830 research outputs found
New observational constraints on cosmology from radio quasars
Using a new recently compiled milliarcsecond compact radio data set of 120
intermediate-luminosity quasars in the redshift range , whose
statistical linear sizes show negligible dependence on redshifts and intrinsic
luminosity and thus represent standard rulers in cosmology, we constrain three
viable and most popular gravity models, where is the torsion scalar
in teleparallel gravity. Our analysis reveals that constraining power of the
quasars data (N=120) is comparable to the Union2.1 SN Ia data (N=580) for all
three models. Together with other standard ruler probes such as Cosmic
Microwave Background and Baryon Acoustic Oscillation distance measurements, the
present value of the matter density parameter obtained by quasars is
much lager than that derived from other observations. For two of the models
considered (CDM and CDM) a small but noticeable deviation from
CDM cosmology is present, while in the framework of CDM the
effective equation of state may cross the phantom divide line at lower
redshifts. These results indicate that intermediate-luminosity quasars could
provide an effective observational probe comparable to SN Ia at much higher
redsifts, and gravity is a reasonable candidate for the modified gravity
theory
Decision-making with Imaginary Opponent Models
Opponent modeling has benefited a controlled agent's decision-making by
constructing models of other agents. Existing methods commonly assume access to
opponents' observations and actions, which is infeasible when opponents'
behaviors are unobservable or hard to obtain. We propose a novel multi-agent
distributional actor-critic algorithm to achieve imaginary opponent modeling
with purely local information (i.e., the controlled agent's observations,
actions, and rewards). Specifically, the actor maintains a speculated belief of
the opponents, which we call the \textit{imaginary opponent models}, to predict
opponents' actions using local observations and makes decisions accordingly.
Further, the distributional critic models the return distribution of the
policy. It reflects the quality of the actor and thus can guide the training of
the imaginary opponent model that the actor relies on. Extensive experiments
confirm that our method successfully models opponents' behaviors without their
data and delivers superior performance against baseline methods with a faster
convergence speed.Comment: 13 pages, 27 figure
Expert Mining Collaborative Filtering Recommendation Algorithm Based on Signal Fluctuation
This paper proposes an advanced expert collaborative filtering recommendation algorithm. Although ordinary expert system filtering algorithms have improved the recommendation accuracy of collaborative filtering technology to a certain extent, they have not screened the level of expertise of experts, and the credibility of experts varies. Therefore, this paper proposes an expert mining system based on signal fluctuations. The algorithm uses signal processing technology to filter the level of experts. This method introduces a kurtosis factor. Regarding the user's rating sequence as a random discrete signal, and then randomly sorting the user's ratings k times, the average kurtosis of the user is obtained. And take the kurtosis value as the credibility of expert users. Through experiments on multiple datasets including MovieLens, Jester, Booking-Crossings, and Last.fm, we have proved the advancement and reliability of our method
Recommended from our members
Lipophilic statins inhibit YAP nuclear localization, co-activator activity and colony formation in pancreatic cancer cells and prevent the initial stages of pancreatic ductal adenocarcinoma in KrasG12D mice.
We examined the impact of statins on Yes-associated Protein (YAP) localization, phosphorylation and transcriptional activity in human and mouse pancreatic ductal adenocarcinoma (PDAC) cells. Exposure of sparse cultures of PANC-1 and MiaPaCa-2 cells to cerivastatin or simvastatin induced a striking re-localization of YAP from the nucleus to the cytoplasm and inhibited the expression of the YAP/TEAD-regulated genes Connective Tissue Growth Factor (CTGF) and Cysteine-rich angiogenic inducer 61 (CYR61). Statins also prevented YAP nuclear import and expression of CTGF and CYR61 stimulated by the mitogenic combination of insulin and neurotensin in dense culture of these PDAC cells. Cerivastatin, simvastatin, atorvastatin and fluvastatin also inhibited colony formation by PANC-1 and MiaPaCa-2 cells in a dose-dependent manner. In contrast, the hydrophilic statin pravastatin did not exert any inhibitory effect even at a high concentration (10 μM). Mechanistically, cerivastatin did not alter the phosphorylation of YAP at Ser127 in either PANC-1 or MiaPaCa-2 cells incubated without or with neurotensin and insulin but blunted the assembly of actin stress fiber in these cells. We extended these findings with human PDAC cells using primary KC and KPC cells, (expressing KrasG12D or both KrasG12D and mutant p53, respectively) isolated from KC or KPC mice. Using cultures of these murine cells, we show that lipophilic statins induced striking YAP translocation from the nucleus to the cytoplasm, inhibited the expression of Ctgf, Cyr61 and Birc5 and profoundly inhibited colony formation of these cells. Administration of simvastatin to KC mice subjected to diet-induced obesity prevented early pancreatic acini depletion and PanIN formation. Collectively, our results show that lipophilic statins restrain YAP activity and proliferation in pancreatic cancer cell models in vitro and attenuates early lesions leading to PDAC in vivo
Rapid Changes of Photospheric Magnetic Field after Tether-Cutting Reconnection and Magnetic Implosion
The rapid, irreversible change of the photospheric magnetic field has been
recognized as an important element of the solar flare process. This Letter
reports such a rapid change of magnetic fields during the 2011 February 13 M6.6
flare in NOAA AR 11158 that we found from the vector magnetograms of the
Helioseismic and Magnetic Imager with 12-min cadence. High-resolution
magnetograms of Hinode that are available at ~-5.5, -1.5, 1.5, and 4 hrs
relative to the flare maximum are used to reconstruct three-dimensional coronal
magnetic field under the nonlinear force-free field (NLFFF) assumption. UV and
hard X-ray images are also used to illuminate the magnetic field evolution and
energy release. The rapid change is mainly detected by HMI in a compact region
lying in the center of the magnetic sigmoid, where the mean horizontal field
strength exhibited a significant increase by 28%. The region lies between the
initial strong UV and hard X-ray sources in the chromosphere, which are
cospatial with the central feet of the sigmoid according to the NLFFF model.
The NLFFF model further shows that strong coronal currents are concentrated
immediately above the region, and that more intriguingly, the coronal current
system underwent an apparent downward collapse after the sigmoid eruption.
These results are discussed in favor of both the tether-cutting reconnection
producing the flare and the ensuing implosion of the coronal field resulting
from the energy release.Comment: 7 pages, 5 figures, accepted to the Astrophysical Journal Letter
- …