分类: 天文学 >> 天文学 提交时间: 2024-05-10 合作期刊: 《Research in Astronomy and Astrophysics》
摘要: The triggering mechanism for radio lobes from late-type galaxies is not fully understood. More samples are desired for a thorough investigation and statistics. By utilizing the optical data from the newly released Dark Energy Spectroscopic Instrument imaging surveys and the radio sources from the NRAO VLA Sky Survey and the Faint Images of the Radio Sky at Twenty-centimeter, we identify four Late-type Galaxies with double Radio Lobes (LaGRLs): J0217−3645, J0947+6220, J1412+3723 and J1736+5108. Including previously known LaGRLs, we confirm the correlation between radio power P1.4 GHz and stellar mass M* of host galaxies. Most (25/35) LaGRLs belong to the blue cloud galaxies, while the newly identified cases in this work are located within the region of the red sequence. We find a clear correlation between the differential radio power, i.e., the offset from the P1.4 GHz − M* relation, and the galaxy color, indicating that bluer galaxies at a fixed M* tend to host more powerful radio lobes. Furthermore, the majority (31/36) of LaGRLs are either located in a galaxy group or displaying a disturbed morphology. We suggest that all of the galaxy mass, color and surrounding environment could play important roles in triggering radio lobes in late-type galaxies.
分类: 生物学 >> 植物学 >> 植物生理学 提交时间: 2016-05-04
摘要: The impact of metabolic engineering on nontarget pathways and outcomes of metabolic engineering from different genomes are poorly understood questions. Therefore, squalene biosynthesis genes FARNESYL DIPHOSPHATE SYNTHASE (FPS) and SQUALENE SYNTHASE (SQS) were engineered via the Nicotiana tabacum chloroplast (C), nuclear (N) or both (CN) genomes to promote squalene biosynthesis. SQS levels were ~4300-fold higher in C and CN lines than in N, but all accumulated ~150-fold higher squalene due to substrate or storage limitations. Abnormal leaf and flower phenotypes, including lower pollen production and reduced fertility, were observed regardless of the compartment or level of transgene expression. Substantial changes in metabolomes of all lines were observed: levels of 65120 unrelated metabolites, including the toxic alkaloid nicotine, changed by as much as 32-fold. Profound effects of transgenesis on nontarget gene expression included changes in the abundance of 19076 transcripts by up to 2000-fold in CN; 7784 transcripts by up to 1400-fold in N; and 5224 transcripts by as much as 2200-fold in C. Transporter-related transcripts were induced, and cell cycle-associated transcripts were disproportionally repressed in all three lines. Transcriptome changes were validated by qRT-PCR. The mechanism underlying these large changes likely involves metabolite-mediated anterograde and/or retrograde signalling irrespective of the level of transgene expression or end product, due to imbalance of metabolic pools, offering new insight into both anticipated and unanticipated consequences of metabolic engineering.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: A 5$^{\circ}$ $\times$ 7$^{\circ}$ sky area containing two large radio structures of G203.1+6.6 and G206.7+5.9 with a size of about 2.5$^{\circ}$ and 3.5$^{\circ}$ respectively is scanned by using the L-band 19-beam receiver of the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The FAST L-band receiver covers a frequency range of 1.0-1.5 GHz. Commissioning of the receiving system, including the measurements of the half-power beam width, gain, and main-beam efficiency is made by observing the calibrators. The multi-channel spectroscopy backend mounted to the receiver allows an in-band spectral-index determination. The brightness-temperature spectral indices of both objects are measured to be $\beta$ $\sim$ $-$2.6 to $-$2.7. Polarized emission is detected from the archival Effelsberg $\lambda$11 cm data for all the shell structures of G203.1+6.6 and G206.7+5.9. These results clearly indicate a non-thermal synchrotron emitting nature, confirming that G203.1+6.6 and G206.7+5.9 are large shell-type supernova remnants (SNRs). Based on morphological correlation between the radio continuum emission of G206.7+5.9 and the HI structures, the kinematic distance to this new SNR is estimated to be about 440 pc, placing it in the Local Arm.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We evaluate the consistency between lensing and clustering probes of
large-scale structure based on measurements of projected galaxy clustering from
BOSS combined with overlapping galaxy-galaxy lensing from three surveys: DES
Y3, HSC Y1, and KiDS-1000. An intra-lensing-survey study finds good agreement
between these lensing data. We model the observations using the Dark Emulator
and fit the data at two fixed cosmologies: Planck, with $S_8=0.83$, and a
Lensing cosmology with $S_8=0.76$. For a joint analysis limited to scales with
$R>5.25h^{-1}$Mpc, we find that both cosmologies provide an acceptable fit to
the data. Full utilisation of the small-scale clustering and lensing
measurements is hindered by uncertainty in the impact of baryon feedback and
assembly bias, which we account for with a reasoned theoretical error budget.
We incorporate a systematic scaling parameter for each redshift bin, $A$, that
decouples the lensing and clustering to capture any inconsistency. When a wide
range of scales ($0.15