. Furthermore, we show that chord personalization using
multiple reference annotations outperforms using a single reference annotation.Comment: Proceedings of the First International Conference on Deep Learning
and Music, Anchorage, US, May, 2017 (arXiv:1706.08675v1 [cs.NE]
On the Integrability and Chaos of an N=2 Maxwell-Chern-Simons-Higgs Mechanical Model
We apply different integrability analysis procedures to a reduced (spatially
homogeneous) mechanical system derived from an off-shell non-minimally coupled
N=2 Maxwell-Chern-Simons-Higgs model that presents BPS topological vortex
excitations, numerically obtained with an ansatz adopted in a special -
critical coupling - parametric regime. As a counterpart of the regularity
associated to the static soliton-like solution, we investigate the possibility
of chaotic dynamics in the evolution of the spatially homogeneous reduced
system, descendant from the full N=2 model under consideration. The originally
rich content of symmetries and interactions, N=2 susy and non-minimal coupling,
singles out the proposed model as an interesting framework for the
investigation of the role played by (super-)symmetries and parametric domains
in the triggering/control of chaotic behavior in gauge systems.
After writing down effective Lagrangian and Hamiltonian functions, and
establishing the corresponding canonical Hamilton equations, we apply global
integrability Noether point symmetries and Painleveproperty criteria to both
the general and the critical coupling regimes. As a non-integrable character is
detected by the pair of analytical criteria applied, we perform suitable
numerical simulations, as we seek for chaotic patterns in the system evolution.
Finally, we present some Comments on the results and perspectives for further
investigations and forthcoming communications.Comment: 18 pages, 5 figure
Highly erosive glaciers on Mars - the role of water
International audiencePolewards of 30 âą in each hemisphere, the surface of Mars hosts a suite of landforms reminiscent of glacial landscapes on Earth. Amongst these landforms are: 1) Viscous Flow Features (VFF), which resemble glaciers on Earth and are thought to contain large volumes of water ice, 2) martian gullies which are km-scale features resembling water-eroded gullies on Earth and 3) arcuate ridges thought to be moraines from previous glaciations. Gullies have been long-associated with a surface unit originally called "pasted-on terrain" and now often called the "latitude dependant mantle". Arcuate ridges are often found at the base of hillslopes with gullies, but are also found on hillslopes with pasted-on terrain and no gullies. We have found a systematic lowering of the slope of the bedrock exposure located topographically above the pasted-on terrain whether that same slope hosts gullies or not. The lowered bedrock exposures display a different surface texture from bedrock exposed on other parts of the crater wall and from fresh crater walls-it appears fragmented and has reduced relief. Using 1-m-digital elevation models from the High Resolution Imaging Science Experiment (HiRISE) we compared the slopes of eight "eroded" craters and seven unmodified craters. We estimated their age using the crater size-frequency distribution of small craters on their ejecta blankets. From this information we calculated bedrock retreat rates for the eroded craters and found they were up to âŒ103 m Myr-1-equivalent to erosion rates of wet-based glaciers on Earth. This is several orders of magnitude higher than previous estimates of erosion by VFF (10-2-101 m Myr-1), which themselves are roughly equivalent to cold-based glaciers on Earth. Such erosion rates are sufficient to erase previously existing landforms, such as martian gullies. We hypothesise, therefore, that the pasted-on terrain is a glacial deposit, overturning its previous interpretation as an airfall deposit of ice nucleated on dust. We maintain the interpretation of the arcuate ridges as moraines, but further conclude that they are likely the result of glaciotectonic deformation of sub-marginal and proglacial sediment in the presence of sediment pore-water. We do not support the generation of large quantities of glacial meltwater because it would have broken-up and degraded the arcuate ridges and pasted-on terrain an produced a suite of landforms (e.g., hummocky moraine, lacustrine forms, outwash plains, eskers) which are not observed
Rural livelihoods and agricultural commercialization in colonial Uganda: conjunctures of external influences and local realities
The economic history of Sub-Saharan Africa is characterized by geographically and temporally dispersed booms and busts. The export-led âcash-crop revolutionâ in parts of Sub-Saharan Africa during the colonial era is a key example of an economic boom. This thesis examines how external influences and local realities shaped the nature, extent and impact of the âcash-crop revolutionâ in colonial Uganda, a landlocked country in central east Africa, where cotton and coffee production for global markets took off following completion of a railway to the coast. The thesis consists of five targeted âinterventionsâ into contemporary debates of comparative African development. Each of these five interventions is grounded in the understanding that the ability of rural Africans to respond to and benefit from trade integration during the colonial era was mediated by colonial policies, resource endowments and local institutions. The first chapter reconstructs welfare development of Ugandan cash-crop farmers. Recent scholarship on historical welfare development in Sub-Saharan Africa has uncovered long-term trends in standards of living. How the majority of rural dwellers fared, however, remains largely elusive. This chapter presents a new approach to reconstructing rural living standards in a historical context, building upon the well-established real wage literature, but moving beyond it to capture rural realities, employing sub-national rural survey, census, and price data. The approach is applied to colonial and early post-colonial Uganda (1915â70), and yields a number of findings. While an expanding smallholder-based cash-crop sector established itself as the backbone of Ugandaâs colonial economy, farm characteristics remained largely stagnant after the initial adoption of cash crops. Smallholders maintained living standards well above subsistence level, and while the profitability of cash crops was low, their cultivation provided a reliable source of cash income. At the same time, there were pronounced limits to rural welfare expansion. Around the time of decolonization, unskilled wages rose rapidly while farm incomes lagged behind. As a result, an urbanârural income reversal took place. The study also reveals considerable differences within Uganda, which were mediated to an important extent by differential resource endowments. Smallholders in Ugandaâs banana regions required fewer labour inputs to maintain a farm income than their grain-farming counterparts, creating opportunities for additional income generation and livelihood diversification. The second chapter zooms in on labour migration which connected Belgian-controlled Ruanda-Urundi to British-controlled Buganda, the central province of Uganda on the shores of Lake Victoria. The emergence of new labour mobility patterns was a key aspect of economic change in colonial Africa. Under conditions of land abundance and labour scarcity, the supply of wage labour required either the âpullâ forces of attractive working conditions and high wages, or the âpushâ forces of taxation and other deliberate colonial interventions. Building upon primary sources, I show that this case diverges from the âconventionalâ narrative of labour scarcity in colonial Africa. I argue that Ruanda-Urundi should be regarded as labour abundant and that migrants were not primarily âpushedâ by colonial labour policies, but rather by poverty and limited access to agricultural resources. This explains why they were willing to work for low wages in Buganda. I show that African rural employers were the primary beneficiaries of migrant labour, while colonial governments on both sides of the border were unable to control the course of the flow. As in the first chapter, this chapter highlights that the effects of trade integration on African rural development were uneven, and mediated by differences in resource endowments, local institutions and colonial policies. The third chapter zooms out of the rural economy, evaluating the broader opportunity structures faced by African men and women in Uganda, and discussing the interaction of local institutions and colonial policies as drivers of uneven educational and occupational opportunities. The chapter engages with a recent article by Meier zu Selhausen and Weisdorf (2016) to show how selection biases in, and Eurocentric interpretations of, parish registers have provoked an overly optimistic account of European influences on the educational and occupational opportunities of African men and women. We confront their dataset, drawn from the marriage registers of the Anglican Cathedral in Kampala, with Ugandaâs 1991 census, and show that trends in literacy and numeracy of men and women born in Kampala lagged half a century behind those who wedded in Namirembe Cathedral. We run a regression analysis showing that access to schooling during the colonial era was unequal along lines of gender and ethnicity. We foreground the role of Africans in the spread of education, argue that European influences were not just diffusive but also divisive, and that gender inequality was reconfigured rather than eliminated under colonial rule. This chapter also makes a methodological contribution. The renaissance of African economic history in the past decade has opened up new research avenues to study the long-term social and economic development of Africa. We show that a sensitive treatment of African realities in the evaluation of European colonial legacies, and a critical stance towards the use of new sources and approaches, is crucial. The fourth chapter singles out the role of resource endowments in explaining Ugandaâs âcotton revolutionâ in a comparative African perspective. Why did some African smallholders adopt cash crops on a considerable scale, while most others were hesitant to do so? The chapter sets out to explore the importance of factor endowments in shaping the degrees to which cash crops were adopted in colonial tropical Africa. We conduct an in-depth case study of the âcotton revolutionâ in colonial Uganda to put the factor endowments perspective to the test. Our empirical findings, based on an annual panel data analysis at the district-level from 1925 until 1960, underscore the importance of Ugandaâs equatorial bimodal rainfall distribution as an enabling factor for its âcotton revolutionâ. Evidence is provided at a unique spatial micro-level, capitalizing on detailed household surveys from the same period. We demonstrate that previous explanations associating the variegated responses of African farmers to cash crops with, either the role of colonial coercion, or the distinction between âforest/bananaâ and âsavannah/grainâ zones, cannot explain the widespread adoption of cotton in Uganda. We argue, instead, that the key to the cotton revolution were Ugandaâs two rainy seasons, which enabled farmers to grow cotton while simultaneously pursuing food security. Our study highlights the importance of food security and labour seasonality as important determinants of uneven agricultural commercialization in colonial tropical Africa. The fifth and final chapter further investigates the experience of African smallholders with cotton cultivation, providing a comparative explanatory analysis of variegated cotton outcomes, focusing in particular on the role of colonial and post-colonial policies. The chapter challenges the widely accepted view that (i) African colonial cotton projects consistently failed, that (ii) this failure should be attributed to conditions particular to Africa, which made export cotton inherently unviable and unprofitable to farmers, and that (iii) the repression and resistance often associated with cotton, all resulted from the stubborn and overbearing insistence of colonial governments on the crop per se. I argue along three lines. Firstly, to show that cotton outcomes were diverse, I compare cases of cotton production in Sub-Saharan Africa across time and space. Secondly, to refute the idea that cotton was a priori unattractive, I argue that the crop had substantial potential to connect farmers to markets and contribute to poverty alleviation, particularly in vulnerable, marginal and landlocked areas. Thirdly, to illustrate how an interaction between local conditions and government policies created conducive conditions for cotton adoption, I zoom in on the few yet significant âcotton success storiesâ in twentieth century Africa. Smallholders in colonial Uganda adopted cotton because of favourable ecological and marketing conditions, and policies had an auxiliary positive effect. Smallholders in post-colonial Francophone West Africa faced much more challenging local conditions, but benefitted from effective external intervention and coordinated policy. On a more general level, this chapter demonstrates that, from a perspective of rural development, colonial policies should not only be seen as overbearing and interventionist, but also as inadequate, failing to aid rural Africans to benefit from new opportunities created by trade integration.</p
Structural basis of the chiral selectivity of Pseudomonas cepacia lipase
To investigate the enantioselectivity of Pseudomonas cepacia lipase, inhibition studies were performed with SC- and RC-(RP,SP)-1,2-dialkylcarbamoylglycero-3-O-p-nitrophenyl alkylphosphonates of different alkyl chain lengths. P. cepacia lipase was most rapidly inactivated by RC-(RP,SP)-1,2-dioctylcarbamoylglycero-3-O-p-nitrophenyl octylphosphonate (RC-trioctyl) with an inactivation half-time of 75 min, while that for the SC-(RP,SP)-1,2-dioctylcarbamoylglycero-3-O-p-nitrophenyl octyl-phosphonate (SC-trioctyl) compound was 530 min. X-ray structures were obtained of P. cepacia lipase after reaction with RC-trioctyl to 0.29-nm resolution at pH 4 and covalently modified with RC-(RP,SP)-1,2-dibutylcarbamoylglycero-3-O-p-nitrophenyl butyl-phosphonate (RC-tributyl) to 0.175-nm resolution at pH 8.5. The three-dimensional structures reveal that both triacylglycerol analogues had reacted with the active-site Ser87, forming a covalent complex. The bound phosphorus atom shows the same chirality (SP) in both complexes despite the use of a racemic (RP,SP) mixture at the phosphorus atom of the triacylglycerol analogues. In the structure of RC-tributyl-complexed P. cepacia lipase, the diacylglycerol moiety has been lost due to an aging reaction, and only the butyl phosphonate remains visible in the electron density. In the RC-trioctyl complex the complete inhibitor is clearly defined; it adopts a bent tuning fork conformation. Unambiguously, four binding pockets for the triacylglycerol could be detected: an oxyanion hole and three pockets which accommodate the sn-1, sn-2, and sn-3 fatty acid chains. Van der Waalsâ interactions are the main forces that keep the radyl groups of the triacylglycerol analogue in position and, in addition, a hydrogen bond to the carbonyl oxygen of the sn-2 chain contributes to fixing the position of the inhibitor.
Inclusion Of The Spatial Dimension Of Population Data In Developing Policies For The Management Of AnGR âThe Case Of The Heritage Sheep Breeds
The sustainable use of farm animal genetic resources is connected with the recognition of their contribution to the society and the environment and the assessment of the threats they are facing. The category of the heritage breeds, which are genetically distinct, geographically concentrated, adapted to their environment, commercially farmed to contribute to the local economy were considered in the frame of the HERITAGESHEEP project. The aim of this project was to deliver the potential of the heritage sheep breeds for a sustainable future for medium to low input production systems, which support local rural communities throughout Europe. This was achieved by addressing the conservation of these breeds, defining the current and future threats and developing new uses and markets for products
Kondo temperature of magnetic impurities at surfaces
Based on the experimental observation, that only the close vicinity of a
magnetic impurity at metal surfaces determines its Kondo behaviour, we
introduce a simple model which explains the Kondo temperatures observed for
cobalt adatoms at the (111) and (100) surfaces of Cu, Ag, and Au. Excellent
agreement between the model and scanning tunneling spectroscopy (STS)
experiments is demonstrated. The Kondo temperature is shown to depend on the
occupation of the d-level determined by the hybridization between adatom and
substrate with a minimum around single occupancy.Comment: 4 pages, 2 figure
The uniting of Europe and the foundation of EU studies: revisiting the neofunctionalism of Ernst B. Haas
This article suggests that the neofunctionalist theoretical legacy left by Ernst B. Haas is somewhat richer and more prescient than many contemporary discussants allow. The article develops an argument for routine and detailed re-reading of the corpus of neofunctionalist work (and that of Haas in particular), not only to disabuse contemporary students and scholars of the normally static and stylized reading that discussion of the theory provokes, but also to suggest that the conceptual repertoire of neofunctionalism is able to speak directly to current EU studies and comparative regionalism. Neofunctionalism is situated in its social scientific context before the theory's supposed erroneous reliance on the concept of 'spillover' is discussed critically. A case is then made for viewing Haas's neofunctionalism as a dynamic theory that not only corresponded to established social scientific norms, but did so in ways that were consistent with disciplinary openness and pluralism
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