78 research outputs found
Consistent histories of systems and measurements in spacetime
Traditional interpretations of quantum theory in terms of wave function
collapse are particularly unappealing when considering the universe as a whole,
where there is no clean separation between classical observer and quantum
system and where the description is inherently relativistic. As an alternative,
the consistent histories approach provides an attractive "no collapse"
interpretation of quantum physics. Consistent histories can also be linked to
path-integral formulations that may be readily generalized to the relativistic
case. A previous paper described how, in such a relativistic spacetime path
formalism, the quantum history of the universe could be considered to be an
eignestate of the measurements made within it. However, two important topics
were not addressed in detail there: a model of measurement processes in the
context of quantum histories in spacetime and a justification for why the
probabilities for each possible cosmological eigenstate should follow Born's
rule. The present paper addresses these topics by showing how Zurek's concepts
of einselection and envariance can be applied in the context of relativistic
spacetime and quantum histories. The result is a model of systems and
subsystems within the universe and their interaction with each other and their
environment.Comment: RevTeX 4; 37 pages; v2 is a revision in response to reviewer
comments, connecting the discussion in the paper more closely to consistent
history concepts; v3 has minor editorial corrections; accepted for
publication in Foundations of Physics; v4 has a couple minor typographical
correction
Dose Precision Using a Pretransplant Test PK of Intravenous Busulfan Prior to BuCyVP-16 Preparative Regimen in Lymphoma
Pesquisa de anticorpos para sÃfilis e toxoplasmose em recém-nascidos em hospital de Ribeirão Preto, SP, Brasil
Cádmio em Latossolo Vermelho cultivado com milho em colunas: mobilidade e biodisponibilidade
The Earth: Plasma Sources, Losses, and Transport Processes
This paper reviews the state of knowledge concerning the source of magnetospheric plasma at Earth. Source of plasma, its acceleration and transport throughout the system, its consequences on system dynamics, and its loss are all discussed. Both observational and modeling advances since the last time this subject was covered in detail (Hultqvist et al., Magnetospheric Plasma Sources and Losses, 1999) are addressed
Effects of the application of sewage sludge and petrochemical residue in maize culture as source of micro-nutrients on soils of Paraná state
Cost-effectiveness of replacing versus discarding the nail in children with nail bed injury
Every year in the UK, around 10 000 children need to have operations to mend injuries to the bed of their fingernails. Currently, most children have their fingernail placed back on the injured nail bed after the operation. The NINJA trial found that children were slightly less likely to have an infection if the nail was thrown away rather than being put back, but the difference between groups was small and could have be due to chance. This study looked at whether replacing the nail is cost-effective compared with throwing it away. Using data from the NINJA trial, we compared costs, healthcare use, and quality of life and assessed the cost-effectiveness of replacing the nail. It was found that throwing the nail away after surgery would save the National Health Service (NHS) £75 (€85) per operation compared with placing the nail back on the nail bed. Changing clinical practice could save the NHS in England £720 000 (€819 000) per year
Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures
Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo
Polyoma Virus Is The Principal Cause Of Cystitis Following Alemtuzumab-Based Allogeneic Stem Cell Transplantation
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