2,107 research outputs found
Magnetic Resonance Spectroscopy discriminates the response to microglial stimulation of wild type and Alzheimer's disease models.
Microglia activation has emerged as a potential key factor in the pathogenesis of Alzheimers disease. Metabolite levels assessed by magnetic resonance spectroscopy (MRS) are used as markers of neuroinflammation in neurodegenerative diseases, but how they relate to microglial activation in health and chronic disease is incompletely understood. Using MRS, we monitored the brain metabolic response to lipopolysaccharides (LPS)-induced microglia activation in vivo in a transgenic mouse model of Alzheimers disease (APP/PS1) and healthy controls (wild-type (WT) littermates) over 4 hours. We assessed reactive gliosis by immunohistochemistry and correlated metabolic and histological measures. In WT mice, LPS induced a microglial phenotype consistent with activation, associated with a sustained increase in macromolecule and lipid levels (ML9). This effect was not seen in APP/PS1 mice, where LPS did not lead to a microglial response measured by histology, but induced a late increase in the putative inflammation marker myoinositol (mI) and metabolic changes in total creatine and taurine previously reported to be associated with amyloid load. We argue that ML9 and mI distinguish the response of WT and APP/PS1 mice to immune mediators. Lipid and macromolecule levels may represent a biomarker of activation of healthy microglia, while mI may not be a glial marker
Reach the Bottom Line of the Sbottom Search
We propose a new search strategy for directly-produced sbottoms at the LHC
with a small mass splitting between the sbottom and its decayed stable
neutralino. Our search strategy is based on boosting sbottoms through an
energetic initial state radiation jet. In the final state, we require a large
missing transverse energy and one or two b-jets besides the initial state
radiation jet. We also define a few kinematic variables to further increase the
discovery reach. For the case that the sbottom mainly decays into the bottom
quark and the stable neutralino, we have found that even for a mass splitting
as small as 10 GeV sbottoms with masses up to around 400 GeV can be excluded at
the 95% confidence level with 20 inverse femtobarn data at the 8 TeV LHC.Comment: 16 pages, 6 figure
Gamma Lines without a Continuum: Thermal Models for the Fermi-LAT 130 GeV Gamma Line
Recent claims of a line in the Fermi-LAT photon spectrum at 130 GeV are
suggestive of dark matter annihilation in the galactic center and other dark
matter-dominated regions. If the Fermi feature is indeed due to dark matter
annihilation, the best-fit line cross-section, together with the lack of any
corresponding excess in continuum photons, poses an interesting puzzle for
models of thermal dark matter: the line cross-section is too large to be
generated radiatively from open Standard Model annihilation modes, and too
small to provide efficient dark matter annihilation in the early universe. We
discuss two mechanisms to solve this puzzle and illustrate each with a simple
reference model in which the dominant dark matter annihilation channel is
photonic final states. The first mechanism we employ is resonant annihilation,
which enhances the annihilation cross-section during freezeout and allows for a
sufficiently large present-day annihilation cross section. Second, we consider
cascade annihilation, with a hierarchy between p-wave and s-wave processes.
Both mechanisms require mass near-degeneracies and predict states with masses
closely related to the dark matter mass; resonant freezeout in addition
requires new charged particles at the TeV scale.Comment: 17 pages, 8 figure
Forecasting substantial data revisions in the presence of model uncertainty
A recent revision to the preliminary measurement of GDP(E) growth for 2003Q2 caused considerable press attention, provoked a public enquiry and prompted a number of reforms to UK statistical reporting procedures. In this article, we compute the probability of 'substantial revisions' that are greater (in absolute value) than the controversial 2003 revision. The predictive densities are derived from Bayesian model averaging over a wide set of forecasting models including linear, structural break and regime-switching models with and without heteroscedasticity. Ignoring the nonlinearities and model uncertainty yields misleading predictives and obscures recent improvements in the quality of preliminary UK macroeconomic measurements
Interplay between Fermi gamma-ray lines and collider searches
We explore the interplay between lines in the gamma-ray spectrum and LHC searches involving missing energy and photons. As an example, we consider a singlet Dirac
fermion dark matter with the mediator for Fermi gamma-ray line at 130 GeV. A new chiral or local U(1) symmetry makes weak-scale dark matter natural and provides the axion or
Z 0 gauge boson as the mediator connecting between dark matter and electroweak gauge bosons. In these models, the mediator particle can be produced in association with a
monophoton at colliders and it produces large missing energy through the decays into a DM pair or ZZ; Z with at least one Z decaying into a neutrino pair. We adopt the monophoton searches with large missing energy at the LHC and impose the bounds on the coupling and mass of the mediator field in the models. We show that the parameter space of the Z 0 mediation model is already strongly constrained by the LHC 8TeV data, whereas a certain region of the parameter space away from the resonance in axion-like mediator models are bounded. We foresee the monophoton bounds on the Z 0 and axion mediation models at the LHC 14 TeV
Technology readiness level assessment of composites recycling technologies
Composite materials made of glass and carbon fibres have revolutionised many industries. Demand for
composites is experiencing rapid growth and global demand is expected to double. As demand for
composites grows it is clear that waste management will become an important issue for businesses.
Technically composite materials evoke difficult recycling challenges due to the heterogeneity of their
composition. As current waste management practices in composites are dominated by landfilling, governments
and businesses themselves foresee that this will need to change in the future. The recycling of
composites will play a vital role in the future especially for the aerospace, automotive, construction and
marine sectors. These industries will require different recycling options for their products based on
compliance with current legislation, the business model as well as cost effectiveness. In order to be able
to evaluate waste management strategies for composites, a review of recycling technologies has been
conducted based on technology readiness levels and waste management hierarchy. This paper analyses
56 research projects to identify growing trends in composite recycling technologies with pyrolysis,
solvolysis and mechanical grinding as the most prominent technologies. These recycling technologies
attained high scores on the waste management hierarchy (either recycling or reuse applications) suggesting
potential development as future viable alternatives to composite landfilling. The research
concluded that recycling as a waste management strategy is most popular exploration area. It was found
mechanical grinding to be most mature for glass fibre applications while pyrolysis has been most mature
in the context of carbon fibre. The paper also highlights the need to understand the use of reclaimed
material as important assessment element of recycling efforts. This paper contributes to the widening
and systematising knowledge on maturity and understanding composites recycling technologies
Resonances in and
A partial wave analysis is presented of and
from a sample of 58M events in the BES II detector. The
is observed clearly in both sets of data, and parameters of the
Flatt\' e formula are determined accurately: (stat)
(syst) MeV/c, MeV/c, . The data also exhibit a strong peak
centred at MeV/c. It may be fitted with and a
dominant signal made from interfering with a smaller
component. There is evidence that the signal is
resonant, from interference with . There is also a state in with MeV/c and
MeV/c; spin 0 is preferred over spin 2. This state, , is
distinct from . The data contain a strong peak due to
. A shoulder on its upper side may be fitted by interference
between and .Comment: 17 pages, 6 figures, 1 table. Submitted to Phys. Lett.
Measurement of the Branching Fraction of J/psi --> pi+ pi- pi0
Using 58 million J/psi and 14 million psi' decays obtained by the BESII
experiment, the branching fraction of J/psi --> pi+ pi- pi0 is determined. The
result is (2.10+/-0.12)X10^{-2}, which is significantly higher than previous
measurements.Comment: 9 pages, 8 figures, RevTex
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