61 research outputs found
Infrared and Radio observations of a small group of protostellar objects in the molecular core, L1251-C
We present a multi-wavelength observational study of a low-mass star-forming
region, L1251-C, with observational results at wavelengths from the
near-infrared to the millimeter. Spitzer Space Telescope observations confirmed
that IRAS 22343+7501 is a small group of protostellar objects. The extended
emission to east-west direction with its intensity peak at the center of L1251A
has been detected at 350 and 850 micron with the CSO and JCMT telescopes,
tracing dense envelope materials around L1251A. The single-dish data from the
KVN and TRAO telescopes show inconsistencies between the intensity peaks of
several molecular line emission and that of the continuum emission, suggesting
complex distributions of molecular abundances around L1251A. The SMA
interferometer data, however, show intensity peaks of CO 2-1 and 13CO 2-1
located at the position of IRS 1, which is both the brightest source in IRAC
image and the weakest source in the 1.3 mm dust continuum map. IRS 1 is the
strongest candidate for the driving source of the newly detected compact CO 2-1
outflow. Over the whole region (14' by 14') of L125l-C, 3 Class I and 16 Class
II sources have been detected, including three YSOs in L1251A. A comparison
with the average projected distance among 19 YSOs in L1251-C and that among 3
YSOs in L1251A suggests L1251-C is an example of low-mass cluster formation,
where protostellar objects are forming in a small group.Comment: 53 pages, 19 figures, accepted for publication in ApJ
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Infrared and Radio Observations of a Small Group of Protostellar Objects in the Molecular Core, L1251-C
We present a multi-wavelength observational study of a low-mass star-forming region, L1251-C, with observational results at wavelengths from the near-infrared to the millimeter. Spitzer Space Telescope observations confirmed that IRAS 22343+7501 is a small group of protostellar objects. The extended emission in the east-west direction with its intensity peak at the center of L1251A has been detected at 350 and 850 mu m with the Caltech Submillimeter Observatory and James Clerk Maxwell telescopes, tracing dense envelope material around L1251A. The single-dish data from the Korean VLBI Network and TRAO telescopes show inconsistencies between the intensity peaks of several molecular emission lines and that of the continuum emission, suggesting complex distributions of molecular abundances around L1251A. The Submillimeter Array interferometer data, however, show intensity peaks of CO 2-1 and (CO)-C-13 2-1 located at the position of IRS 1, which is both the brightest source in the Infrared Array Camera image and the weakest source in the 1.3 mm dust-continuum map. IRS 1 is the strongest candidate for the driving source of the newly detected compact CO 2-1 outflow. Over the entire region (14' x 14') of L125l-C, 3 Class I and 16 Class II sources have been detected, including three young stellar objects (YSOs) in L1251A. A comparison between the average projected distance among the 19 YSOs in L1251-C and that among the 3 YSOs in L1251A suggests that L1251-C is an example of low-mass cluster Formation where protostellar objects form in a small group.Basic Science Research Program through the National Research Foundation of Korea (NRF) - Ministry of Education of the Korean government NRF-2012R1A1A2044689BK21 plus program through the National Research Foundation (NRF) - Ministry of Education of KoreaKorea Astronomy and Space Science Institute (KASI) grant - Korea government (MEST)National Science Foundation 0708158NASA NNX13AE54G, 1224608, 1230782, 1407Astronom
Skin care benefits of bioactive compounds isolated from Zanthoxylum piperitum DC. (Rutaceae)
Purpose: To investigate skin care efficacies of Zanthoxylum pipetitum extract and isolated compounds.
Methods: Ethanol extracts of leaves, branches and fruits of what were partitioned into n-hexane, chloroform, ethyl acetate, n-butanol and aqueous layers and some fractions were further analyzed to isolate five compounds. The isolated compounds were identified based on the proton and carbon nuclear magnetic resonance (NMR) spectra. Cosmetic efficacy tests of the extracts and isolated compounds were evaluated by in vitro tests.
Results: Phytochemical studies of the chloroform and ethyl acetate layers led to the isolation of five compounds; quercitrin (1), afzelin (2), hydroxy-α-sanshool (3), α-sanshool (4) and hyperoside (5). In activity tests, the extracts showed inhibitory activity against inflammation response and melanin synthesis, and induction of procollagen type I C-peptide (PIP). Among the isolated compounds, hydroxy-α-sanshool (3) and α-sanshool (4) displayed significant anti-inflammatory activity.
Conclusion: The results demonstrate that Z. piperitum extract and its active compounds possess a significant potential as a cosmeeutical agent for enhancing skin quality
Spectral survey of a Hot core with an Eruptive Accretion in S255IR NIRS3 (SHEA): The discovery of class I and class II millimeter methanol maser transitions
We report the detection of the millimeter CHOH masers including a new
detection of class I (11-10A) and class II
(6-5E) maser transitions toward the high-mass protostar S255IR
NIRS3 in post-burst phase. The CHOH emissions were detected as a mixture of
maser and thermal characteristics. We examine the detected transitions using an
excitation diagram and LTE model spectra and compare the observed properties
with those of thermal lines. Class II CHOH maser transitions showed
distinctive intensity and velocity distributions from those of thermal
transitions. Bright distinct emission components in addition to the fragmented
and arc-shaped emissions are only detected in class I CHOH maser
transitions toward southern and western directions from the protostellar
position, implying the presence of the slow outflow shocks.Comment: 9 pages, 4 Figures, 1 Table, Accepted for publication in ApJ
The Risk Factors of COVID-19 Infection and Mortality among Older Adults in South Korea
Background This study aimed to identify the risk factors associated with coronavirus disease 2019 (COVID-19) infection and mortality among older adults in South Korea. Methods Using Korean National Health Insurance data from January 1, 2020, to March 31, 2022, we analyzed the impact of various factors, including age, comorbidity burden, and insurance type, on COVID-19 infection and mortality rates. Results Age was the most significant risk factor for mortality in older adults. A higher comorbidity burden was also associated with increased infection (odds ratio [OR]=1.33 for Charlson Comorbidity Index [CCI] ≥2, 95% confidence interval [CI] 1.321–1.339) and mortality (OR=1.537 for CCI ≥2, 95% CI 1.459–1.618) rates. While Medical Aid recipients exhibited lower infection rates (OR=0.898, 95% CI 0.89–0.906) than National Health Insurance beneficiaries, they had higher mortality rates (OR=1.692, 95% CI 1.623–1.763). Conclusion These results emphasized the need to prioritize vaccination and allocate healthcare resources for older adults, particularly those with multiple comorbidities. Addressing socioeconomic disparities and ensuring equitable access to testing and healthcare services are crucial for mitigating the impact of COVID-19 on older adults
Impact of very preterm birth and post-discharge growth on cardiometabolic outcomes at school age: a retrospective cohort study
Background
Adverse metabolic outcomes later in life have been reported among children or young adults who were born as preterm infants. This study was conducted to examine the impact of very preterm/very low birth weight (VP/VLBW) birth and subsequent growth after hospital discharge on cardiometabolic outcomes such as insulin resistance, fasting glucose, and systolic and diastolic blood pressure (BP) among children at 6–8 years of age.
Methods
This retrospective cohort study included children aged 6–8 years and compared those who were born at < 32 weeks of gestation or weighing < 1,500 g at birth (n = 60) with those born at term (n = 110). Body size, fat mass, BP, glucose, insulin, leptin, adiponectin, and lipid profiles were measured. Weight-for-age z-score changes between discharge and early school-age period were also calculated, and factors associated with BP, fasting glucose, and insulin resistance were analyzed.
Results
Children who were born VP/VLBW had significantly lower fat masses, higher systolic BP and diastolic BP, and significantly higher values of fasting glucose, insulin, and homeostatic model assessment of insulin resistance (HOMA-IR), compared to children born at term. VP/VLBW was correlated with HOMA-IR and BPs after adjusting for various factors, including fat mass index and weight-for-age z-score changes. Weight-for-age z-score changes were associated with HOMA-IR, but not with BPs.
Conclusions
Although children aged 6–8 years who were born VP/VLBW showed significantly lower weight and fat mass, they had significantly higher BPs, fasting glucose, HOMA-IR, and leptin levels. The associations of VP/VLBW with cardiometabolic factors were independent of fat mass and weight gain velocity.This research was supported by a grant from the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHID I), funded by the Ministry of Health & Welfare, Republic of Korea (HI14C3451)
Characterization of Cronobacter sakazakii Strains Originating from Plant-Origin Foods Using Comparative Genomic Analyses and Zebrafish Infectivity Studies
Cronobacter sakazakii continues to be isolated from ready-to-eat fresh and frozen produce, flours, dairy powders, cereals, nuts, and spices, in addition to the conventional sources of powdered infant formulae (PIF) and PIF production environments. To understand the sequence diversity, phylogenetic relationship, and virulence of C. sakazakii originating from plant-origin foods, comparative molecular and genomic analyses, and zebrafish infection (ZI) studies were applied to 88 strains. Whole genome sequences of the strains were generated for detailed bioinformatic analysis. PCR analysis showed that all strains possessed a pESA3-like virulence plasmid similar to reference C. sakazakii clinical strain BAA-894. Core genome analysis confirmed a shared genomic backbone with other C. sakazakii strains from food, clinical and environmental strains. Emerging nucleotide diversity in these plant-origin strains was highlighted using single nucleotide polymorphic alleles in 2000 core genes. DNA hybridization analyses using a pan-genomic microarray showed that these strains clustered according to sequence types (STs) identified by multi-locus sequence typing (MLST). PHASTER analysis identified 185 intact prophage gene clusters encompassing 22 different prophages, including three intact Cronobacter prophages: ENT47670, ENT39118, and phiES15. AMRFinderPlus analysis identified the CSA family class C β-lactamase gene in all strains and a plasmid-borne mcr-9.1 gene was identified in three strains. ZI studies showed that some plant-origin C. sakazakii display virulence comparable to clinical strains. Finding virulent plant-origin C. sakazakii possessing significant genomic features of clinically relevant STs suggests that these foods can serve as potential transmission vehicles and supports widening the scope of continued surveillance for this important foodborne pathogen
Molecular Cloud Cores with a High Deuterium Fraction : Nobeyama Single-pointing Survey
We present the results of a single-pointing survey of 207 dense cores embedded in Planck Galactic Cold Clumps distributed in five different environments (lambda Orionis, Orion A, Orion B, the Galactic plane, and high latitudes) to identify dense cores on the verge of star formation for the study of the initial conditions of star formation. We observed these cores in eight molecular lines at 76-94 GHz using the Nobeyama 45 m telescope. We find that early-type molecules (e.g., CCS) have low detection rates and that late-type molecules (e.g., N(2)H(+)and c-C3H2) and deuterated molecules (e.g., N(2)D(+)and DNC) have high detection rates, suggesting that most of the cores are chemically evolved. The deuterium fraction (D/H) is found to decrease with increasing distance, indicating that it suffers from differential beam dilution between the D/H pair of lines for distant cores (>1 kpc). For lambda Orionis, Orion A, and Orion B located at similar distances, D/H is not significantly different, suggesting that there is no systematic difference in the observed chemical properties among these three regions. We identify at least eight high-D/H cores in the Orion region and two at high latitudes, which are most likely to be close to the onset of star formation. There is no clear evidence of the evolutionary change in turbulence during the starless phase, suggesting that the dissipation of turbulence is not a major mechanism for the beginning of star formation as judged from observations with a beam size of 0.04 pc.Peer reviewe
Astrochemical Properties of Planck Cold Clumps
We observed 13 Planck cold clumps with the James Clerk Maxwell Telescope/SCUBA-2 and with the Nobeyama 45 m radio telescope. The N2H+ distribution obtained with the Nobeyama telescope is quite similar to SCUBA-2 dust distribution. The 82 GHz HC3N, 82 GHz CCS, and 94 GHz CCS emission are often distributed differently with respect to the N2H+ emission. The CCS emission, which is known to be abundant in starless molecular cloud cores, is often very clumpy in the observed targets. We made deep single-pointing observations in DNC, (HNC)-C-13, N2D+, and cyclic-C3H2 toward nine clumps. The detection rate of N2D+ is 50%. Furthermore, we observed the NH3 emission toward 15 Planck cold clumps to estimate the kinetic temperature, and confirmed that most targets are cold (less than or similar to 20 K). In two of the starless clumps we observed, the CCS emission is distributed as it surrounds the N2H+ core (chemically evolved gas), which resembles the case of L1544, a prestellar core showing collapse. In addition, we detected both DNC and N2D+. These two clumps are most likely on the verge of star formation. We introduce the chemical evolution factor (CEF) for starless cores to describe the chemical evolutionary stage, and analyze the observed Planck cold clumps.Peer reviewe
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