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

Diagnosing 0.1–10 au Scale Morphology of the FU Ori Disk Using ALMA and VLTI/GRAVITY

We report new Atacama Large Millimeter/submillimeter Array Band 3 (86–100 GHz; ~80 mas angular resolution) and Band 4 (146–160 GHz; ~50 mas angular resolution) observations of the dust continuum emission toward the archetypal and ongoing accretion burst young stellar object FU Ori, which simultaneously covered its companion, FU Ori S. In addition, we present near-infrared (2–2.45 μm) observations of FU Ori taken with the General Relativity Analysis via VLT InTerferometrY (GRAVITY; ~1 mas angular resolution) instrument on the Very Large Telescope Interferometer (VLTI). We find that the emission in both FU Ori and FU Ori S at (sub)millimeter and near-infrared bands is dominated by structures inward of ~10 au radii. We detected closure phases close to zero from FU Ori with VLTI/GRAVITY, which indicate the source is approximately centrally symmetric and therefore is likely viewed nearly face-on. Our simple model to fit the GRAVITY data shows that the inner 0.4 au radii of the FU Ori disk has a triangular spectral shape at 2–2.45 μm, which is consistent with the H2O and CO absorption features in a 10−4 M ⊙ yr−1, viscously heated accretion disk. At larger (~0.4–10 au) radii, our analysis shows that viscous heating may also explain the observed (sub)millimeter and centimeter spectral energy distribution when we assume a constant, ~10−4 M ⊙ yr−1 mass inflow rate in this region. This explains how the inner 0.4 au disk is replenished with mass at a modest rate, such that it neither depletes nor accumulates significant masses over its short dynamic timescale. Finally, we tentatively detect evidence of vertical dust settling in the inner 10 au of the FU Ori disk, but confirmation requires more complete spectral sampling in the centimeter bands

Detection of intrinsic source structure at ~3 Schwarzschild radii with Millimeter-VLBI observations of SAGITTARIUS A*

We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A*, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional {\it uv} coverage in the N-S direction, and leads to a spatial resolution of $\sim$30 $\mu$as ($\sim$3 Schwarzschild radii) for Sgr A*. The source is detected even at the longest baselines with visibility amplitudes of $\sim$4-13% of the total flux density. We argue that such flux densities cannot result from interstellar refractive scattering alone, but indicate the presence of compact intrinsic source structure on scales of $\sim$3 Schwarzschild radii. The measured nonzero closure phases rule out point-symmetric emission. We discuss our results in the context of simple geometric models that capture the basic characteristics and brightness distributions of disk- and jet-dominated models and show that both can reproduce the observed data. Common to these models are the brightness asymmetry, the orientation, and characteristic sizes, which are comparable to the expected size of the black hole shadow. Future 1.3 mm VLBI observations with an expanded array and better sensitivity will allow a more detailed imaging of the horizon-scale structure and bear the potential for a deep insight into the physical processes at the black hole boundary.Comment: 11 pages, 5 figures, accepted to Ap

CONTINUOUS HYDROLOGIC MODELING FOR ANALYZING THE EFFECTS OF DROUGHT ON THE LOWER COLORADO RIVER IN TEXAS

A physically based hydrologic model, the HEC-Hydrologic Modeling System (HMS), developed by the U.S. Army Corps of Engineers, has been parameterized using the Soil Moisture Accounting (SMA) algorithm, calibrated, and validated for the Lake Travis and Lake Lyndon B. Johnson (LBJ) contributing basins in central Texas. The basins are divided into a total of 15 sub-basins, and HEC-HMS with the SMA algorithm represents each sub-basin with five water storage layers involving twelve parameters--surface depression storage, canopy interception storage, upper zone soil storage, tension zone soil storage, infiltration rate, and soil percolation rate, along with storage depths, storage coefficients and percolation rates for one shallow and one deep groundwater layer. The first six parameters and the percolation rate for the interflow were estimated objectively using a combination of the National Land Cover Database 2011 (NLCD 2011) and Soil Survey Geographic Database (SSURGO). The next four parameters were estimated based on analysis of historical streamflow records, and the last parameter was determined through model calibration. The parameter analysis shows that the tension zone storage, interflow storage coefficient and the baseflow percolation rate are the most sensitive parameters for this watershed model. Comparison of simulated and observed streamflows showed that the estimated parameters can be used with meteorological data to simulate flows into the Highland Lakes system in central Texas. The results of the statistical analysis indicate that the simulated flows and observed flows are reasonably well correlated. The model performance is rated as good to very good for all the metrics. The PBIAS coefficient is 9.6 and the Nash-Sutcliffe efficiency value is 0.71 for the entire simulation period, 2004-2016. The model performance can potentially be improved through further calibration and by using the hourly climatic input data instead of daily data. xi In future work, the validated HEC-HMS model can be employed with seasonal climate forecasts and under long-range land-use and climate projections. In addition, radar-based precipitation data can be used to represent the climatic variability on a grid-based scale

Acidosis potentiates endothelium-dependent vasorelaxation and gap junction communication in the superior mesenteric artery.

Extracellular pH is an important physiological determinant of vascular tone that is normally maintained within 7.35-7.45. Any change outside this range leads to severe pathological repercussions. We investigated the unknown effects of extracellular acidosis on relaxation in the superior mesenteric artery (SMA) of goat. SMA rings were employed to maintain isometric contractions at extracellular pH (p

Reduction of Structural Damage from the Thermal Expansion of Concrete Using Multifunctional Materials

This study leveraged past successes in the analysis and design of shape memory alloy (SMA) components to address the issue of thermal expansion in concrete structures. Since the SMA used in the current work is relatively cheaper than other common SMAs (less than $50/lb compared to NiTi which is$200/lb due to difficulties in processing), it is anticipated that the findings of the study could be implemented in real infrastructures made of concrete, asphalt concrete, and other complex large infrastructure. Low-cost Fe-SMAs and other multifunctional materials can be considered as a replacement for components made of steel (e.g., in reinforced or plain jointed concrete pavements) to control distresses resulting from thermal expansion during seasonal/daily temperature change. This study conducted a series of finite element (FE) case studies of various configurations of concrete (blocks, slabs, and beams) with embedded, pre-strained SMA rods. This included developing new models to investigate temperature induced deflection in concrete slabs to analyze their curling behavior. It also included investigating the optimal position of the SMA rod and required rod radius. It is hoped that the results of this work could help to design smarter civil infrastructure incorporating multifunctional materials into established civil engineering materials