1,019 research outputs found
The Phenomenology of Universal Extra Dimensions at Hadron Colliders
Theories with extra dimensions of inverse TeV size (or larger) predict a
multitude of signals which can be searched for at present and future colliders.
In this paper, we review the different phenomenological signatures of a
particular class of models, universal extra dimensions, where all matter fields
propagate in the bulk. Such models have interesting features, in particular
Kaluza-Klein (KK) number conservation, which makes their phenomenology similar
to that of supersymmetric theories. Thus, KK excitations of matter are produced
in pairs, and decay to a lightest KK particle (LKP), which is stable and weakly
interacting, and therefore will appear as missing energy in the detector
(similar to a neutralino LSP). Adding gravitational interactions which can
break KK number conservation greatly expands the class of possible signatures.
Thus, if gravity is the primary cause for the decay of KK excitations of
matter, the experimental signals at hadron colliders will be jets + missing
energy, which is typical of supergravity models. If the KK quarks and gluons
decay first to the LKP, which then decays gravitationally, the experimental
signal will be photons and/or leptons (with some jets), which resembles the
phenomenology of gauge mediated supersymmetry breaking models.Comment: review article, 39 pages, 10 figures, uses IJMPA style file
CATS: linearizability and partition tolerance in scalable and self-organizing key-value stores
Distributed key-value stores provide scalable, fault-tolerant, and self-organizing
storage services, but fall short of guaranteeing linearizable consistency
in partially synchronous, lossy, partitionable, and dynamic networks, when data
is distributed and replicated automatically by the principle of consistent hashing.
This paper introduces consistent quorums as a solution for achieving atomic
consistency. We present the design and implementation of CATS, a distributed
key-value store which uses consistent quorums to guarantee linearizability and partition tolerance in such adverse and dynamic network conditions. CATS is
scalable, elastic, and self-organizing; key properties for modern cloud storage
middleware. Our system shows that consistency can be achieved with practical
performance and modest throughput overhead (5%) for read-intensive workloads
An evidence based guide to a safe intraoperative approach of avoiding iatrogenic lesions during difficult laparoscopic cholecystectomies
Introduction: Although there are many sources for iatrogenic lesions during laparoscopic cholecystectomy, only a few stand out as being one of the most difficult to predict due to their nature of being very hard to diagnose before surgery. Materials and Methods: a short guide of cases with an evidence-based approach to avoid laparoscopic iatrogenic lesions. Results: these cases have been classified and presented into 3 main groups: cases with abnormal arterial layout, cases with heavy alteration of the normal anatomy, and cases with anomalies of the main biliary pathway. Conclusions: while not a complete guide covering all aspects of intraoperative traps during laparoscopic cholecystectomy, this series of cases points out some dangerous situations and some simple solutions to avoid those fiercely iatrogenic lesions of the ductal and vascular landmarks associated with an otherwise simple surgical intervention that has become the golden standard of the gallbladder lithiasic pathology
Dirac-Coulomb scattering with plane wave energy eigenspinors on de Sitter expanding universe
The lowest order contribution of the amplitude of Dirac-Coulomb scattering in
de Sitter spacetime is calculated assuming that the initial and final states of
the Dirac field are described by exact solutions of the free Dirac equation on
de Sitter spacetime with a given energy and helicity. We find that the total
energy is conserved in the scattering process.Comment: 9 pages, no figure
Are we seeing the beginnings of Inflation?
Phantom Cosmology provides an unique opportunity to "connect" the phantom
driven (low en- ergy meV scale) dark energy phase to the (high energy GUT
scale) inflationary era. This is possible because the energy density increases
in phantom cosmology. We present a concrete model where the energy density, but
not the scale factor, cycles through phases of standard radiation/matter domi-
nation followed by dark energy/inflationary phases, and the pattern repeating
itself. An interesting feature of the model is that once we include
interactions between the "phantom fluid" and ordinary matter, the Big rip
singularity is avoided with the phantom phase naturally giving way to a near
exponential inflationary expansion.Comment: 17 pages, 1 figur
Remarks on the spherical waves of the Dirac field on de Sitter spacetime
The Shishkin's solutions of the Dirac equation in spherical moving frames of
the de Sitter spacetime are investigated pointing out the set of commuting
operators whose eigenvalues determine the integration constants. It is shown
that these depend on the usual angular quantum numbers and, in addition, on the
value of the scalar momentum. With these elements a new result is obtained
finding the system of solutions normalized (in generalized sense) in the scale
of scalar momentum.Comment: 7 pages, no figure
The role of reactive astrocitose in the chronological evolution of traumatic brain injury
Introduction and objectives. This study aims to investigate whether the cerebral modifications of posttraumatic reactive astrocitose can be considered an objective criterion for determining the age of traumatic cranio-cerebral lesions.
Materials and methods. The present study consists of a series of 23 medico-legal cases that underwent autopsy inTeleormanCounty(Romania) Department of Forensic Medicine during 2007–2016, with full immune-histochemical microscopic examination using GFAP staining. The study consists of two groups, a series of 13 cases with cranio-cerebral trauma with different posttraumatic survival periods and 9 cases as a control group.
Results and discussions. We discovered GFAP+ reactive astrocytes even when death occurred immediately after the trauma event and up to 4 months after the traumatic incident. We also discovered an intense positive correlation between the density of the GFAP+ cell from the perilesional area and the posttraumatic survival period. The highest cerebral density of the GFAP+ astrocytes occurred with acute death prior (1 to 24 hours) and the lowest in the chronic period (over 2 weeks).
Conclusions. The gradual and differentiated appearance of the reactive astrocytes in close relation with the cerebral posttraumatic interval, with specific lesional and perilesional distribution as well as in surrounding area, clearly demonstrates that the state of the reactive astrocitose may constitute an objective index for evaluation of the elapsed time after the posttraumatic event
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