We present ground-based and Swift observations of iPTF16fnl, a likely tidal disruption event (TDE) discovered by the intermediate Palomar Transient Factory (iPTF) survey at 66.6 Mpc. The light curve ...of the object peaked at an absolute mag . The maximum bolometric luminosity (from optical and UV) was erg s−1, an order of magnitude fainter than any other optical TDE discovered so far. The luminosity in the first 60 days is consistent with an exponential decay, with , where t0 = 57631.0 (MJD) and days. The X-ray shows a marginal detection at erg s−1 (Swift X-ray Telescope). No radio counterpart was detected down to 3 , providing upper limits for monochromatic radio luminosities of erg s−1 and erg s−1 (Very Large Array, 6.1 and 22 GHz). The blackbody temperature, obtained from combined Swift UV and optical photometry, shows a constant value of 19,000 K. The transient spectrum at peak is characterized by broad He ii and H emission lines, with FWHMs of about 14,000 km s−1 and 10,000 km s−1, respectively. He i lines are also detected at λλ 5875 and 6678. The spectrum of the host is dominated by strong Balmer absorption lines, which are consistent with a post-starburst (E+A) galaxy with an age of ∼650 Myr and solar metallicity. The characteristics of iPTF16fnl make it an outlier on both luminosity and decay timescales, as compared to other optically selected TDEs. The discovery of such a faint optical event suggests a higher rate of tidal disruptions, as low-luminosity events may have gone unnoticed in previous searches.
The Landsat Multispectral Scanner (MSS) data sensed by the Landsat 1–5 satellites make up a significant portion of the early Landsat data record. However, accurate MSS image geolocation has been ...difficult to achieve systematically due to a number of factors associated primarily with the older sensor and satellite technology. As of August 2019, only 49% of the Landsat MSS archive could be processed at the highest-level L1TP (precision and terrain corrected) level, and the remainder were processed as L1GS (systematically corrected) with inaccurate geolocation and no terrain correction. This paper presents a methodology to improve the geolocation of MSS time series. The methodology uses an area- and feature-based least-squares matching scale-space algorithm, with a time series registration implementation, that we developed previously using Landsat-8 and Sentinel-2 imagery. The methodology requires that at least three L1TP images in the time series acquired over a given path/row are available. A linear combination of a polynomial transformation and multiple radially symmetric radial-basis-functions (RBFs) to model local uncorrected terrain relief effects present in the L1GS images are used. The processing is automated and applied in two passes. The first pass screens L1TP images to select the well-aligned ones that are used as references. The second pass registers the target images, including the L1GS images and any misaligned L1TP images, to all the reference L1TP images. The transformation coefficients for each registered target image are derived by least-squares adjustment using densely-matched tie-points between the target and the reference images. The methodology is demonstrated using 12 months of Landsat-4 MSS images at four Landsat path/row locations that contain agricultural, mountainous, and coastal regions, including a total of 43 L1TP and 31 L1GS images. There were sufficient tie-points to characterize the degree of misregistration of 14 L1GS images that had significant mean misregistration shifts ranging from 7.33 to 17.42 60 m pixels. In addition, at one site, two L1TP images were found to be misaligned and have mean misregistration shifts of 1.27 and 2.20 60 m pixels. The methodology provides sub-pixel registration accuracy - after registration, the mean misregistration shifts for the 14 L1GS and two misaligned L1TP images varied from only 0.10 to 0.41 60 m pixels. The methodology does not use a digital elevation model, and examples illustrate that although the RBF transformations can compensate terrain relief distortion effects, larger (~0.5 to 1.0 pixel) misregistration errors can remain in areas with highly variable terrain relief. Results are also provided for Landsat-1 MSS imagery to demonstrate the applicability of the methodology to even the earliest part of the Landsat record. Detailed qualitative and quantitative results are presented and indicate the potential of the methodology to improve the geolocation of the Landsat MSS data record that is discussed with recommendations for future research.
•Automated registration of Landsat MSS imagery.•Applied systematically to time series at given path/row.•Significant MSS misregistration errors documented.•≤ 0.5 60 m pixel registration accuracy achieved.•Potential to improve the geolocation of the MSS archive.
Previous studies have established the link between aberrant microRNA (miRNA) expression and hypoxia in various neoplasms. However, how these hypoxia-related miRNAs modulate tumor progression is still ...unclear. Therefore, the patterns of miRNA in colorectal carcinoma cell lines in response to hypoxia or not were first screened and the hypoxia-induced repression of the miR-15-16 cluster was confirmed. Then, this repression was found to be associated with high tumor stage and poor prognosis in colorectal carcinoma and is shown to promote tumor angiogenesis and metastasis by the loss of restriction of its target gene, fibroblast growth factor-2 (FGF2). Moreover, the general and alterative promoters of the miR-15-16 host (deleted in lymphocytic leukemia 2, DLEU2) were mapped, and three c-Myc/Max binding sites in response to the hypoxia-induced repression of miR-15-16 were further identified. Finally, an enhanced stability of c-Myc/Max heterodimer promoted by increased hypoxia-inducible factor-2α (HIF-2α) was validated, and we also verified that the enhancement contributed to the hypoxia-induced repression of miR-15-16. In brief, the c-Myc-mediated transcriptional repression of miR-15-16 in hypoxia is induced by increased HIF-2α and promoted tumor angiogenesis and hematogenous metastasis by the further loss of post-transcriptional inhibition of FGF2. Our study provides a better understanding of the coping mechanisms in response to tumor hypoxia and may be helpful in developing an effective prognostic marker or treatment target against solid tumors.
Background Myocardial infarction (MI) is a significant clinical and public health problem worldwide. However, little research has assessed the interplay between genetic susceptibility and social ...environment in the development of MI. Methods and Results Data were from the HRS (Health and Retirement Study). The polygenic risk score and polysocial score for MI were classified as low, intermediate, and high. Using Cox regression models, we assessed the race-specific association of polygenic score and polysocial score with MI and examined the association between polysocial score and MI in each polygenic risk score category. We also examined the joint effect of genetic (low, intermediate, and high) and social environmental risks (low/intermediate, high) on MI. A total of 612 Black and 4795 White adults aged ≥65 years initially free of MI were included. We found a risk gradient of MI across the polygenic risk score and polysocial score among White participants; no significant risk gradient across the polygenic risk score was found among Black participants. A disadvantaged social environment was associated with a higher risk of incident MI among older White adults with intermediate and high genetic risk but not those with low genetic risk. We revealed the joint effect of genetics and social environment in the development of MI among White participants. Conclusions Living in a favorable social environment is particularly important for people with intermediate and high genetic risk for MI. It is critical to developing tailored interventions to improve social environment for disease prevention, especially among adults with a relatively high genetic risk.
ABSTRACT
For the first time, we present an extensive study of stars with individual non-LTE (NLTE) abundances for 17 chemical elements from Li to Eu in a sample of stars uniformly distributed over ...the −2.62 ≤ Fe/H ≤ +0.24 metallicity range that is suitable for the Galactic chemical evolution research. The star sample has been kinematically selected to trace the Galactic thin and thick disks and halo. We find new results and improve earlier ones as follows: (i) the element-to-iron ratios for Mg, Si, Ca, and Ti form a metal-poor (MP) plateau at a similar height of 0.3 dex, and the knee occurs at common Fe/H ≃ −0.8. The knee at the same metallicity is observed for O/Fe, and the MP plateau is formed at O/Fe = 0.61. (ii) The upward trend of C/O with decreasing metallicity exists at Fe/H < −1.2, supporting the earlier finding of Akerman et al. (iii) An underabundance of Na relative to Mg in the Fe/H < −1 stars is nearly constant, with the mean Na/ Mg ≃ −0.5. (iv) The K/Sc, Ca/Sc, and Ti/Sc ratios form well-defined trends, suggesting a common site of the K–Ti production. (v) Sr follows the Fe abundance down to Fe/H ≃ −2.5, while Zr is enhanced in MP stars. (vi) The comparisons of our results with some widely used Galactic evolution models are given. The use of the NLTE element abundances gives increased credit to the interpretation of the data in the context of the chemical evolution of the Galaxy.
Abstract
Based on the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution spectroscopic survey (MRS), we report the discovery of nine super Li-rich unevolved stars ...with A(Li) > 3.8 dex. These objects show unusually high levels of lithium abundances, up to three times higher than the meteoritic value of 3.3 dex, which indicates that they must have experienced a history of lithium enrichment. It is found that seven of our program stars are fast rotators with
v
sin
i
> 9 km s
−1
, which suggests that the accretion of circumstellar matter may be the main contributor to the lithium enhancement of these unevolved stars; however, other sources cannot be excluded.
We present the ancillary data and basic physical measurements for the galaxies in the ALMA Large Program to Investigate C+ at Early Times (ALPINE) survey-the first large multiwavelength survey that ...aims at characterizing the gas and dust properties of 118 main-sequence galaxies at redshifts 4.4 < z < 5.9 via the measurement of emission at (64% at >3.5 ) and the surrounding far-infrared continuum in conjunction with a wealth of optical and near-infrared data. We outline in detail the spectroscopic data and selection of the galaxies as well as the ground- and space-based imaging products. In addition, we provide several basic measurements including stellar masses, star formation rates (SFR), rest-frame ultra-violet (UV) luminosities, UV continuum slopes (β), and absorption line redshifts, as well as H emission derived from Spitzer colors. We find that the ALPINE sample is representative of the 4 < z < 6 galaxy population selected by photometric methods and only slightly biased toward bluer colors (Δβ ∼ 0.2). Using as tracer of the systemic redshift (confirmed for one galaxy at z = 4.5 out of 118 for which we obtained optical λ3727 emission), we confirm redshifted Ly emission and blueshifted absorption lines similar to findings at lower redshifts. By stacking the rest-frame UV spectra in the rest frame, we find that the absorption lines in galaxies with high specific SFR are more blueshifted, which could be indicative of stronger winds and outflows.
The origin of the deformation in metallic glasses is attributed to rearrangements of atoms in some structurally weak spots behaving as flow units, which are associated with free volumes. In the ...present study, Xe-ion beam is used to manipulate the free-volume fraction, and influence on the mechanical behavior of a Zr-based metallic glass. The irradiation at low dosages can change the structure by increasing the free volume, and by homogenising the distribution of free volume. The increase in the free-volume fraction is equivalent to the increase in the deformation temperature, thus resulting in the decrease in the yield strength. The analysis of stochastic strain burst size in the metallic glass irradiated at different dosages indicates that the strain burst depends on the yield strength and homogeneity of the glassy phase. The results of this study highlight the fact that the quantitative manipulation of the homogeneity and the amount of free volumes can be achieved through low-dose ion irradiation, which can modify the mechanical behavior of metallic glasses.
Display omitted
Abstract The daily light dark cycle is the most salient entraining factor for the circadian system. However, in modern society, darkness at night is vanishing as light pollution steadily increases. ...The impact of brighter nights on wild life ecology and human physiology is just now being recognized. In the present study, we tested the possible detrimental effects of dim light exposure on the regulation of circadian rhythms, using CD1 mice housed in light/dim light (LdimL, 300 lux:20 lux) or light/dark (LD, 300 lux:1 lux) conditions. We first examined the expression of clock genes in the suprachiasmatic nucleus (SCN), the locus of the principal brain clock, in the animals of the LD and LdimL groups. Under the entrained condition, there was no difference in PER1 peak expression between the two groups, but at the trough of the PER 1 rhythm, there was an increase in PER1 in the LdimL group, indicating a decrease in the amplitude of the PER1 rhythm. After a brief light exposure (30 min, 300 lux) at night, the light-induced expression of mPer1 and mPer2 genes was attenuated in the SCN of LdimL group. Next, we examined the behavioral rhythms by monitoring wheel-running activity to determine whether the altered responses in the SCN of LdimL group have behavioral consequence. Compared to the LD controls, the LdimL group showed increased daytime activity. After being released into constant darkness, the LdimL group displayed shorter free-running periods. Furthermore, following the light exposure, the phase shifting responses were smaller in the LdimL group. The results indicate that nighttime dim light exposure can cause functional changes of the circadian system, and suggest that altered circadian function could be one of the mechanisms underlying the adverse effects of light pollution on wild life ecology and human physiology.
PDF
![The ALPINE-ALMA [C ii] Surv...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0067-0049/small "The ALPINE-ALMA [C ii] Survey: Multiwavelength Ancillary Data and Basic Physical Measurements")
