7,201 research outputs found
Light Colored Scalar as Messenger of Up-Quark Flavor Dynamics in Grand Unified Theories
The measured forward-backward asymmetry in the t tbar production at the
Tevatron might be explained by the additional exchange of a colored weak
singlet scalar. Such state appears in some of the grand unified theories and
its interactions with the up-quarks are purely antisymmetric in flavor space.
We systematically investigate the resulting impact on charm and top quark
physics. The constraints on the relevant Yukawa couplings come from the
experimentally measured observables related to D0--D0bar oscillations, as well
as di-jet and single top production measurements at the Tevatron. After fully
constraining the relevant Yukawa couplings, we predict possible signatures of
this model in rare top quark decays. In a class of grand unified models we
demonstrate how the obtained information enables to constrain the Yukawa
couplings of the up-quarks at very high energy scale.Comment: 13 pages, 11 figures, version as published in PR
Monitoring accretion rate variability in the Orion Nebula Cluster with the Wendelstein Wide Field Imager
The understanding of the accretion process has a central role in the
understanding of star and planet formation. We aim to test how accretion
variability influences previous correlation analyses of the relation between
X-ray activity and accretion rates, which is important for understanding the
evolution of circumstellar disks and disk photoevaporation. We monitored
accreting stars in the Orion Nebula Cluster from November 24, 2014, until
February 17, 2019, for 42 epochs with the Wendelstein Wide Field Imager in the
Sloan Digital Sky Survey u'g'r' filters on the 2 m Fraunhofer Telescope on
Mount Wendelstein. Mass accretion rates were determined from the measured
ultraviolet excess. The influence of the mass accretion rate variability on the
relation between X-ray luminosities and mass accretion rates was analyzed
statistically. We find a typical interquartile range of ~ 0.3 dex for the mass
accretion rate variability on timescales from weeks to ~ 2 years. The
variability has likely no significant influence on a correlation analysis of
the X-ray luminosity and the mass accretion rate observed at different times
when the sample size is large enough. The observed anticorrelation between the
X-ray luminosity and the mass accretion rate predicted by models of
photoevaporation-starved accretion is likely not due to a bias introduced by
different observing times
Zur Diagnostik des Diabetes insipidus unter besonderer Berücksichtigung hypophysektomierter Patienten
Verschiedene, am gleichen Patienten durchgeführte Stimulationsteste für die ADH-Sekretion (17-Std.-Durstversuch, Carter-Robbins-Test, osmotische Diurese) zeigen eine ausgezeichnete Korrelation. Auf Grund dieser Ergebnisse werden Richtlinien zur möglichst einfachen Diagnostik einer Konzentrationsstörung vorgeschlagen. In den meisten Fällen kann allein schon auf Grund eines exakt durchgeführten Durstversuchs eine Konzentrationsstörung nachgewiesen (höchste Urinosmolalität 750 mOsm/kg) werden. Lediglich bei einer höchsten Urinosmolalität im 17-Std.-Durstversuch zwischen 500 und 750 mOsm/kg müssen aufwendigere und den Patienten mehr belastende Tests (z. B. Carter-Robbins-Test) eingesetzt werden, um das Vorliegen bzw. den Grad einer Konzentrationsstörung endgültig diagnostizieren zu können. ADH-Injektionen dienen dabei zur Differenzierung zwischen einem ADH-Mangel und einer mangelhaften ADH-Ansprechbarkeit der Niere. Unsere Untersuchungen an hypophysektomierten Patienten (N=29) zeigen auch bei Patienten ohne polyurisch-polydiptisches Syndrom (N=22) eine gegenüber Normalpersonen signifikant eingeschränkte Konzentrationsleistung im 17-Std.-Durstversuch.The results of three different stimulation tests for ADH (17 hours thirst period, Carter-Robbins-test, osmotic diuresis) correlate well in the same patient. Because of this we propose a simplified procedure for the detection of failure to produce a concentrated urine. In most cases merely on the basis of a precisely executed thirst period test, one can either recognize an abnormality of concentration (highest urine osmolality less than 500 mOsm/kg), or exlude it (highest urine osmolality greater than 750 mOsm/kg). Only when the highest urine osmolality lies between 500 and 750 mOsm/kg after a 17 hour thirst must more painstaking tests (e.g. Carter-Robbins test) be employed to determine both the presence of and the degree of a failure to produce a concentrated urine. An injection of ADH can be used to differentiate between a deficiency of ADH and a defective response of the kidneys to ADH. Our investigations on hypophysectomized patients (n=29) showed that also in patients without the syndrome of polyuria-polydypsia (n=22), there was a significantly reduced capacity to concentrate urine during a 17 hour thirst period, as compared with normal people
Separated Oscillatory Fields for High-Precision Penning Trap Mass Spectrometry
Ramsey's method of separated oscillatory fields is applied to the excitation
of the cyclotron motion of short-lived ions in a Penning trap to improve the
precision of their measured mass. The theoretical description of the extracted
ion-cyclotron-resonance line shape is derived out and its correctness
demonstrated experimentally by measuring the mass of the short-lived Ca
nuclide with an uncertainty of using the ISOLTRAP Penning
trap mass spectrometer at CERN. The mass value of the superallowed beta-emitter
Ca is an important contribution for testing the conserved-vector-current
hypothesis of the electroweak interaction. It is shown that the Ramsey method
applied to mass measurements yields a statistical uncertainty similar to that
obtained by the conventional technique ten times faster.Comment: 5 pages, 4 figures, 0 table
A format for phylogenetic placements
We have developed a unified format for phylogenetic placements, that is,
mappings of environmental sequence data (e.g. short reads) into a phylogenetic
tree. We are motivated to do so by the growing number of tools for computing
and post-processing phylogenetic placements, and the lack of an established
standard for storing them. The format is lightweight, versatile, extensible,
and is based on the JSON format which can be parsed by most modern programming
languages. Our format is already implemented in several tools for computing and
post-processing parsimony- and likelihood-based phylogenetic placements, and
has worked well in practice. We believe that establishing a standard format for
analyzing read placements at this early stage will lead to a more efficient
development of powerful and portable post-analysis tools for the growing
applications of phylogenetic placement.Comment: Documents version 3 of the forma
Penning trap mass measurements on (99-109)$Cd with ISOLTRAP and implications on the rp process
Penning trap mass measurements on neutron-deficient Cd isotopes (99-109)Cd
have been performed with the ISOLTRAP mass spectrometer at ISOLDE/CERN, all
with relative mass uncertainties below 3*10^8. A new mass evaluation has been
performed. The mass of 99Cd has been determined for the first time which
extends the region of accurately known mass values towards the doubly magic
nucleus 100Sn. The implication of the results on the reaction path of the rp
process in stellar X-ray bursts is discussed. In particular, the uncertainty of
the abundance and the overproduction created by the rp-process for the mass A =
99 is demonstrated by reducing the uncertainty of the proton-separation energy
of 100In Sp(100In) by a factor of 2.5.Comment: 14 pages, 9 figure
Generating reversible circuits from higher-order functional programs
Boolean reversible circuits are boolean circuits made of reversible
elementary gates. Despite their constrained form, they can simulate any boolean
function. The synthesis and validation of a reversible circuit simulating a
given function is a difficult problem. In 1973, Bennett proposed to generate
reversible circuits from traces of execution of Turing machines. In this paper,
we propose a novel presentation of this approach, adapted to higher-order
programs. Starting with a PCF-like language, we use a monadic representation of
the trace of execution to turn a regular boolean program into a
circuit-generating code. We show that a circuit traced out of a program
computes the same boolean function as the original program. This technique has
been successfully applied to generate large oracles with the quantum
programming language Quipper.Comment: 21 pages. A shorter preprint has been accepted for publication in the
Proceedings of Reversible Computation 2016. The final publication is
available at http://link.springer.co
HITRAP: A facility at GSI for highly charged ions
An overview and status report of the new trapping facility for highly charged
ions at the Gesellschaft fuer Schwerionenforschung is presented. The
construction of this facility started in 2005 and is expected to be completed
in 2008. Once operational, highly charged ions will be loaded from the
experimental storage ring ESR into the HITRAP facility, where they are
decelerated and cooled. The kinetic energy of the initially fast ions is
reduced by more than fourteen orders of magnitude and their thermal energy is
cooled to cryogenic temperatures. The cold ions are then delivered to a broad
range of atomic physics experiments.Comment: 8 pages, 11 figure
Direct mass measurements beyond the proton drip-line
First on-line mass measurements were performed at the SHIPTRAP Penning trap
mass spectrometer. The masses of 18 neutron-deficient isotopes in the
terbium-to-thulium region produced in fusion-evaporation reactions were
determined with relative uncertainties of about , nine of them
for the first time. Four nuclides (Ho and Tm) were
found to be proton-unbound. The implication of the results on the location of
the proton drip-line is discussed by analyzing the one-proton separation
energies
Production and trapping of carbon clusters for absolute mass measurements at ISOLTRAP
Singly-charged carbon clusters C/sub n//sup +/ (n >or= 1) have been produced by laser-induced desorption and fragmentation of C/sub 60/ fullerenes and have been injected into and stored in the Penning trap system of the ISOLTRAP mass spectrometer at ISOLDE/CERN. The present study is the first step to extend the until now direct mass measurements at ISOLTRAP to absolute mass measurements by using clusters of /sup 12/C. (10 refs)
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