976 research outputs found
Dark matter scenarios in a constrained model with Dirac gauginos
We perform the first analysis of Dark Matter scenarios in a constrained model
with Dirac Gauginos. The model under investigation is the Constrained Minimal
Dirac Gaugino Supersymmetric Standard model (CMDGSSM) where the Majorana mass
terms of gauginos vanish. However, -symmetry is broken in the Higgs sector
by an explicit and/or effective -term. This causes a mass splitting
between Dirac states in the fermion sector and the neutralinos, which provide
the dark matter candidate, become pseudo-Dirac states. We discuss two
scenarios: the universal case with all scalar masses unified at the GUT scale,
and the case with non-universal Higgs soft-terms. We identify different regions
in the parameter space which fullfil all constraints from the dark matter
abundance, the limits from SUSY and direct dark matter searches and the Higgs
mass. Most of these points can be tested with the next generation of direct
dark matter detection experiments.Comment: 28 pages, 11 figures; v2: minor changes, title modified; matches
published versio
Effect-directed analysis for estrogenic compounds in a fluvial sediment sample using transgenic cyp19a1b-GFP zebrafish embryos.
International audienceXenoestrogens may persist in the environment by binding to sediments or suspended particulate matter serving as long-term reservoir and source of exposure, particularly for organisms living in or in contact with sediments. In this study, we present for the first time an effect-directed analysis (EDA) for identifying estrogenic compounds in a sediment sample using embryos of a transgenic reporter fish strain. In the tg(cyp19a1b-GFP) transgenic zebrafish strain, the expression of GFP (green fluorescent protein) in the brain is driven by an oestrogen responsive element in the promoter of the cyp19a1b (aromatase) gene. The selected sediment sample of the Czech river Bilina had already been analysed in a previous EDA using the yeast oestrogen screening assay and had revealed fractions containing estrogenic compounds. When normal phase HPLC (high performance liquid chromatography) fractionation was used for the separation of the sediment sample, the biotest with transgenic fish embryos revealed two estrogenic fractions. Chemical analysis of candidate compounds in these sediment fractions suggested alkylphenols and estrone as candidate compounds responsible for the observed estrogenic effect. Alkylphenol concentrations could partially explain the estrogenicity of the fractions. However, xenoestrogens below the analytical detection limit or non-targeted estrogenic compounds have probably also contributed to the sample's estrogenic potency. The results indicated the suitability of the tg(cyp19a1b-GFP) fish embryo for an integrated chemical-biological analysis of estrogenic effects
Functional lesional neurosurgery for tremor: back to the future?
For nearly a century, functional neurosurgery has been applied in the treatment of tremor. While deep brain stimulation has been in the focus of academic interest in recent years, the establishment of incisionless technology, such as MRI-guided high-intensity focused ultrasound, has again stirred interest in lesional approaches.In this article, we will discuss the historical development of surgical technique and targets, as well as the technological state-of-the-art of conventional and incisionless interventions for tremor due to Parkinson's disease, essential and dystonic tremor and tremor related to multiple sclerosis (MS) and midbrain lesions. We will also summarise technique-inherent advantages of each technology and compare their lesion characteristics. From this, we identify gaps in the current literature and derive future directions for functional lesional neurosurgery, in particularly potential trial designs, alternative targets and the unsolved problem of bilateral lesional treatment. The results of a systematic review and meta-analysis of the consistency, efficacy and side effect rate of lesional treatments for tremor are presented separately alongside this article
Quantum Monte Carlo Calculations for a large number of bosons in a harmonic trap
In this paper, I present a precise Quantum Monte Carlo calculation at finite
temperature for a very large number (many thousands) of bosons in a harmonic
trap, which may be anisotropic. The calculation applies directly to the recent
experiments of Bose-Einstein condensation of atomic vapors in magnetic traps. I
show that the critical temperature of the system decreases with the
interaction. I also present profiles for the overall density and the one of
condensed particles, and obtain excellent agreement with solutions of the
Gross-Pitaevskii equation.Comment: 8 pages, 3 figures, Revte
- …