55 research outputs found
Electrospun Perovskite Photoabsorber, Electron- and Hole Transport Materials for Flexible Photovoltaics
L’Europa centrale fra le culture politiche nazionali tradizionali ed una nuova identità europea = Central Europe between traditional national political culture and a new European identity. ZEI Discussion Paper: 2004, C 132
No abstract
ETHOS -- An effective parametrization and classification for structure formation: the non-linear regime at
We propose two effective parameters that fully characterise galactic-scale
structure formation at high redshifts () for a variety of dark
matter (DM) models that have a primordial cutoff in the matter power spectrum.
Our description is within the recently proposed ETHOS framework and includes
standard thermal Warm DM (WDM) and models with dark acoustic oscillations
(DAOs). To define and explore this parameter space, we use high-redshift
zoom-in simulations that cover a wide range of non-linear scales from those
where DM should behave as CDM (), down to those
characterised by the onset of galaxy formation ().
We show that the two physically motivated parameters and , the amplitude and scale of the first DAO peak, respectively, are
sufficient to parametrize the linear matter power spectrum and classify the DM
models as belonging to effective non-linear structure formation regions. These
are defined by their relative departure from Cold DM () and WDM () according to the non-linear
matter power spectrum and halo mass function. We identify a region where the
DAOs still leave a distinct signature from WDM down to , while a large
part of the DAO parameter space is shown to be degenerate with WDM. Our
framework can then be used to seamlessly connect a broad class of particle DM
models to their structure formation properties at high redshift without the
need of additional -body simulations.Comment: 19 pages, 17 figures; Updated version accepted for publication in
MNRA
Interference in the resonance fluorescence of two incoherently coupled transitions
The fluorescence light emitted by a 4-level system in to
configuration driven by a monochromatic laser field and in an external magnetic
field is studied. We show that the spectrum of resonance fluorescence emitted
on the transitions shows a signature of spontaneously generated
interference effects. The degree of interference in the fluorescence spectrum
can be controlled by means of the external magnetic field, provided that the
Land\'e g-factors of the excited and the ground state doublet are different.
For a suitably chosen magnetic field strength, the relative weight of the
Rayleigh line can be completely suppressed, even for low intensities of the
coherent driving field. The incoherent fluorescence spectrum emitted on the
transitions exhibits a very narrow peak whose width and weight depends on
the magnetic field strength. We demonstrate that the spectrum of resonance
fluorescence emitted on the transitions show an indirect signature of
interference. A measurement of the relative peak heights in the spectrum from
the transitions allows to determine the branching ratio of the
spontaneous decay of each excited state into the channel
ETHOS - an Effective Theory of Structure Formation: detecting dark matter interactions through the Lyman- forest
We perform a series of cosmological hydrodynamic simulations to investigate
the effects of non-gravitational dark matter (DM) interactions on the
intergalactic medium (IGM). In particular, we use the ETHOS framework
(Cyr-Racine et al. 2016; Vogelsberger et al. 2016) to compare statistics of the
Lyman- forest in cold dark matter (CDM) with an alternative model in
which the DM couples strongly with a relativistic species in the early
universe. These models are characterised by a cutoff in the linear power
spectrum, followed by a series of 'dark acoustic oscillations' (DAOs) on
sub-dwarf scales. While the primordial cutoff delays the formation of the first
galaxies, structure builds-up more rapidly in the interacting DM model compared
to CDM. We show that although DAOs are quickly washed away in the non-linear
clustering of DM at , their signature can be imprinted prominently
in the Lyman- flux power spectrum at . On scales larger than the
cutoff ( s/km for the specific model considered here), the relative
difference to CDM is reminiscent of a warm dark matter (WDM) model with a
similar initial cutoff; however, the redshift evolution on smaller scales is
distinctly different. The appearance and disappearance of DAOs in the
Lyman- flux spectrum provides a powerful way to distinguish interacting
DM models from WDM and, indeed, variations in the thermal history of the IGM
that may also induce a small-scale cutoff.Comment: 15 pages, 12 figures, 1 table. Updated version accepted for
publication in MNRA
Collectively enhanced Ramsey readout by cavity sub- to superradiant transition
When an inverted ensemble of atoms is tightly packed on the scale of its
emission wavelength or when the atoms are collectively strongly coupled to a
single cavity mode, their dipoles will align and decay rapidly via a
superradiant burst. However, a spread-out dipole phase distribution theory
predicts a required minimum threshold of atomic excitation for superradiance to
occur. Here we experimentally confirm this predicted threshold for superradiant
emission on a narrow optical transition when exciting the atoms transversely
and show how to take advantage of the resulting sub- to superradiant
transition. A -pulse places the atoms in a subradiant state, protected
from collective cavity decay, which we exploit during the free evolution period
in a corresponding Ramsey pulse sequence. The final excited state population is
read out via superradiant emission from the inverted atomic ensemble after a
second -pulse, and with minimal heating this allows for multiple Ramsey
sequences within one experimental cycle. Our scheme is a fundamentally new
approach to atomic state readout characterized by its speed, simplicity, and
high sensitivity. It demonstrates the potential of sensors using collective
effects in cavity-coupled quantum emitters
SRT1720 improves survival and healthspan of obese mice
Sirt1 is an NAD+-dependent deacetylase that extends lifespan in lower organisms and improves metabolism and delays the onset of age-related diseases in mammals. Here we show that SRT1720, a synthetic compound that was identified for its ability to activate Sirt1 in vitro, extends both mean and maximum lifespan of adult mice fed a high-fat diet. This lifespan extension is accompanied by health benefits including reduced liver steatosis, increased insulin sensitivity, enhanced locomotor activity and normalization of gene expression profiles and markers of inflammation and apoptosis, all in the absence of any observable toxicity. Using a conditional SIRT1 knockout mouse and specific gene knockdowns we show SRT1720 affects mitochondrial respiration in a Sirt1- and PGC-1α-dependent manner. These findings indicate that SRT1720 has long-term benefits and demonstrate for the first time the feasibility of designing novel molecules that are safe and effective in promoting longevity and preventing multiple age-related diseases in mammals
Natalizumab treatment shows low cumulative probabilities of confirmed disability worsening to EDSS milestones in the long-term setting.
Abstract Background Though the Expanded Disability Status Scale (EDSS) is commonly used to assess disability level in relapsing-remitting multiple sclerosis (RRMS), the criteria defining disability progression are used for patients with a wide range of baseline levels of disability in relatively short-term trials. As a result, not all EDSS changes carry the same weight in terms of future disability, and treatment benefits such as decreased risk of reaching particular disability milestones may not be reliably captured. The objectives of this analysis are to assess the probability of confirmed disability worsening to specific EDSS milestones (i.e., EDSS scores ≥3.0, ≥4.0, or ≥6.0) at 288 weeks in the Tysabri Observational Program (TOP) and to examine the impact of relapses occurring during natalizumab therapy in TOP patients who had received natalizumab for ≥24 months. Methods TOP is an ongoing, open-label, observational, prospective study of patients with RRMS in clinical practice. Enrolled patients were naive to natalizumab at treatment initiation or had received ≤3 doses at the time of enrollment. Intravenous natalizumab (300 mg) infusions were given every 4 weeks, and the EDSS was assessed at baseline and every 24 weeks during treatment. Results Of the 4161 patients enrolled in TOP with follow-up of at least 24 months, 3253 patients with available baseline EDSS scores had continued natalizumab treatment and 908 had discontinued (5.4% due to a reported lack of efficacy and 16.4% for other reasons) at the 24-month time point. Those who discontinued due to lack of efficacy had higher baseline EDSS scores (median 4.5 vs. 3.5), higher on-treatment relapse rates (0.82 vs. 0.23), and higher cumulative probabilities of EDSS worsening (16% vs. 9%) at 24 months than those completing therapy. Among 24-month completers, after approximately 5.5 years of natalizumab treatment, the cumulative probabilities of confirmed EDSS worsening by 1.0 and 2.0 points were 18.5% and 7.9%, respectively (24-week confirmation), and 13.5% and 5.3%, respectively (48-week confirmation). The risks of 24- and 48-week confirmed EDSS worsening were significantly higher in patients with on-treatment relapses than in those without relapses. An analysis of time to specific EDSS milestones showed that the probabilities of 48-week confirmed transition from EDSS scores of 0.0–2.0 to ≥3.0, 2.0–3.0 to ≥4.0, and 4.0–5.0 to ≥6.0 at week 288 in TOP were 11.1%, 11.8%, and 9.5%, respectively, with lower probabilities observed among patients without on-treatment relapses (8.1%, 8.4%, and 5.7%, respectively). Conclusions In TOP patients with a median (range) baseline EDSS score of 3.5 (0.0–9.5) who completed 24 months of natalizumab treatment, the rate of 48-week confirmed disability worsening events was below 15%; after approximately 5.5 years of natalizumab treatment, 86.5% and 94.7% of patients did not have EDSS score increases of ≥1.0 or ≥2.0 points, respectively. The presence of relapses was associated with higher rates of overall disability worsening. These results were confirmed by assessing transition to EDSS milestones. Lower rates of overall 48-week confirmed EDSS worsening and of transitioning from EDSS score 4.0–5.0 to ≥6.0 in the absence of relapses suggest that relapses remain a significant driver of disability worsening and that on-treatment relapses in natalizumab-treated patients are of prognostic importance
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SRT1720 improves survival and healthspan of obese mice
Sirt1 is an NAD1-dependent deacetylase that extends lifespan in lower organisms and improves metabolism and delays the onset of age-related diseases in mammals. Here we show that SRT1720, a synthetic compound that was identified for its ability to activate Sirt1 in vitro, extends both mean and maximum lifespan of adult mice fed a high-fat diet. This lifespan extension is accompanied by health benefits including reduced liver steatosis, increased insulin sensitivity, enhanced locomotor activity and normalization of gene expression profiles and markers of inflammation and apoptosis, all in the absence of any observable toxicity. Using a conditional SIRT1 knockout mouse and specific gene knockdowns we show SRT1720 affects mitochondrial respiration in a Sirt1- and PGC-1a-dependent manner. These findings indicate that SRT1720 has long-term benefits and demonstrate for the first time the feasibility of designing novel molecules that are safe and effective in promoting longevity and preventing multiple age-related diseases in mammals
PeerLA- Assistant for individual learning goals an d self-regulation competency improvement in online learning scenarios
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