16,073 research outputs found

    First-principles calculations of the structural, electronic, vibrational and magnetic properties of C_{60} and C_{48}N_{12}: a comparative study

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    In this work, we perform first-principles calculations of the structural, electronic, vibrational and magnetic properties of a novel C48N12{\rm C}_{48}{\rm N}_{12} azafullerene. Full geometrical optimization shows that C48N12{\rm C}_{48}{\rm N}_{12} is characterized by several distinguishing features: only one nitrogen atom per pentagon, two nitrogen atoms preferentially sitting in one hexagon, S6{\rm S}_{6} symmetry, 6 unique nitrogen-carbon and 9 unique carbon-carbon bond lengths. The highest occupied molecular orbital of C48N12{\rm C}_{48}{\rm N}_{12} is a doubly degenerate level of aga_{g} symmetry and its lowest unoccupied molecular orbital is a nondegenerate level of aua_{u} symmetry. Vibrational frequency analysis predicts that C48N12{\rm C}_{48}{\rm N}_{12} has in total 116 vibrational modes: 58 infrared-active and 58 Raman-active modes. C48N12{\rm C}_{48}{\rm N}_{12} is also characterized by 8 13C^{13}{\rm C} and 2 15N^{15}{\rm N} NMR spectral signals. Compared to C60{\rm C}_{60}, C48N12{\rm C}_{48}{\rm N}_{12} shows an enhanced third-order optical nonlinearities which implies potential applications in optical limiting and photonics.Comment: a long version of our manuscript submitted to J.Chem.Phy

    Modelling Molecular Motors as Folding-Unfolding Cycles

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    We propose a model for motor proteins based on a hierarchical Hamiltonian that we have previously introduced to describe protein folding. The proposed motor model has high efficiency and is consistent with a linear load-velocity response. The main improvement with respect to previous models is that this description suggests a connection between folding and function of allosteric proteins.Comment: 5 pages RevTeX, 2 Postscript figures, replaced due to LaTeX proble

    The Calgary student run clinic in context: a mixed-methods case study

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    Background: Student Run Clinics (SRCs) provide students with clinical education while caring for underserved populations. While much of the research on SRCs comes from the USA, SRCs in other contexts need to be appraised in the context of the systems they interact with. This study explored how stakeholders in the University of Calgary’s SRC perceived its purpose and beneficiaries with respect to patients, students, undergraduate medical education, and its intersections within the healthcare system in Calgary.  Methods: Data came from the SRC’s EMR and stakeholder interviews at the Inn from the Cold (IFTC) shelter. Qualitative data were analyzed using standard grounded theory techniques. Results: There were 13 interviews - seven with student clinicians and six with preceptors and other stakeholders. Interviews highlighted the uncertainty of the SRCs role. Majority of participants saw the SRC as facilitating further access to other healthcare services, while some commented on its primarily education-focused role. Major limitations in the SRC’s scope of care and its integration with other services were identified. Conclusion: SRCs need to consider theiraccountabilities, both educational and healthcare-focused at individual and organization levels, in order to function as responsible healthcare providers in Calgary

    Resonant Steps in the Characteristics of a Josephson Junction Coupled to a Transmission Line

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    A novel circuit is described which functions as an electronic analog of lumped element transmission line. The circuit requires only operational amplifiers, resistors, and capacitors. This module was coupled to a Josephsonj unction simulator and current voltage characteristics of the combined system were recorded. Steps were observed at voltages determined by the appropriate line resonances. When the transmission line was terminated with loads less than the characteristic impedance, chaos was seen in the lower steps. Similar results were obtained by numerical integration of the corresponding system of differential equations

    Documentation of a fully integrated epidemiological-demographic-macroeconomic model of Malaria: The case of Ghana

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    We develop a novel and fully integrated epidemiological-demographic-macroeconomic EDM-malaria simulation model framework for modelling of P. falciparum malaria transmission in Ghana. Our model framework represents a milestone, as the first fully integrated EDM model framework for any type of infectious disease. The complex specification and integration of regional epidemiological-demographic models within a malaria-focussed macroeconomic Computable General Equilibrium model is fully described and documented, and ideas are outlined for future applications to investigate the interplay between macroeconomic and health disease burdens, to measure the health and economic impacts of economic growth and malaria interventions, and to study the importance (or lack thereof) of the general omission of proper epidemiological underpinnings and integration of economic incentive feedback effects in the existing literature on macroeconomic assessment of infectious disease

    The Impact of Alzheimer's Disease on the Chinese Economy.

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    BACKGROUND: Recent increases in life expectancy may greatly expand future Alzheimer's Disease (AD) burdens. China's demographic profile, aging workforce and predicted increasing burden of AD-related care make its economy vulnerable to AD impacts. Previous economic estimates of AD predominantly focus on health system burdens and omit wider whole-economy effects, potentially underestimating the full economic benefit of effective treatment. METHODS: AD-related prevalence, morbidity and mortality for 2011-2050 were simulated and were, together with associated caregiver time and costs, imposed on a dynamic Computable General Equilibrium model of the Chinese economy. Both economic and non-economic outcomes were analyzed. FINDINGS: Simulated Chinese AD prevalence quadrupled during 2011-50 from 6-28 million. The cumulative discounted value of eliminating AD equates to China's 2012 GDP (US8trillion),andtheannualpredictedrealvalueapproachesUSADcost−of−illness(COI)estimates,exceedingUS8 trillion), and the annual predicted real value approaches US AD cost-of-illness (COI) estimates, exceeding US1 trillion by 2050 (2011-prices). Lost labor contributes 62% of macroeconomic impacts. Only 10% derives from informal care, challenging previous COI-estimates of 56%. INTERPRETATION: Health and macroeconomic models predict an unfolding 2011-2050 Chinese AD epidemic with serious macroeconomic consequences. Significant investment in research and development (medical and non-medical) is warranted and international researchers and national authorities should therefore target development of effective AD treatment and prevention strategies

    Echolocation click source parameters of Australian snubfin dolphins (Orcaella heinsohni)

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    Author Posting. © Acoustical Society of America, 2018. This article is posted here by permission of Acoustical Society of America for personal use, not for redistribution. The definitive version was published in Journal of the Acoustical Society of America 143 (2018): 2564, doi: 10.1121/1.5034174.The Australian snubfin dolphin (Orcaella heinsohni) is endemic to Australian waters, yet little is known about its abundance and habitat use. To investigate the feasibility of Passive Acoustic Monitoring for snubfin dolphins, biosonar clicks were recorded in Cygnet Bay, Australia, using a four-element hydrophone array. Clicks had a mean source level of 200 ± 5 dB re 1 μPa pp, transmission directivity index of 24 dB, mean centroid frequency of 98 ± 9 kHz, and a root-mean-square bandwidth of 31 ± 3 kHz. Such properties lend themselves to passive acoustic monitoring, but are comparable to similarly-sized delphinids, thus requiring additional cues to discriminate between snubfins and sympatric species.We thank the Fitzroy Basin Association for funding fieldwork in Gladstone May 2013 as well as the Australian Marine Mammal Centre who funded J.N.S. with the Bill Dawbin Fellowship and provided fieldwork funding. P.T.M. was funded by a Sir Walter Murdoch Honorary Professorship from Murdoch University and frame grants from FNU. F.H.J. was supported by the office of naval research (N00014-1410410) and an AIAS-COFUND fellowship from Aarhus Institute of Advanced Studies, Aarhus University, under EU's FP7 programme (Agreement No. 609033)

    X-ray accretion signatures in the close CTTS binary V4046 Sgr

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    We present Chandra HETGS observations of the classical T Tauri star (CTTS) V4046 Sgr. The He-like triplets of O VII, Ne IX, and Si XIII are clearly detected. Similar to the CTTS TW Hya and BP Tau, the forbidden lines of O VII and Ne IX are weak compared to the intercombination line, indicating high plasma densities in the X-ray emitting regions. The Si XIII triplet, however, is within the low-density limit, in agreement with the predictions of the accretion funnel infall model with an additional stellar corona. V4046 Sgr is the first close binary exhibiting these features. Together with previous high-resolution X-ray data on TW Hya and BP Tau, and in contrast to T Tau, now three out of four CTTS show evidence of accretion funnels.Comment: 5 pages, 5 figure

    Nitrogen transfer from forage legumes to nine neighbouring plants in a multi-species grassland

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    Legumes play a crucial role in nitrogen supply to grass-legume mixtures for ruminant fodder. To quantify N transfer from legumes to neighbouring plants in multi-species grasslands we established a grass-legume-herb mixture on a loamy-sandy site in Denmark. White clover (Trifolium repens L.), red clover (Trifolium pratense L.) and lucerne (Medicago sativa L.) were leaf-labelled with 15N enriched urea during one growing season. N transfer to grasses (Lolium perenne L. and xfestulolium), white clover, red clover, lucerne, birdsfoot trefoil (Lotus corniculatus L.), chicory (Cichorium intybus L.), plantain (Plantago lanceolata L.), salad burnet (Sanguisorba minor L.)and caraway (Carum carvi L.) was assessed. Neighbouring plants contained greater amounts of N derived from white clover (4.8 gm-2) compared with red clover (2.2 gm-2) and lucerne (1.1 gm-2). Grasses having fibrous roots received greater amounts of N from legumes than dicotyledonous plants which generally have taproots. Slurry application mainly increased N transfer from legumes to grasses. During the growing season the three legumes transferred approximately 40 kg N ha-1 to neighbouring plants. Below-ground N transfer from legumes to neighbouring plants differed among nitrogen donors and nitrogen receivers and may depend on root characteristics and regrowth strategies of plant species in the multi-species grassland
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