289 research outputs found
Geometry from divergence functions and complex structures
Motivated by the geometrical structures of quantum mechanics, we introduce an
almost-complex structure on the product of any parallelizable
statistical manifold . Then, we use to extract a pre-symplectic form and
a metric-like tensor on from a divergence function. These tensors
may be pulled back to , and we compute them in the case of an N-dimensional
symplex with respect to the Kullback-Leibler relative entropy, and in the case
of (a suitable unfolding space of) the manifold of faithful density operators
with respect to the von Neumann-Umegaki relative entropy.Comment: 19 pages, comments are welcome
Covariant Variational Evolution and Jacobi Brackets: Fields
The analysis of the covariant brackets on the space of functions on the
solutions to a variational problem in the framework of contact geometry
initiated in the companion letter Ref.19 is extended to the case of the
multisymplectic formulation of the free Klein-Gordon theory and of the free
Schr\"{o}dinger equation.Comment: 16 page
Epistocracy for Online Deliberative Bioethics
The suggestion that deliberative democratic approaches would suit the management of bioethical policymaking in democratic pluralistic societies has triggered what has been called the deliberative turn in health policy and bioethics. Most of the empirical work in this area has focused on the allocation of healthcare resources and priority setting at the local or national level. The variety of the more or less articulated theoretical efforts behind such initiatives is remarkable and has been accompanied, to date, by an overall lack of method specificity. We propose a set of methodological requirements for online deliberative procedures for bioethics. We provide a theoretical motivation for these requirements. In particular, we discuss and adapt an epistocratic proposal and argue that, regardless of its merits as a general political theory, a more refined version of its normative claims can generate a useful framework for the design of bioethical forums that combine maximal inclusiveness with informed and reasonable deliberation
The aftermath of the Merck's HIV vaccine trial
The recently released results of the Merck's Phase IIb "test-of concept" vaccine trials have shown no protection from HIV-1 infection in the vaccinated group compared with a control group vaccinated with placebo. The study was designed to test the Merck's MRKAd5 trivalent candidate vaccine. The vaccine formulation was expected to stimulate a HIV-specific T cell immune response and to either prevent infection, or to reduce the levels of the viral load in vaccinated subjects. Upon the first evaluation of the interim data, the independent Data and Safety Monitoring Board (DSMB) underscored no protection from HIV-1 infection in the vaccine-inoculated volunteers compared with the control group; accordingly, the vaccine trial was stopped. This disappointing outcome warrants a critical analysis of the current vaccine studies and calls for a renewed effort toward a rational design of novel immunogens to be tested in large primate trials
Lagrangian description of Heisenberg and Landau-von Neumann equations of motion
An explicit Lagrangian description is given for the Heisenberg equation on
the algebra of operators of a quantum system, and for the Landau-von Neumann
equation on the manifold of quantum states which are isospectral with respect
to a fixed reference quantum state.Comment: 13 page
Covariant Variational Evolution and Jacobi Brackets: Particles
The formulation of covariant brackets on the space of solutions to a
variational problem is analyzed in the framework of contact geometry. It is
argued that the Poisson algebra on the space of functionals on fields should be
read as a Poisson subalgebra within an algebra of functions equipped with a
Jacobi bracket on a suitable contact manifold.Comment: 16 page
Covariant reduction of classical Hamiltonian Field Theories: From D'Alembert to Klein-Gordon and Schr\"odinger
A novel reduction procedure for covariant classical field theories,
reflecting the generalized symplectic reduction theory of Hamiltonian systems,
is presented. The departure point of this reduction procedure consists in the
choice of a submanifold of the manifold of solutions of the equations
describing a field theory. Then, the covariance of the geometrical objects
involved, will allow to define equations of motion on a reduced space. The
computation of the canonical geometrical structure is performed neatly by using
the geometrical framework provided by the multisymplectic description of
covariant field theories. The procedure is illustrated by reducing the
D'Alembert theory on a five-dimensional Minkowski space-time to a massive
Klein-Gordon theory in four dimensions and, more interestingly, to the
Schr\"odinger equation in 3+1 dimensions.Comment: 14 page
Periprosthetic knee infection: treatment options
Infection is one of the most catastrophic complication following total knee arthroplasty (TKA) and represents the second most common cause of TKA failure. Treatment of a patient with periprosthetic joint infection (PJI) could require often costly and prolonged hospital stays, weeks or months of antibiotic therapy, and multiple surgical procedures. The best management is still highly debating, whereas many treatment options are available. These include suppressive antibiotics, arthroscopic irrigation and debridement, open debridement with insert exchange, single-stage reimplantation and two-stage reimplantation. The choice of the treatment depends on many variables, including integrity of implant, timing of the infection, host factors (age, health, immunologic status), virulence of the infecting organism and wishes of the patient. The aim of this review is to provide a comprehensive understaning of the different options for knee PJIs
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