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After the Fall: The Dust and Gas in E+A Post-starburst Galaxies
Smercina, A.,Smith, J. D. T.,Dale, D. A.,French, K. D.,Croxall, K. V.,Zhukovska, S.,Togi, A.,Bell, E. F.,Crocker, A. F.,Draine, B. T.,Jarrett, T. H.,Tremonti, C.,Yang, Yujin,Zabludoff, A. I. American Astronomical Society 2018 The Astrophysical journal Vol.855 No.1
<P>The traditional picture of post-starburst galaxies as dust-and gas-poor merger remnants, rapidly transitioning to quiescence, has been recently challenged. Unexpected detections of a significant interstellar medium (ISM) in many post-starburst galaxies raise important questions. Are they truly quiescent, and if so, what mechanisms inhibit further star formation? What processes dominate their ISM energetics? We present an infrared spectroscopic and photometric survey of 33 E+A post-starbursts selected by the Sloan Digital Sky Survey, aimed at resolving these questions. We find compact, warm dust reservoirs with high PAH abundances and total gas and dust masses significantly higher than expected from stellar recycling alone. Both polycyclic aromatic hydrocarbon (PAH)/total infrared (TIR) and dust-to-burst stellar mass ratios are seen to decrease with post-burst age, indicative of the accumulating effects of dust destruction and an incipient transition to hot, early-type ISM properties. Their infrared spectral properties are unique, with dominant PAH emission, very weak nebular lines, unusually strong H-2. rotational emission, and deep [C II] deficits. There is substantial scatter among star formation rate (SFR) indicators, and both PAH and TIR luminosities provide overestimates. Even as potential upper limits, all tracers show that the SFR has typically experienced a decline of more than two orders of magnitude since the starburst and that the SFR is considerably lower than expected given both their stellar masses and molecular gas densities. These results paint a coherent picture of systems in which star formation was, indeed, rapidly truncated, but in which the ISM was not completely expelled, and is instead supported against collapse by latent or continued injection of turbulent or mechanical heating. The resulting aging burst populations provide a 'high-soft' radiation field that seemingly dominates the E+A galaxies' unusual ISM energetics.</P>
Rohs, Patricia D. A.,Buss, Jackson,Sim, Sue I.,Squyres, Georgia R.,Srisuknimit, Veerasak,Smith, Mandy,Cho, Hongbaek,Sjodt, Megan,Kruse, Andrew C.,Garner, Ethan C.,Walker, Suzanne,Kahne, Daniel E.,Bern Public Library of Science 2018 PLoS genetics Vol.14 No.10
<▼1><P>Cell elongation in rod-shaped bacteria is mediated by the Rod system, a conserved morphogenic complex that spatially controls cell wall assembly by the glycan polymerase RodA and crosslinking enzyme PBP2. Using <I>Escherichia coli</I> as a model system, we identified a PBP2 variant that promotes Rod system function when essential accessory components of the machinery are inactivated. This PBP2 variant hyperactivates cell wall synthesis in vivo and stimulates the activity of RodA-PBP2 complexes in vitro. Cells with the activated synthase also exhibited enhanced polymerization of the actin-like MreB component of the Rod system. Our results define an activation pathway governing Rod system function in which PBP2 conformation plays a central role in stimulating both glycan polymerization by its partner RodA and the formation of cytoskeletal filaments of MreB to orient cell wall assembly. In light of these results, previously isolated mutations that activate cytokinesis suggest that an analogous pathway may also control cell wall synthesis by the division machinery.</P></▼1><▼2><P><B>Author summary</B></P><P>The cell wall of bacteria determines their shape and protects them from osmotic lysis. Two enzymatic activities are required for cell wall synthesis: glycan polymerization and crosslinking. A major new family of glycan polymerases was recently discovered and was proposed to work in complex with crosslinking enzymes called penicillin-binding proteins (PBPs). How the activities of these enzymes are coordinated to prevent the toxic generation of uncrosslinked glycans has remained unknown. Our analysis of the cell elongation system of <I>Escherichia coli</I> has revealed that this coupling is mediated by changes in the PBP that activate glycan chain synthesis by the polymerase. Furthermore, we present genetic evidence that this activation event is mediated by a component of the elongation machinery with a previously unknown function. Discovery of this activation pathway provides new mechanistic insight into the cell wall biogenesis process and identifies a new avenue to disrupt it for antibiotic development.</P></▼2>
Brannan E. O’Neill,Jamila A. Godil,Spencer Smith,Ali I. Rae,Christina H. Wright,James M. Wright,Donald A. Ross,Josiah N. Orina,Jesse J. Liu,Clifford Lin,Travis C. Philipp,Jonathan Kark,Jung U. Yoo,Won 대한척추신경외과학회 2023 Neurospine Vol.20 No.4
Objective: The purpose of this study is to examine the utilization of kyphoplasty/vertebroplasty procedures in the management of compression fractures. With the growing elderly population and the associated increase in rates of osteoporosis, vertebral compression fractures have become a daily encounter for spine surgeons. However, there remains a lack of consensus on the optimal management of this patient population. Methods: A retrospective analysis of 91 million longitudinally followed patients from 2016 to 2019 was performed using the PearlDiver Patient Claims Database. Patients with compression fractures were identified using International Classification of Disease, 10th Revision codes, and a subset of patients who received kyphoplasty/vertebroplasty were identified using Common Procedural Terminology codes. Baseline demographic and clinical data between groups were acquired. Multivariable regression analysis was performed to determine predictors of receiving kyphoplasty/vertebroplasty. Results: A total of 348,457 patients with compression fractures were identified with 9.2% of patients receiving kyphoplasty/vertebroplasty as their initial treatment. Of these patients, 43.5% underwent additional kyphoplasty/vertebroplasty 30 days after initial intervention. Patients receiving kyphoplasty/vertebroplasty were significantly older (72.2 vs. 67.9, p < 0.05), female, obese, had active smoking status and had higher Elixhauser Comorbidity Index scores. Multivariable analysis demonstrated that female sex, smoking status, and obesity were the 3 strongest predictors of receiving kyphoplasty/vertebroplasty (odds ratio, 1.27, 1.24, and 1.14, respectively). The annual rate of kyphoplasty/vertebroplasty did not change significantly (range, 8%–11%). Conclusion: The majority of vertebral compression fractures are managed nonoperatively. However, certain patient factors such as smoking status, obesity, female sex, older age, osteoporosis, and greater comorbidities are predictors of undergoing kyphoplasty/vertebroplasty.
A. Kirchner,I.W.M. Brown,M.E. Bowden,T. Kemmitt,G. Smith 한국물리학회 2008 Current Applied Physics Vol.8 No.3,4
Porous anodic alumina discs supporting palladium lms as elements of hydrogen-purifying membranes have been examined for theirhigh-temperature behaviour. The method employed to fabricate the porous alumina support is the so-called ‘hard anodising’ technique,which oers substantially higher growth rates while producing mechanically robust lms. These alumina membranes were found to pos-sess a thermal stability better than commercial Anopore. membranes. Upon long-term exposure at 800.C they transform intoc-aluminawithout major deformation. Ultra-thin palladium lms deposited across the alumina pores by physical vapour deposition are continuousand stable in reducing atmospheres to at least 700.C but are oxidised and destroyed by heating in air.
Point Source effect on Overlay Accuracy in IBBI Aligning System
Lee, Jawoong,Moon, Euclid E.,Everett, Patrick N.,Smith, Henry I. 順天大學校 1999 論文集 Vol.18 No.1
In order to satisfy <130 nm ground rules, several nanometer (σ) overlay accuracy is required. Recently, IBBI(Interferometric Broad Band Imaging) system is being developed to obtain the nanometer overlay accuracy with the point X-ray source at the NSL(NanoStructures Lab.) of MIT. In this paper we theoretically analyzed the various error sources which affect the overlay accuracy and derived the comprehensive equations which represent the overlay accuracy between two adjacent exposure levels. The equations include gap, position of the source, slant angle, rotational angle, and electron-beam writing error as the independent variables. Some criteria to achieve 1 nm overlay accuracy within one-inch-square exposure field for IBBI system were prepared. To reduce the magnification error, we found that the control of gap, source position, slant angle should be to less than 10 nm, 30μm, 0.4 μrad respectively. The rotational angular uncertainty should be less than 0.04 μrad. The electron-beam writing error should be less than 0.5 nm.