179 research outputs found
The substructure and halo population of the Double Cluster and Persei
In order to study the stellar population and possible substructures in the
outskirts of Double Cluster and Persei, we investigate using the
GAIA DR2 data a sky area of about 7.5 degrees in radius around the Double
Cluster cores. We identify member stars using various criteria, including their
kinematics (viz, proper motion), individual parallaxes, as well as photometric
properties. A total of 2186 member stars in the parameter space were identified
as members. Based on the spatial distribution of the member stars, we find an
extended halo structure of and Persei, about 6 - 8 times larger than
their core radii. We report the discovery of filamentary substructures
extending to about 200 pc away from the Double Cluster. The tangential
velocities of these distant substructures suggest that they are more likely to
be the remnants of primordial structures, instead of a tidally disrupted stream
from the cluster cores. Moreover, the internal kinematic analysis indicates
that halo stars seems to be experiencing a dynamic stretching in the RA
direction, while the impact of the core components is relatively negligible.
This work also suggests that the physical scale and internal motions of young
massive star clusters may be more complex than previously thought.Comment: 9 pagges, 9 figures, Accecpted to A&
The Chocolate Chip Cookie Model: Dust Geometry of Milky-Way like Disk Galaxies
We present a new two-component dust geometry model, the \textit{Chocolate
Chip Cookie} model, where the clumpy nebular regions are embedded in a diffuse
stellar/ISM disk, like chocolate chips in a cookie. By approximating the
binomial distribution of the clumpy nebular regions with a continuous Gaussian
distribution and omitting the dust scattering effect, our model solves the dust
attenuation process for both the emission lines and stellar continua via
analytical approaches. Our Chocolate Chip Cookie model successfully fits the
inclination dependence of both the effective dust reddening of the stellar
components derived from stellar population synthesis and that of the emission
lines characterized by the Balmer decrement for a large sample of Milky-Way
like disk galaxies selected from the main galaxy sample of the Sloan Digital
Sky Survey (SDSS). Our model shows that the clumpy nebular disk is about 0.55
times thinner and 1.6 times larger than the stellar disk for MW-like galaxies,
whereas each clumpy region has a typical optical depth in band. After considering the aperture effect, our model prediction
on the inclination dependence of dust attenuation is also consistent with
observations. Not only that, in our model, the dust attenuation curve of the
stellar population naturally depends on inclination and its median case is
consistent with the classical Calzetti law. Since the modelling constraints are
from the optical wavelengths, our model is unaffected by the optically thick
dust component, which however could bias the model's prediction of the infrared
emissions.Comment: 27 pages, 11 figures, 1 tabl
BLSP: Bootstrapping Language-Speech Pre-training via Behavior Alignment of Continuation Writing
The emergence of large language models (LLMs) has sparked significant
interest in extending their remarkable language capabilities to speech.
However, modality alignment between speech and text still remains an open
problem. Current solutions can be categorized into two strategies. One is a
cascaded approach where outputs (tokens or states) of a separately trained
speech recognition system are used as inputs for LLMs, which limits their
potential in modeling alignment between speech and text. The other is an
end-to-end approach that relies on speech instruction data, which is very
difficult to collect in large quantities. In this paper, we address these
issues and propose the BLSP approach that Bootstraps Language-Speech
Pre-training via behavior alignment of continuation writing. We achieve this by
learning a lightweight modality adapter between a frozen speech encoder and an
LLM, ensuring that the LLM exhibits the same generation behavior regardless of
the modality of input: a speech segment or its transcript. The training process
can be divided into two steps. The first step prompts an LLM to generate texts
with speech transcripts as prefixes, obtaining text continuations. In the
second step, these continuations are used as supervised signals to train the
modality adapter in an end-to-end manner. We demonstrate that this
straightforward process can extend the capabilities of LLMs to speech, enabling
speech recognition, speech translation, spoken language understanding, and
speech conversation, even in zero-shot cross-lingual scenarios
PA-X is a virulence factor in avian H9N2 influenza virus
H9N2 influenza viruses have been circulating worldwide in multiple avian species, and regularly infect pigs and humans. Recently, a novel protein, PA-X, produced from the PA gene by ribosomal frameshifting, was demonstrated to be an antivirulence factor in pandemic 2009 H1N1, highly pathogenic avian H5N1 and 1918 H1N1 viruses. However, a similar role of PA-X in the prevalent H9N2 avian influenza viruses has not been established. In this study, we compared the virulence and cytopathogenicity of H9N2 WT virus and H9N2 PA-X-deficient virus. Loss of PA-X in H9N2 virus reduced apoptosis and had a marginal effect on progeny virus output in human pulmonary adenocarcinoma (A549) cells. Without PA-X, PA was less able to suppress co-expressed GFP in human embryonic kidney 293T cells. Furthermore, absence of PA-X in H9N2 virus attenuated viral pathogenicity in mice, which showed no mortality, reduced progeny virus production, mild-to-normal lung histopathology, and dampened proinflammatory cytokine and chemokine response. Therefore, unlike previously reported H1N1 and H5N1 viruses, we show that PA-X protein in H9N2 virus is a pro-virulence factor in facilitating viral pathogenicity and that the pro- or antivirulence role of PA-X in influenza viruses is virus strain-dependent
Prevailing PA mutation K356R in avian influenza H9N2 virus increases mammalian replication and pathogenicity
Adaptation of the viral polymerase complex comprising PB1, PB2, and PA is necessary for efficient influenza A virus replication in new host species. We found that PA mutation K356R (PA-K356R) has become predominant since 2014 in avian H9N2 viruses in China as with seasonal human H1N1 viruses. The same mutation is also found in most human isolates of emergent avian H7N9 and H10N8 viruses whose six internal gene segments are derived from the H9N2 virus. We further demonstrated the mammalian adaptive functionality of the PA-K356R mutation. Avian H9N2 virus with the PA-K356R mutation in human A549 cells showed increased nuclear accumulation of PA and increased viral polymerase activity that resulted in elevated levels of viral transcription and virus output. The same mutant virus in mice also enhanced virus replication and caused lethal infection. In addition, combined mutation of PA-K356R and PB2-E627K, a well-known mammalian adaptive marker, in the H9N2 virus showed further cooperative increases in virus production and severity of infection in vitro and in vivo. In summary, PA-K356R behaves as a novel mammalian tropism mutation, which, along with other mutations such as PB2-E627K, might render avian H9N2 viruses adapted for human infection
Smart dielectric materials for next-generation electrical insulation
Smart dielectric materials with bioinspired and autonomous functions are expected to be designed and fabricated for next-generation electrical insulation. Similar to organisms, such dielectrics with self-adaptive, self-reporting, and self-healing capabilities can be employed to avoid, diagnose, and repair electrical damage to prevent catastrophic failure and even a blackout. Compared with traditional dielectrics, the utilization of smart materials not only increases the stability and durability of power apparatus but also reduces the costs of production and manufacturing. In this review, researches on self-adaptive, self-reporting, and self-healing dielectrics in the field of electrical insulation, and illuminating studies on smart polymers with autonomous functions in other fields are both introduced. The principles, methods, mechanisms, applications, and challenges of these materials are also briefly presented
Transgenic studies reveal the positive role of LeEIL-1 in regulating shikonin biosynthesis in Lithospermum erythrorhizon hairy roots
Time-course accumulation of shikonin in four typical hairy root lines. Value of Ei-19 or EO-13 is significantly different from that of the control line WT-1 or EV-9 at each time point from 3 to 12 days, respectively (Student’s t-test, P < 0.05). (TIF 125 kb
One Amino Acid Change of Angiotensin II Diminishes Its Effects on Abdominal Aortic Aneurysm
Angiotensin (Ang) A is formed by the decarboxylation of the N terminal residue of AngII. The present study determined whether this one amino acid change impacted effects of AngII on abdominal aortic aneurysm (AAA) formation in mice. Computational analyses implicated that AngA had comparable binding affinity to both AngII type 1 and 2 receptors as AngII. To compare effects of these two octapeptides in vivo, male low-density lipoprotein receptor (Ldlr) or apolipoprotein E (Apoe) deficient mice were infused with either AngII or AngA (1 μg/kg/min) for 4 weeks. While AngII infusion induced AAA consistently in both mouse strains, the equivalent infusion rate of AngA did not lead to AAA formation. We also determined whether co-infusion of AngA would influence AngII-induced aortic aneurysm formation in male Apoe−/− mice. Co-infusion of the same infusion rate of AngII and AngA did not change AngII-induced AAA formation. Since it was reported that a 10-fold higher concentration of AngA elicited comparable vasoconstrictive responses as AngII, we compared a 10-fold higher rate (10 μg/kg/min) of AngA infusion into male Apoe−/− mice with AngII (1 μg/kg/min). This rate of AngA led to abdominal aortic dilation in three of ten mice, but no aortic rupture, whereas the 10-fold lower rate of AngII infusion led to abdominal aortic dilation or rupture in eight of ten mice. In conclusion, AngA, despite only being one amino acid different from AngII, has diminished effects on aortic aneurysmal formation, implicating that the first amino acid of AngII has important pathophysiological functions
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