5,453 research outputs found
Two-Sample Hypothesis Testing for Random Graphs
Hypothesis testing for latent position random graphs is a growing area of research, particularly motivated by needs in areas such as neuroscience, fraud detection, and social networks. We explore two problems of statistical inference. Currently, methods such as adjacency spectral embedding (ASE) are used to create test statistics for random graphs. The first chapter of our study presents non-metric multidimensional scaling as an alternative to ASE. We show our procedure is functional for both simulated data and for graphs generated from MRI scans. In the second chapter we explore classical applications of statistical inference in a multi-graph setting. We will isolate important vertices across a set of graphs, and then determine correlations between the important vertices and physical vertex features. We use the same MRI data from Chapter 1. The overall goal of these studies is to test new concepts of statistical inference on graphs via simulations and explorations of real-world data
Production, Fate and Pathogenicity of Plasma Microparticles in Murine Cerebral Malaria
In patients with cerebral malaria (CM), higher levels of cell-specific microparticles (MP) correlate with the presence of neurological symptoms. MP are submicron plasma membrane-derived vesicles that express antigens of their cell of origin and phosphatidylserine (PS) on their surface, facilitating their role in coagulation, inflammation and cell adhesion. In this study, the in vivo production, fate and pathogenicity of cell-specific MP during Plasmodium berghei infection of mice were evaluated. Using annexin V, a PS ligand, and flow cytometry, analysis of platelet-free plasma from infected mice with cerebral involvement showed a peak of MP levels at the time of the neurological onset. Phenotypic analyses showed that MP from infected mice were predominantly of platelet, endothelial and erythrocytic origins. To determine the in vivo fate of MP, we adoptively transferred fluorescently labelled MP from mice with CM into healthy or infected recipient mice. MP were quickly cleared following intravenous injection, but microscopic examination revealed arrested MP lining the endothelium of brain vessels of infected, but not healthy, recipient mice. To determine the pathogenicity of MP, we transferred MP from activated endothelial cells into healthy recipient mice and this induced CM-like brain and lung pathology. This study supports a pathogenic role for MP in the aggravation of the neurological lesion and suggests a causal relationship between MP and the development of CM. © 2014 El-Assaad et al
On spectral analysis of a magnetic Schrodinger operator on planar mixed automorphic forms
We characterize the space of the so-called planar mixed automorphic forms of
type with respect to an equivariant pair as the image
of the usual automorphic forms by an appropriate transform and we investigate
some concrete basic spectral properties of a magnetic Schrodinger operator
acting on them. The associated polynomials constitute classes of generalized
complex polynomials of Hermite type.Comment: 10 pages. This is a substantially reorganized, revised and improved
exposition. Misprints corrected and references added. Submitte
Radiocarbon Ecology of the Land Snail Helix Melanostoma in Northeastern Libya
Terrestrial gastropods are problematical for radiocarbon (14C) measurement because they tend to incorporate carbon from ancient sources as a result of their dietary behavior. The 14C ecology of the pulmonate land snail, Helix melanostoma in Cyrenaica, northeastern Libya, was investigated as part of a wider study on the potential of using terrestrial mollusk shell for 14C dating of archaeological deposits. H. melanostoma was selected out of the species available in the region as it has the most predictable 14C ecology and also had a ubiquitous presence within the local archaeology. The ecological observations indicate that H. melanostoma has a very homogenous 14C ecology with consistent variations in F14C across sample sites controlled by availability of dietary vegetation. The majority of dated specimens from nonurbanized sample locations have only a small old carbon effect, weighted mean of 476±48 14C yr, with between ~1% and 9% of dietary F14C from non-organic carbonate sources. Observed instabilities in the 14C ecology can all be attributed to the results of intense human activity not present before the Roman Period. Therefore, H. melanostoma and species with similar ecological behavior are suitable for 14C dating of archaeological and geological deposits with the use of a suitable offset
A three-step approach for co-locating nature-based solutions within offshore wind farms
This is the final version. Available from Frontiers Media via the DOI in this record. Data availability statement:
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.The extent of seabed licensed for offshore renewables is being expanded with the global requirement to reduce carbon emissions. The opportunity for Nature-based Solutions for restoration, conservation, mariculture, infrastructure protection, and carbon sequestration initiatives are being explored internationally. Co-location of marine renewable or structures with conservation initiatives offers the opportunity to support populations of threatened species and contribute to wider ecosystem services and benefits. Building on experience from a North Sea project, we explore the feasibility to co-locate bivalve species at offshore wind farms. We present a three-step approach to identify offshore wind farm sites with the potential to co-locate with compatible species within a marine licensed area, based on environmental and physical conditions and biological tolerances. These steps are, (1) information collection and data synthesis, (2) data analysis through site suitability and species compatibility assessments, and (3) numerical modelling approaches to test the feasibility of pilot studies and scale-up planned operations. This approach supports feasibility assessment by identification of sites where Nature-based Solution project success is more likely or certain, thereby reducing project costs and risk of failure. An example case study is provided using Gunfleet Sands offshore wind farm (southeast England) and the restoration and conservation of the commercially valuable European Flat Oyster (Ostrea edulis).European Regional Development Fund (ERDF)Danish Hydraulics Institut
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Couple-Based HIV Prevention in the United States: Advantages, Gaps, and Future Directions
This article presents an overview of couple-based HIV prevention research to date, advantages of using and core components of couple-based interventions, gaps in the current understanding of couple-based HIV prevention, status of dissemination research and the transportability of effective couple-based HIV prevention and treatment to real-world settings, and recommendations for future directions in couple-based prevention and treatment. Couple-based studies conducted among several populations—heterosexuals, men who have sex with men, and drug users—reported in the research literature were reviewed. Commonalities and limitations were noted in customary focus areas of the couple-based approaches: sexual and drug risk reduction, HIV testing behaviors, adherence to HIV treatment, and prevention of mother-to-child transmission. Couple-based intervention strategies have been rigorously tested and are a valuable addition to the arsenal of HIV prevention strategies.
Immediate needs and opportunities include couple-based intervention strategies for prevention of HIV and other sexually transmitted infections among serodiscordant couples, couples who do not know their HIV status, and couples in whom both partners are HIV negative, but at risk of HIV infection. There is a particular need to develop couple-based intervention strategies for men who have sex with men and for drug-involved couples
Covalent organic frameworks
The first members of covalent organic frameworks (COF) have been designed and successfully synthesized by
condensation reactions of phenyl diboronic acid C6H4[B(OH)2]2 and hexahydroxytriphenylene C18H6(OH)6. The
high crystallinity of the products (C3H2BO)6 (C9H12)1 (COF-1) and C9H4BO2 (COF-5) has allowed definitive
resolution of their structure by powder X-ray diffraction methods which reveal expanded porous graphitic layers that
are either staggered (COF-1, P63/mmc) or eclipsed (COF-5, P6/mmm). They exhibit high thermal stability (to
temperatures up to 500- to 600-C), permanent porosity, and high surface areas (711 and 1590 m2/g, respectively)
surpassing those of related inorganic frameworks. A similar approach has been used for the design of other extended
structures
Band dispersion in the deep 1s core level of graphene
Chemical bonding in molecules and solids arises from the overlap of valence
electron wave functions, forming extended molecular orbitals and dispersing
Bloch states, respectively. Core electrons with high binding energies, on the
other hand, are localized to their respective atoms and their wave functions do
not overlap significantly. Here we report the observation of band formation and
considerable dispersion (up to 60 meV) in the core level of the carbon
atoms forming graphene, despite the high C binding energy of 284
eV. Due to a Young's double slit-like interference effect, a situation arises
in which only the bonding or only the anti-bonding states is observed for a
given photoemission geometry.Comment: 12 pages, 3 figures, including supplementary materia
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