1,205 research outputs found
Electron Radiated Power in Cyclotron Radiation Emission Spectroscopy Experiments
The recently developed technique of Cyclotron Radiation Emission Spectroscopy
(CRES) uses frequency information from the cyclotron motion of an electron in a
magnetic bottle to infer its kinetic energy. Here we derive the expected radio
frequency signal from an electron in a waveguide CRES apparatus from first
principles. We demonstrate that the frequency-domain signal is rich in
information about the electron's kinematic parameters, and extract a set of
measurables that in a suitably designed system are sufficient for disentangling
the electron's kinetic energy from the rest of its kinematic features. This
lays the groundwork for high-resolution energy measurements in future CRES
experiments, such as the Project 8 neutrino mass measurement.Comment: 15 pages, 10 figure
Near-threshold production of omega mesons in the pn -> d omega reaction
The first measurement of the p n -> d omega total cross section has been
achieved at mean excess energies of Q = 28 and 57 MeV by using a deuterium
cluster-jet target. The momentum of the fast deuteron was measured in the ANKE
spectrometer at COSY-Juelich and that of the slow "spectator" proton p(sp) from
the p d -> p(sp) d omega reaction in a silicon telescope placed close to the
target. The cross sections lie above those measured for p p -> p p omega but
seem to be below theoretical predictions.Comment: 7 pages, 8 figures; second approach to describe the background has
been added; results changed insignificantly, EPJ in pres
The copy number variant involving part of the \u3b17 nicotinic receptor gene contains a polymorphic inversion.
The \u3b17 nicotinic acetylcholine receptor gene (CHRNA7) is located at 15q13\u2013q14 in a region that is strongly linked to the P50 sensory gating deficit, an endophenotype of schizophrenia and bipolar disorder. Part of the gene is a copy number variant, due to a duplication of exons 5\u201310 and 3\u2032 sequence in CHRFAM7A, which is present in many but not all humans. Maps of this region show that the two genes are in opposite orientation in the individual mainly represented in the public access human DNA sequence database (Build 36), suggesting that an inversion had occurred since the duplication. We have used fluorescent in situ hybridization to investigate this putative inversion. Analysis of interphase chromosomes in 12 individuals confirms the occurrence of an inversion and indicates that CHRFAM7A exists in both orientations with similar frequency. We showed that the 2\u2009bp deletion polymorphism in exon 6 of CHRFAM7A is in strong linkage disequilibrium with the inversion polymorphism (r2=0.82, CI 0.53\u20131.00, P=0.00003), which can therefore be used as a surrogate marker. Previous associations of endophenotypes of schizophrenia with the 2\u2009bp deletion might therefore be due to the orientation of the duplicon containing CHRFAM7A
Extended morphometric analysis of neuronal cells with Minkowski valuations
Minkowski valuations provide a systematic framework for quantifying different
aspects of morphology. In this paper we apply vector- and tensor-valued
Minkowski valuations to neuronal cells from the cat's retina in order to
describe their morphological structure in a comprehensive way. We introduce the
framework of Minkowski valuations, discuss their implementation for neuronal
cells and show how they can discriminate between cells of different types.Comment: 14 pages, 18 postscript figure
No Dynamics in the Extremal Kerr Throat
Motivated by the Kerr/CFT conjecture, we explore solutions of vacuum general
relativity whose asymptotic behavior agrees with that of the extremal Kerr
throat, sometimes called the Near-Horizon Extreme Kerr (NHEK) geometry. We
argue that all such solutions are diffeomorphic to the NHEK geometry itself.
The logic proceeds in two steps. We first argue that certain charges must
vanish at all times for any solution with NHEK asymptotics. We then analyze
these charges in detail for linearized solutions. Though one can choose the
relevant charges to vanish at any initial time, these charges are not
conserved. As a result, requiring the charges to vanish at all times is a much
stronger condition. We argue that all solutions satisfying this condition are
diffeomorphic to the NHEK metric.Comment: 42 pages, 3 figures. v3: minor clarifications and correction
Deadwood in forest stands close to old-growthness under Mediterranean conditions in the Italian Peninsula
Considering that indicators of old-growth features can vary across the European ecoregions, this paper provides some results to identify the distinctive traits of old-growth forests in the Mediterranean ecoregion. Deadwood occurrence as indicator of naturalness is investigated in some remote forest areas that have developed in absence of anthropogenic disturbance over the past few decades. Eleven study sites across the Italian peninsula were elected and records of deadwood were carried out in 1-ha size plots. Deadwood volume, deadwood types and decay stages were inventoried in the selected sites. The amounts of deadwood indicate a large variability among the investigated forest stands: the total volume ranged between 2 and 143 m3ha-1, with an average of 60 m3ha-1. Lying deadwood is the most abundant component of deadwood in the investigated forests, due to the natural mortality occurring in the stands in relation to the processes established in the last decades. On the contrary, stumps are the less represented type of deadwood in almost all the study areas. All the decay classes are present in each study site. The amount of deadwood in Southern Europe, even if lower than that reported for North and Central European countries, could have a different meaning due to the faster decay occurring in Mediterranean forest ecosystems. For this reason, old-growth features and the characteristics of each indicator should be framed and referred to well-defined climatic and biogeographic contexts. Distinctively, under the conditions here investigated, three main deadwood features prove to characterize forest stands close to old-growthness: a ratio of dead to living wood not lower than 10%; lying deadwood much more abundant than the standing one; large range of deadwood size and decay classes across all the deadwood components
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