522 research outputs found
Field dynamics and tunneling in a flux landscape
We investigate field dynamics and tunneling between metastable minima in a
landscape of Type IIB flux compactifications, utilizing monodromies of the
complex structure moduli space to continuously connect flux vacua. After
describing the generic features of a flux-induced potential for the complex
structure and Type IIB axio-dilaton, we specialize to the Mirror Quintic
Calabi--Yau to obtain an example landscape. Studying the cosmological dynamics
of the complex structure moduli, we find that the potential generically does
not support slow-roll inflation and that in general the landscape separates
neatly into basins of attraction of the various minima. We then discuss
tunneling, with the inclusion of gravitational effects, in many-dimensional
field spaces. A set of constraints on the form of the Euclidean paths through
field space are presented, and then applied to construct approximate instantons
mediating the transition between de Sitter vacua in the flux landscape. We find
that these instantons are generically thick-wall and that the tunneling rate is
suppressed in the large-volume limit. We also consider examples where
supersymmetry is not broken by fluxes, in which case near-BPS thin-wall bubbles
can be constructed. We calculate the bubble wall tension, finding that it
scales like a D- or NS-brane bubble, and comment on the implications of this
correspondence. Finally, we present a brief discussion of eternal inflation in
the flux-landscape.Comment: 23 PRD-style pages with 11 embedded figures. Added refs, corrected
typos, and clarified Sec. V. Replaced to match published versio
Brane Gas Inflation
We consider the brane gas picture of the early universe. At later stages,
when there are no winding modes and the background is free to expand, we show
that a moving 3-brane, which we identify with our universe, can inflate even
though it is radiation-dominated. The crucial ingredients for successful
inflation are the coupling to the dilaton and the equation of state of the
bulk. If we suppose the brane initially forms in a collision of
higher-dimensional branes, then the spectrum of primordial density fluctuations
naturally has a thermal origin.Comment: 4 pages, 1 figur
Atom chips on direct bonded copper substrates
We present the use of direct bonded copper (DBC) for the straightforward
fabrication of high power atom chips. Atom chips using DBC have several
benefits: excellent copper/substrate adhesion, high purity, thick (> 100
microns) copper layers, high substrate thermal conductivity, high aspect ratio
wires, the potential for rapid (< 8 hr) fabrication, and three dimensional atom
chip structures. Two mask options for DBC atom chip fabrication are presented,
as well as two methods for etching wire patterns into the copper layer. The
wire aspect ratio that optimizes the magnetic field gradient as a function of
power dissipation is determined to be 0.84:1 (height:width). The optimal wire
thickness as a function of magnetic trapping height is also determined. A test
chip, able to support 100 A of current for 2 s without failing, is used to
determine the thermal impedance of the DBC. An assembly using two DBC atom
chips to provide magnetic confinement is also shown.Comment: 8 pages, 5 figure
Posterior segment eye disease in sub-Saharan Africa: review of recent population-based studies.
OBJECTIVE: To assess the burden of posterior segment eye diseases (PSEDs) in sub-Saharan Africa (SSA). METHODS: We reviewed published population-based data from SSA and other relevant populations on the leading PSED, specifically glaucoma, diabetic retinopathy and age-related macular degeneration, as causes of blindness and visual impairment in adults. Data were extracted from population-based studies conducted in SSA and elsewhere where relevant. RESULTS: PSEDs, when grouped or as individual diseases, are a major contributor to blindness and visual impairment in SSA. PSED, grouped together, was usually the second leading cause of blindness after cataract, ranging as a proportion of blindness from 13 to 37%. CONCLUSIONS: PSEDs are likely to grow in importance as causes of visual impairment and blindness in SSA in the coming years as populations grow, age and become more urban in lifestyle. African-based cohort studies are required to help estimate present and future needs and plan services to prevent avoidable blindness
A 3D searchable database of transgenic zebrafish gal4 and cre lines for functional neuroanatomy studies
Citation: Marquart, G. D., Tabor, K. M., Brown, M., Strykowski, J. L., Varshney, G. K., LaFave, M. C., . . . Burgess, H. A. (2015). A 3D searchable database of transgenic zebrafish gal4 and cre lines for functional neuroanatomy studies. Frontiers in Neural Circuits, 9(November), 1-17. doi:10.3389/fncir.2015.00078Transgenic methods enable the selective manipulation of neurons for functional mapping of neuronal circuits. Using confocal microscopy, we have imaged the cellular-level expression of 109 transgenic lines in live 6 day post fertilization larvae, including 80 Gal4 enhancer trap lines, 9 Cre enhancer trap lines and 20 transgenic lines that express fluorescent proteins in defined gene-specific patterns. Image stacks were acquired at single micron resolution, together with a broadly expressed neural marker, which we used to align enhancer trap reporter patterns into a common 3-dimensional reference space. To facilitate use of this resource, we have written software that enables searching for transgenic lines that label cells within a selectable 3-dimensional region of interest (ROI) or neuroanatomical area. This software also enables the intersectional expression of transgenes to be predicted, a feature which we validated by detecting cells with co-expression of Cre and Gal4. Many of the imaged enhancer trap lines show intrinsic brain-specific expression. However, to increase the utility of lines that also drive expression in non-neuronal tissue we have designed a novel UAS reporter, that suppresses expression in heart, muscle, and skin through the incorporation of microRNA binding sites in a synthetic 3? untranslated region. Finally, we mapped the site of transgene integration, thus providing molecular identification of the expression pattern for most lines. Cumulatively, this library of enhancer trap lines provides genetic access to 70% of the larval brain and is therefore a powerful and broadly accessible tool for the dissection of neural circuits in larval zebrafish. © 2015 Marquart, Tabor, Brown, Strykowski, Varshney, LaFave, Mueller, Burgess, Higashijima and Burgess
Reductions in movement-associated fear are dependent upon graded exposure in chronic low back pain : an exploratory analysis of a modified 3-item fear hierarchy
Objective: To explore the effectiveness of a modified fear hierarchy on measuring improvements in movement-associated fear in chronic low back pain. Methods: A modified 3-item fear hierarchy was created and implemented based on principles of graded exposure. This study was an exploratory analysis of the modified 3-item fear hierarchy from a larger clinical trial data set. Both groups received pain education and exercise, either bodyweight or strength training. Both groups performed item one on the hierarchy, the squat. Only the strength training group performed item 2, the deadlift. Neither group performed item 3, the overhead press. Analysis of Covariance and stepwise linear regression were used to explore results. Results: Improvement in movement-associated fear was conditional upon graded exposure. Both groups improved in the squat movement (p †0.05), which both performed. Only the strength training group improved in the deadlift (p †0.01), and neither improved in the overhead press (p ℠0.05). Conclusion: Reductions in movement-associated fear are conditional upon graded exposure, based on the use of a novel modified 3-item fear hierarchy. Further research is needed to understand the utility of this tool in a patient-led approach to co-designing a graded exposure-based intervention
The Relationship Between Race, Patient Activation, and Working Alliance: Implications for Patient Engagement in Mental Health Care
This study explored the relationship between race and two key aspects of patient engagementâpatient activation and working allianceâamong a sample of African-American and White veterans (Nâ=â152) seeking medication management for mental health conditions. After adjusting for demographics, race was significantly associated with patient activation, working alliance, and medication adherence scores. Patient activation was also associated with working alliance. These results provide support for the consideration of race and ethnicity in facilitating patient engagement and patient activation in mental healthcare. Minority patients may benefit from targeted efforts to improve their active engagement in mental healthcare
Direct activation of NADPH oxidase 2 by 2-deoxyribose-1-phosphate triggers nuclear factor kappa B-dependent angiogenesis.
AbstractAims: Deoxyribose-1-phosphate (dRP) is a proangiogenic paracrine stimulus released by cancer cells, platelets, and macrophages and acting on endothelial cells. The objective of this study was to clarify how dRP stimulates angiogenic responses in human endothelial cells.Results: Live cell imaging, electron paramagnetic resonance, pull-down of dRP-interacting proteins, followed by immunoblotting, gene silencing of different NADPH oxidases (NOXs), and their regulatory cosubunits by small interfering RNA (siRNA) transfection, and experiments with inhibitors of the sugar transporter glucose transporter 1 (GLUT1) were utilized to demonstrate that dRP acts intracellularly by directly activating the endothelial NOX2 complex, but not NOX4. Increased reactive oxygen species generation in response to NOX2 activity leads to redox-dependent activation of the transcription factor nuclear factor kappa B (NF-ÎșB), which, in turn, induces vascular endothelial growth factor receptor 2 (VEGFR2) upregulation. Using endothelial tube formation assays, gene silencing by siRNA, and antibody-based receptor inhibition, we demonstrate that the activation of NF-ÎșB and VEGFR2 is necessary for the angiogenic responses elicited by dRP. The upregulation of VEGFR2 and NOX2-dependent stimulation of angiogenesis by dRP were confirmed in excisional wound and Matrigel plug vascularization assays in vivo using NOX2â/â mice.Innovation: For the first time, we demonstrate that dRP acts intracellularly and stimulates superoxide anion generation by direct binding and activation of the NOX2 enzymatic complex.Conclusions: This study describes a novel molecular mechanism underlying the proangiogenic activity of dRP, which involves the sequential activation of NOX2 and NF-ÎșB and upregulation of VEGFR2. Antioxid. Redox Signal. 28, 110â130
Rebound effects could offset more than half of avoided food loss and waste
Acknowledgements We thank Peter Newton, Sebastian Dueñas-Ocampo, Rayna Benzeev, Lee Frankel-Goldwater, Waverly Eichhorst, Ryan Langendorf, and Hilary Brumberg for their feedback on earlier drafts of this document; and Ryan Langendorf for helpful feedback and discussion on the economic analysis. M.H. and M.G.B. acknowledge funding from the US Department of Agriculture (USDA) National Institute of Food and Agriculture (NIFA) (Award number: 2020-38420-30727), and the University of Colorado Boulder Cooperative Institute for Research in Environmental Sciences (CIRES) (start-up grant to M.G.B.). S.J.D. was supported by the US National Science Foundation and US Department of Agriculture (INFEWS grant EAR 1639318) and by the ClimateWorks Foundation (grant 22-2100). .Peer reviewedPostprin
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