468 research outputs found
Towards a sustainable and equitable blue economy
The global rush to develop the \u2018blue economy\u2019 risks harming both the marine environment and human wellbeing. Bold policies and actions are urgently needed. We identify five priorities to chart a course towards an environmentally sustainable and socially equitable blue economy
Field Induced Reduction of the Low Temperature Superfluid Density in YBa2Cu3O6.95
A novel high magnetic field (8 T) spectrometer for muon spin rotation has
been used to measure the temperature dependence of the in-plane magnetic
penetration depth in YBa2Cu3O6.95. At low H and low T, the penetration depth
exhibits the characteristic linear T dependence associated with the energy gap
of a d_x^2-y^2-wave superconductor. However, at higher fields the penetration
depth is essentially temperature independent at low T. We discuss possible
interpretations of this surprising new feature in the low-energy excitation
spectrum.Comment: 8 pages, 4 figures, 1 RevTex file and 4 postscript figure
Frustrated kinetic energy, the optical sum rule, and the mechanism of superconductivity
The theory that the change of the electronic kinetic energy in a direction
perpendicular to the CuO-planes in high-temperature superconductors is a
substantial fraction of the condensation energy is examined. It is argued that
the consequences of this theory based on a rigorous -axis conductivity sum
rule are consistent with recent optical and penetration depth measurements.Comment: 4 pages (RevTeX) and 2 eps figure
Impairment of NO-Dependent Relaxation in Intralobar Pulmonary Arteries: Comparison of Urban Particulate Matter and Manufactured Nanoparticles
International audienceBACKGROUND AND OBJECTIVES: Because pulmonary circulation is the primary vascular target of inhaled particulate matter (PM), and nitric oxide is a major vasculoprotective agent, in this study we investigated the effect of various particles on the NO-cyclic guanosine monophosphate (cGMP) pathway in pulmonary arteries. METHODS: We used intrapulmonary arteries and/or endothelial cells, either exposed in vitro to particles or removed from PM-instilled animals for assessment of vasomotricity, cGMP and reactive oxygen species (ROS) levels, and cytokine/chemokine release. RESULTS: Endothelial NO-dependent relaxation and cGMP accumulation induced by acetylcholine (ACh) were both decreased after 24 hr exposure of rat intrapulmonary arteries to standard reference material 1648 (SRM1648; urban PM). Relaxation due to NO donors was also decreased by SRM1648, whereas responsiveness to cGMP analogue remained unaffected. Unlike SRM1648, ultrafine carbon black and ultrafine and fine titanium dioxide (TiO2) manufactured particles did not impair NO-mediated relaxation. SRM1648-induced decrease in relaxation response to ACh was prevented by dexamethasone (an anti-inflammatory agent) but not by antioxidants. Accordingly, SRM1648 increased the release of proinflammatory mediators (tumor necrosis factor-alpha, interleukin-8) from intrapulmonary arteries or pulmonary artery endothelial cells, but did not elevate ROS levels within intrapulmonary arteries. Decreased relaxation in response to ACh was also evidenced in intrapulmonary arteries removed from rats intratracheally instilled with SRM1648, but not with fine TiO2. CONCLUSION: In contrast to manufactured particles (including nanoparticles), urban PM impairs NO but not cGMP responsiveness in intrapulmonary arteries. We attribute this effect to oxidative-stress-independent inflammatory response, resulting in decreased guanylyl cyclase activation by NO. Such impairment of the NO pathway may contribute to urban-PM-induced cardiovascular dysfunction
Melting and Dimensionality of the Vortex Lattice in Underdoped YBa2Cu3O6.60
Muon spin rotation measurements of the magnetic field distribution in the
vortex state of the oxygen deficient high-Tc superconductor YBa{2}Cu{3}O{6.60}
reveal a vortex-lattice melting transition at much lower temperature than that
in the fully oxygenated material. The transition is best described by a model
in which adjacent layers of ``pancake'' vortices decouple in the liquid phase.
Evidence is also found for a pinning-induced crossover from a solid 3D to
quasi-2D vortex lattice, similar to that observed in the highly anisotropic
superconductor Bi{2+x}Sr{2-x}CaCu{2}O{8+y}.Comment: 8 pages, 4 figures, 5 postscript file
I Me Mine: on a Confusion Concerning the Subjective Character of Experience
In recent debates on phenomenal consciousness, a distinction is sometimes made, after Levine (2001) and Kriegel (2009), between the “qualitative character” of an experience, i.e. the specific way it feels to the subject (e.g. blueish or sweetish or pleasant), and its “subjective character”, i.e. the fact that there is anything at all that it feels like to her. I argue that much discussion of subjective character is affected by a conflation between three different notions. I start by disentangling the three notions in question, under the labels of “for-me-ness”, “me-ness” and “mineness”. Next, I argue that these notions are not equivalent; in particular, there is no conceptual implication from for-me-ness to me-ness or mineness. Empirical considerations based on clinical cases additionally suggest that the three notions may also correspond to different properties (although the claim of conceptual non-equivalence does not depend on this further point). The aim is clarificatory, cautionary but also critical: I examine four existing arguments from subjective character that are fuelled by an undifferentiated use of the three notions, and find them to be flawed for this reason
Indigenous identity, natural resources, and contentious politics in Bolivia: a disaggregated conflict analysis; 2000-2011
How do natural resources and ethnic identity interact to incite or to mitigate
social conflict? This article argues that high-value natural resources can act as an
important catalyst for the politicization of ethnic, specifically indigenous identity,
and contribute to social conflict as they limit the malleability of identity frames
and raise the stakes of confrontations. We test this argument using unique subnational
data from Bolivian provinces. Drawing on Bolivian newspaper reports,
we code conflict events for all of the 112 provinces from 2000 to 2011. We
join this conflict data with information on local ethnic composition from the
census, the political representation of ethnic groups at the national level, as well
as geo-spatial information on gas deposits. Using time-series cross-sectional
count models, we show a significant conflict-promoting effect of the share of
indigenous people in provinces with gas reserves, but not without
Mechanism of cell death resulting from DNA interstrand cross-linking in mammalian cells
DNA interstrand cross-links (ICLs) are critical cytotoxic lesions produced by cancer chemotherapeutic agents such as the nitrogen mustards and platinum drugs; however, the exact mechanism of ICL-induced cell death is unclear. Here, we show a novel mechanism of p53-independent apoptotic cell death involving prolonged cell-cycle (G2) arrest, ICL repair involving HR, transient mitosis, incomplete cytokinesis, and gross chromosomal abnormalities resulting from ICLs in mammalian cells. This characteristic ‘giant' cell death, observed by using time-lapse video microscopy, was reduced in ICL repair ERCC1- and XRCC3-deficient cells. Collectively, the results illustrate the coordination of ICL-induced cellular responses, including cell-cycle arrest, DNA damage repair, and cell death
Adipose-Derived Stem Cells Stimulate Regeneration of Peripheral Nerves: BDNF Secreted by These Cells Promotes Nerve Healing and Axon Growth De Novo
Transplantation of adipose-derived mesenchymal stem cells (ASCs) induces tissue regeneration by accelerating the growth of blood vessels and nerve. However, mechanisms by which they accelerate the growth of nerve fibers are only partially understood. We used transplantation of ASCs with subcutaneous matrigel implants (well-known in vivo model of angiogenesis) and model of mice limb reinnervation to check the influence of ASC on nerve growth. Here we show that ASCs stimulate the regeneration of nerves in innervated mice's limbs and induce axon growth in subcutaneous matrigel implants. To investigate the mechanism of this action we analyzed different properties of these cells and showed that they express numerous genes of neurotrophins and extracellular matrix proteins required for the nerve growth and myelination. Induction of neural differentiation of ASCs enhances production of brain-derived neurotrophic factor (BDNF) as well as ability of these cells to induce nerve fiber growth. BDNF neutralizing antibodies abrogated the stimulatory effects of ASCs on the growth of nerve sprouts. These data suggest that ASCs induce nerve repair and growth via BDNF production. This stimulatory effect can be further enhanced by culturing the cells in neural differentiation medium prior to transplantation
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