4,611 research outputs found
The Electrostatic Ion Beam Trap : a mass spectrometer of infinite mass range
We study the ions dynamics inside an Electrostatic Ion Beam Trap (EIBT) and
show that the stability of the trapping is ruled by a Hill's equation. This
unexpectedly demonstrates that an EIBT, in the reference frame of the ions
works very similar to a quadrupole trap. The parallelism between these two
kinds of traps is illustrated by comparing experimental and theoretical
stability diagrams of the EIBT. The main difference with quadrupole traps is
that the stability depends only on the ratio of the acceleration and trapping
electrostatic potentials, not on the mass nor the charge of the ions. All kinds
of ions can be trapped simultaneously and since parametric resonances are
proportional to the square root of the charge/mass ratio the EIBT can be used
as a mass spectrometer of infinite mass range
Clinicians’ perceptions of Norwegian women’s experiences of infertility diseases
Background: Norway has one of the best health systems in the world. However, it has a low birth rate, which decreased by 21.2% between 2009 and 2018, and one of the highest rates of infertility prevalence. The aim of this study is to understand how Norwegian doctors perceive female infertility diseases, namely those that are more difficult to diagnose and to treat, and that are more common in their practice. Method: Descriptive qualitative study was conducted with gynecologists and general practitioners. The sample resulted from the establishment of five criteria and on the doctors’ acceptance to participate in this study. Our sample comprised thirteen highly qualified and experienced doctors. Qualitative content analysis was the method chosen to analyze the collected data. Results: Clinical diseases (polycystic ovary syndrome, endometriosis and vulvodynia) and consequences of these diseases were the pinpointed themes. These led to a set of sub-themes: the main symptoms and the treatment of the diseases, from the perspective of both women and doctors (stigmatization, disturbances in women’s daily life, diagnostic delay, and governmental support). Conclusions: The three most relevant disorders mentioned were polycystic ovary syndrome, endometriosis and vulvodynia. These diseases cause several impacts on the lives of women, because they feel stigmatized and limited in their daily life and sexuality, and the diagnosis of these diseases takes too much time. Governments should better redistribute the financing of women’s health and allocate resources to specialized centers.info:eu-repo/semantics/publishedVersio
Selection for the combination of total protein and endurance in mice
International audienc
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 activation energy for GaAs/AlGaAs interdiffusion
Copyright 1997 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. This article appeared in Journal of Applied Physics 82, 4842 (1997) and may be found at
Spatial Hypersurfaces in Causal Set Cosmology
Within the causal set approach to quantum gravity, a discrete analog of a
spacelike region is a set of unrelated elements, or an antichain. In the
continuum approximation of the theory, a moment-of-time hypersurface is well
represented by an inextendible antichain. We construct a richer structure
corresponding to a thickening of this antichain containing non-trivial
geometric and topological information. We find that covariant observables can
be associated with such thickened antichains and transitions between them, in
classical stochastic growth models of causal sets. This construction highlights
the difference between the covariant measure on causal set cosmology and the
standard sum-over-histories approach: the measure is assigned to completed
histories rather than to histories on a restricted spacetime region. The
resulting re-phrasing of the sum-over-histories may be fruitful in other
approaches to quantum gravity.Comment: Revtex, 12 pages, 2 figure
Noninvasive electron microscopy with interaction-free quantum measurements
We propose the use of interaction-free quantum measurements with electrons to eliminate sample damage in electron microscopy. This might allow noninvasive molecular-resolution imaging. We show the possibility of such measurements in the presence of experimentally measured quantum decoherence rates and using a scheme based on existing charged particle trapping techniques.David and Lucile Packard Foundatio
The role of antihydrogen formation in the radial transport of antiprotons in positron plasmas
Simulations of the behaviour of antiprotons in positron clouds during antihydrogen formation.The work added to our understanding of the underlying processes, including the dominant role played by antihydrogen formation itself
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