Nuclear Bar Catalyzed Star Formation: 13^CO, C18^O and Molecular Gas Properties in the Nucleus of Maffei 2

(Abridged) We present resolution maps of CO, its isotopologues, and HCN from in the center of Maffei 2. The J=1-0 rotational lines of 12^CO, 13^CO, C18^O and HCN, and the J=2-1 lines of 13^CO and C18^O were observed with the OVRO and BIMA arrays. The 2-1/1-0 line ratios of the isotopologues constrain the bulk of the molecular gas to originate in low excitation, subthermal gas. From LVG modeling, we infer that the central GMCs have n(H_2) ~10^2.75 cm^-3 and T_k ~ 30 K. Continuum emission at 3.4 mm, 2.7 mm and 1.4 mm was mapped to determine the distribution and amount of HII regions and dust. Column densities derived from C18^O and 1.4 mm dust continuum fluxes indicate the CO conversion factor in the center of Maffei 2 is lower than Galactic by factors of ~2-4. Gas morphology and the clear ``parallelogram'' in the Position-Velocity diagram shows that molecular gas orbits within the potential of a nuclear (~220 pc) bar. The nuclear bar is distinct from the bar that governs the large scale morphology of Maffei 2. Giant molecular clouds in the nucleus are nonspherical and have large linewidths. Dense gas and star formation are concentrated at the sites of the x_1-x_2 orbit intersections of the nuclear bar, suggesting that the starburst is dynamically triggered.Comment: 50 pages, 14 figures, accepted for publication in Ap

Component release and mechanical properties of endodontic sealers following incorporation of antimicrobial agents

Root canal sealers with antimicrobial activity are highly beneficial; therefore, their antimicrobial properties could be improved by incorporation of antimicrobial agents. In the present study, the release of the quaternary ammonium compounds from endodontic sealers admixed with either benzalkonium chloride (BC) or cetylpyridinium chloride (CPC) at loadings of 2% wt was monitored. The effect of these additives on the compressive strengths and their release from the sealers was determined after 1 and 4 weeks. All of the materials studied were found to be capable of releasing antimicrobial additive in useful quantities. The release of CPC occurred to a statistically significant greater extent than BC for all materials. The addition of both BC and CPC generally decreased the compressive strength of all the endodontic sealers, with the exception of CPC in AH Plus, where the compressive strength was significantly increased. This suggests that, for these endodontic sealers, the antimicrobial additives alter the setting chemistry. AH Plus is an epoxy-based material cured with an amine, and in this case the increase in compressive strength with CPC is attributed to an enhanced cure reaction with this system. In all other cases, the additive inhibited the cure reaction to a greater or lesser extent

Measurement and analysis of needle penetration forces in industrial high-speed sewing machine

The industrial manufacturing of sewn products has always been one of the critical processes of the textile chain concerning quality assurance. Assuring the appropriate set-up and operation of all the machines, and thus the final seam quality, is a very complex task. Traditionally, this task is accomplished through empirical methods, with the machine setting and quality control relying on the skills of operators and technicians. This work presents an approach to a more knowledge-based and integrated process planning and control. A system was developed to measure and analyze the most important mechanical effects occurring during high-speed sewing. The paper will focus mainly on the measurement and evaluation of needle penetration and withdrawal force. After an overview of the system, the most important experimental results obtained in a series of experiments will be described

Impact of a sketch-based tutoring system at multiple universities

Large class sizes in engineering programs often prevent instructors from providing detailed and meaningful feedback to students on their homework problems. While the literature shows that frequent and immediate formative feedback has several benefits in terms of knowledge gain and academic motivation, several instructors struggle to provide any feedback. Motivated by this inability, a sketch-based virtual tutoring system, named Mechanix, has been developed and implemented. Mechanix lets the students to sketch their freebody diagram on a virtual interface and the process involved is very close to using a pencil and paper. The system provides real-time feedback on the accuracy of their Freebody diagrams and the solution to the problem. This paper reports the implementation of Mechanix at two large public universities in the United States - Georgia Institute of Technology and Texas State University. Mechanix is used to solve specific assignments from each school that involve the use of freebody diagrams. Pre- and post- concept inventories are used to measure the improvements in the conceptual understanding of the students. The results show that students who solve their homework using Mechanix outperform their peers who do not in one school, whereas the results are similar across the two groups in the second school. The evaluation of the concept inventories shows that the students who used Mechanix has the same level of improvement in their conceptual knowledge compared to the control group

Biogenesis of mitochondrial porin

We review here the present knowledge about the pathway of import and assembly of porin into mitochondria and compare it to those of other mitochondrial proteins. Porin, like all outer mitochondrial membrane proteins studied so far is made as a precursor without a cleavble lsquosignalrsquo sequence; thus targeting information must reside in the mature sequence. At least part of this information appears to be located at the amino-terminal end of the molecule. Transport into mitochondria can occur post-translationally. In a first step, the porin precursor is specifically recognized on the mitochondrial surface by a protease sensitive receptor. In a second step, porin precursor inserts partially into the outer membrane. This step is mediated by a component of the import machinery common to the import pathways of precursor proteins destined for other mitochondrial subcompartments. Finally, porin is assembled to produce the functional oligomeric form of an integral membrane protein wich is characterized by its extreme protease resistance

Robin conditions on the Euclidean ball

Techniques are presented for calculating directly the scalar functional determinant on the Euclidean d-ball. General formulae are given for Dirichlet and Robin boundary conditions. The method involves a large mass asymptotic limit which is carried out in detail for d=2 and d=4 incidentally producing some specific summations and identities. Extensive use is made of the Watson-Kober summation formula.Comment: 36p,JyTex, misprints corrected and a section on the massive case adde

Association Between Chronic Hepatitis C Virus Infection and Myocardial Infarction Among People Living With HIV in the United States.

Hepatitis C virus (HCV) infection is common among people living with human immunodeficiency virus (PLWH). Extrahepatic manifestations of HCV, including myocardial infarction (MI), are a topic of active research. MI is classified into types, predominantly atheroembolic type 1 MI (T1MI) and supply-demand mismatch type 2 MI (T2MI). We examined the association between HCV and MI among patients in the Centers for AIDS Research (CFAR) Network of Integrated Clinical Systems, a US multicenter clinical cohort of PLWH. MIs were centrally adjudicated and categorized by type using the Third Universal Definition of Myocardial Infarction. We estimated the association between chronic HCV (RNA+) and time to MI while adjusting for demographic characteristics, cardiovascular risk factors, clinical characteristics, and history of injecting drug use. Among 23,407 PLWH aged ≥18 years, there were 336 T1MIs and 330 T2MIs during a median of 4.7 years of follow-up between 1998 and 2016. HCV was associated with a 46% greater risk of T2MI (adjusted hazard ratio (aHR) = 1.46, 95% confidence interval (CI): 1.09, 1.97) but not T1MI (aHR = 0.87, 95% CI: 0.58, 1.29). In an exploratory cause-specific analysis of T2MI, HCV was associated with a 2-fold greater risk of T2MI attributed to sepsis (aHR = 2.01, 95% CI: 1.25, 3.24). Extrahepatic manifestations of HCV in this high-risk population are an important area for continued research

UV Spectropolarimetry of Narrow-line Radio Galaxies

We present the results of UV spectropolarimetry (2000 - 3000A) and far-UV spectroscopy (1500 - 2000A) of two low-redshift narrow-line radio galaxies (NLRGs) taken with the Faint Object Spectrograph onboard the Hubble Space Telescope (HST). Spectropolarimetry of several NLRGs has shown that, by the presence of broad permitted lines in polarized flux spectrum, they have hidden quasars seen through scattered light. Imaging polarimetry has shown that NLRGs including our targets often have large scattering regions of a few kpc to >~10 kpc scale. This has posed a problem about the nature of the scatterers in these radio galaxies. Their polarized continuum has the spectral index similar to or no bluer than that of quasars, which favors electrons as the dominant scattering particles. The large scattering region size, however, favors dust scattering, because of its higher scattering efficiency compared to electrons. In this paper, we investigate the polarized flux spectrum over a wide wavelength range, combining our UV data with previous optical/infrared polarimetry data. We infer that the scattering would be often caused by opaque dust clouds in the NLRGs and this would be a part of the reason for the apparently grey scattering. In the high-redshift radio galaxies, these opaque clouds could be the proto-galactic subunits inferred to be seen in the HST images. However, we still cannot rule out the possibility of electron scattering, which could imply the existence of a large gas mass surrounding these radio galaxies.Comment: 25 pages, 21 figures. To appear in Ap