406 research outputs found
Who\u27s Black, Who\u27s White, and Who Cares: Reconceptualizing the United States Definition of Race and Racial Classifications
How much would it be worth to a young man entering upon the practice of law, to be regarded as a white man rather than a colored one?... Probably most white persons if given a choice, would prefer death to life in the United States as a colored person.... Indeed, [being white] is the master-key that unlocks the golden door of opportunity.
There is no law of the United States, or of the state of Louisiana defining the limits of race-who are white and who are colored\u27? By what rule then shall any tribunal be guided in determining racial character? It may be said that all those should be classed as colored in whom appears a visible admixture of colored blood. By what law? With what justice? Why not count every- one as white in whom is visible any trace of white blood? There is but one reason to wit, the domination of the white race.\u2
Non-randomised comparison of acute and long-term outcomes of robotic versus manual ventricular tachycardia ablation in a single centre ischemic cohort.
Dynamic Nonlinear X-waves for Femtosecond Pulse Propagation in Water
Recent experiments on femtosecond pulses in water displayed long distance
propagation analogous to that reported in air. We verify this phenomena
numerically and show that the propagation is dynamic as opposed to self-guided.
Furthermore, we demonstrate that the propagation can be interpreted as due to
dynamic nonlinear X-waves whose robustness and role in long distance
propagation is shown to follow from the interplay between nonlinearity and
chromatic dispersion.Comment: 4 page
Non-randomised comparison of acute and long-term outcomes of robotic versus manual ventricular tachycardia ablation in a single centre ischemic cohort.
Quantum Cryptography
Quantum cryptography is a new method for secret communications offering the
ultimate security assurance of the inviolability of a Law of Nature. In this
paper we shall describe the theory of quantum cryptography, its potential
relevance and the development of a prototype system at Los Alamos, which
utilises the phenomenon of single-photon interference to perform quantum
cryptography over an optical fiber communications link.Comment: 36 pages in compressed PostScript format, 10 PostScript figures
compressed tar fil
Covariant Lagrange multiplier constrained higher derivative gravity with scalar projectors
We formulate higher derivative gravity with Lagrange multiplier constraint
and scalar projectors. Its gauge-fixed formulation as well as vector fields
formulation is developed and corresponding spontaneous Lorentz symmetry
breaking is investigated. We show that the only propagating mode is higher
derivative graviton while scalar and vector modes do not propagate. Despite to
higher derivatives structure of the action, its first FRW equation is the first
order differential equation which admits the inflationary universe solution.Comment: Physics Letters B published version. LaTeX 12 page
Temperature variations at diffuse and focused flow hydrothermal vent sites along the northern East Pacific Rise
Author Posting. © American Geophysical Union, 2006. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 7 (2006): Q03002, doi:10.1029/2005GC001094.In the decade following documented volcanic activity on the East Pacific Rise near 9°50′N, we monitored hydrothermal vent fluid temperature variations in conjunction with approximately yearly vent fluid sampling to better understand the processes and physical conditions that govern the evolution of seafloor hydrothermal systems. The temperature of both diffuse flow (low-temperature) and focused flow (high-temperature) vent fluids decreased significantly within several years of eruptions in 1991 and 1992. After mid-1994, focused flow vents generally exhibited periods of relatively stable, slowly varying temperatures, with occasional high- and low-temperature excursions lasting days to weeks. One such positive temperature excursion was associated with a crustal cracking event. Another with both positive and negative excursions demonstrated a subsurface connection between adjacent focused flow and diffuse flow vents. Diffuse flow vents exhibit much greater temperature variability than adjacent higher-temperature vents. On timescales of a week or less, temperatures at a given position within a diffuse flow field often varied by 5°–10°C, synchronous with near-bottom currents dominated by tidal and inertial forcing. On timescales of a week and longer, diffuse flow temperatures varied slowly and incoherently among different vent fields. At diffuse flow vent sites, the conceptual model of a thermal boundary layer immediately above the seafloor explains many of the temporal and spatial temperature variations observed within a single vent field. The thermal boundary layer is a lens of warm water injected from beneath the seafloor that is mixed and distended by lateral near-bottom currents. The volume of the boundary layer is delineated by the position of mature communities of sessile (e.g., tubeworms) and relatively slow-moving organisms (e.g., mussels). Vertical flow rates of hydrothermal fluids exiting the seafloor at diffuse vents are less than lateral flow rates of near-bottom currents (5–10 cm/s). The presence of a subsurface, shallow reservoir of warm hydrothermal fluids can explain differing temperature behaviors of adjacent diffuse flow and focused flow vents at 9°50′N. Different average temperatures and daily temperature ranges are explained by variable amounts of mixing of hydrothermal fluids with ambient seawater through subsurface conduits that have varying lateral permeability.Field and shore-based analyses have been supported by the National Science Foundation (OCE-0096468, OCE-8917311, OCE-9217026, OCE-9302205, OCE-0327261), the Woods Hole Oceanographic Institution's Vetlesen Fund and W. A. Clark Senior Scientist Chair (DJF), and the Devonshire Foundation (TMS)
Anticipating and Adapting to the Future Impacts of Climate Change on the Health, Security and Welfare of Low Elevation Coastal Zone (LECZ) Communities in Southeastern USA
Low elevation coastal zones (LECZ) are extensive throughout the southeastern United States. LECZ communities are threatened by inundation from sea level rise, storm surge, wetland degradation, land subsidence, and hydrological flooding. Communication among scientists, stakeholders, policy makers and minority and poor residents must improve. We must predict processes spanning the ecological, physical, social, and health sciences. Communities need to address linkages of (1) human and socioeconomic vulnerabilities; (2) public health and safety; (3) economic concerns; (4) land loss; (5) wetland threats; and (6) coastal inundation. Essential capabilities must include a network to assemble and distribute data and model code to assess risk and its causes, support adaptive management, and improve the resiliency of communities. Better communication of information and understanding among residents and officials is essential. Here we review recent background literature on these matters and offer recommendations for integrating natural and social sciences. We advocate for a cyber-network of scientists, modelers, engineers, educators, and stakeholders from academia, federal state and local agencies, non-governmental organizations, residents, and the private sector. Our vision is to enhance future resilience of LECZ communities by offering approaches to mitigate hazards to human health, safety and welfare and reduce impacts to coastal residents and industries
Three-year follow-up study exploring metacognition and function in individuals with first episode psychosis
Introduction: Research has demonstrated that functional outcome in psychosis is predicted by factors such as neurocognition, functional capacity, symptoms and, more recently, metacognition. Metacognitive ability has been demonstrated to mediate between neurocognition and functional outcome in First Episode Psychosis (FEP). Whether metacognition also predicts longer-term recovery in first episode is unknown. This study assessed whether neurocognition, functional capacity and metacognitive ability in FEP predicted functional outcome three years later.
Methods: Eighty individuals with First Episode Psychosis were re-contacted after an average three years (range: 26-45 month follow-up) from baseline. Twenty-six participants (33%) completed neurocognitive measures, metacognition, functional capacity, functional outcome (hours spent in structured activity per week) and psychopathology at baseline and at follow-up.
Results: Individual regression analyses demonstrated neurocognition, functional capacity and metacognitive ability at baseline significantly predicted functional outcome at three years. However, when baseline functional outcome was controlled, only metacognitive ability was a significant predictor of change in functional outcome from baseline to follow-up, p<.001. This model explained 72% (adjusted r² = .69) of the variance in functional outcome at follow-up. Negative symptoms did not change the model.
Discussion: This study demonstrated that better metacognitive ability significantly predicted improvement in functioning in FEP across a 3-year period. This highlights the potential value of clinical interventions that focus on improving metacognitive ability at first point of illness to maximize recovery
Special phase transformation and crystal growth pathways observed in nanoparticles†
Phase transformation and crystal growth in nanoparticles may happen via mechanisms distinct from those in bulk materials. We combine experimental studies of as-synthesized and hydrothermally coarsened titania (TiO(2)) and zinc sulfide (ZnS) with thermodynamic analysis, kinetic modeling and molecular dynamics (MD) simulations. The samples were characterized by transmission electron microscopy, X-ray diffraction, synchrotron X-ray absorption and scattering, and UV-vis spectroscopy. At low temperatures, phase transformation in titania nanoparticles occurs predominantly via interface nucleation at particle–particle contacts. Coarsening and crystal growth of titania nanoparticles can be described using the Smoluchowski equation. Oriented attachment-based crystal growth was common in both hydrothermal solutions and under dry conditions. MD simulations predict large structural perturbations within very fine particles, and are consistent with experimental results showing that ligand binding and change in aggregation state can cause phase transformation without particle coarsening. Such phenomena affect surface reactivity, thus may have important roles in geochemical cycling
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