1,175 research outputs found
Some comments on the universal constant in DSR
Deformed Special Relativity is usually presented as a deformation of Special
Relativity accommodating a new universal constant, the Planck mass, while
respecting the relativity principle. In order to avoid some fundamental
problems (e.g. soccer ball problem), we argue that we should switch point of
view and consider instead the Newton constant as the universal constant.Comment: 12 pages, Proceedings of DICE2006 (Piombino, Italy
Changing quantum reference frames
We consider the process of changing reference frames in the case where the
reference frames are quantum systems. We find that, as part of this process,
decoherence is necessarily induced on any quantum system described relative to
these frames. We explore this process with examples involving reference frames
for phase and orientation. Quantifying the effect of changing quantum reference
frames serves as a first step in developing a relativity principle for theories
in which all objects including reference frames are necessarily quantum.Comment: 21 pages, 6 figures, comments welcome; v2 added some references; v3
published versio
Singular topologies in the Boulatov model
Through the question of singular topologies in the Boulatov model, we
illustrate and summarize some of the recent advances in Group Field Theory.Comment: 4 pages; proceedings of Loops'11 (May 2011, Madrid); v2: minor
modifications matching published versio
Density fluctuations in -deformed inflationary universe
We study the spectrum of metric fluctuation in -deformed inflationary
universe. We write the theory of scalar metric fluctuations in the
deformed Robertson-Walker space, which is represented as a non-local
theory in the conventional Robertson-Walker space. One important consequence of
the deformation is that the mode generation time is naturally determined by the
structure of the deformation.
We expand the non-local action in , with being the Hubble
parameter and the deformation parameter, and then compute the power
spectra of scalar metric fluctuations both for the cases of exponential and
power law inflations up to the first order in . We show that the
power spectra of the metric fluctuation have non-trivial corrections on the
time dependence and on the momentum dependence compared to the commutative
space results. Especially for the power law inflation case, the power spectrum
for UV modes is weakly blue shifted early in the inflation and its strength
decreases in time. The power spectrum of far-IR modes has cutoff proportional
to which may explain the low CMB quadrupole moment.Comment: final revision; 19 pages, 3 figures; to appear in Phys. Rev.
Hyperferritinemia without iron overload in patients with bilateral cataracts: a case series
Hepatologists and internists often encounter patients with unexplained high serum ferritin concentration. After exclusion of hereditary hemochromatosis and hemosiderosis, rare disorders like hereditary hyperferritinemia cataract syndrome should be considered in the differential diagnosis. This autosomal dominant syndrome, that typically presents with juvenile bilateral cataracts, was first described in 1995 and has an increasing number of recognized molecular defects within a regulatory region of the L-ferritin gene (FTL).
CASE PRESENTATION: Two patients (32 and 49-year-old Caucasian men) from our ambulatory clinic were suspected as having this syndrome and a genetic analysis was performed. In both patients, sequencing of the FTL 5' region showed previously described mutations within the iron responsive element (FTL c.33 C > A and FTL c.32G > C).
CONCLUSION: Hereditary hyperferritinemia cataract syndrome should be considered in all patients with unexplained hyperferritinemia without signs of iron overload, particularly those with juvenile bilateral cataracts. Liver biopsy and phlebotomy should be avoided in this disorder
Holonomic quantum computation in the presence of decoherence
We present a scheme to study non-abelian adiabatic holonomies for open
Markovian systems. As an application of our framework, we analyze the
robustness of holonomic quantum computation against decoherence. We pinpoint
the sources of error that must be corrected to achieve a geometric
implementation of quantum computation completely resilient to Markovian
decoherence.Comment: I. F-G. Now publishes under name I. Fuentes-Schuller Published
versio
The Free Particle in Deformed Special Relativity
The phase space of a classical particle in DSR contains de Sitter space as
the space of momenta. We start from the standard relativistic particle in five
dimensions with an extra constraint and reduce it to four dimensional DSR by
imposing appropriate gauge fixing. We analyze some physical properties of the
resulting theories like the equations of motion, the form of Lorentz
transformations and the issue of velocity. We also address the problem of the
origin and interpretation of different bases in DSR.Comment: 15 page
An algebraic Birkhoff decomposition for the continuous renormalization group
This paper aims at presenting the first steps towards a formulation of the
Exact Renormalization Group Equation in the Hopf algebra setting of Connes and
Kreimer. It mostly deals with some algebraic preliminaries allowing to
formulate perturbative renormalization within the theory of differential
equations. The relation between renormalization, formulated as a change of
boundary condition for a differential equation, and an algebraic Birkhoff
decomposition for rooted trees is explicited
Ultrasound as first line step in anaemia diagnostics
This review covers the role of ultrasonography as an essential non-invasive diagnostic approach when facing patients with anaemia, a common clinical problem. Abdomen ultrasound is well recognised as a first-line examination in the setting of blood loss, both acute and chronic. Less is clear about the additional opportunities, given by ultrasound in anaemia, due to the many other possible causes. Here we provide information on the utility of ultrasound in different contexts and a practical guide for clinicians facing anaemic patients
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