Singly-Peaked P-Cygni type Lyα\alpha from starburst galaxies

We present results of Monte Carlo calculations for the Lya line transfer in an expanding dusty supershell, where Lya source is a well-localized star cluster in a starburst galaxy.The escape of Lya photons from such system is achieved by a number of back-scattering, and so a series of emission peaks are formed redward of the systemic redshift by back-scattering. However, majority of observed Lya emission from starbursts show singly-peaked asymmetric profiles. We find in this paper that, in order to form a singly-peaked Lya emission, dust should be distributed in the ionized bubble, as well as within the supershell of neutral hydrogen. We also find that the overall escape fraction of Lya photons is determined by the HI column density of the supershell, the expansion velocity of the supershell, and the spatial distribution of dust. However, the kinematic information of the expanding supershell is preserved in the profile of Lya emission even when the supershell is dusty. Our results are potentially useful to fit the P-Cygni type Lya line profiles from starburst galaxies, either nearby galaxies or high-z Lyman break galaxies (LBGs).Comment: Original version was submitted to MNRAS on 13, Jan, 2003, which was withdrawn. After heavey revison, its essence was resubmitted to ApJL on 18 Aug. 2003. 2nd revision. 10 pages, 3 figure

Lyman alpha line formation in starbursting galaxies II. Extremely Thick, Dustless, and Static HI Media

The Lya line transfer in an extremely thick medium of neutral hydrogen is investigated by adopting an accelerating scheme in our Monte Carlo code to skip a large number of core or resonant scatterings. This scheme reduces computing time significantly with no sacrifice in the accuracy of the results. We applied this numerical method to the Lya transfer in a static, uniform, dustless, and plane-parallel medium. Two types of photon sources have been considered, the midplane source and the uniformly distributed sources. The emergent profiles show double peaks and absorption trough at the line-center. We compared our results with the analytic solutions derived by previous researchers, and confirmed that both solutions are in good agreement with each other. We investigated the directionality of the emergent Lya photons and found that limb brightening is observed in slightly thick media while limb darkening appears in extremely thick media. The behavior of the directionality is noted to follow that of the Thomson scattered radiation in electron clouds, because both Lya wing scattering and Thomson scattering share the same Rayleigh scattering phase function. The mean number of wing scatterings just before escape is in exact agreement with the prediction of the diffusion approximation. The Lya photons constituting the inner part of the emergent profiles follow the relationship derived from the diffusion approximation. We present a brief discussion on the application of our results to the formation of Lya broad absorption troughs and P-Cygni type Lya profiles seen in the UV spectra of starburst galaxies.Comment: 24 papges, 12 figures, The revised version submitted to Ap

Lyman alpha line formation in starbursting galaxies I. Moderately thick, dustless, and static HI media

We investigate the Lyman alpha line transfer in nearby and high redshift starbursting galaxies, where the effect of high optical depths and the role of dust in the scattering medium are expected to be conspicuous and should be treated in a very careful manner. We present our first results in dustless, static, and uniform HI media with moderate Lyman alpha line center optical depths \tau_0=10^{3-6}. We assume that the temperatures of media to be T=10^{1-4}K, and use a Monte Carlo technique. We investigate the basic processes of the line transfer and confirm the criterion of a\tau_0>10^3 for the validity of diffusion approximation suggested by Neufeld in 1990, where $a$ is the Voigt parameter. Adopting the model suggested by Tenorio-Tagle et al., we performed calculations on the Lyman alpha line formation for each evolutionary stage of an expanding supershell. The emergent Lyman alpha profiles are characterized by the double peaks and the absorption trough at the line center. We found that the absorption troughs expected in most of the evolutionary stages are not wide enough to be observed with current instruments. However, the absorption trough in the Lyman alpha emission profile from an expanding recombining supershell can be marginally detected.Comment: 38 pages, 12 figures, Accepted for publication in the Ap

Enhanced cardiac expression of two isoforms of matrix metalloproteinase-2 in experimental diabetes mellitus.

BackgroundDiabetic cardiomyopathy (DM CMP) is defined as cardiomyocyte damage and ventricular dysfunction directly associated with diabetes independent of concomitant coronary artery disease or hypertension. Matrix metalloproteinases (MMPs), especially MMP-2, have been reported to underlie the pathogenesis of DM CMP by increasing extracellular collagen content.PurposeWe hypothesized that two discrete MMP-2 isoforms (full length MMP-2, FL-MMP-2; N-terminal truncated MMP-2, NTT-MMP-2) are induced by high glucose stimulation in vitro and in an experimental diabetic heart model.MethodsRat cardiomyoblasts (H9C2 cells) were examined to determine whether high glucose can induce the expression of the two isoforms of MMP-2. For the in vivo study, we used the streptozotocin-induced DM mouse heart model and age-matched controls. The changes of each MMP-2 isoform expression in the diabetic mice hearts were determined using quantitative real-time polymerase chain reaction (qRT-PCR). Immunohistochemical stains were conducted to identify the location and patterns of MMP-2 isoform expression. Echocardiography was performed to compare and analyze the changes in cardiac function induced by diabetes.ResultsQuantitative RT-PCR and immunofluorescence staining showed that the two MMP-2 isoforms were strongly induced by high glucose stimulation in H9C2 cells. Although no definite histologic features of diabetic cardiomyopathy were observed in diabetic mice hearts, left ventricular systolic dysfunction was determined by echocardiography. Quantitative RT-PCR and IHC staining showed this abnormal cardiac function was accompanied with the increases in the mRNA levels of the two isoforms of MMP-2 and related to intracellular localization.ConclusionTwo isoforms of MMP-2 were induced by high glucose stimulation in vitro and in a Type 1 DM mouse heart model. Further study is required to examine the role of these isoforms in DM CMP

Polarization of the Lyman alpha line from an anisotropically expanding H~I shell in primeval galaxies

We compute the polarization of the Lyman alpha line photons emerging from an anisotropically expanding and optically thick medium, which is expected to operate in many Lyman alpha emitting objects including the primeval galaxy DLA~2233+131 and Lyman break galaxies. In the case of a highly optically thick medium, the escape of resonance line photons is achieved by a large number of resonant local scatterings followed by a small number of scatterings in the damping wing. We show that some polarization can develop because the wing scatterings are coupled with strong spatial diffusion which depends on the scattering geometry and kinematics. The case of a slab with a finite scattering optical depth and expansion velocity of ~ 100 kms^{-1} is investigated and it is found that Lyman alpha photons are emergent with the linear degree of polarization up to 10% when the typical scattering optical depth tau>=10^5. We subsequently investigate the polarization of Lyman alpha photons emerging from a spherical shell obscured partially by an opaque component and we obtain ~ 5 % of polarization. It is proposed that a positive detection of polarized Lyman alpha with with P-Cygni type profile from cosmological objects can be a strong test of the expanding shell structure obscured by a disk-like component.Comment: Submitted to ApJ Lette

Non-alcoholic Fatty Liver Disease and the Risk of Incident Atrial Fibrillation in Young Adults:A Nationwide Population-Based Cohort Study

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a multisystem disease including cardiovascular. However, the association between NAFLD and the risk of incident atrial fibrillation (AF), especially in young adults, remains unclear. We aimed to evaluate the association between NAFLD as assessed by the fatty liver index (FLI) and the risk of AF in young adults. METHODS: We identified individuals aged 20–39 years who underwent health examinations conducted by the Korean National Health Insurance Corporation between January 2009 and December 2012. Individuals with significant liver disease, heavy alcohol consumption, or prevalent AF were excluded. We categorized based on FLI: <30, 30 to <60, and ≥60. Incident AF was evaluated as the primary outcome. RESULTS: We included 5,333,907 subjects (mean age, 31 ± 5 years; men, 57%). During a mean follow-up of 7.4 ± 1.1 years, 12,096 patients had newly diagnosed AF (incidence rate 0.31 per 1,000 person-years). After adjustment, subjects with FLI 30 to <60 and FLI ≥60 showed a higher risk of AF compared to those with FLI <30 (hazard ratio [HR] 1.21, 95% confidence interval [CI, 1.15–1.27] and HR 1.47, 95% CI [1.39–1.55], p < 0.001, respectively). In women, the increased AF risk was accentuated in the higher FLI group than in the individuals with FLI <30, compared with men (p-for-interaction = 0.023). A higher incident AF risk in the higher FLI groups was consistently observed in various subgroups. CONCLUSION: Among young adults, NAFLD assessed using FLI was positively correlated with the AF risk. These findings support the evidence of AF screening in young adults with high FLI scores

Habitual Alcohol Intake and Risk of Atrial Fibrillation in Young Adults in Korea

IMPORTANCE: Guidelines recommend that all risk factors for early-onset atrial fibrillation, including lifestyle factors, be proactively managed, considering the poor prognosis of the disease. Not much is known about the association of cumulative alcohol intake with the risk of atrial fibrillation in young adults aged 20 to 39 years, especially among heavy drinkers. OBJECTIVE: To explore the association of alcohol consumption with the risk of incident atrial fibrillation in young adults. DESIGN, SETTING, AND PARTICIPANTS: Using the National Health Insurance Service database, a nationwide population-based cohort study of adults aged 20 to 39 years without prior atrial fibrillation who underwent 4 serial annual health examinations between 2009 and 2012 was conducted. The cumulative alcohol consumption burden over 4 years was calculated by assigning 1 point to more than moderate drinking (≥105 g of alcohol per week) each year. Additionally, a semiquantitative cumulative burden was calculated by assigning 0, 1, 2, and 3 points to non, mild (<105 g per week), moderate (105-210 g per week), and heavy (≥210 g per week) drinking, respectively. Data were analyzed from May to June 2021. EXPOSURE: Amount of alcohol intake in 4 years. MAIN OUTCOMES AND MEASURES: The primary outcome was incident atrial fibrillation during the follow-up period. RESULTS: A total of 1 537 836 participants (mean [SD] age 29.5 [4.1] years, 1 100 099 [71.5%] male) were included in the final analysis. According to the 4-year cumulative burden of alcohol consumption stratified by moderate to heavy drinking, 889 382 participants (57.8%) were in the burden 0 group, 203 374 participants (13.2%) in the burden 1 group, 148 087 participants (9.6%) in the burden 2 group, 144 023 participants (9.4%) in the burden 3 group, and 152 970 participants (9.9%) in the burden 4 group. During a median (IQR) follow-up of 6.13 (4.59-6.48) years, atrial fibrillation was newly diagnosed in 3066 participants (0.36 per 1000 person-years). Participants with a cumulative burden of 4 points who continued more than moderate drinking for 4 years showed a 25% higher risk of atrial fibrillation compared with 0-point participants who kept non-to-mild drinking over 4 years (adjusted HR, 1.25; 95% CI, 1.12-1.40). In a semiquantitative analysis, participants who sustained heavy drinking for 4 consecutive years were associated with a 47% higher atrial fibrillation risk than those who remained nondrinkers over 4 years (aHR, 1.47, CI 1.18-1.83). CONCLUSIONS AND RELEVANCE: Persistent moderate to heavy drinking and higher cumulative alcohol consumption burden might increase the risk of atrial fibrillation even in young adults aged 20 to 39 years