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A Milky Way-like barred spiral galaxy at a redshift of 3
The majority of massive disk galaxies in the local Universe show a stellar barred structure in their central regions, including our Milky Way. Bars are supposed to develop in dynamically cold stellar disks at low redshift, as the strong gas turbulence typical of disk galaxies at high redshift suppresses or delays bar formation. Moreover, simulations predict bars to be almost absent beyond z = 1.5 in the progenitors of Milky Way-like galaxies. Here we report observations of ceers-2112, a barred spiral galaxy at redshift zphot ≈ 3, which was already mature when the Universe was only 2 Gyr old. The stellar mass (M★ = 3.9 × 109 M⊙) and barred morphology mean that ceers-2112 can be considered a progenitor of the Milky Way, in terms of both structure and massassembly history in the frst 2 Gyr of the Universe, and was the closest in mass in the frst 4 Gyr. We infer that baryons in galaxies could have already dominated over dark matter at z ≈ 3, that high-redshift bars could form in approximately 400 Myr and that dynamically cold stellar disks could have been in place by redshift z = 4–5 (more than 12 Gyrs ago)
Review of Post-Multicultural Writers as Neo-Cosmopolitan Mediators by Sneja Gunew
Review of Post-Multicultural Writers as Neo-Cosmopolitan Mediators by Sneja Gune
The Differential Assembly History of the Centers and Outskirts of Main Sequence Galaxies at
We present a study of spatially-resolved star formation histories (SFHs) for
60 main-sequence, star-forming galaxies selected from the MOSDEF
spectroscopic survey in the GOODS-N field. Photometry is decomposed into a
central and outer spatial component using observed
colors. The Prospector code is used to
model spectral energy distributions for the centers, outskirts, and integrated
galaxy using HST/ACS and WFC3, Spitzer/IRAC, and ground-based photometry, with
additional constraints on metallicity and spectroscopic redshift from MOSDEF
spectroscopy. For the low-resolution bands, spatially-resolved photometry is
determined with an iterative approach. The reconstructed SFHs indicate that the
majority of galaxies with are observed while their
central regions undergo relatively recent ( Myr) bursts of star
formation, while the outskirts have a smooth, quasi-steady SFH. The enhanced
star formation activity of the central parts is broadly consistent with the
idea that it is produced by highly dissipative gas compaction and accretion.
The broad dispersion of central density and size observed in the sample
suggests that for the selected galaxies this process has started but is still
far from being completed. The implication would be that selecting star-forming
galaxies at cosmic noon frequently includes systems in an "evolved"
evolutionary phase where the centers have recently started a burst of star
formation activity that will likely initiate inside-out quenching in the next
several hundred million years.Comment: 25 pages, 18 figures. Submitted for publication in Ap
The Equivalent Relationship between Space Vector and Carrier-based PWM Modulation Strategy in Current Source five-level Inverters
Sharper Asymptotically Optimal CDC Schemes via Combinatorial Designs
Coded distributed computing (CDC) was introduced to greatly reduce the
communication load for MapReduce computing systems. Such a system has
nodes, input files, and Reduce functions. Each input file is mapped by
nodes and each Reduce function is computed by nodes. The architecture
must allow for coding techniques that achieve the maximum multicast gain. Some
CDC schemes that achieve optimal communication load have been proposed before.
The parameters and in those schemes, however, grow too fast with
respect to to be of great practical value. To improve the situation,
researchers have come up with some asymptotically optimal cascaded CDC schemes
with from symmetric designs.
In this paper, we propose new asymptotically optimal cascaded CDC schemes.
Akin to known schemes, ours have and make use of symmetric designs as
construction tools. Unlike previous schemes, ours have much smaller
communication loads, given the same set of parameters , , , and .
We also expand the construction tools to include almost difference sets. Using
them, we have managed to construct a new asymptotically optimal cascaded CDC
scheme
A Construction of Asymptotically Optimal Cascaded CDC Schemes via Combinatorial Designs
A coded distributed computing (CDC) system aims to reduce the communication
load in the MapReduce framework. Such a system has nodes, input files,
and Reduce functions. Each input file is mapped by nodes and each
Reduce function is computed by nodes. The objective is to achieve the
maximum multicast gain. There are known CDC schemes that achieve optimal
communication load. In some prominent known schemes, however, and grow
too fast in terms of , greatly reducing their gains in practical scenarios.
To mitigate the situation, some asymptotically optimal cascaded CDC schemes
with have been proposed by using symmetric designs. In this paper, we put
forward new asymptotically optimal cascaded CDC schemes with by using
-designs. Compared with earlier schemes from symmetric designs, ours have
much smaller computation loads while keeping the other relevant parameters the
same. We also obtain new asymptotically optimal cascaded CDC schemes with more
flexible parameters compared with previously best-performing schemes
Demographic information prediction: a portrait of smartphone application Users
Demographic information is usually treated as private data (e.g., gender and age), but has been shown great values in personalized services, advertisement, behavior study and other aspects. In this paper, we propose a novel approach to make efficient demographic prediction based on smartphone application usage. Specifically, we firstly consider to characterize the data set by building a matrix to correlate users with types of categories from the log file of smartphone applications. Then, by considering the category-unbalance problem, we make use of the correlation between users’ demographic information and their requested Internet resources to make the prediction, and propose an optimal method to further smooth the obtained results with category neighbors and user neighbors. The evaluation is supplemented by the dataset from real world workload. The results show advantages of the proposed prediction approach compared with baseline prediction. In particular, the proposed approach can achieve 81.21% of Accuracy in gender prediction. While in dealing with a more challenging multi-class problem, the proposed approach can still achieve good performance (e.g., 73.84% of Accuracy in the prediction of age group and 66.42% of Accuracy in the prediction of phone level)
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