180 research outputs found
Early Quintessence in Light of theWilkinson Microwave Anisotropy Probe
We examine the cosmic microwave background (CMB) anisotropy for signatures of early quintessence dark energy—a nonnegligible quintessence energy density during the recombination and structure formation eras. Only very recently does the quintessence overtake the dark matter and push the expansion into overdrive. Because the presence of early quintessence exerts an influence on the clustering of dark matter and the baryon-photon fluid, we may expect to find trace signals in the CMB and the mass fluctuation power spectrum. In detail, we demonstrate that suppressed clustering power on small length scales, as suggested by the combined Wilkinson Microwave Anisotropy Probe/CMB/large-scale structure data set, is characteristic of early quintessence. We identify a set of concordant models and map out directions for further investigation of early quintessence
Modelling the unfolding pathway of biomolecules: theoretical approach and experimental prospect
We analyse the unfolding pathway of biomolecules comprising several
independent modules in pulling experiments. In a recently proposed model, a
critical velocity has been predicted, such that for pulling speeds
it is the module at the pulled end that opens first, whereas for
it is the weakest. Here, we introduce a variant of the model that is
closer to the experimental setup, and discuss the robustness of the emergence
of the critical velocity and of its dependence on the model parameters. We also
propose a possible experiment to test the theoretical predictions of the model,
which seems feasible with state-of-art molecular engineering techniques.Comment: Accepted contribution for the Springer Book "Coupled Mathematical
Models for Physical and Biological Nanoscale Systems and Their Applications"
(proceedings of the BIRS CMM16 Workshop held in Banff, Canada, August 2016),
16 pages, 6 figure
Visual Reasoning with Multi-hop Feature Modulation
Recent breakthroughs in computer vision and natural language processing have
spurred interest in challenging multi-modal tasks such as visual
question-answering and visual dialogue. For such tasks, one successful approach
is to condition image-based convolutional network computation on language via
Feature-wise Linear Modulation (FiLM) layers, i.e., per-channel scaling and
shifting. We propose to generate the parameters of FiLM layers going up the
hierarchy of a convolutional network in a multi-hop fashion rather than all at
once, as in prior work. By alternating between attending to the language input
and generating FiLM layer parameters, this approach is better able to scale to
settings with longer input sequences such as dialogue. We demonstrate that
multi-hop FiLM generation achieves state-of-the-art for the short input
sequence task ReferIt --- on-par with single-hop FiLM generation --- while also
significantly outperforming prior state-of-the-art and single-hop FiLM
generation on the GuessWhat?! visual dialogue task.Comment: In Proc of ECCV 201
Physical parameters for Orion KL from modelling its ISO high resolution far-IR CO line spectrum
As part of the first high resolution far-IR spectral survey of the Orion KL
region (Lerate et al. 2006), we observed 20 CO emission lines with Jup=16 to
Jup=39 (upper levels from approx 752 K to 4294 K above the ground state).
Observations were taken using the Long Wavelength Spectrometer (LWS) on board
the Infrared Space Observatory (ISO), in its high resolution Fabry-Perot (FP)
mode (approx 33 km s). We present here an analysis of the final
calibrated CO data, performed with a more sophisticated modelling technique
than hitherto, including a detailed analysis of the chemistry, and discuss
similarities and differences with previous results. The inclusion of chemical
modelling implies that atomic and molecular abundances are time-predicted by
the chemistry. This provides one of the main differences with previous studies
in which chemical abundances needed to be assumed as initial condition. The
chemistry of the region is studied by simulating the conditions of the
different known components of the KL region: chemical models for a hot core, a
plateau and a ridge are coupled with an accelerated Lambda-iteration
(ALI)radiative transfer model to predict line fluxes and profiles. We conclude
that the CO transitions with 18<Jup<25 mainly arise from a hot core of diameter
0.02 pc and a density of 10 cm rather from the plateau as previous
studies had indicated.Comment: The paper contains 10 pages, 7 figures and 4 tables. MNRAS accepte
- …