4,962 research outputs found
Urban fiscal austerity, infrastructure provision and the struggle for regional transit in 'Motor City'
Studies suggest that urban fiscal crises trigger the institutional separation of strategic services from general purpose municipal functions. Traditional reformists have highlighted the economic benefits of regional approaches. Global austerity has created fiscal problems for central cities and suburbs alike, transforming the motives for regional solutions. This paper examines how the City of Detroit engineered a new regional arrangement with the surrounding suburbs to raise debt for the delivery of mass transit infrastructure. It represents a dual 'spatial fix' in the form of (i) a 'state territorial fix' providing fiscally stressed municipalities access to municipal bond markets and (ii) a 'speculative spatial fix' that benefits the Detroit growth coalition by linking regional mass transit to the prospect of land-use intensification. © The Author 2014
Adaptivity and a posteriori error control for bifurcation problems II: Incompressible fluid flow in open systems with Z_2 symmetry
In this article we consider the a posteriori error estimation and adaptive mesh refinement of discontinuous Galerkin finite element approximations of the bifurcation problem associated with the steady incompressible Navier-Stokes equations. Particular attention is given to the reliable error estimation of the critical Reynolds number at which a steady pitchfork or Hopf bifurcation occurs when the underlying physical system possesses reflectional or Z_2 symmetry. Here, computable a posteriori error bounds are derived based on employing the generalization of the standard Dual-Weighted-Residual approach, originally developed for the estimation of target functionals of the solution, to bifurcation problems. Numerical experiments highlighting the practical performance of the proposed a posteriori error indicator on adaptively refined computational meshes are presented
Two-versus one photon excitation laser scanning microscopy: Critical importance of excitation wavelength
It is often anticipated that two-photon excitation (TPE) laser scanning microscopy should improve cell survival and tissue penetration relative to conventional one-photon excitation (OPE) confocal scanning laser microscopy (CLSM). However few studies have directly compared live cell imaging using one- vs two-photon laser scanning microscopy. We have used calcein-loaded in situ chondrocytes within cartilage as a model for quantitatively comparing these techniques. TPE reduced photo-bleaching and improved cell viability compared to OPE. Using improved detection sensitivity coupled with increased tissue penetration of the near infra-red TPE laser, it was possible to capture images deeper within the cartilage. However, the advantages of TPE vs OPE were strongly dependent on excitation wavelength. We conclude that optimising TPE conditions is essential if the full benefits of this approach are to be realised
Solving the Hierarchy Problem with Noncompact Extra Dimensions
We show that gravitational effects of global cosmic 3-branes can be
responsible for compactification from six to four space-time dimensions,
naturally producing the observed hierarchy between electroweak and
gravitational forces. The finite radius of the transverse dimensions follows
from Einstein's equation, and is exponentially large compared with the scales
associated with the 3-brane. The space-time ends on a mild naked singularity at
the boundary of the transverse dimensions; nevertheless unitary boundary
conditions render the singularity harmless.Comment: 11 pages. Several references adde
Effects of antibiotics on α-toxin levels during Staphylococcus aureus culture: implications for the protection of chondrocytes in a model of septic arthritis.
Closing the Nuclear Fuel Cycle with a Simplified Minor Actinide Lanthanide Separation Process (ALSEP) and Additive Manufacturing
Expanded low-carbon baseload power production through the use of nuclear fission can be enabled by recycling long-lived actinide isotopes within the nuclear fuel cycle. This approach provides the benefits of (a) more completely utilizing the energy potential of mined uranium, (b) reducing the footprint of nuclear geological repositories, and (c) reducing the time required for the radiotoxicity of the disposed waste to decrease to the level of uranium ore from one hundred thousand years to a few hundred years. A key step in achieving this goal is the separation of long-lived isotopes of americium (Am) and curium (Cm) for recycle into fast reactors. To achieve this goal, a novel process was successfully demonstrated on a laboratory scale using a bank of 1.25-cm centrifugal contactors, fabricated by additive manufacturing, and a simulant containing the major fission product elements. Americium and Cm were separated from the lanthanides with over 99.9% completion. The sum of the impurities of the Am/Cm product stream using the simulated raffinate was found to be 3.2 × 10−3 g/L. The process performance was validated using a genuine high burnup used nuclear fuel raffinate in a batch regime. Separation factors of nearly 100 for 154Eu over 241Am were achieved. All these results indicate the process scalability to an engineering scale
Highly lubricious SPMK-g-PEEK implant surfaces to facilitate rehydration of articular cartilage
To enable long lasting osteochondral defect repairs which preserve the native function of synovial joint counter-face, it is essential to develop surfaces which are optimised to support healthy cartilage function by providing a hydrated, low friction and compliant sliding interface. PEEK surfaces were modified using a biocompatible 3-sulfopropyl methacrylate potassium salt (SPMK) through UV photo-polymerisation, resulting in a ∼350 nm thick hydrophilic coating rich in hydrophilic anionic sulfonic acid groups. Characterisation was done through Fourier Transformed Infrared Spectroscopy, Focused Ion Beam Scanning Electron Microscopy, and Water Contact Angle measurements. Using a Bruker UMT TriboLab, bovine cartilage sliding tests were conducted with real-time strain and shear force measurements, comparing untreated PEEK, SPMK functionalised PEEK (SPMK-g-PEEK), and Cobalt Chrome Molybdenum alloy. Tribological tests over 2.5 h at physiological loads (0.75 MPa) revealed that SPMK-g-PEEK maintains low friction (μ < 0.024) and minimises equilibrium strain, significantly reducing forces on the cartilage interface. Post-test analysis showed no notable damage to the cartilage interfacing against the SPMK functionalised surfaces. The application of a constitutive biphasic cartilage model to the experimental strain data reveals that SPMK surfaces increase the interfacial permeability of cartilage in sliding, facilitating fluid and strain recovery. Unlike previous demonstrations of sliding-induced tribological rehydration requiring specific hydrodynamic conditions, the SPMK-g-PEEK introduces a novel mode of tribological rehydration operating at low speeds and in a stationary contact area. SPMK-g-PEEK surfaces provide an enhanced cartilage counter-surface, which provides a highly hydrated and lubricious boundary layer along with supporting biphasic lubrication. Soft polymer surface functionalisation of orthopaedic implant surfaces are a promising approach for minimally invasive synovial joint repair with an enhanced bioinspired polyelectrolyte interface for sliding against cartilage. These hydrophilic surface coatings offer an enabling technology for the next generation of focal cartilage repair and hemiarthroplasty implant surfaces.</p
MitoNeoD:a mitochondria-targeted superoxide probe
Mitochondrial superoxide (O2⋅−) underlies much oxidative damage and redox signaling. Fluorescent probes can detect O2⋅−, but are of limited applicability in vivo, while in cells their usefulness is constrained by side reactions and DNA intercalation. To overcome these limitations, we developed a dual-purpose mitochondrial O2⋅− probe, MitoNeoD, which can assess O2⋅− changes in vivo by mass spectrometry and in vitro by fluorescence. MitoNeoD comprises a O2⋅−-sensitive reduced phenanthridinium moiety modified to prevent DNA intercalation, as well as a carbon-deuterium bond to enhance its selectivity for O2⋅− over non-specific oxidation, and a triphenylphosphonium lipophilic cation moiety leading to the rapid accumulation within mitochondria. We demonstrated that MitoNeoD was a versatile and robust probe to assess changes in mitochondrial O2⋅− from isolated mitochondria to animal models, thus offering a way to examine the many roles of mitochondrial O2⋅−production in health and disease
A case-control study of autism and mumps-measles-rubella vaccination using the general practice research database: design and methodology
BACKGROUND: An association between mumps-measles-rubella (MMR) vaccination and the onset of symptoms typical of autism has recently been suggested. This has led to considerable concern about the safety of the vaccine. METHODS: A matched case-control study using data derived form the United Kingdom General Practice Research Database. Children with a possible diagnosis of autism will be identified from their electronic health records. All diagnoses will be validated by a detailed review of hospital letters and by using information derived from a parental questionnaire. Ten controls per case will be selected from the database. Conditional logistic regression will be used to assess the association between MMR vaccination and autism. In addition case series analyses will be undertaken to estimate the relative incidence of onset of autism in defined time intervals after vaccination. The study is funded by the United Kingdom Medical Research Council. DISCUSSION: Electronic health databases offer tremendous opportunities for evaluating the adverse effects of vaccines. However there is much scope for bias and confounding. The rigorous validation of all diagnoses and the collection of additional information by parental questionnaire in this study are essential to minimise the possibility of misleading results
Antibodies against 9-O-acetylated sialoglycans: a potent marker to monitor clinical status in childhood acute lymphoblastic leukemia
Background: Although childhood acute lymphoblastic leukemia (ALL) is highly responsive to chemotherapy, reliable techniques are needed to determine treatment outcome and predict impending relapse. In ALL, the cell surface over expression of 9-O-acetylated sialoglycans (9-OAcSGs) on lymphoblasts and concomitant high antibody titers in patients' sera was reported. Objectives: The present study was aimed to evaluate whether anti-9-OAcSG titers can be harnessed to monitor the clinical outcome of ALL. Design and methods: Anti-9-OAcSGs were analyzed by ELISA in children receiving either UK ALL X (n = 69, Group I) in India or UK ALL 97 (n = 47, Group II) in UK along with age-matched normal healthy controls at different time points over a period of > 2 years. An attempt was also made to investigate subclass distribution of disease-specific IgG. Moreover, 17 patients having a higher sample size were longitudinally monitored. Results: Antibody levels were raised at disease presentation, decreased with remission induction, and importantly, reappeared with clinical relapse. Sera from patients with other hematological disorders and normal controls showed negligible levels of circulating anti-9-OAcSGs. In patients of both Groups I and II, the assay showed high sensitivity (98.92% and 96.77%) and specificity (92.1% and 95.91%), respectively. IgG subclass analyses during different phases of treatment revealed that 9-OAcSG-specific IgG1 could serve as a better prognostic marker in ALL. Conclusions: This study demonstrated the potential of this disease-specific antibody as an alternate marker in diagnosis and long-term assessment of ALL patients, suggesting its application in detection and prediction of impending relapse. Therefore, the expression of anti-9-OAcSGs, irrespective of their treatment protocol, may serve as an economical yet effective index for monitoring of childhood ALL
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