4,091 research outputs found
About the dynamics and thermodynamics of trapped ions
This tutorial introduces the dynamics of charged particles in a
radiofrequency trap in a very general manner to point out the differences
between the dynamics in a quadrupole and in a multipole trap. When dense
samples are trapped, the dynamics is modified by the Coulomb repulsion between
ions. To take into account this repulsion, we propose to use a method,
originally developed for particles in Penning trap, that model the ion cloud as
a cold fluid. This method can not reproduce the organisation of cold clouds as
crystals but it allows one to scale the size of large samples with the trapping
parameters and the number of ions trapped, for different linear geometries of
trap.Comment: accepted for publication in the "Modern Applications of Trapped Ions"
special issu
The Effect of Patient Weight and Provider Training and Experience on Dosing of Rocuronium
Introduction. Maintenance dosing of neuromuscular blocking agents is complex and varies with patient, procedure, and clinical situation. With this in mind, we sought to identify factors impacting the maintenance dosing of neuromuscular blockers as a step toward identifying best practice with respect to minimizing residual neuromuscular blockade. Methods. Cases utilizing rocuronium from July 1, 2010, to June 30, 2014, at the sponsoring institution were analyzed. Using a mixed model to account for repeated measures, patients were analyzed by dose and weight category as defined by the World Health Organization (eight categories ranging from very severely underweight to very severely obese) as well as by the administering provider’s level of experience. Results. The study included 12,671 patients with a mean age of 49.7 (SD 16.7). Increasing weight category and higher levels of provider experience were associated with higher doses for rocuronium. There were no differences in initial dose or in frequency of maintenance dosing by weight category after controlling for case length. Discussion. The two dosing patterns identified, higher doses for overweight patients and higher doses administered by experienced providers, are modifiable factors that could enhance patient safety
Conceptual design study for heat exhaust management in the ARC fusion pilot plant
The ARC pilot plant conceptual design study has been extended beyond its
initial scope [B. N. Sorbom et al., FED 100 (2015) 378] to explore options for
managing ~525 MW of fusion power generated in a compact, high field (B_0 = 9.2
T) tokamak that is approximately the size of JET (R_0 = 3.3 m). Taking
advantage of ARC's novel design - demountable high temperature superconductor
toroidal field (TF) magnets, poloidal magnetic field coils located inside the
TF, and vacuum vessel (VV) immersed in molten salt FLiBe blanket - this
follow-on study has identified innovative and potentially robust power exhaust
management solutions.Comment: Accepted by Fusion Engineering and Desig
Penning traps as a versatile tool for precise experiments in fundamental physics
This review article describes the trapping of charged particles. The main
principles of electromagnetic confinement of various species from elementary
particles to heavy atoms are briefly described. The preparation and
manipulation with trapped single particles, as well as methods of frequency
measurements, providing unprecedented precision, are discussed. Unique
applications of Penning traps in fundamental physics are presented.
Ultra-precise trap-measurements of masses and magnetic moments of elementary
particles (electrons, positrons, protons and antiprotons) confirm
CPT-conservation, and allow accurate determination of the fine-structure
constant alpha and other fundamental constants. This together with the
information on the unitarity of the quark-mixing matrix, derived from the
trap-measurements of atomic masses, serves for assessment of the Standard Model
of the physics world. Direct mass measurements of nuclides targeted to some
advanced problems of astrophysics and nuclear physics are also presented
EP-1054: Accelerated partial breast irradiation with 3D conformal external beams - 4-year results of a phase II study
Cosmological Histories for the New Variables
Histories and measures for quantum cosmology are investigated through a
quantization of the Bianchi IX cosmology using path integral techniques. The
result, derived in the context of Ashtekar variables, is compared with earlier
work. A non-trivial correction to the measure is found, which may dominate the
classical potential for universes on the Planck scale.Comment: 14, CGPG-94/2-
An integrated genomic analysis of lung cancer reveals loss of DUSP4 in EGFR-mutant tumors.
To address the biological heterogeneity of lung cancer, we studied 199 lung adenocarcinomas by integrating genome-wide data on copy number alterations and gene expression with full annotation for major known somatic mutations in this cancer. This showed non-random patterns of copy number alterations significantly linked to EGFR and KRAS mutation status and to distinct clinical outcomes, and led to the discovery of a striking association of EGFR mutations with underexpression of DUSP4, a gene within a broad region of frequent single-copy loss on 8p. DUSP4 is involved in negative feedback control of EGFR signaling, and we provide functional validation for its role as a growth suppressor in EGFR-mutant lung adenocarcinoma. DUSP4 loss also associates with p16/CDKN2A deletion and defines a distinct clinical subset of lung cancer patients. Another novel observation is that of a reciprocal relationship between EGFR and LKB1 mutations. These results highlight the power of integrated genomics to identify candidate driver genes within recurrent broad regions of copy number alteration and to delineate distinct oncogenetic pathways in genetically complex common epithelial cancers
Evaluation of patients treated with natalizumab for progressive multifocal leukoencephalopathy
Background: Progressive multifocal leukoencephalopathy (PML) was reported to have developed in three patients treated with natalizumab. We conducted an evaluation to determine whether PML had developed in any other treated patients.
Methods: We invited patients who had participated in clinical trials in which they received recent or long-term treatment with natalizumab for multiple sclerosis, Crohn's disease, or rheumatoid arthritis to participate. The clinical history, physical examination, brain magnetic resonance imaging (MRI), and testing of cerebrospinal fluid for JC virus DNA were used by an expert panel to evaluate patients for PML. We estimated the risk of PML in patients who completed at least a clinical examination for PML or had an MRI.
Results: Of 3417 patients who had recently received natalizumab while participating in clinical trials, 3116 (91 percent) who were exposed to a mean of 17.9 monthly doses underwent evaluation for PML. Of these, 44 patients were referred to the expert panel because of clinical findings of possible PML, abnormalities on MRI, or a high plasma viral load of JC virus. No patient had detectable JC virus DNA in the cerebrospinal fluid. PML was ruled out in 43 of the 44 patients, but it could not be ruled out in one patient who had multiple sclerosis and progression of neurologic disease because data on cerebrospinal fluid testing and follow-up MRI were not available. Only the three previously reported cases of PML were confirmed (1.0 per 1000 treated patients; 95 percent confidence interval, 0.2 to 2.8 per 1000).
Conclusions: A detailed review of possible cases of PML in patients exposed to natalizumab found no new cases and suggested a risk of PML of roughly 1 in 1000 patients treated with natalizumab for a mean of 17.9 months. The risk associated with longer treatment is not known
Particle Motion in Rapidly Oscillating Potentials: The Role of the Potential's Initial Phase
Rapidly oscillating potentials with a vanishing time average have been used
for a long time to trap charged particles in source-free regions. It has been
argued that the motion of a particle in such a potential can be approximately
described by a time independent effective potential, which does not depend upon
the initial phase of the oscillating potential. However, here we show that the
motion of a particle and its trapping condition significantly depend upon this
initial phase for arbitrarily high frequencies of the potential's oscillation.
We explain this novel phenomenon by showing that the motion of a particle is
determined by the effective potential stated in the literature only if its
initial conditions are transformed according to a transformation which we show
to significantly depend on the potential's initial phase for arbitrarily high
frequencies. We confirm our theoretical findings by numerical simulations.
Further, we demonstrate that the found phenomenon offers new ways to manipulate
the dynamics of particles which are trapped by rapidly oscillating potentials.
Finally, we propose a simple experiment to verify the theoretical findings of
this work.Comment: 9 pages, 8 figures, published in PR
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