Toward Improving Understanding of the Structure and Biophysics of Glycosaminoglycans

Glycosaminoglycans (GAGs) are the linear carbohydrate components of proteoglycans (PGs) that mediate PG bioactivities, including signal transduction, tissue morphogenesis, and matrix assembly. To understand GAG function, it is important to understand GAG structure and biophysics at atomic resolution. This is a challenge for existing experimental and computational methods because GAGs are heterogeneous, conformationally complex, and polydisperse, containing up to 200 monosaccharides. Molecular dynamics (MD) simulations come close to overcoming this challenge but are only feasible for short GAG polymers. To address this problem, we developed an algorithm that applies conformations from unbiased all-atom explicit-solvent MD simulations of short GAG polymers to rapidly construct 3-D atomic-resolution models of GAGs of arbitrary length. MD simulations of GAG 10-mers (i.e., polymers containing 10 monosaccharides) and 20-mers were run and conformations of all monosaccharide rings and glycosidic linkages were analyzed and compared to existing experimental data. These analyses demonstrated that (1) MD-generated GAG conformations are in agreement with existing experimental data; (2) MD-generated GAG 10-mer ring and linkage conformations match those in corresponding GAG 20-mers, suggesting that these conformations are representative of those in longer GAG biopolymers; and (3) rings and linkages in GAG 10- and 20-mers behave randomly and independently in MD simulation. Together, these findings indicate that MD-generated GAG 20-mer ring and linkage conformations can be used to construct thermodynamically-correct models of GAG polymers. Indeed, our findings demonstrate that our algorithm constructs GAG 10- and 20-mer conformational ensembles that accurately represent the backbone flexibility seen in MD simulations. Furthermore, within a day, our algorithm constructs conformational ensembles of GAG 200-mers that we would reasonably expect from MD simulation, demonstrating the efficiency of the algorithm and reduction in its time and computational cost compared to simulation. While there are other programs that can quickly construct atomic-resolution models of GAGs, those programs use conformations from short GAG subunits in solid state. Our findings suggest that GAG 20-mers are more flexible than short GAG subunits, meaning our program constructs ensembles that more accurately represent GAG polymer backbone flexibility and provide valuable insights toward improving the understanding of the structure and biophysics of GAGs

“Cuban Music is African Music”: Productive Frictions in the World Music Industry

This paper examines the ways in which Orchestra Baobab and AfroCubism, two bands that combine West African and Cuban musics, negotiate musical mixing across the black Atlantic. Looking at the frictions between different musical sounds and meanings, I explore the ways in which musicians re-imagine and reconstruct the black Atlantic and their own identities as they creatively combine Cuban and African musics. I argue that musicians are strategic in their combining of music and social meanings, idealistic in their belief in connecting people and musics across the Atlantic and pragmatic in their discussions of the limits of musical mixing and collaboration.Cet article se penche sur les différentes manières dont Orchestra Baobab et AfroCubism, deux groupes qui allient les musiques de l’Afrique de l’Ouest et de Cuba, négocient le mélange musical de part et d’autre de l’Atlantique noir. En examinant les frictions entre les différents sons et sens musicaux, j’examine la manière dont les musiciens ré-imaginent et reconstruisent l’Atlantique noir et leurs propres identités, en combinant avec créativité les musiques africaines et cubaines. J’avance que les musiciens sont tacticiens lorsqu’ils combinent musique et significations sociales ; idéalistes quant à leur sentiment de relier les gens et les musiques de part et d’autre de l’Atlantique ; et pragmatiques lorsqu’ils discutent des limites du mélange musical et de la collaboration

Is it possible to increase the sustainability of arable and ruminant agriculture by reducing inputs?

Until recently, agricultural production was optimised almost exclusively for profit but now farming is under pressure to meet environmental targets. A method is presented and applied for optimising the sustainability of agricultural production systems in terms of both economics and the environment. Components of the agricultural production chain are analysed using environmental life-cycle assessment (LCA) and a financial value attributed to the resources consumed and burden imposed on the environment by agriculture, as well as to the products. The sum of the outputs is weighed against the inputs and the system considered sustainable if the value of the outputs exceeds those of the inputs. If this ratio is plotted against the sum of inputs for all levels of input, a diminishing returns curve should result and the optimum level of sustainability is located at the maximum of the curve. Data were taken from standard economic almanacs and from published LCA reports on the extent of consumption and environmental burdens resulting from farming in the UK. Land-use is valued using the concept of ecosystem services. Our analysis suggests that agricultural systems are sustainable at rates of production close to current levels practiced in the UK. Extensification of farming, which is thought to favour non-food ecosystem services, requires more land to produce the same amount of food. The loss of ecosystem services hitherto provided by natural land brought into production is greater than that which can be provided by land now under extensive farming. This loss of ecosystem service is large in comparison to the benefit of a reduction in emission of nutrients and pesticides. However, food production is essential, so the coupling of subsidies that represent a relatively large component of the economic output in EU farming, with measures to reduce pollution are well-aimed. Measures to ensure that as little extra land is brought into production as possible or that marginal land is allowed to revert to nature would seem to be equally well-aimed, even if this required more intensive use of productive areas. We conclude that current arable farming in the EU is sustainable with either realistic prices for products or some degree of subsidy and that productivity per unit area of land and greenhouse gas emission (subsuming primary energy consumption) are the most important pressures on the sustainability of farming

Polynomial disaggregation procedures

January 1991.Includes bibliographical references.In air quality monitoring, often aerosol samples are collected using various filter methods in regular sampling cycles. Some aerosol species samples may be collected at 12 hour cycles while others may be collected at 6 hour cycles or 24 hour cycles, etc. If some species are collected at 6 hour intervals and others at 12 hour intervals, then a statistical analysis of these data are often carried out after aggregating the 6 hour data to produce 12 hour data so that all data correspond to the same time cycle. It is of some interest to investigate the alternative possibility of disaggregating the 12 hour data to obtain "6 hour (pseudo) data" and then performing statistical analyses on the 6 hour scale. In this report we investigate this possibility by studying how well a certain class of disaggregation procedures is able to disaggregate aggregated data. The performance of the methods considered are evaluated using real data collected as part of the WHITEX study.Research supported by the National Oceanic Atmospheric Administration under Grant no. NA90RAH00077

Medical Tourism in Barbados: Negotiating Inherent Tensions

This chapter draws on our long term-research program examining medical tourism in Barbados and the wider Anglophone Caribbean. Since 2011 we have undertaken 69 semi-structured interviews and three focus groups with a wide range of health system and tourism sector stakeholders in Barbados, compiled a comprehensive collection of state and media reports discussing medical tourism, and collectively spent over a year conducting on-site ethnographic fieldwork that has included many informal conversations with users of the Barbadian health system from a wide range of backgrounds. Together, these datasets and experiences provide a rich understanding of the potential considerations and hopes arising from the ongoing discussion about medical tourism development in a small island setting. Exploring these considerations and hopes suggests ways in which Barbados and other small island states seeking to develop their medical tourism sectors can negotiate a structure for medical tourism that can best meet their development goals

The Significance of Micas in Ancient Cross-bedded Sandstones

In our study of thin sections of the cross-bedded Coconino Sandstone we encountered muscovite as a trace mineral in almost every thin section of the hundreds that we cut. As we began to study other similar cross-bedded sandstones like the Tensleep, Lyons and Hopeman the same pattern began to emerge. All of these sandstones have been conventionally interpreted as desert wind-blown deposits. A novel set of experiments were performed and recently published by some Cedarville University geology students and the lead author of this paper (Anderson et al., 2017). They found when muscovite-rich quartz sand was experimentally placed into a simulated eolian setting, muscovite only survived for a matter of days. When muscovite-rich quartz sand was experimentally placed into a simulated subaqueous setting it was still present after a year of constant agitation before the experiment was finally terminated. Even though this was a simple experiment and only a limited number of trials were performed it confirms field observations by the authors that mica is rare in modern eolian deposits (unless they are very near a granitic source) and its relative abundance in beach and marine sands. The implications are significant. Although more experiments could be performed, the experiments and observations suggest that mica is rapidly degraded in wind-blown environments and survives when transported by water. Evidently water cushions the grain-to-grain collisions and prevents rapid deterioration of the muscovite in subaqueous settings. This proposed paper will catalog and illustrate the large number of cross-bedded sandstones we have found that contain mica (mostly muscovite) as an accessory mineral. The dominant conventional view is that these sandstones are eolian, but the presence of muscovite based on experimental data and field observations suggests otherwise. The presence of muscovite in cross-bedded sandstones can be used as one of many criteria to argue for subaqueous deposition

Imaging of the Merging Galaxy NGC 3597 and its Population of Proto--Globular Clusters

We present wide field-of-view near-infrared imaging from the NTT and very deep optical imaging from the HST of the young merging galaxy NGC 3597. The morphology of the galaxy and the properties of the newly formed proto-globular clusters (PGCs) are examined. Our K band data reveals the presence of a second nucleus, which provides further evidence that NGC 3597 is the result of a recent merger. Combining new K band photometry with optical photometry, we are able for the first time to derive a unique age for the newly formed PGCs of a few Myrs. This is consistent with the galaxy starburst age of < 10 Myrs. From deep HST imaging, we are able to probe the luminosity function ~8 magnitudes fainter than normal, old globular clusters, and confirm that the PGCs have a power-law distribution with a slope of ~-2.Comment: 19 pages, Latex, 10 figures, 4 tables, accepted by MNRA