527 research outputs found
Accurate Modeling of Weak Lensing with the sGL Method
We revise and extend the stochastic approach to cumulative weak lensing
(hereafter the sGL method) first introduced in Ref. [1]. Here we include a
realistic halo mass function and density profiles to model the distribution of
mass between and within galaxies, galaxy groups and galaxy clusters. We also
introduce a modeling of the filamentary large-scale structures and a method to
embed halos into these structures. We show that the sGL method naturally
reproduces the weak lensing results for the Millennium Simulation. The strength
of the sGL method is that a numerical code based on it can compute the lensing
probability distribution function for a given inhomogeneous model universe in a
few seconds. This makes it a useful tool to study how lensing depends on
cosmological parameters and its impact on observations. The method can also be
used to simulate the effect of a wide array of systematic biases on the
observable PDF. As an example we show how simple selection effects may reduce
the variance of observed PDF, which could possibly mask opposite effects from
very large scale structures. We also show how a JDEM-like survey could
constrain the lensing PDF relative to a given cosmological model. The updated
turboGL code is available at turboGL.org.Comment: PRD style: 20 pages, 10 figures; replaced to match the improved
version accepted for publication in PRD. The updated turboGL code can be
downloaded at http://www.turbogl.org
The stellar content of the infalling molecular clump G286.21+0.17
The early evolution during massive star cluster formation is still uncertain.
Observing embedded clusters at their earliest stages of formation can provide
insight into the spatial and temporal distribution of the stars and thus probe
different star cluster formation models. We present near-infrared imaging of an
8'*13'(5.4pc*8.7pc) region around the massive infalling clump G286.21+0.17(also
known as BYF73). The stellar content across the field is determined and
photometry is derived in order to { obtain} stellar parameters for the cluster
members. We find evidence for some sub-structure (on scales less than a pc
diameter) within the region with apparently at least three different
sub-clusters associated with the molecular clump based on differences in
extinction and disk fractions. At the center of the clump we identify a deeply
embedded sub-cluster. Near-infrared excess is detected for 39-44% in the two
sub-clusters associated with molecular material and 27% for the exposed
cluster. Using the disk excess as a proxy for age this suggests the clusters
are very young. The current total stellar mass is estimated to be at least 200
Msun. The molecular core hosts a rich population of pre-main sequence stars.
There is evidence for multiple events of star formation both in terms of the
spatial distribution within the star forming region and possibly from the disk
frequency.Comment: Submitted to A
Chaos, Determinacy and Fractals in Active-Sterile Neutrino Oscillations in the Early Universe
The possibility of light sterile neutrinos allows for the resonant production
of lepton number in the early universe through matter-affected neutrino mixing.
For a given a mixing of the active and sterile neutrino states it has been
found that the lepton number generation process is chaotic and strongly
oscillatory. We undertake a new study of this process' sensitivity to initial
conditions through the quantum rate equations. We confirm the chaoticity of the
process in this solution, and moreover find that the resultant lepton number
and the sign of the asymmetry produces a fractal in the parameter space of
mass, mixing angle and initial baryon number. This has implications for future
searches for sterile neutrinos, where arbitrary high sensitivity could not be
determinate in forecasting the lepton number of the universe.Comment: 6 pages, 3 figure
Superweakly interacting dark matter from the Minimal Walking Technicolor
We study a superweakly interacting dark matter particle motivated by minimal
walking technicolor theories. Our WIMP is a mixture of a sterile state and a
state with the charges of a standard model fourth family neutrino. We show that
the model can give the right amount of dark matter over a range of the WIMP
mass and mixing angle. We compute bounds on the model parameters from the
current accelerator data including the oblique corrections to the precision
electroweak parameters, as well as from cryogenic experiments, Super-Kamiokande
and from the IceCube experiment. We show that consistent dark matter solutions
exist which satisfy all current constraints. However, almost the entire
parameter range of the model lies within the the combined reach of the next
generation experiments.Comment: 29 pages, 6 figure
Gas Kinematics and Excitation in the Filamentary IRDC G035.39-00.33
Some theories of dense molecular cloud formation involve dynamical
environments driven by converging atomic flows or collisions between
preexisting molecular clouds. The determination of the dynamics and physical
conditions of the gas in clouds at the early stages of their evolution is
essential to establish the dynamical imprints of such collisions, and to infer
the processes involved in their formation. We present multi-transition 13CO and
C18O maps toward the IRDC G035.39-00.33, believed to be at the earliest stages
of evolution. The 13CO and C18O gas is distributed in three filaments
(Filaments 1, 2 and 3), where the most massive cores are preferentially found
at the intersecting regions between them. The filaments have a similar
kinematic structure with smooth velocity gradients of ~0.4-0.8 km s-1 pc-1.
Several scenarios are proposed to explain these gradients, including cloud
rotation, gas accretion along the filaments, global gravitational collapse, and
unresolved sub-filament structures. These results are complemented by HCO+,
HNC, H13CO+ and HN13C single-pointing data to search for gas infall signatures.
The 13CO and C18O gas motions are supersonic across G035.39-00.33, with the
emission showing broader linewidths toward the edges of the IRDC. This could be
due to energy dissipation at the densest regions in the cloud. The average H2
densities are ~5000-7000 cm-3, with Filaments 2 and 3 being denser and more
massive than Filament 1. The C18O data unveils three regions with high CO
depletion factors (f_D~5-12), similar to those found in massive starless cores.Comment: 20 pages, 14 figures, 6 tables, accepted for publication in MNRA
Higgs Phenomenology with CPsuperH
The MSSM contains CP-violating phases that may have important observable
effects in Higgs physics. We review recent highlights in Higgs phenomenology
obtained with the code CPsuperH, a useful tool for studies of the production,
mixing and decay of a coupled system of the neutral Higgs bosons at future high
energy colliders such as the LHC, ILC (LC), and a muon collider (MC).
CPsuperH implements the constraints from upper limits on electric dipole
moments, and may be extended to include other related low-energy observables,
such as b -> s \gamma and B -> K l l, and to compute the relic abundance of the
lightest neutralino.Comment: 20 pages, LaTeX, 7 figures, invited article by Modern Physics Letters
A (review section
Potential for the use of exogenous chemical elicitors in disease and insect pest management of conifer seedling production
Modeling of weak lensing statistics. II. Configuration-space statistics
We investigate the performance of an analytic model of the 3D matter
distribution, which combines perturbation theory with halo models, for
weak-lensing configuration-space statistics. We compared our predictions for
the weak-lensing convergence two-point and three-point correlation functions
with numerical simulations and fitting formulas proposed in previous works. We
also considered the second- and third-order moments of the smoothed convergence
and of the aperture-mass. As in our previous study of Fourier-space
weak-lensing statistics, we find that our model agrees better with simulations
than previously published fitting formulas. Moreover, we recover the dependence
on cosmology of these weak-lensing statistics and we can describe multi-scale
moments. This approach allows us to obtain the quantitative relationship
between these integrated weak-lensing statistics and the various contributions
to the underlying 3D density fluctuations, decomposed over perturbative,
two-halo, or one-halo terms.Comment: 11 page
Long-term quality of life after surgery of head and neck cancer with microvascular reconstruction : a prospective study with 4.9-years follow-up
Purpose The aim of this study was to evaluate the long-term health-related quality of life (HRQoL) of head and neck cancer patients with microvascular surgery. Surgical treatment causes great changes in patient HRQoL. Studies focusing on long-term HRQoL after microvascular reconstruction for head and neck cancer patients are scarce. Methods We conducted a prospective study of 93 patients with head and neck cancer and microvascular reconstruction in Helsinki University Hospital Finland. HRQoL was measured using the 15D instrument at baseline and after a mean 4.9-years follow up. Results were compared with those of an age-standardized general population. Results Of the 93 patients, 61 (66%) were alive after follow-up; of these, 42 (69%) answered the follow-up questionnaire. The median time between surgery and HRQoL assessment was 4.9 years (range 3.7-7.8 years). The mean 15D score of all patients (n = 42) at the 4.9-years follow up was statistically significantly (p = 0.010) and clinically importantly lower than at baseline. The dimensions of "speech" and "usual activities" were significantly impaired at the end of follow up. There was a significant difference at the 4.9-years follow-up in the mean 15D score between patients and the general population (p = 0.014). After follow up, patients were significantly (p <0.05) worse off on the dimensions of "speech," "eating," and "usual activities." Conclusions Long-term HRQoL was significantly reduced in the whole patient cohort. Speech and usual activities were the most affected dimensions in head and neck cancer patients with microvascular reconstruction at the end of the 4.9-years follow up.Peer reviewe
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